JPH06222322A - Projection type image display device - Google Patents

Abstract

(57) [Abstract] [Purpose] In a projection type image display device, it is less susceptible to the distortion generated in the housing after convergence adjustment, and the distortion of the shape of the projected image due to the distortion of the reflecting surface of the image synthesis mirror, the poor focus and the mirror. It suppresses the deviation of convergence due to the inclination of. [Structure] An image synthesizing mirror has an opening through which light emitted from an image display element passes, and is fixed to a support frame that is cantilevered on the housing, so that the influence of distortion on the housing is reduced. is doing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a projection type image display device for synthesizing and enlarging and projecting images from a plurality of image display devices.

[0002]

2. Description of the Related Art With the increase in size of televisions, the demand for projection-type image display devices is increasing because they can more easily accommodate larger screens than conventional direct-view image display devices.

Among them, a projection type image display device using a liquid crystal as a light valve is a product because it is easy to operate in order to obtain a large screen at home, the device itself is not large, and no installation work is required. And is expanding the market.

In such a projection-type image display device, a plurality of image display elements are used in order to realize high quality image quality and no installation adjustment is required, and the image is optically combined in a set. It is becoming mainstream. The synthetic optical system can be roughly classified into two types. One is a method of using a prism which is subjected to some surface treatment, and the other is a method of using a mirror which is obtained by subjecting a plane parallel plate to some surface treatment. In the former case, there is no problem if the image display element is small, but the image display element becomes large as the brightness and image quality are improved. As a result, the prism becomes large, and the marketability in terms of cost and weight is lost. Therefore, at present, in the latter configuration, a dichroic mirror is mainly used as the display unit of the image display device having a diagonal length of about 2 inches or more.

[0005]

In a projection type image display device using a plurality of image display elements for high image quality, image combination is performed by a mirror provided tilted to the optical axis of light emitted from the image display elements. When trying to do so, one image is transmitted through the mirror and the other image is reflected by the mirror. At this time, the mirror needs to satisfy at least the following two conditions to realize a composite image in which the reflected image is enlarged and projected without distortion and the transmitted image is not displaced.

First, if the flatness of the reflecting surface of the mirror is not sufficiently high, the reflected image will be distorted. In order to satisfy this, if the plate thickness of the mirror is increased, the workability is improved, but the projected image of the transmitted image is displaced from the image forming position in the vertical and horizontal directions. As a result, strict convergence adjustment cannot be performed. Therefore, it is necessary to maintain the flatness using a substrate glass that is as thin as possible.

Another problem relates to the support of the mirror.
It is necessary to fix the support frame that supports this without distorting the mirror and fix it so that it does not shift after the convergence adjustment of the projected image. Here, a conventional example of the support frame and its peripheral mechanism will be described. The support frame is die-cast aluminum in order to increase the rigidity, and the support frame is fixed to the housing from both sides with a mirror in between by screws. . Further, the housing is composed of two side plates and a member connecting the plates. The problem at this time is that distortion occurs in the housing when attaching or carrying exterior parts to the housing after completing the convergence adjustment, and at this time, the support frame held in the housing is twisted or collapsed. Occurs, and the image does not match the convergence.

As a countermeasure against this, there has recently been a structure in which the housing and the supporting frame are integrally formed as a die-cast component so as not to be easily distorted. There are problems such as poor performance and lack of versatility.

[0009]

The present invention relates to the latter mirror support among the above problems, and includes a plurality of image display elements, a projection lens provided so as to project an image of the image display elements, and Between the image display element and the projection lens, there are provided a plurality of mirrors tilted on the optical axis of the image display element and a housing, and the mirror emits light emitted from the image display element and transmitted through the mirror. Has an opening through which
By adopting a structure characterized in that it is fixed to a support frame that is cantilevered by the housing, accuracy can be maintained and high image quality can be realized while suppressing cost increase.

At this time, the image display element may be a cathode ray tube or a liquid crystal panel, a light source and a light guide section. Further, the support frame is cantilevered and fixed to at least three positions on the surface perpendicular to the mirror surface, which cannot be connected by one straight line. The support frame is configured such that its cross-sectional area is smaller on the opposite side with respect to the mirror-supported side with respect to the side supported by the cantilever.

Further, the mirror may be a dichroic mirror or a half mirror.

[0012]

As described above, by constructing the mirror support frame by cantilevered support on the housing as described above, the effect of external force after the convergence adjustment or distortion of the housing when attaching exterior parts is performed as in the conventional housing. It is more difficult to receive than a device in which the mirror support frame is supported on both sides with the body sandwiching the mirror. As a result, it is possible to suppress the distortion of the shape of the projected image due to the distortion of the mirror surface, and the deviation of the projection position between the image transmitted through the mirror and the image reflected by the mirror due to poor focus or tilt of the mirror. Furthermore, in addition to the fact that the mold cost can be greatly reduced as compared with the case where the housing and the mirror support frame are integrated, it becomes easy to develop the common parts with those of other specifications.

