JP2000111862A - Projection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid the increase of back focus and to easily and surely compensate astigmatism generated by a dichroic mirror by increasing the amount of the astigmatism of one video light beam or setting the thickness and/or the inclination of the dichroic mirror so that the amount of the astigmatism of one video light beam and that of the other video light beam may coincide with each other. SOLUTION: In this projection type display device, the 1st and the 2nd dichroic mirrors 22 and 23 are arranged so that the astigmatism may be generated in the respective video light beams LG, LR and LB, and the generated amount of the astigmatism is made equal among the respective video light beams LG, LR and LB. At such a time, since the astigmatism of synthesized video light beam is compensated altogether by a compensation lens arranged on the emitting surface side of a polarizing beam splitter after easily and accurately compensating so that the astigmatism may be equal by generating the astigmatism by a plate glass in the video light beams LG, LR and LB, the astigmatism is easily and accurately compensated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type display device, and can be applied to, for example, a projector device for projecting image light spatially modulated by a reflection type liquid crystal panel onto a screen. The present invention increases the amount of astigmatism of one image light so that the amount of astigmatism of one image light coincides with the amount of astigmatism of another image light. By setting the thickness and / or inclination of the dichroic mirror so that the amount of astigmatism coincides with the amount of astigmatism of the other image light, an increase in back focus is effectively avoided, and astigmatism generated by the dichroic mirror Can be easily and reliably corrected.

[0002]

2. Description of the Related Art Conventionally, in a projection type display device, spatially modulated image light is generated using a reflection type liquid crystal panel, and the image light is projected on a screen so that a desired color image can be formed. What was done is proposed.

In such a projection display device, a projector device for displaying a high-luminance, high-resolution image uses three reflective liquid crystal panels for red, blue, and green. In a projection display device using such three reflective liquid crystal panels, illumination light obtained from a light source is decomposed into red, blue, and green illumination light and supplied to the corresponding reflective liquid crystal panels, respectively. As means for synthesizing red, blue and green image light obtained from each reflection type liquid crystal panel, a device using a dichroic mirror and a device using a dichroic prism have been proposed.

In a projection type display device using a dichroic prism, a light source 2 is composed of, for example, a discharge lamp 3 and a reflector 4, as shown in FIG. . The projection display device 1 guides the illumination light emitted from the light source to the cold mirror 5 via a predetermined optical system, and the cold mirror 5 bends the optical path of the illumination light by an angle of substantially 90 degrees.

The polarizing plate 6 selectively transmits, for example, only the S-polarized light component of the illumination light emitted from the cold mirror 5, and the subsequent polarizing beam splitter 7 illuminates with the S-polarized light emitted from the polarizing plate 6. The light selectively reflects and emits the light, and selectively transmits the P-polarized light component of the synthesized image light incident along the optical path of the illumination light due to the S-polarized light, and transmits the S-polarized light component to the light source 2 side. To reflect.

The dichroic prism 8 is formed by bonding three prisms each having a predetermined shape, and is arranged such that each bonding surface crosses an optical path emitted from the polarization beam splitter 7. Dichroic prism 8
A dielectric film having a predetermined thickness is repeatedly formed on a bonding surface traversing the optical path, and blue and red illumination light of the illumination light emitted from the polarizing beam splitter 7 is sequentially and selectively applied to each bonding surface. reflect. As a result, the dichroic prism 8 decomposes the illumination light emitted from the polarization beam splitter 7 into blue, red, and green illumination light, and reflects the blue, red, and green reflective light disposed on the bottom surface of each prism. It is supplied to the liquid crystal panels 9B, 9R, 9G.

[0007] Each of the reflective liquid crystal panels 9B, 9R, 9G is
Each pixel is driven by a corresponding color signal, and for each pixel,
The polarization plane of the incident illumination light of S-polarized light is rotated and reflected, thereby emitting image light whose polarization plane changes according to each color signal.

