JPH04366936A - Projection type display device - Google Patents

Abstract

PURPOSE:To realize the projection type display device which can switch two kinds of projection system, i.e., a front system and a rear system. CONSTITUTION:The optical path of projection light 110 is switched by changing the attitude of a mirror 150 by a mirror driving mechanism 152 which drives the mirror 150 arranged right behind a projection lens 4. When the rear system is selected, the projection light 110 is bent by mirrors 150 and 160 to project an enlarged image on a transmission type screen 5R. When the front system is selected, on the other hand, the light travels straight without being reflected by the mirror 150 and then passed through a projection opening 500A provided to a cabinet 170 to project an enlarged image on a reflection type screen 5F.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a projection display device.
The present invention provides a device configuration that can switch between two types of projection methods: front projection and rear projection.

0002

2. Description of the Related Art FIG. 4 is an explanatory diagram of an optical system of a conventional front-type projection display device using a liquid crystal panel, such as the device disclosed in Japanese Patent Laid-Open No. 1-120192. In the figure, 1 is a light source, 120 is a lamp, 130 is a reflecting mirror, 2 is an illumination light flux emitted from the light source 1, 14B, 1
4G is dichroic mirror, 11a, 11b, 11c
3R, 3G, 3B are liquid crystal panels, 15 is a dichroic prism, 4 is a projection lens, and 5F is a reflective screen.

Next, the operation will be explained. The light source 1 consists of a lamp 120 and a reflecting mirror 130, and emits an illumination light beam 2. As the lamp 120, a white light source such as a metal halide lamp, a xenon lamp, or a halogen lamp is used, for example. Further, the reflecting surface of the reflecting mirror 130 is typically a paraboloid, and as is known, the lamp 12 is placed at the focal point of the paraboloid.
By arranging the emission center of 0, a parallel illumination light flux 2 is obtained. The illumination light flux 2 is separated into the three primary colors of red, green, and blue by a dichroic mirror 14B that reflects blue light and transmits green and red light, and a dichroic mirror 14G that reflects green light and transmits red light, and is separated into three primary colors of red, green, and blue. 1
The light is bent by 1b and 11c and irradiated onto liquid crystal panels 3R, 3G, and 3B that display monochrome images corresponding to each primary color. The illustration of a drive circuit for displaying images on the liquid crystal panels 3R, 3G, and 3B is omitted. The light flux modulated by the image formed on the liquid crystal panel is combined into a single light flux by a dichroic prism 15 that selectively reflects red and blue light and selectively transmits green light, and then is combined into a single light flux by the projection lens 4. It is converted into projection light 110, and an enlarged image is formed on the reflective screen 5F. The projection lens 4 needs to suppress various aberrations to a small level in order to obtain a good projected image, and is constructed by combining a plurality of single lenses (not shown) as is well known. The projection image on the screen is focused by driving part of the single lens constituting the projection lens 4 or the entire projection lens 4 in the optical axis direction. 200 is a projection lens 4;
This is a box that holds the previous optical system, and the box 200 and the projection lens 4 constitute a projector 300. In the front-type projection display device, the observer 400 views the displayed image on the reflective screen 5F from the direction in which the projector 300 is arranged.

[0004] The above explanation is about a front-type display device, but a so-called rear-type projection display device in which the entire optical system is housed in a cabinet is also known. Next, as a second conventional example, for example, Utility Model Application Publication No. 1-1157
FIG. 5 shows the configuration of a rear projection display device disclosed in No. 78. In the figure, 300 is a projector composed of a box 200 and a projection lens 4, 150 and 160 are folding mirrors, 5R is a transmission screen, and 170 is a cabinet. Next, the operation of the apparatus shown in FIG. 5 will be described. The projector 300 has the same configuration as the projector 300 shown in FIG. 4, and an optical system from the light source 1 to the dichroic prism 15 is held inside the box 200, but is not shown for simplicity. are doing. The projection light 110 emitted from the projection lens 4 passes through bending mirrors 150 and 160.
After being reflected by the beam, it is imaged on the transmission screen 5R as an enlarged image. Note that the bending mirrors 150 and 160 are used to bend the optical path from the tip of the projection lens 4 to the transmission screen 5R, and to compactly store it in the relatively small cabinet 170. Then, the viewer 400 views the enlarged image on the transmissive screen from the opposite direction from the projector 300.

