JP4148571B2 - Rear projection display - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rear projection display device, and more particularly, a rear projection in which a projected image from a video projection device is received on the back side of a screen and image light is emitted toward an observer located on the front side of the screen. The present invention relates to a type display device.
[0002]
[Prior art]
FIG. 7 is a schematic configuration diagram showing a conventional rear projection display device. This rear projection display device includes an image projection device 102 including a liquid crystal image display panel disposed in a housing 101, and a projection. The lens 103, the reflection mirror 104, and the transmission type diffusion screen 105 are configured. The projection image light from the image projection device 102 is reflected by the reflection mirror 104 through the projection lens 103, and this projection image light is incident on the back side of the transmissive screen 105 and diffused and emitted from the front side of the screen 105. Thus, the observer can view the image at the front position of the screen 105. This type of rear projection display device has an advantage that it is easy to enlarge the screen as compared with a structure using a cathode ray tube as a screen.
[0003]
[Problems to be solved by the invention]
By the way, in the above-described conventional rear projection display device, the main point is to reduce the size of the device and increase the screen size, and a device such as providing a large screen on the smallest body possible to increase the optical path distance and the like. The screen is enlarged and projected on the screen.
[0004]
However, in an observer's observation situation, if the display is too large, the screen may be difficult to see. For example, when the distance between the observer and the screen is small, a smaller screen is suitable for observation.
[0005]
Further, when a rear projection display device is used for a monitor of a personal computer, the resolution is often changed depending on software used.
[0006]
However, in the conventional rear projection display device, the size of the screen displayed on the screen is constant, and the current situation is that it cannot cope with the various applications as described above in an optimal state.
[0007]
The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a rear projection display device capable of changing the size of a screen displayed according to the usage.
[0008]
[Means for Solving the Problems]
The present invention relates to a lower cabinet, an upper cabinet attached to the lower cabinet so as to be movable up and down, an image projection device that is disposed in the lower cabinet and projects an image vertically upward, and an upper cabinet that moves up and down. Correspondingly moving up and down, the projection lens for enlarging and projecting the image, and the image projected from the image projection device via the projection lens are directly projected on the upper cabinet above the image projection device. And a total reflection mirror that reflects the projected image, and a diffusion screen that is disposed in the upper cabinet and transmits the image reflected by the total reflection mirror to the outside of the upper cabinet. And
[0010]
According to the configuration described above, the display image area can be changed according to the intended use.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0012]
FIG. 1 is an external perspective view showing an embodiment of a rear projection display device of the present invention, FIG. 2 is a sectional view showing a schematic configuration, and FIG. 3 is a schematic configuration diagram showing a video projection device portion of the present invention.
[0013]
The rear projection display device 1 includes a video projection device 3, a projection lens 4, a total reflection mirror 6, and a transmissive diffusion screen 7 disposed in a housing 2.
[0014]
The casing 2 includes an upper cabinet 2a and a lower cabinet 2b. A screen 7 including a total reflection mirror 6 is disposed in the upper cabinet 2a, and an image projection device 3 and a projection lens 4 are disposed in the lower cabinet 2b. ing.
[0015]
A speaker 8 is provided on the front surface of the lower cabinet 2b, and an image input / output terminal 9 is provided on the side surface.
[0016]
In this embodiment, the upper cabinet 2a is attached to the lower cabinet 2b so as to be movable in the vertical direction. By extending and contracting the support plate 2c provided in the upper cabinet 2a from the lower cabinet 2b, the upper cabinet 2a is provided. 2a moves up and down.
[0017]
As shown in FIG. 5, when the support plate 2c is extended to the intermediate position from the state shown in FIG. 1, the upper cabinet 2a is raised to the intermediate position, and when the support plate 2c is further extended, as shown in FIG. The upper cabinet 2a rises to the highest position.
[0018]
FIG. 3 is a configuration diagram illustrating an example of a video projection apparatus using a three-panel liquid crystal panel as the video projection apparatus.