[0008] The dichroic prism 8 is, as opposed to the case of the illumination light, in this manner, each of the reflective liquid crystal panels 9B,
The red, blue and green image lights obtained from 9R and 9G are combined to generate a combined image light, and the combined image light is emitted to the polarization beam splitter 7. As a result, the combined image light is
The combined light of the P-polarized light and the S-polarized light according to each color signal is emitted to the polarization beam splitter 7 by tracing the optical path of the illumination light in reverse, and only the P-polarized light component is
Is transmitted to the projection lens 10.

The projection lens 10 transmits the combined image light transmitted through the polarizing beam splitter 7 in this manner to the screen 1.
1 so that the reflective liquid crystal panels 9B, 9R,
A color image formed by enlarging and projecting a video generated in 9G onto a screen is displayed.

Although the system using the dichroic prism 8 has an advantage that the optical system can be made compact, it is necessary to use a special glass having a very small photoelastic coefficient for the dichroic prism 8, thereby using the illumination light efficiently. Is low.

FIG. 9 is a schematic diagram showing a projection type display device using a dichroic mirror. In FIG. 9, the same components as those in FIG. 8 are denoted by the corresponding reference numerals, and redundant description will be omitted.

That is, in the projection type display device 16, dichroic mirrors 17 and 18 are arranged in place of the dichroic prism 8. Here, the dichroic mirrors 17 and 18 are formed by laminating a transparent dielectric film having a predetermined thickness on the surface of an optical glass, which is a transparent plate member, to form reflection surfaces MB and MR. And selectively reflects the blue and red image light from the illumination light emitted from the polarizing beam splitter 7, and selectively transmits the remaining components. This causes the dichroic mirrors 17 and 18 to move the polarization beam splitter 7
The emitted illumination light is decomposed into blue, red, and green illumination light, and emitted toward the corresponding reflective liquid crystal panels 9B, 9R, and 9G. Each of the reflective liquid crystal panels 9B, 9R, 9
The blue, red, and green image lights emitted from G are combined and emitted to the polarization beam splitter 7.

In the projection display device 16, FIG.
0, the dichroic mirrors 17 and 18 which are transparent plate-like members are obliquely arranged on the optical path, so that, in the transmitted light, FIG.
The optical path length differs between the direction perpendicular to the plane of the drawing and the direction parallel to the plane of the drawing, thereby causing astigmatism.

For this reason, in the projection type display device 16, the dichroic mirror 17, which is closest to the polarizing beam splitter 7, has a reflecting surface MB whose polarizing surface MB is
It is arranged so as to face the side, so that astigmatism does not occur for blue image light. The subsequent dichroic mirror 18 has a reflecting surface MR whose polarization beam splitter 7
It is arranged so as to face the side, and the generation amount of astigmatism is reduced for the red image light. Further, the projection display device 16
Are arranged on the optical paths of the red and green image light correction lenses 19R and 19G such as cylindrical lenses and toric lenses having different curvatures in the longitudinal section and the transverse section, respectively. The aberration is corrected.

Such dichroic mirrors 17, 1
In the projection type display device 16 using the optical system 8, an optical system can be configured without using a glass material as in the case of using a dichroic prism, and illumination light can be used more efficiently.

[0016]

However, in the projection type display device 16 using the dichroic mirror, the distance from the reflection type liquid crystal panels 9B, 9R, 9G to the projection lens 10 is increased by the amount of disposing the correction lenses 19R and 19G. That is, there is a problem that the back focus of the projection lens 10 becomes long. When the back focus of the projection lens 10 becomes longer as described above, the projection lens 10 of the projection display device 16 becomes larger accordingly.

Further, in the projection type display device 16 using the dichroic mirror, there is a problem that astigmatism cannot be easily and reliably corrected. That is, this type of correction lens has a drawback that it is difficult to make it. In the projection display device 16, since the amount of astigmatism is different for each color, the correction lens is made to correspond to the amount of astigmatism of each color. make,
Need to be placed. If the astigmatism correction amount cannot be set correctly, the registration accuracy of the projection display apparatus will be degraded accordingly. A similar problem occurs when the correction lens is not mechanically fixed at a correct position. For example, when the correction lens is slightly tilted, trapezoidal distortion occurs in the projected screen image, and the registration is reduced accordingly.