[0005]

[Problems to be Solved by the Invention] Above, FIGS. 4 and 5
Conventional front-type and rear-type projection display devices have been described. Front-type projection display devices are not limited by the size of the cabinet, so the projection distance (
In Figure 4, the reflective screen 5F is viewed from the output end of the projection lens 4.
distance) can be increased. For this reason, the front type is suitable for large-screen display where the projection magnification (the magnification at which the original image on the liquid crystal panel is enlarged and projected onto the screen) is larger than that of the rear type. However, this method had the following problems. (1) While an image is being displayed, people cannot freely enter and exit the space between the projector 300 and the reflective screen 5F (within the range of the projection light 110). Furthermore, when the projector 300 is permanently installed indoors, placing furniture or the like between the projector 300 and the screen 5F will obstruct the projection light path, so it must be moved out of the range of the projection light 110 when displaying an image. It's really inconvenient. (2) The screen 5F is generally made of a material with high reflectance so as to obtain a high-brightness image. For this reason, if the indoor lighting (not shown) is brightened while viewing the image, parts of the image that should be displayed darkly become brighter, deteriorating the contrast. In order to obtain a good image with the front-facing method, it can only be viewed in a dark environment with no indoor lighting, such as a movie theater, and it is inconvenient to watch large-screen images while doing other tasks (such as writing notes or doing housework). be. (3) When the reflective screen 5F is installed next to the wall,
The projector 300 may have to be installed near the center of the room, which becomes an obstacle when considering a free layout of the room.

[0006] The rear system is advantageous in dealing with the above problems. This is because, regarding item (1), all rear-type optical systems are housed within the cabinet 170, so the projection light 110 is not blocked by people or furniture. For item (2), the conventional transmission type screen 5R
A black stripe is provided on the surface of the projection light 110.
Devices have been developed in which the screen 5R is made of a material that selectively transmits only the spectral components of the spectral components, which cause less contrast deterioration even under normal indoor lighting. Regarding item (3), by installing the relatively small cabinet 170 along a wall or in a corner of the room, it will not interfere with the layout in the center of the room. In order to obtain a large screen with a rear type device, it is necessary to increase the projection distance or the angle of view of the projection lens 4. However, the former has the problem that the cabinet 170 is generally large (particularly deep) and requires a large installation space, while the latter has the problem of increasing the number of lens components to accommodate the wide-angle projection lens. There was a problem with the price. On the other hand, the front type did not use a cabinet, so it was advantageous for making the screen larger. Considering the characteristics of both types as described above, for example, in the case of home video projectors, the rear type is the mainstream device that displays an image with a diagonal of 40 to 70 inches, while the front type displays a diagonal of 60 to 200 inches. Devices that displayed images on a large corner screen were the mainstream.

As explained above, the front type is particularly suitable for viewing large-screen images, although there are many restrictions on installation. Also, although the images of the rear type are smaller than those of the front type, they are suitable for viewing medium-sized large-screen images in normal lighting environments. Conventionally, users have taken the characteristics of both of these types into account and used a device that is more suitable for them. However, in general households, using both types depending on the usage situation has problems in terms of installation space and the cost of purchasing two devices, so it is necessary to view images with one of the devices. There wasn't. The present invention allows switching between both the rear method and the front method with one device.
It is an object of the present invention to provide a projection type display device that allows a user to easily select and use the characteristics of both of the above types.

[0008]

[Means for Solving the Problems] A projection type display device according to the present invention is provided with a mechanism for changing the attitude of a bending mirror disposed immediately after a projector in a cabinet, and the projection light is reflected and folded. The optical path can be switched to a state where the vehicle travels straight without moving. When performing front projection, set the mirror so that the projection light travels straight,
Projection light is emitted from an exit opening provided in the cabinet to form an image on a reflective screen. When rear projection is performed, the mirror reflects and bends the projection light, and the projection light is guided to a transmission screen within the cabinet to form an image.

