JPH1039415A - Projection lens device and projection image display device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the expansion and deformation of lens elements and to suppress reduction in focusing performance by making air outside a projection lens device flow into at least one of the spaces among the plural lens elements. SOLUTION: The outer lens barrel 6b of a lens barrel is provided with at least one first communicative hole 8 or more (a communicative window, when the entire length of a hole is short) through which the inside of the lens barrel and the outside of the projection lens device communicate with each other. Further, the inner lens barrel 6a of the lens barrel is fitted/held by plural fitting projection parts provided on the side of the inside surface of the outer lens barrel 6b and the groove part between the fitting projection parts is used as a second communicative hole 7. Therefore, low temperature air C (outdoor air) flowing in through the first communicative hole 8 is heated by a projection cathode-ray tube 1, to raise temp. and be lighter by cubical expansion, in the air between a nearest lens element 2a and a second nearest lens element 2b to the projection cathode-ray tube 1. Then, the air H being lighter because of a high temp. flows out through the second communicative hole 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type image display device such as a projection television and a projection lens device used for the same, and more particularly, to an expansion due to a rise in the temperature of a lens element when an image generation source or the like generates heat. The present invention relates to a configuration of a projection lens device that prevents a decrease in focus performance due to deformation.

[0002]

2. Description of the Related Art As a projection lens apparatus for enlarging and projecting an original image projected on an image source such as a projection type cathode ray tube onto a screen, a lens barrel has conventionally been composed of an outer barrel and an outer barrel.
An inner lens barrel housed inside the outer lens barrel and slidable in the lens optical axis direction without misalignment. The inner lens barrel is vertically split in the radial direction of the lens along the lens optical axis. An apparatus having a structure capable of being divided and having a groove for holding a plurality of lens elements with high precision at predetermined intervals on the inner surface has been used more often than ever. Such a projection lens device is disclosed, for example, in Japanese Utility Model Laid-Open Publication No. 2-51478.

[0003] An example of this conventional projection lens device will be described with reference to FIG. In FIG. 12, 8
Denotes a projection type cathode ray tube as an image generation source, 20 denotes a lens element, 6 denotes a lens barrel as a lens holding member, and 4 denotes a bracket as a connecting member. The lens barrel 6 has an inner barrel 6a and an outer barrel 6b.
Except for the lens element 20a closest to the projection type cathode ray tube 8,
The lens element 20 is held with high precision. At this time,
The inside of the lens barrel 6 has a substantially sealed structure.
For this reason, the temperature of the lens element 20 and the temperature of the air in the closed space between the lens elements are controlled by the projection type cathode ray tube 8.
Etc. gradually increase due to the propagation of heat generated in the above.
This heat is almost exclusively transferred to the outside of the projection lens device 17 from the outer surface of the bracket 4, the outer surface of the lens barrel 6, and the outer surface of the lens element of the lens element 20 farthest from the projection type cathode ray tube 8. The heat is dissipated.

[0004]

However, the material of the lens element is usually glass or plastic, and when the lens barrel 6 is made of synthetic resin from the viewpoint of moldability, the outer surfaces of these lenses are made of synthetic resin. Heat transfer coefficient from the metal surface is smaller than the heat transfer coefficient from the metal surface. For this reason, the amount of heat released outside the projection lens device 17 depends on the projection type cathode ray tube 8.
, And the temperature of the air in the closed space and the temperature of the lens element become even higher. As a result, the lens element heated to a high temperature causes expansion and deformation, which causes a problem that the focus performance of the projection lens device is significantly reduced.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems in the prior art projection lens apparatus, and to prevent the lens element from expanding and deforming even when heat is generated from an image source or the like, thereby improving the focus performance. It is an object of the present invention to provide a projection lens device that suppresses a decrease and a projection-type image display device using the same.

[0006]

In order to achieve the above object, in the projection lens device according to the present invention, air outside the projection lens device is formed by the plurality of lens elements and the lens element holding member. At least one of the spaces between the plurality of lens elements is circulated. Then, the air outside the projection lens device is circulated through at least one communication hole or communication window communicating from the space between the lens elements to the outside of the projection lens device.