The present invention has been made in consideration of the above points, and a projection type display device capable of simply and reliably correcting astigmatism generated by a dichroic mirror by effectively avoiding an increase in back focus. It is intended to propose.

[0019]

In order to solve the above-mentioned problems, the present invention provides a method for astigmatism generated in a second image light so as to be equal to the amount of astigmatism generated in a first image light. Astigmatism correcting means for increasing the amount of generated aberration is provided, and the astigmatism correcting means is a transparent flat plate member arranged on the optical path of the second image light with an inclination substantially equal to that of the dichroic mirror. To

Also, the second dichroic mirror is adjusted so that the amount of astigmatism generated in the first image light becomes equal to the amount of astigmatism generated in the second or third image light. To set the thickness and / or inclination of the first dichroic mirror.

It is preferable to provide astigmatism correction means for increasing the amount of astigmatism generated in the second image light so as to be equal to the amount of astigmatism generated in the first image light. For example, the amount of astigmatism generated in one image light and the amount of astigmatism in another image light can be made equal. As a result, astigmatism can be corrected on the optical path of the combined image light, which is a common optical path, as needed, and the astigmatism can be corrected simply and reliably. At this time, the astigmatism correction means makes the second
If it is a transparent flat plate member arranged on the optical path of the image light,
It is possible to correct the astigmatism with high accuracy while keeping the increase in the back focus to the minimum necessary.

Also, the second dichroic mirror is adjusted so that the amount of astigmatism generated in the first image light becomes equal to the amount of astigmatism generated in the second or third image light. Even if the thickness and / or inclination of the first dichroic mirror is set, the amount of astigmatism generated can be easily and reliably set to be equal, thereby effectively preventing an increase in back focus and using the dichroic mirror. Can be easily and reliably corrected.

[0023]

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

(1) First Embodiment (1-1) Configuration of First Embodiment FIG. 2 is a schematic diagram showing a projection type display device according to a first embodiment of the present invention. is there. In the projection type display device 21, the same components as those of the projection type display devices 1 and 16 described above with reference to FIGS. 8 to 10 are denoted by the corresponding reference numerals, and redundant description will be omitted.

In the projection display device 21, the first and second dichroic mirrors 22 and 23 separate the illumination light emitted from the polarizing beam splitter 7 into blue, red, and green illumination light. The red and green image lights are combined, and the combined image light is emitted to the polarization beam splitter 7. In the projection display device 21, a correction lens 24 for correcting astigmatism is arranged on the exit surface of the polarization beam splitter 7 on the optical path of the synthesized image light. Here, the correction lens 24 is constituted by a cylindrical lens or a toric lens.

Here, as shown in FIG. 1, the first and second dichroic mirrors 22 and 23 are shown together with peripheral components, so that the first and second dichroic mirrors 22 and 23 are shown.
Reference numeral 3 is arranged in parallel to the optical axis of the illumination light at an angle of 45 degrees.

The first dichroic mirror 22 is formed by laminating a transparent dielectric film having a predetermined thickness on optical glass having a refractive index n with a thickness of 2T. The first dichroic mirror 22 selectively reflects blue illumination light by the dielectric film, and selectively transmits remaining red and green illumination light. The first dichroic mirror 22 is arranged such that the reflection surface MB of the dielectric film is on the opposite side to the polarization beam splitter 7, whereby the light is reflected by the reflection surface MB and enters the polarization beam splitter 7. Image light L
B passes through the optical glass of the first dichroic mirror 22, enters, and exits.

On the other hand, the second dichroic mirror 23 is composed of two optical glasses 23 having a refractive index n according to the plate thickness T.
The reflective surface MR is formed by laminating a transparent dielectric film having a predetermined thickness on the bonded surface. Thereby, the second dichroic mirror 23
Is the dichroic mirror 18 described above with reference to FIG.
In addition to the configuration described above, a flat glass having a thickness T is integrally disposed on the optical path on the reflection surface MR side. Second
Dichroic mirror 23 selectively reflects red illumination light and selectively transmits remaining green illumination light.
Further, in the second dichroic mirror 23, the image light LR reflected on the reflection surface MR of the dielectric film and entering the polarization beam splitter 7 is transmitted through the optical glass 23a of the second dichroic mirror 23 and enters. , And are emitted. Further, the green image light LG is sequentially transmitted through the optical glasses 23 a and 23 b having the plate thickness T and emitted to the polarization beam splitter 7.