[0009]

[Operation] In the device of the present invention, the drive mechanism of the bending mirror allows selection of whether the optical path of the projection light is guided outside the cabinet through the exit aperture or confined within the cabinet, making it possible to switch between the front method and the rear method. be.

0010

【Example】

Example 1. FIG. 1 is a block diagram of a projection type display device according to an embodiment of the present invention. In the figure, 300 is a projector composed of a box body 200 and a projection lens 4, 150 and 160 are folding mirrors, 5R is a transmission screen, 5F is a reflection screen, 170 is a cabinet, and 151 is installed at one end of the folding mirror 150. 152 is a drive mechanism for the mirror 150; 153 is a mirror drive mechanism 152;
A button 41 is used to drive part of a plurality of single lenses (not shown) constituting the projection lens 4 or the entire projection lens 4 in the optical axis direction to focus the projected image on the screen. Focus drive mechanism, 42 is a button for instructing the focus drive mechanism 41 to operate, 500A
5 is an exit opening provided in a part of the cabinet 170;
00 is a light shielding plate that covers the output aperture 500A.

First, the operation of the first embodiment will be explained. FIG. 1 shows an optical path when the projection type display device of the present invention is used in a rear type. The internal configuration of the projector 300 is the same as that shown in FIG. 4 showing the first conventional example, so illustration and description will be omitted. The projection light 110 emitted from the projection lens 4 passes through the bending mirror 150 as in the case of the second conventional example shown in FIG.
, 160 in the cabinet 170 and projected onto the transmission screen 5R to form an enlarged image for viewing. At this time, an opening 500A provided in the cabinet is covered with a light shielding plate 500 so that unnecessary light inside the cabinet 170 does not leak outside and interfere with image viewing. Also, mirror 150
is set at the bending position 155.

Next, the operation when using the apparatus of the present invention in a front type will be explained. When switching to the front method, the drive mechanism 152 is activated by operating the button 153, the folding mirror 150 is rotated around the pivot shaft 151, and fixed at the flip-up position 154. FIG. 2 shows a state in which the mirror 150 is flipped up in this manner and the light shielding plate 500 is removed. In the state of FIG. 2, the mirror 150 does not reflect the projected light 110, and the projected light 110 is emitted from the exit opening 500A, and an enlarged image is formed on the reflective screen 5F placed outside the cabinet 170 for viewing. be done. Since the projection distance is different from the rear method described above, operate the button 42 as appropriate to adjust the focus drive mechanism 4.
1 to drive part of a plurality of single lenses constituting the lens 4 or the entire projection lens 4 in the optical axis direction, and adjust the enlarged image on the screen 5f to a focused state.

Furthermore, the operation when switching from the front type state shown in FIG. 2 to the rear type state shown in FIG. 1 will be described. The mirror drive mechanism 152 is activated in response to the operation of the button 153, and the mirror 150 is rotated about the pivot shaft 151, and is reset from the flip-up position 154 shown by the broken line in FIG. 1 to the folded position 155. In the case of rear projection, the light shielding plate 500 has an exit aperture 50.
Although it is preferable to set the aperture 500A so as to cover the aperture 0A, there is no problem even if the aperture 500A is left open as long as it is not harmful to viewing images. With the above operations, the optical path is switched to the rear type optical path as shown in FIG. To adjust the focus of the enlarged image,
The focus drive mechanism 41 may be activated by operating the button 42 to drive part or all of the projection lens.