In taking this structure, the mirror support frame and the housing are fixed at a position which is not in a straight line, and the cantilever support suppresses the inclination of the contact surface due to floating.

Further, in order to suppress the moment generated in the fixed portion in the cantilevered support, the mirror support frame is configured such that its cross-sectional area becomes smaller as it goes away from the fixed surface with the housing.

As described above, according to the present invention, once the convergence adjustment is performed, it is possible to provide a good projection image while suppressing the die cost.

[0016]

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

FIG. 1 is a sectional view showing the configuration of a first embodiment of a two-body projection type image display device using a liquid crystal panel.
Reference numeral 1 denotes a light source, which is driven by a light source drive circuit 3 which is operated by electric power supplied from a power supply circuit 2 to emit light. The light emitted from this is sent to the ultraviolet and infrared cut filter 7 supported by the optical housing 6 fixed to the housing 5 by the reflector 4. Only the visible light component of the light incident on the ultraviolet and infrared cut filters 7 is incident on the green reflection dichroic mirror 8. At this time, only the light of the green wavelength is guided to the condenser lens 10 by the rear surface mirror 9 and transmitted therethrough, and then enters the polarizing plate 11. Only light of a necessary polarization component is incident on the liquid crystal panel unit 12 by the polarizing plate 11. The liquid crystal drive circuit provided in the liquid crystal panel unit 12 is connected to the signal processing circuit 13. And
The signal processing circuit 13 is supplied with power from the power supply circuit 2 and has an input terminal 14 for receiving a signal from the outside.

The green light transmitted through the liquid crystal panel unit 12 passes through the red reflection dichroic mirror 15 and the blue reflection dichroic mirror 16, and then enters the projection lens 18 supported by the lens barrel 17. Here, the image on the liquid crystal panel unit 12 is enlarged and projected.

Next, the light transmitted through the green reflecting dichroic mirror 8 is separated by the red reflecting dichroic mirror 19 into light in the red wavelength range and light in the blue wavelength range. Of these, the red light is reflected, passes through the condenser lens 20 in the same manner as the green light, and then enters the polarizing plate 21. Only light of a required polarization component is incident on the liquid crystal panel unit 22 by the polarizing plate 21. The liquid crystal panel unit 22 contains a liquid crystal drive circuit (not shown). This liquid crystal drive circuit is connected to the signal processing circuit 13.

The red light transmitted through the liquid crystal panel unit 22 is then incident on the red reflection dichroic mirror 15. The light is reflected by the red reflection dichroic coat surface, passes through the blue reflection dichroic mirror 16, and then enters the projection lens 18 supported by the lens barrel 17. The blue light transmitted through the red reflection dichroic mirror 19 is the green light,
After passing through the condenser lens 23 like red light,
The light enters the polarizing plate 24 attached to the flat glass plate.
Only light of a necessary polarization component is incident on the liquid crystal panel unit 25 by the polarizing plate 24. The liquid crystal panel unit 25 contains a liquid crystal drive circuit (not shown). This liquid crystal drive circuit is connected to the signal processing circuit 13.

The blue light transmitted through the liquid crystal panel unit 25 is then reflected by the front surface mirror 26, reflected by the blue reflection dichroic mirror 16, and then enters the projection lens 19 supported by the lens barrel 17. Since the red reflection dichroic mirror 15, the blue reflection dichroic mirror 16, and the front surface mirror 26 are required to have surface precision, vapor deposition is performed after the polishing process to maintain the surface precision.

Further, FIG. 2 shows the structure of the optical housing 6. The structure is made by connecting a right side plate 27 formed by aluminum die casting and a left side plate 28 of a metal plate via a support rod 29. Between the both side plates, the above-mentioned ultraviolet ray / infrared ray cut filter 7, green reflection dichroic mirror 8, rear surface mirror 9, condenser lenses 10, 20, 23, polarizing plate 1
1, 21, 24, liquid crystal panel units 12, 22, 2
5, the lens barrel 17, and the red reflection dichroic mirror 19 are fixed to both side plates by respective supporting frames. However, the red reflection dichroic mirror 15 is the color synthesis mirror support frame 3
0, the blue reflection dichroic mirror 16 is fixed to the color synthesizing mirror support frame 31 and the surface mirror 26 is fixed to the color synthesizing mirror support frame 32 without distortion, and the color synthesizing mirror support frames 30, 31, 32 are fixed.
Are fixed to the right side plate only.

Here, the color synthesis mirror support frames 30 and 3 are provided.
As shown in the figure, 1 and 32 have an opening at the center after fixing the mirror, and the one closer to the left side plate on the opposite side than the right side plate contact surface is largely caused by cantilever support. The cross-sectional area is small so as to suppress the moment.