Further, for at least one space among the spaces between the lens elements, the communication hole or the communication window is located at at least two level positions with respect to a horizontal plane in a use state of the projection lens device. It shall be a configuration arranged separately or continuously. At this time, the communication hole or communication window at a low position functions as an air inlet, and the communication hole or communication window at a high position functions as an air outlet.

In arranging the communication hole or the communication window, one of the following methods (1) to (4) is used, or these methods are used in combination.

(1) A lens element holding member that holds at least one lens element and covers a space between the lens elements, and at least near a connection point between the lens holding member and a connection member that connects the lens holding member to an image generation source. A communication hole is provided as a space surrounded by the lens element holding member and the connection member. In this case, the volume of the space may be restricted by the size of the protrusion provided on the lens element holding member or the size of the protrusion provided on the connection member.

(2) A communication hole or a communication window is provided in the lens element holding member itself.

(3) A lens element holding member is constituted by a first holding member for holding at least one lens element and a second holding member for fitting and holding the first holding member. A communication hole or a communication window is provided between the one holding member and the second holding member. In this case, at least one groove provided in a concave shape on the inner side surface of the second holding member may function as a communication hole.

(4) A communication hole is provided near the outer edge of the lens element.

When the communication hole is provided by the above-described method, the target space is a lens element which is disposed closest to the image generation source among a plurality of lens elements, and a second space is provided for the image generation source. Is preferably a space between the lens element and the lens element disposed close to the lens element.

The communication hole or the communication window is provided to ventilate heated air in the space between the lens elements with air outside the projection lens device. In this case,
Foreign matter such as dust may enter from the communication hole or the communication window and adhere to the lens element, or external light may enter the inside of the projection lens device to lower the image contrast performance of the projection lens device. Further, when this projection lens device is used in a projection type image display device, the image contrast performance of the projection type image display device may be reduced due to light leakage from inside the projection lens device.

In this case, in the above-mentioned projection lens device, a dustproof member, for example, a flange-like member is disposed at the opening of the communication hole to the outside of the projection lens device so as not to impair the air permeability. . Alternatively, the shape of the communication hole itself is a bent or curved shape, or a torsionally bent shape.

In the projection lens device according to the present invention, the communication hole may be a low-temperature air (outside air) in a space between the lens elements provided with the communication hole or the communication window.
Acts as an air inlet for taking in air and an air outlet for discharging air heated to a high temperature by heat. As a result, the efficiency of heat dissipation from the lens element is increased by the convection of air, and the temperature of the lens element is suppressed from rising, so that the expansion and deformation due to the temperature increase are suppressed. As a result, the lens performance, especially the focusing performance Is prevented from decreasing.

When a projection type cathode ray tube is used as an image generating source, the projection type cathode ray tube becomes a heat source, so that a space between a lens element closest to the projection type cathode ray tube and a lens element closest to the second is used. When the communication hole is provided, the effect of the above operation is remarkable. Further, since the air has a property that when heated, the specific gravity decreases and flows upward, the air outlet and the air outlet are located at a position higher than the position of the communication hole or the communication window serving as the air inlet with respect to a certain horizontal plane. If the height of the position of the communication hole or the communication window is set to be high, the above-described operation has a practically sufficient effect.

On the other hand, when a dust-proof member is provided in the opening of the communication hole to the outside of the projection lens device, or the shape of the communication hole itself is bent or curved, or a torsionally bent shape. In this case, invasion of foreign matter or light into the projection lens device and light leakage from inside the projection lens device are prevented. As a result, the contrast performance of the projection lens device itself does not decrease,
Further, the image contrast when this projection lens device is used in a projection type image display device does not decrease.

[0019]

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

FIG. 1 is a sectional view showing a main part of an embodiment of a projection lens apparatus according to the present invention, wherein 1 is a projection type cathode ray tube as an image generating source, 2 is a lens element, and 6 is a lens holding member. The lens barrel 4 is a bracket as a connection member. The lens barrel 6 has an inner barrel 6a and an outer barrel 6b that slidably holds the inner barrel 6a. A lens element closest to the projection type cathode ray tube 1 is provided in the inner barrel 6a. 2
Except for a, the lens element 2 is held with high precision. The lens element 2a and the projection type cathode ray tube 1 are both pressed and held on the bracket 4 by an appropriate fixing means via an elastic body 3 and are surrounded by the lens element 2a, the projection type cathode ray tube 1 and the bracket 4. Inside, a transparent cooling liquid 5 is sealed. The lens element 2a closest to the projection type cathode ray tube 1 is, for example, a meniscus lens.