As a result, in the projection display device 21, the first and second dichroic mirrors 22 and 23 in which the respective image lights LG, LR and LB are held at the same inclination.
Propagating through the glass plate constituting the polarizing beam splitter 7
Then, at this time, in a plane parallel to the plane of FIG. 2 and in a plane perpendicular to the plane of FIG. 2, the optical path length propagating through the plate glass is made equal for each image light.

Thus, in the projection display device 21, the first and second dichroic mirrors 22 and 23 are arranged so that astigmatism is generated in each of the image lights LG, LR and LB. Is made equal for each of the image lights LG, LR, and LB.

(1-2) Operation of the First Embodiment In the above configuration, the illumination light emitted from the light source 2 (FIG. 2) is bent 90 degrees in the cold mirror 5 in the optical path of the components other than the infrared rays. The S-polarized component selectively passes through the polarizing plate 6 and enters the polarizing beam splitter 7. Here, the illumination light has a first dichroic mirror 22 whose S-polarized component is selectively reflected.
To the first dichroic mirror 2
2, the blue illumination light is selectively reflected and emitted toward the reflective liquid crystal panel 9B for green, and the remaining green and red illumination light passes through the first dichroic mirror 22 and continues to the second dichroic. The light enters the mirror 23.

The illumination light incident on the second dichroic mirror 23 is decomposed into red illumination light and green illumination light, and the red and green illumination lights are reflected and transmitted by the second dichroic mirror 23, respectively. Red reflective liquid crystal panel 9R and green reflective liquid crystal panel 9G
And emitted. Thus, illumination light having a wavelength corresponding to each of the blue, red, and green reflective liquid crystal panels 9B, 9R, and 9G is supplied, and each of the reflective liquid crystal panels 9B, 9
In R and 9G, the plane of polarization is rotated by the corresponding color signal, and blue, red, and green image light is generated by P-polarized light and S-polarized light.

The blue color due to such P-polarized light and S-polarized light,
The red and green image light is reflected by each of the reflective liquid crystal panels 9B and 9B.
The light path of the illuminating light incident on R and 9G is traced in the opposite direction and combined by the first and second dichroic mirrors 22 and 23. Of the resultant combined image light, the P-polarized light component passes through the polarization beam splitter 7. Then, the light is projected on the screen 11 by the projection lens 10. As a result, the blue, red, and green images created by the reflective liquid crystal panels 9B, 9R, and 9G are enlarged and projected on the screen 11, and a color display image is formed.

In the image light projected onto the screen 11 in this manner (FIG. 2), the image light LG emitted from the green reflective liquid crystal panel 9G is arranged at an angle of 45 degrees with respect to the optical axis. Optical glass 23b by 2T,
After passing through 23a, the light passes through the optical glass of the first dichroic mirror 22 having a thickness of 2T, which is similarly arranged at an angle, and is emitted to the polarization beam splitter 7.
As a result, the image light LG is transmitted through a medium having a thickness of 4T having a refractive index n arranged at an angle of 45 degrees and is emitted to the polarization beam splitter 7.

On the other hand, the red reflective liquid crystal panel 9R
The image light LR emitted from the optical glass 23a is transmitted through the optical glass 23a having a thickness T disposed at an angle of 45 degrees with respect to the optical axis, is reflected by the reflection surface MR, and is then again reflected by the optical glass 23 having the thickness T. 23a, and subsequently a first dichroic mirror 22 of thickness 2T, which is likewise arranged obliquely
Is transmitted to the polarizing beam splitter 7 through the optical glass. As a result, even in this image light LR,
The light is transmitted through a medium having a thickness of 4T having a refractive index n arranged at an angle of 45 degrees and emitted to the polarization beam splitter 7.