In the conventional structure, as shown in FIG. 3, the color synthesizing mirror support frames 33, 34 and 35 are also fixed to both side plates in the same manner as other components supported by the optical housing.
In the projection type image device using the liquid crystal panel having the conventional configuration, convergence adjustment is performed by mechanically aligning the position of the liquid crystal panel in the state of the optical housing. Even in the finished product state, the distortion caused by the external force changes the positional relationship between the three liquid crystal panels and the color synthesizing mirror for synthesizing the three liquid crystal panels, resulting in deviation of the convergence. In particular, when the color synthesizing mirror is used for reflection, the reflected light is deviated by twice the shift angle with respect to the incident angle caused by the distortion, so that the influence is particularly great.

Therefore, according to the present invention, the color synthesizing mirror support frames 30, 31, and 32 are configured as described above, and further by the cantilever support, even if the optical housing 6 is distorted, the influence on the projected image is exerted. Can be minimized.

In the present embodiment, the supporting frame of the present invention is used only for supporting the dichroic mirror and the front surface mirror, but the present invention is not limited to this, and it goes without saying that it can also be used for a half mirror or the like.

Further, in the above-mentioned embodiment, the optical housings are vertically stacked. However, when the optical housings are arranged on a plane as in the other embodiment shown in FIG. 6, they serve as a lower reference. Only the lower plate 36 is provided with the color combining mirror support frames 37, 38, 3
9 is fixed so that it does not contact the upper plate 40, the same effect as in the first embodiment can be obtained.

Although the liquid crystal panel is used as the image display element in both the first and second embodiments, the present invention is not limited to this, and the image can be obtained by using a cathode ray tube or other image display elements. Needless to say, it can be applied to a portion that reflects light.

[0029]

As described above, according to the present invention, a plurality of image display elements, a projection lens provided so as to project an image of the image display element, and between the image display element and the projection lens are provided. Is composed of a plurality of mirrors tilted on the optical axis of the image display element and a housing, and the mirror has an opening for transmitting light emitted from the image display element and transmitted through the mirror, The structure is fixed to a supporting frame that is cantilevered by. Alternatively, the mirror support frame and the housing are fixed at a position that is not in a straight line, and the cantilever support suppresses the inclination due to floating from the contact surface. Further, in order to suppress the moment generated in the fixed portion in the cantilever support, the mirror support frame is configured so that its cross-sectional area becomes smaller as it goes away from the fixed surface with the housing. It becomes more difficult to receive the influence of the distortion generated in the housing at the time of mounting or the like as compared with the conventional device in which the mirror is supported by the both sides of the mirror with the housing sandwiching the mirror. As a result, it is possible to suppress the distortion of the shape of the projected image due to the distortion of the mirror surface, and the deviation of the projection position between the image transmitted through the mirror and the image reflected by the mirror due to poor focus or tilt of the mirror. Furthermore, in addition to the fact that the mold cost can be greatly reduced as compared with the case where the housing and the mirror support frame are integrated, it becomes easy to develop the common parts with those of other specifications.

As described above, according to the present invention, once the convergence adjustment is performed, it is possible to provide a good projection image while suppressing the cost.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment of a two-body projection type image display device according to the present invention.

FIG. 2 is an enlarged view of the optical housing of the first embodiment of the two-body projection type image display device according to the present invention.

FIG. 3 is an enlarged view of an optical housing of a conventional two-body projection image display device.

FIG. 4 is an enlarged view of a conventional color synthesis mirror support frame.

FIG. 5 is an enlarged view of a color synthesis mirror support frame according to the present invention.

FIG. 6 is an enlarged view of an optical housing of a second embodiment of the two-body type projection image display device according to the present invention.

[Explanation of symbols]

1 Light Source 2 Power Supply Circuit 3 Light Source Driving Circuit 4 Reflector 5 Housing 6 Optical Housing 7 Ultraviolet / Infrared Cut Filter 8 Green Reflection Dichroic Mirror 9 Backside Mirror 10, 20, 23 Condenser Lens 11, 21, 24 Polarizing Plate 12, 22 , 25 liquid crystal panel unit 13 signal processing circuit 14 input terminal 15, 19 red reflection dichroic mirror 16 blue reflection dichroic mirror 17 lens barrel 18 projection lens 26 surface mirror 27 right side plate 28 left side plate 29 support bar 30, 31, 32, 33, 34, 35, 37, 38, 3
9 color synthetic mirror support frame 36 Lower plate 40 Upper plate

Claims (1)

[Claims] 1. A plurality of image display elements, a projection lens provided so as to project an image of the image display element, and a space between the image display element and the projection lens on an optical axis of the image display element. It is composed of a plurality of tilted mirrors and a housing, and the mirror has an opening through which the light emitted from the image display element and transmitted through the mirror is passed, and is supported by a cantilevered support frame on the housing. A projection type image display device characterized by being fixed.