In FIG. 1, the outer barrel 6b of the lens barrel 6
Is provided with at least one or more first communication holes (communication windows when the total length of the holes is short) 8 for communicating the inside of the lens barrel 6 with the outside of the projection lens device.

FIG. 2 is a cross-sectional view showing a main part when the cross section of the lens barrel 6 is viewed in the direction of arrow A in the projection lens apparatus of FIG. The inner barrel 6a is fitted and held by a plurality of fitting projections 15 provided on the inner surface side of the outer barrel 6b, whereby the groove 7a between the fitting projections 15 becomes the second communication hole 7. . In FIG. 2, the fitting projections 15 on the inner surface side of the outer lens barrel 6b are arranged at four locations in one section perpendicular to the optical axis, but it is not limited to this configuration. Absent. For example, the number of the fitting projections 15 may be three or any number, and these fitting projections 15 may be cut off in the optical axis direction. Any configuration may be used as long as it can slide inside the outer lens barrel 6b without play and sufficiently fulfills the function as a communication hole.

According to such a configuration, when the projection lens device is actually used, for example, when incorporated in a rear projection type image display device, the right side (the side with the projection type cathode ray tube) of FIG. Below, the left side (the side on which the lens elements are arranged) is generally at the top, so that the position of the second communication hole 7 is generally higher than the position of the first communication hole 8. Accordingly, the low-temperature air C (outside air) flowing from the first communication hole 8 is projected in the space between the lens element 2a closest to the projection type cathode ray tube 1 and the lens element 2b closest to the second type. In response to the heat from 1, the temperature rises and becomes lighter due to volume expansion. The air H that has become light at high temperature flows out from the second communication hole 7. The lens element 2 is efficiently radiated heat by repeating this series of phenomena, so that expansion and deformation can be suppressed, and there is an effect that the focus performance can be prevented from lowering.

FIG. 3 is a sectional view showing a main part of a second embodiment of the projection lens apparatus according to the present invention. The same parts as those in FIG.

In the first embodiment, the first communication hole is provided in the outer lens barrel 6b of the lens barrel 6, whereas in the second embodiment, as shown in FIG. Outer barrel 6b
For example, three or more joint projections 17 are provided on one or both of the bracket 4 and the outer projection 6 b and the bracket 4 are joined at the joint projection 17, and a gap other than the joint projection 17 is provided. 8a,
The gap 8a functions as a first communication hole 8 that communicates from the space between the lens elements to the outside of the projection lens device.

FIG. 4 is a perspective view of a main part showing a specific configuration of the first communication hole 8 of FIG. In FIG.
7 are provided at three places on the end surface of the bracket 4, and a gap 8 a between the joint projections 17 forms a first communication hole 8. The joining projection 17 may be provided not on the end face of the bracket 4 but on the flange face or the like at the end of the outer lens barrel 6b.
In addition, there is no substantial difference in the configuration in which both are provided and they are matched, and in each case, the same effect as that of the above-described first embodiment is obtained.

FIG. 5 is a cross-sectional view showing a main part of a third embodiment of the projection lens apparatus according to the present invention. Parts equivalent to those in FIGS. I do.

The difference between the third embodiment and the second embodiment is that the first communication hole 8 and the second communication hole 7 are provided with dustproof portions at the openings to the outside of the projection lens device, respectively. The point is that the first flange 6d and the second flange 6c are provided as the application members. At this time, if the portions up to the ends of the dustproof members 6d and 6c are regarded as communication holes, the communication holes themselves may be bent. In this embodiment,
In addition to the effects achieved in the first and second embodiments,
Since there is an effect that foreign matter and light are prevented from entering the inside of the projection lens device and light leakage from the inside of the projection lens device, the contrast performance of the projection lens device itself does not decrease. Further, there is an effect that the image contrast when the projection lens device is used in a projection type image display device does not decrease.