On the other hand, a blue reflective liquid crystal panel 9B
The video light LB emitted from the optical glass of the first dichroic mirror 22 having a thickness of 2T disposed at an angle of 45 degrees with respect to the optical axis, is reflected by the reflection surface MB, and then again. The light passes through the optical glass of the first dichroic mirror 22 having a thickness of 2T and is emitted to the polarization beam splitter 7. As a result, even in the case of this image light LB, after all, it passes through a medium having a thickness of 4T with a refractive index n arranged at an angle of 45 degrees and is emitted to the polarization beam splitter 7.

With these, these image lights LB, LR,
In LG, after astigmatism occurs by an equal amount,
The astigmatism of the combined image light is corrected by the correction lens 24 disposed on the exit surface side of the polarization beam splitter 7.

At this time, in the image lights LB, LR, and LG, astigmatism is generated by the plate glass, so that the astigmatism is corrected simply and accurately so that the astigmatism becomes equal. Astigmatism is corrected, so that astigmatism can be corrected easily and accurately, and deterioration of registration can be prevented.

Further, since the amount of astigmatism can be set to be the same simply by using a glass plate, interference with other optical elements can be effectively avoided, thereby preventing an increase in the back focus of the projection lens. Accordingly, the size of the projection lens can be reduced accordingly.

According to the above configuration, the dichroic mirror 23 is formed by sandwiching the reflection surface MR between the optical glasses 23a and 23b, and the optical glass 23a is a flat glass.
Is arranged on the optical path on the side of the reflecting surface MR, the amount of astigmatism in the blue image light is reduced with respect to the green image light transmitted through the second dichroic mirror 23. It is possible to simply and accurately increase the amount of astigmatism of the blue image light so as to be equal.

The dichroic mirror 22 is arranged so that the reflection surface MB is on the second dichroic mirror 23 side, and the amount of astigmatism generated in the blue image light is generated in the green and red image light. By setting the thickness of the first dichroic mirror 22 so as to be equal to the amount of astigmatism, the astigmatism of three image lights emitted from the dichroic mirror 22 can be generated simply and accurately. The amounts can be set equal.

As a result, astigmatism is collectively corrected by one correction lens 24 disposed on a common optical path of these three image lights, thereby preventing registration deterioration and correcting astigmatism with high accuracy. be able to. Also, by simply selecting the thickness of the dichroic mirror 22,
Further, by simply arranging the flat glass 23a on the optical path of the red image light, the amount of astigmatism can be set to be equal.
It is possible to prevent an increase in back focus, thereby preventing an increase in the size of the projection lens 10.

In particular, in this embodiment, the optical glass 23a for providing astigmatism to the blue image light is integrated with the dichroic mirror 23 with the reflecting surface MR sandwiched between the optical glasses 23a and 23b. Accordingly, the amount of astigmatism can be set to be equal with high accuracy with a simple configuration as a whole, and the overall shape can be further reduced in size.

(2) Second Embodiment FIG. 3 is a schematic diagram showing a projection display apparatus according to a second embodiment of the present invention in comparison with FIG. The projection display device according to the second embodiment differs from the projection display device according to the first embodiment except that the configuration of a first dichroic mirror 27 that separates blue illumination light is different. Since the configuration is the same as that of 21, the corresponding components are denoted by the same reference numerals, and redundant description will be omitted.

Here, the dichroic mirror 27 is
In parallel with the dichroic mirror 23, the reflecting surface MB is arranged facing the second dichroic mirror 23 side. Further, the reflection surface MB of the dichroic mirror 27 is formed on the optical glass having the same thickness T and refractive index n as the optical glass of the second dichroic mirror 23.

As a result, in this projection type display device, the first dichroic mirror 27 can be formed using the same optical components as the second dichroic mirror 23, and the reflection surface MB is correspondingly moved to the dichroic mirror 23 side. Although increasing astigmatism for blue image light toward, but also for red and green image light,
Although the amount of astigmatism is the same, the amount of astigmatism in the blue image light is different from those of the red and green image light.