[0014] When obtaining a large-screen image using the front method with the configuration shown in Fig. 2, it is better to stand the reflective screen 5F vertically (in the direction of gravity; see the arrow at the top left of Fig. 2) to create a feeling of pressure on the viewer. Less is. For this purpose, it is preferable that the optical axis of the projection lens 4 (indicated by a chain line in FIG. 2) is set to coincide with the horizontal direction (direction perpendicular to the direction of gravity). Furthermore, in the configurations shown in FIGS. 1 and 2, the projector 300 is arranged above the transmission screen 5R. The configuration in which the projector 300 is placed below the transmission screen 5R can be realized by turning the cabinet in FIG. 1 upside down. However, in this case, the exit aperture 50
0A is located close to the bottom surface of the cabinet 170, and the optical path is likely to be blocked by the floor surface on which the cabinet 170 is placed during front projection. For this reason, Figures 1 and 2
It is advantageous to arrange the projector 300 above the transmission screen 5R as shown in FIG.

Example 2. Embodiment 2 FIG. 3 is a configuration diagram of a projection type display device according to a second embodiment of the present invention. FIG. 3 shows an optical path diagram in the case of rear projection. The changes from Example 1 are as follows:
There are now three folding mirrors, 150, 160, and 180. The rest of the configuration is the same as that in FIG. 1, and the explanation will be omitted.

Next, the operation of rear projection will be described. The projection light 110 emitted from the projection lens 4 of the projector 300 passes through the bending mirror 15 arranged immediately after the projection lens 4.
0 toward the bottom surface of the cabinet, then reflected to the upper right by the bending mirror 160, further reflected to the left by the bending mirror 180, and enlarged and projected onto the transmission screen 5R. In the configuration of FIG. 3, three folding mirrors are used, one more than in the configurations of FIGS. 1 and 2. Therefore, compared to the optical path in Example 1, even if the same size cabinet 170 is used, the projection distance (the optical path length from the output end of the lens 4 to the screen 5R) can be made longer, so that a larger rear projected image can be obtained. Obtainable. To switch to the front method, switch the mirror drive mechanism 152 by operating the button 153.
The mirror 150 is driven to rotate around the pivot shaft 151 and set at the flip-up position 154. Then, by removing the light shielding plate 500 covering the opening 500A, enlarged projection onto the reflective screen 5F can be performed as in the case of the first embodiment. Furthermore, since the switching from the front method to the rear method and the focus adjustment on the screens 5F and 5R are the same as in the first embodiment, their explanation will be omitted.

In each of the embodiments described above, front/rear optical path switching is performed by rotating the mirror 150; The configuration may be such that the projection light 110 is switched between a state in which it is bent and a state in which it travels straight. In addition, the mirror 150 can be manually attached and detached without providing the button 153 and the mirror drive mechanism 152, and in the case of the rear type, the mirror 150 is attached and the projected light 110 is bent, and in the case of the front type, the mirror 150 is attached and the projected light 110 is bent. The projection light 110 may be made to travel straight by taking it out from the cabinet 170.

[0018] Furthermore, an example has been described in which the projection lens 4 constituting the projector 300 is one (one lens system). That is, as described in FIG. 4, the three primary color projection lights are combined at the stage of entering the projection lens. Therefore, in the one-lens system, images are projected onto the screen through a common optical path after the projection lens, and even if the projection distance changes, the images of the three primary colors will not be projected with deviations from each other. On the other hand, a method (three-lens method) in which separate projection lenses are provided for each primary color and the projected light is combined on a screen is also known. However, in the three-lens system, since the optical paths of the three primary colors after the projection lens are different, it is known that the images of the three primary colors shift when the projection distance changes. This requires a complex convergence adjustment (
(adjustment to properly superimpose the images of the three primary colors on each other) is required. This adjustment is especially necessary in the case of the front method where the projection distance changes. Considering that the projection type display device of the present invention switches to front type projection, it is advantageous to use the one-lens type projector 300 in that a convergence adjustment mechanism is not required. However, as long as a known convergence adjustment mechanism is provided, the present invention can be applied even when a three-lens projector is used.

Furthermore, the liquid crystal panel inside the projector 300 has three
Although the explanation was based on the case of a single LCD panel (Figure 4), it is possible to
A method of compositely projecting two or four or more display images is also known. Of course, the present invention can be applied regardless of the number of liquid crystal panels.