The same effect can be obtained when the shape of the communication hole is not only a bent shape but also a curved shape or a twisted shape.

FIG. 6 is a sectional view showing a main part of a fourth embodiment of the projection lens apparatus according to the present invention.
The same parts as those in FIG. 5 are denoted by the same reference numerals, and description thereof will be omitted.

The fourth embodiment differs from the first embodiment in that the lens barrel 6 is of an integral type which is not separated into an outer barrel and an inner barrel. In the present embodiment, the second communication hole 7 is formed as a through hole inside the wall surface of the lens barrel 6. With such a configuration, the same effects as those of the first and second embodiments can be obtained. Similarly to the third embodiment, when a dustproof member (not shown) is provided at the opening of the communication hole to the outside of the projection lens device, the same effect as that of the third embodiment can be obtained.

FIG. 7 is a sectional view showing a main part of a fifth embodiment of the projection lens apparatus according to the present invention.
5 and 6 are denoted by the same reference numerals, and description thereof will be omitted.

The difference between the fifth embodiment and the fourth embodiment is that the second communication hole 7 is not formed as a through hole inside the wall surface of the lens barrel 6 but near the outer edge of each lens element. The point is that it is formed as a through hole. With such a configuration, the same effects as those of the first, second, and fourth embodiments can be obtained. Similarly to the third embodiment, when a dustproof member (not shown) is provided at the opening of the communication hole to the outside of the projection lens device, the same effect as that of the third embodiment can be obtained.

Next, a configuration when the projection lens device as described in each of the above embodiments is used for a projection type image display device will be described.

FIG. 8 shows a projection lens apparatus 1 according to the present invention.
It is sectional drawing which shows the principal part of the longitudinal cross-section of the rear projection type image display apparatus using 6, 10 is a reflecting mirror, 11 is a transmissive screen, 9 is a housing | casing, 12 is a projection lens device holding member. The inside of the housing 9 is partitioned into an upper space 14 and a lower space 13 by a projection lens device holding member 12. In addition, the same parts as those in FIGS. 1 to 7 are denoted by the same reference numerals, and description thereof will be omitted.

In the rear projection type image display device shown in FIG. 8, the above-mentioned projection lens device 16 is held by the projection lens device holding member 12, and includes the lens barrel 6 and the lens elements therein, and the bracket. 4 is disposed in the upper space 14 in the housing 9.

The original image projected on the projection type cathode ray tube 1 which is a video source is enlarged by a projection lens unit 16,
After the optical path is turned back by the reflecting mirror 10, the light is projected on the transmission screen 11.

FIG. 9 shows a projection lens device 1 according to the present invention.
8 is a cross-sectional view showing a vertical section of the rear-projection image display device when the rear-projection image display device shown in FIG. Yes, 14 ', 1
3 'is an upper space and a lower space in the housing 9, respectively.
In addition, the same parts as those in FIG. 8 are denoted by the same reference numerals.

FIG. 10 is a sectional view showing details of the projection lens unit 16 of the rear projection type image display device shown in FIG.

FIG. 11 is a sectional view showing details of the projection lens device 16 of the rear projection type image display device shown in FIG.

The projection lens device 16 shown in FIGS. 10 and 11 has the same configuration as that of the fourth embodiment of the projection lens device 16 described above.

In the projection lens device 16 shown in FIG. 10, the lens element 2 closest to the projection type cathode ray tube 1 is generated by heat generated in the projection type cathode ray tube 1 which is an image generation source.
a, and the air in the space between the lens element 2a and the second closest lens element 2b is sequentially heated, and the heated high-temperature air H is supplied to the second communication hole formed in the lens barrel 6. 7 flows into the upper space 14, while low-temperature air (outside air) C flows from the first communication hole 8. FIG.
Of the projection type cathode ray tube 1
, The air in the lens element 2a closest to the projection type cathode ray tube 1 and the air in the space between the lens element 2a and the second closest lens element 2b are sequentially heated, and the heated high temperature The air H flows out of the first communication hole 8 into the lower space 13 ′, while low-temperature air (outside air) C flows in from the second communication hole 7 formed in the lens barrel 6. As a result, the efficiency of heat radiation from the lens element is increased, the temperature rise of the lens elements 2a and 2b is suppressed, the expansion and thermal deformation are almost eliminated, and the temperature change of the focus performance as a projection lens device is prevented. Can be.