[0019]
In this video projection device 3, white light is removed from the condensing reflector 31 having a halogen lamp or metal halide lamp 32 as a light source by the UV / IR filter 33 and then applied to the dichroic mirror 51. The dichroic mirror 51 transmits red light (R) and reflects green light (G) and blue light (B). The red light separated by the dichroic mirror 51 is reflected by the total reflection mirror 52 and applied to the red liquid crystal panel 53 that displays a red image. The red light passes through the liquid crystal panel 53 while changing the transmittance, and is then given to a dichroic prism 54 as a color synthesizing means.
[0020]
On the other hand, the green light and the blue light reflected by the dichroic mirror 51 are given to the dichroic mirror 55. The dichroic mirror 55 transmits green light (G) and reflects blue light (B). The green light separated by the dichroic mirror 55 is given to a green liquid crystal panel 56 that displays a green image. The green light passes through the liquid crystal panel 56 while changing the transmittance, and is then given to the dichroic prism 54.
[0021]
Further, the blue light transmitted through the dichroic mirror 55 is reflected by the total reflection mirrors 57 and 58 and applied to the blue liquid crystal panel 59 that displays a blue image. The blue light passes through the liquid crystal panel 59 while changing the transmittance, and is then given to the dichroic prism 54 as a color synthesizing means.
[0022]
The color lights incident on the dichroic prism 54 are combined and emitted as color video light (R, G, B) light.
[0023]
Then, the color image light emitted from the dichroic prism 54 of the image projection device 3 is reflected in the orthogonal direction by the total reflection mirror 5 and given to the projection lens 4. The projection lens 4 enlarges and projects the color image light obtained by the dichroic prism 54.
[0024]
The color image light emitted from the projection lens 4 is reflected by the total reflection mirror 6 and enlarged and projected onto the screen 7.
[0025]
Next, the operation of this embodiment will be further described with reference to the drawings.
[0026]
In the rear projection display device, the size of the image projected on the screen 7 varies depending on the optical path length. The longer the optical path length, the larger the image is projected on the screen 7.
[0027]
Therefore, in the present invention, the optical path length is varied by changing the distance between the total reflection mirror 6 and the projection lens 4. As shown in FIG. 4, at the first mirror position (A) where the distance between the total reflection mirror 6 and the projection lens 6 is the shortest, the optical path length becomes short, so the image projected on the screen 7 becomes small, This is the display image area (A) shown in the figure.
[0028]
Further, at the second mirror position (A ′) where the distance between the total reflection mirror 6 and the projection lens 6 is longer than the first mirror position (A), the image projected on the screen is more than the first mirror position. The display image area projected on the screen 7 has an intermediate size (A ′).
[0029]
At the third mirror position (A ″) where the distance between the total reflection mirror 6 and the projection lens 4 is the longest, the optical path length becomes short, so the image projected on the screen 7 becomes small and the display image area shown in the figure. (A ").
[0030]
As described above, the magnification of the image projected and displayed on the screen 7 is changed by the vertical movement of the total reflection mirror 6, and the display area displayed on the screen 7 is changed.
[0031]
When the total reflection mirror 6 is moved up and down, the distance to the projection lens 4 changes, and the focus may be lost at this time. Therefore, in this embodiment, the projection lens 4 is also moved and focused in response to the vertical movement of the total reflection mirror 6. At the first mirror position (A), the projection lens 4 is also at the first position (B), and at the second mirror position (A ′), the projection lens 4 is also at the second position (B ′), the third position. At the mirror position (A ″), the projection lens 4 is also moved to the third position (B ″). This movement can be adjusted manually while looking at the screen, but it is more convenient to make the movement in conjunction with the movement of the total reflection mirror 6.
[0032]
In this embodiment, the screen 7 and the total reflection mirror 6 are housed in the upper cabinet 2a. As described above, the screen 7 and the total reflection mirror 6 are integrally moved up and down by the expansion and contraction of the support plate of the upper cabinet 2a. Move.