Further, although only the case where a liquid crystal is used as a device for displaying an original image has been described, a projector for enlarging and projecting a CRT display image is also known, and the present invention is applicable to such a projector. can also be effectively applied.

Furthermore, in the embodiment, a configuration in which the focus can be adjusted by driving the projection lens 4 by the focus drive mechanism 41 has been described. On the other hand, it is also known that if the projection lens 4 is a zoom lens, the size of the projected image can be changed. When projecting by the front method, the size of the reflective screen 5F can be selected independently of the size of the cabinet 170, so adjusting the magnification using a zoom lens is particularly useful. Of course, the present invention can be applied without any problem even if the projection lens 4 is a zoom lens.
In this case, in addition to the focus adjustment button 42 and focus drive mechanism 41 shown in FIGS. 1 to 3, a button for issuing a command for zoom adjustment and a zoom drive mechanism for driving the lens in accordance with the command from the button are provided. This will improve operability (not shown).

[0022]

As described above, according to the present invention, the projection optical path of the rear method and the front method can be easily switched with one device, so that the user can use both methods depending on the situation. Specifically, when viewing an image on a particularly large screen, it can be projected using the front method, and when viewing an image on a medium-sized large screen with the indoor lights on, it can be projected using the rear method. Furthermore, since a projector is used in common, compared to the conventional method of installing one front-type device and one rear-type device, the installation space can be reduced, and the cost required for introducing the device can be reduced.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of the operation when the first embodiment of the present invention is used in a front method.

FIG. 3 is a configuration diagram showing a second embodiment of the present invention.

[Figure 4] First conventional projection display device (front type)
FIG.

FIG. 5 is a configuration diagram of a second conventional projection display device (rear type).

[Explanation of symbols]

150 First mirror 152 Mirror drive mechanism 160 Mirror 170 Cabinet 300 Projector 5F Reflective screen 5R Transparent screen 500A Output aperture

Claims (5)

[Claims] 1. A projector that includes a built-in image display device and enlarges and projects an image displayed on the image display device;
a projection lens provided at the output section of the projector, a plurality of mirror means for bending and guiding the optical path of the projection light emitted from the projection lens, and the projection light guided by the plurality of mirror means entering, In a projection display device comprising a transmission screen for forming an enlarged image, and cabinet means incorporating the projector, a plurality of mirror means, and a projection lens and holding the transmission screen, a mirror drive mechanism for driving a first mirror means into which light emitted from the projection lens first enters; an exit aperture for emitting the projection light from the cabinet to the outside; and an exit opening disposed outside the cabinet means. When projecting by rear method, the first mirror means is set in a posture to reflect the projected light by the mirror drive mechanism, and the projected light is directed to the transmissive screen. When guided by the screen and projected by the front method, the first mirror means is set in a posture such that the projection light does not reflect and travels straight by the mirror drive mechanism, and the straight projection light passes through the exit opening to the cabinet. A projection type display device characterized in that the light is emitted to the outside of the means, guided to the reflective screen, and can be switched between front type projection and rear type projection. 2. The mirror drive mechanism causes the first
2. The projection type display device according to claim 1, wherein the first mirror means is rotated about a support shaft provided at one end of the mirror means to switch between a front type and a rear type projection optical path. . 3. The mirror drive mechanism causes the first
2. The projection type display device according to claim 1, wherein the projection optical path of the front type and the rear type is switched by moving the mirror means in parallel. 4. The apparatus according to claim 1, further comprising a first operation button, and when the first operation button is operated, the mirror drive mechanism is activated to switch between a front type and a rear type projection optical path. 2. The projection display device according to item 1. 5. The projection lens is composed of a plurality of lens elements, and has a second operation button and a focus drive mechanism activated by operation of the second operation button, A part of a plurality of lens elements constituting the projection lens or the entire projection lens is driven by operating an operation button to adjust the focus of the projected image on the transmissive screen or the reflective screen. A projection type display device according to claim 1.