The projection lens device 16 shown in FIGS. 10 and 11 may be configured as in the other embodiments of the projection lens device 16, and the same effects as in the above case can be obtained. Further, when a dustproof member (not shown) is provided at the opening of each communication hole to the outside of the projection lens device as in the third embodiment described above, the projection lens device 16 is used. Of foreign matter and light into the interior of the projection lens apparatus and light leakage from inside the projection lens apparatus, so that the image contrast of the rear projection type image display apparatus does not decrease. This has the effect.

In the above description, the configuration in which each communication hole is disposed in the space between the lens element closest to the image generating source and the lens element closest to the second is mainly described. Is not limited to this. In other words, the same effect can be obtained for other lens elements that are considered to be affected by heat by providing the communication holes in the space between the lens elements.

Although only the case where a projection type cathode ray tube is used as an image generation source has been described, a case where a liquid crystal panel is used in combination with a light source is also used.
Since the light source is a heat source, the same effect as described above is obtained.

Further, a rear projection type image display device has been described as an example of a projection type image display device using the projection lens device of the present invention, but the same applies to a front projection type image display device. It goes without saying that it works.

[0047]

As described above, according to the present invention,
By arranging the communication hole or the communication window described in each of the above embodiments in the lens barrel or the like of the projection lens device, the heat radiation from the lens element is made more efficient by the convection action of air, and the temperature of the lens element becomes lower. The rise is suppressed and expansion and deformation due to temperature rise are suppressed, resulting in lens performance,
In particular, there is an effect that a decrease in focus performance is prevented.

Further, the communication hole or the communication window
By disposing a dustproof member having a flange shape or the like at an appropriate position of the opening to the outside of the projection lens device, or by changing the shape of the communication hole or the communication window itself to a bent or curved shape, or The twisted shape makes it possible for foreign matter or light to enter the projection lens device,
In addition, light leakage from the inside of the projection lens device is prevented, the contrast performance of the projection lens device itself does not decrease, and an image when this projection lens device is used for a projection type image display device. There is an effect that the contrast is not reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a main part of a first embodiment of a projection lens device according to the present invention.

FIG. 2 is a cross-sectional view showing a main part when a cross section of a lens barrel 6 of the projection lens device of FIG.

FIG. 3 is a sectional view showing a main part of a second embodiment of the projection lens device according to the present invention.

FIG. 4 is a main part perspective view showing a specific configuration of a first communication hole 8 of FIG. 3;

FIG. 5 is a sectional view showing a main part of a third embodiment of the projection lens device according to the present invention.

FIG. 6 is a sectional view showing a main part of a fourth embodiment of the projection lens apparatus according to the present invention.

FIG. 7 is a sectional view showing a main part of a fifth embodiment of the projection lens apparatus according to the present invention.

FIG. 8 is a sectional view showing a main part of a vertical section of a rear projection type image display device using the projection lens device according to the present invention.

FIG. 9 is a sectional view showing a main part of a longitudinal section of another embodiment of a rear projection type image display device using a projection lens device according to the present invention.

FIG. 10 is a sectional view showing details of a part of a projection lens device of the rear projection type image display device shown in FIG. 8;

11 is a sectional view showing details of a part of a projection lens device of the rear projection type image display device shown in FIG. 9;

FIG. 12 is a cross-sectional view showing a main part of an example of a projection lens device according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Projection type cathode ray tube, 2 ... Lens element, 2a ... Lens element closest to an image generation source, 2b ... Lens element closest to an image generation source, 3 ... Elastic body, 4 ... Bracket, 5 ... Transparent liquid, 6 ... lens barrel 6a ... inner barrel 6b ... outer barrel 6c ... second flange 6d ... first flange 7 ... second communication hole 8 ... first communication hole 9 ... Case: 10: Reflecting mirror, 11: Screen, 12: Projection lens device holding member, 13, 13 ': Lower space, 14, 14': Upper space, 15: Fitting protrusion, 16: Projection lens Apparatus, 17: joining projection, H: high temperature air, C: low temperature air.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location G03B 21/00 G02B 27/00 B