Thus, for a blue image,
Originally, it has the feature of low resolution with the naked eye. Thus, as in this embodiment, even if the amount of astigmatism is set to be different only for the blue image light compared to the other image light, the astigmatism is small in a small range. Up,
It is possible to prevent the deterioration of the image due to the blue astigmatism from being perceived.

On the other hand, if the plate thickness of the dichroic mirror 27 is reduced, the back focus can be reduced accordingly, and the projection lens 10 can be reduced in size. The dichroic mirror 27 also transmits red and green image light. If the thickness of the dichroic mirror 27 is reduced, the overall amount of astigmatism is reduced. Correction of aberrations is also facilitated.

According to the configuration shown in FIG. 3, the thickness of the first dichroic mirror 27 through which each image light is transmitted is reduced, and the amount of astigmatism of the blue image light is reduced with respect to other image light. Even if they are different, astigmatism can be simply and reliably corrected with practically sufficient characteristics. Further, the configuration of the entire apparatus can be simplified.

(3) Third Embodiment FIG. 4 is a schematic diagram showing a projection display apparatus according to a third embodiment of the present invention in comparison with FIG. Also in the projection display device according to the third embodiment, the same components as those of the projection display device 21 according to the first embodiment are denoted by the same reference numerals for the corresponding components, and overlapped. Description is omitted.

In this projection type display device, the first dichroic mirror 28 reflects the red illumination light,
In the dichroic mirror 29, reflection surfaces MR and MB are formed so as to reflect blue image light. In the projection type display device, reflection type liquid crystal panels 9R, 9B and 9G are arranged corresponding to the configurations of the dichroic mirrors 28 and 29, respectively.

The dichroic mirrors 28 and 29 have reflection surfaces MR and MB formed on a plate glass having the same plate thickness T and the same refractive index n, and are arranged with the same inclination. Thus, in the projection display device, the first and second dichroic mirrors 28 and 29 can be created using the same optical components. The red and green image lights have the same amount of astigmatism, but the red and green image light have a different amount of astigmatism in the blue image light.

According to the configuration shown in FIG. 4, the arrangement of the reflection type liquid crystal panel is changed with respect to the projection type display device according to the second embodiment, and the second dichroic mirror 2 is provided.
Even if 9 is configured in the same way as the first dichroic mirror 28, the same effect as in the second embodiment can be obtained. Further, at this time, the configuration of the second dichroic mirror 29 can be simplified, and the overall configuration can be further simplified accordingly.

(4) Fourth Embodiment FIG. 5 is a schematic diagram showing a projection display apparatus according to a fourth embodiment of the present invention in comparison with FIG. Also in the projection display device according to the fourth embodiment, the same components as those of the projection display device 21 according to the first embodiment are denoted by the same reference numerals for the corresponding components, and overlapped. Description is omitted.

In this projection type display device, the first dichroic mirror 30 reflects the red illumination light,
In the dichroic mirror 31, the reflection surfaces MR and MG are respectively formed so as to reflect the green image light. In the projection type display device, reflection type liquid crystal panels 9R, 9G and 9B are arranged corresponding to the configurations of the dichroic mirrors 30 and 31, respectively.

The dichroic mirrors 30 and 31 have the same refractive index n, and the reflecting surfaces MR and MG are formed on the plate glass having the plate thicknesses 2T and T, respectively, and are arranged with the same inclination. As a result, in this projection display device, the amount of astigmatism is the same for red and green image light, but the amount of astigmatism for blue image light is different from these red and green image light. It has been made like that.

As shown in FIG. 5, a reflective liquid crystal panel for blue is disposed on the rearmost side, and correction is made so that the astigmatism amounts are equal for only the image light from the other reflective liquid crystal panels. The same effects as those of the second embodiment can be obtained.

(5) Fifth Embodiment FIG. 6 is a schematic diagram showing a projection display apparatus according to a fifth embodiment of the present invention in comparison with FIG. Also in the projection display device according to the fifth embodiment, the same components as those of the projection display device 21 according to the first embodiment are denoted by the same reference numerals for the corresponding components, and overlapped. Description is omitted.