[0033]
As shown in FIG. 1, the state in which the support plate 2c is contracted most is the first state (A) in FIG. 4, which is the smallest display image area as shown in the figure. Next, as shown in FIG. 5, when the support plate 2c is in the intermediate position, it is in the second state (A ′) of FIG. 4, and as shown in the figure, the display image region has an intermediate size. . Then, as shown in FIG. 6, when the support plate 2c is at the most extended position, it is in the third state (A ″) of FIG. 4, and as shown in FIG. It becomes an area.
[0034]
As described above, according to the rear projection display device according to the present invention, the size of the screen area can be changed according to the intended use of the observer. For example, when viewing alone or when the screen is too close without sufficient space between the observer and the screen, the state shown in FIG. 2 or FIG. 5 is selected to make the image display area smaller and smaller. When the image display area or the intermediate image display area is used, and when viewing in a large number or when the space between the observer and the screen is sufficiently large, the state shown in FIG. 6 is selected to enlarge the image display area and display a large image. By doing so, the observer can observe the projection image in an optimum state. In the above example, the state of FIG. 6 is configured to be a full screen display. However, the state of FIG. 2 may be configured to be a full screen display. When the state shown in FIG. 2 is selected, the screen (small image) displayed at a low resolution is optically enlarged by selecting the state shown in FIG. 5 or FIG. 6 according to the resolution (screen size). It can be displayed on the screen. That is, when the specifications of the liquid crystal panels 53, 56, and 59 of the rear projection display device are XGA (1024 × 768 dots), the XGA image is displayed in full screen when the state of FIG. 2 is selected. When the state 2 is selected, when the resolution is displayed with a low resolution of VGA (640 × 480 dots), the displayed image is not enlarged or reduced, and the small image display area (A 6), by selecting the state shown in FIG. 6, the VGA screen can be optically enlarged and displayed in the image display area (A ″) displayed in full screen. Since the display screen is enlarged and reduced optically, the image can be linearly enlarged and reduced without performing a smoothing process as in a direct-view LCD display device or the like. .
[0035]
In the above-described embodiment, the image projection apparatus having the three-plate type liquid crystal panel has been described. However, even when a single-plate type liquid crystal panel is used, the same configuration can be made.
[0036]
In the above-described embodiment, the case where the size of the image is changed in three steps has been described. However, the image size can be changed in a stepless manner.
[0037]
【The invention's effect】
As described above, according to the present invention, since the size of the projection image can be arbitrarily changed according to the usage application of the observer, the projection image can be observed in an optimum state.
[Brief description of the drawings]
FIG. 1 is an external perspective view showing an embodiment of a rear projection display device according to the present invention, and shows a case where a display image area is minimum.
FIG. 2 is a cross-sectional view showing a schematic configuration of an embodiment of a rear projection display device of the present invention.
FIG. 3 is a schematic configuration diagram showing a video projection device portion of the present invention.
FIG. 4 is a schematic diagram for explaining the distance between the total reflection mirror and the projection lens and the size of the projection image of the rear projection display device of the present invention.
FIG. 5 is an external perspective view showing an embodiment of a rear projection display device according to the present invention, and shows a case where a display image region is intermediate.
FIG. 6 is an external perspective view showing an embodiment of a rear projection display device according to the present invention, and shows a case where a display image area is maximum.
FIG. 7 is a schematic configuration diagram of a conventional rear projection display device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rear projection display device 2 Housing 3 Image projection device 4 Projection lens 6 Total reflection mirror 7 Screen

Claims (1)

A lower cabinet, an upper cabinet mounted so as to be movable up and down with respect to the lower cabinet, an image projection device that is arranged in the lower cabinet and projects an image vertically upward, and is moved up and down corresponding to the vertical movement of the upper cabinet A projection lens for moving and enlarging and projecting the image; and disposed in an upper cabinet at a position above the image projection device and configured to directly project the image projected from the image projection device through the projection lens. And a rear projection , comprising: a total reflection mirror that reflects the projected image; and a diffusion screen that is disposed in the upper cabinet and transmits the image reflected by the total reflection mirror to the outside of the upper cabinet. Type display device.

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