Claims (19)

[Claims] 1. A plurality of lens elements arranged in the direction of an optical axis on a front surface of an image source for enlarging and projecting an image from an image source onto a screen, and a cylindrical lens element holding the lens elements. A projection lens device having a holding member, wherein air outside the projection lens device forms at least one of spaces between the plurality of lens elements and the plurality of lens elements formed by the lens element holding member. A projection lens device that is distributed. 2. A plurality of lens elements arranged in the direction of an optical axis on a front surface of the image generating source for enlarging and projecting an image from the image generating source onto a screen, and a cylindrical lens element holding the lens elements. A projection lens device having a holding member, wherein air outside the projection lens device has at least the image in a space between the plurality of lens elements and the plurality of lens elements formed by the lens element holding member. A projection lens device, wherein the lens flows through a space between a lens element closest to a generation source and a lens element disposed in front of the lens element. 3. The lens element closest to the image source,
The projection lens device according to claim 2, further comprising a meniscus lens. 4. A projection lens device for enlarging and projecting an image from a video source onto a screen, wherein the projection lens device holds a plurality of lens elements and at least one lens element among the plurality of lens elements. A lens element holding member that covers the space between the lens elements, and a connecting member that connects the lens holding member to an image generation source, and the space between the lens elements and the projection lens device. A projection lens device comprising one or more communication holes or communication windows communicating with the outside. 5. In at least one of the spaces between the lens elements, the communication hole or the communication window is located at at least two level positions with respect to a horizontal plane in a use state of the projection lens device. 5. The projection lens device according to claim 4, wherein the projection lens device is provided separately or continuously. 6. At least one of said communication holes or communication windows is provided near a connection point between said lens element holding member and said connection member as a space surrounded by at least said lens element holding member and said connection member. 5. The projection lens device according to claim 4, wherein the projection lens device is provided. 7. The space surrounded by the lens element holding member and the connection member has a space volume that is equal to the size of a projection provided on the lens element holding member or a projection provided on the connection member. The projection lens device according to claim 4, wherein the projection lens device is configured to be restricted by the following. 8. The projection lens device according to claim 4, wherein at least one of the communication hole or the communication window is provided in the lens element holding member. 9. The lens element holding member includes a first holding member that holds at least two lens elements of the plurality of lens elements, and a second holding member that fits and holds the first holding member. 5. A holding member, wherein at least one of the communication hole or the communication window is provided between the first holding member and the second holding member. 6. Projection lens device. 10. The projection lens device according to claim 9, wherein at least one valley provided in a concave shape on the inner side surface of the second holding member is the communication hole or the communication window. . 11. The projection lens device according to claim 4, wherein at least one of the communication hole or the communication window is provided near an outer edge of the lens element. 12. A dustproof member is provided in at least one of said communication holes or communication windows at an opening thereof to the outside of said projection lens device. 3. The projection lens device according to 1. 13. The projection lens device according to claim 4, wherein at least one of the communication holes or the communication windows has a bent or curved shape or a twisted shape. 14. A space between the lens elements which is communicated with the outside of the projection lens device through the communication holes or communication windows, is provided between the lens element disposed closest to the image generation source and the image generation source. 5. The projection lens device according to claim 4, wherein the projection lens device is a space between a lens element and a lens element disposed closest to the projection lens element. 15. A lens element disposed closest to an image source among the plurality of lens elements is a transparent body on an image display surface of the image source and disposed closest to the image source. 15. The projection lens device according to claim 14, wherein one lens group is configured by combining a transparent liquid filled in a space between the lens element and the transparent body. 16. The projection type cathode ray tube according to claim 15, wherein said image source is a projection type cathode ray tube, and a transparent body of an image display surface of said image generation source is a face panel of said projection type cathode ray tube. Projection lens device. 17. A projection lens device according to claim 4, wherein said projection lens device is provided in front of an image generation source, and a transmission screen is provided on an image forming surface in front of said projection lens device. A rear projection type image display device characterized by having a configuration as described above. 18. The rear projection type image display device according to claim 17, wherein said image source is a projection type cathode ray tube. 19. The rear projection type image display device according to claim 17, wherein said image source is a liquid crystal panel.