In this projection type display device, the above-described first dichroic mirror 23 is applied to the second dichroic mirror, so that the astigmatism amounts of the green and red image lights are matched. It has been done.

On the other hand, in the first dichroic mirror 32, the reflection surface MB is formed on the same optical glass as the optical glass used for the second dichroic mirror 23, and the inclination is equal to that of the second dichroic mirror 23. , The reflection surface MB is arranged so as to face the dichroic mirror 23 side.

In the projection type display device, a flat glass 33 is disposed between the first dichroic mirror 32 and the reflection type liquid crystal panel 9B at an angle of 45 degrees with respect to the optical axis of the blue image light LB. Is done. Here the flat glass 3
3 is made of the same optical glass as the optical glass used for the second dichroic mirror 23, whereby the blue image light LB is adjusted so that the amounts of astigmatism coincide with the red and green image lights LR and LG. Increases the amount of astigmatism.

Further, as shown by the arrow A, the flat glass 33 is configured so that the inclination with respect to the optical axis can be finely adjusted by a predetermined adjusting mechanism.
The amount of astigmatism given to B can be finely adjusted.

As shown in FIG. 6, the same effect as in the first embodiment can be obtained even if the flat glass is separately arranged to increase the amount of astigmatism of the blue image light.

Further, at this time, the amount of astigmatism given to the blue image light LB can be finely adjusted by finely adjusting the inclination of the flat glass, so that the aberrations can be more precisely matched as compared with the first embodiment. This makes it possible to improve the imaging performance of the entire optical system.

(6) Other Embodiments In the above-described embodiment, the case where the astigmatism amount is increased by variously changing the thickness of the flat glass having the same refractive index has been described. The present invention is not limited to this, and the astigmatism amount may be increased by an appropriate amount depending on the refractive index and the inclination instead of or in addition to the thickness.

In each of the above embodiments, the case where the correction lens is disposed on the exit surface side of the polarizing beam splitter 7 has been described. However, the present invention is not limited to this, and the point is that the common The astigmatism can be corrected with high accuracy by arranging a correction lens on the optical path of the combined image light on the optical path. For example, as shown in FIG. ), When disposed on the incident surface side of the polarizing beam splitter 7 (denoted by reference numeral C), when disposed on the exit surface or inside of the projection lens 10 (denoted by reference characters D and E), and a plurality of correction lenses. The present invention can be widely applied to a case where these lenses are arranged at a plurality of positions shown in FIG.

Further, in the above-described embodiment, the case where the astigmatism is corrected by the correction lens has been described. However, the present invention is not limited to this. The aberration amounts may simply be matched.

[0068]

As described above, according to the present invention, the amount of astigmatism of one image light is increased so that the amount of astigmatism of one image light matches the amount of astigmatism of another image light. By letting
Alternatively, by setting the thickness and / or inclination of the dichroic mirror so that the amount of astigmatism of one image light coincides with the amount of astigmatism of another image light, the dichroic can be effectively avoided from increasing the back focus. Astigmatism generated by using a mirror can be easily and reliably corrected.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a projection display device according to a first embodiment of the present invention in a partially enlarged manner.

FIG. 2 is a schematic diagram illustrating the entire configuration of FIG. 1;

FIG. 3 is a schematic diagram illustrating a projection display device according to a second embodiment of the present invention in a partially enlarged manner in comparison with FIG.

FIG. 4 is a schematic diagram showing a projection display device according to a third embodiment of the present invention in a partially enlarged manner in comparison with FIG. 1;

FIG. 5 is a schematic diagram showing a projection display device according to a fourth embodiment of the present invention in a partially enlarged manner in comparison with FIG. 1;

FIG. 6 is a schematic diagram showing a projection display device according to a fifth embodiment of the present invention in a partially enlarged manner in comparison with FIG. 1;

FIG. 7 is a schematic diagram illustrating a projection display device according to another embodiment in comparison with FIG.

FIG. 8 is a schematic diagram illustrating a projection display device using a dichroic prism.

FIG. 9 is a schematic diagram illustrating a projection display device using a dichroic mirror.

FIG. 10 is a schematic diagram showing a partially enlarged view of the projection display device of FIG. 9 in comparison with FIG. 1;

[Explanation of symbols]

1, 16, 21 ... Projection display device, 2 ... Light source, 7 ...
... polarizing beam splitters, 9B, 9G, 9R ... reflective liquid crystal panels, 10 ... projection lenses, 17, 18, 22,
23, 27, 28, 29, 30, 31, 32 ... dichroic mirror, 19R, 19G, 24 ... correction lens, 33 ... flat glass

Claims (5)

[Claims] 1. A first illumination device that spatially modulates and reflects a first illumination light having a predetermined polarization plane and emits a first image light obtained by rotating the polarization plane with respect to the polarization plane of the illumination light. A reflection-type image forming unit that spatially modulates and reflects the second illumination light having a predetermined polarization plane and emits second image light obtained by rotating the polarization plane with respect to the polarization plane of the illumination light. A second reflection-type image forming means, and the incident light is decomposed by a wavelength corresponding to the first and second reflection-type image forming means, and the first illumination light is converted into the first light by the first light.
And the second illumination light is output to the second reflection-type image forming means, and the first illumination light is output from the first and second reflection-type image formation means.
A dichroic mirror that combines the second image light and emits a combined image light, a projection optical system that projects the combined image light onto a predetermined projection target, and a predetermined polarization from illumination light emitted from a predetermined light source While emitting the surface component toward the dichroic mirror,
A polarizing beam splitter that emits the combined image light obtained from the dichroic mirror to the projection optical system, wherein the second image light is equal to an amount of astigmatism generated in the first image light. Has astigmatism correction means for increasing the amount of astigmatism generated in the image light, wherein the astigmatism correction means has an inclination substantially equal to that of the dichroic mirror on the optical path of the second image light. A projection type display device comprising a transparent plate member arranged. 2. The projection type display device according to claim 1, wherein the transparent flat plate member is adhered to the dichroic mirror and arranged together with the dichroic mirror. 3. The projection type display device according to claim 1, wherein said transparent flat plate member is held so that an angle with respect to said dichroic mirror can be finely adjusted. 4. The projection type display device according to claim 1, further comprising an astigmatism correcting means for correcting astigmatism of the first image light on an optical path of the synthesized image light. 5. A first illumination device that spatially modulates and reflects first illumination light having a predetermined polarization plane and emits first image light obtained by rotating the polarization plane with respect to the polarization plane of the illumination light. A reflection-type image forming unit that spatially modulates and reflects the second illumination light having a predetermined polarization plane and emits second image light obtained by rotating the polarization plane with respect to the polarization plane of the illumination light. 2) a reflection type image forming means, and spatially modulates and reflects the third illumination light having a predetermined polarization plane, and emits third image light obtained by rotating the polarization plane with respect to the polarization plane of the illumination light. A third reflection type image forming unit that separates incident light by a wavelength corresponding to the first reflection type image forming unit, and outputs the first illumination light to the first reflection type image forming unit. And emits the remaining components, and the first reflection-type image forming means obtains the first component. A first dichroic mirror that combines the image light with the second and third image light to emit a combined image light; and a second dichroic mirror that emits the remaining component illumination light emitted from the first dichroic mirror to the second dichroic mirror. And the second and third illumination light beams are separated by the wavelengths corresponding to the third and the third reflection type image forming means, and emitted to the second and the third reflection type image forming means, A second dichroic mirror that combines the second and third image lights obtained by the third reflection type image forming means and emits the combined light to the first dichroic mirror; and projects the combined image light onto a predetermined projection target. And a projection optical system that emits a predetermined polarization plane component from the illumination light emitted from a predetermined light source toward the first dichroic mirror and is obtained from the first dichroic mirror. A polarizing beam splitter that emits the combined image light to the projection optical system, wherein the first dichroic mirror is arranged such that a reflection surface faces the second dichroic mirror; The first dichroic mirror with respect to the second dichroic mirror so that the amount of astigmatism generated in the light is equal to the amount of astigmatism generated in the second or third video light. A projection type display device, wherein a thickness and / or an inclination of a mirror are set.