JPH10115869A - Liquid crystal projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To display plural display modes on a large screen. SOLUTION: This projector is constituted of a projecting lens 11 having a focal distance corresponding to the display mode, a disk-shaped holder 15 pivotally supported to a liquid crystal projector main body so as to be turned with a central shaft, and also having two lenses 11 whose centers are along the same periphery 12 and which are placed side by side, for example, a light source part 3 constituted of a reflection mirror which makes the light emitted from a lamp parallel light rays, and reflects the light forward while making an optical axis 6 a center, etc., a liquid crystal panel part 2 having a constitution interposing a TN(twisted nematic) type liquid crystal panel or a TFT(thin film transistor) type liquid crystal panel provided with a color filter set in front of the part 3 so that the center is aligned with the optical axis 6 by a polarizing board, and a motor 13 rotating and driving the central shaft of the holder 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal projector which performs projection display using a light source, a liquid crystal panel, and a projection lens.

[0002]

2. Description of the Related Art There is a liquid crystal projector as a device for projecting and displaying a large screen image using a liquid crystal panel as a light valve.

FIG. 5 is a conceptual diagram showing a configuration of an optical system of a conventional liquid crystal projector using one liquid crystal panel. The light source unit 3 includes a lamp and a reflecting mirror that reflects light of the lamp forward as parallel rays. A TN (Twisted Nematic) having a color filter is provided in front of the light source section 3.
) A liquid crystal panel section 2 having a configuration in which a liquid crystal panel is sandwiched between polarizing plates.
Is disposed, and a projection lens 1 having a fixed focus for enlarging and projecting a light ray is disposed further forward. The uniform white light from the light source unit 3 is modulated by an image signal or the like by passing through the liquid crystal panel unit 2. That is, the light that has been aligned to one polarization plane by the first polarizing plate is modulated by a liquid crystal panel that performs a shutter operation based on an image signal or the like so that the polarization plane is twisted by 90 degrees based on the image signal or the like for each RGB pixel. Then, only the modulated light passes through the second polarizing plate, and the unmodulated light is blocked.

FIG. 6 is a diagram for explaining the projection principle of a liquid crystal projector. The enlarged projection will be described with reference to FIG. The modulated light is once focused on the focus F by the projection lens 1.
And then diverges from the focal point F, reaches the screen located far away, and operates to obtain an enlarged image. By the way, recently, in a liquid crystal projector, a plurality of display modes of a personal computer, for example, VGA (Vide
o Graphics Array), SVGA (Super Video Graphics)
An array that further displays an XGA (eXtended Graphics Array) or the like on a single device has been commercialized. FIG. 6 (C)
The light in the area (a) displays a large screen shown in FIG. 6A, for example, in the SVGA mode at a resolution corresponding to 800 × 600 pixels on the screen. The light in the area B in FIG. 6 (C) is displayed on the screen in the small screen shown in FIG. 6 (B).
For example, display with a resolution corresponding to 640 × 480 pixels is performed in the VGA mode.

However, as shown in FIGS. 6A and 6B, for example, although a large screen (A) on a screen can be obtained in the SVGA mode with a high resolution, a VGA with a lower resolution The display screen such as the mode becomes a small screen (B). In a so-called liquid crystal projector supporting a plurality of display modes, there is a problem that a display screen in a low-resolution display mode cannot be displayed on a full screen and becomes a small screen.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a liquid crystal projector in which a plurality of display modes are all displayed at the same angle of view on a large screen. .

[0007]

To achieve the above object, a liquid crystal projector comprising a light source, a liquid crystal panel and a projection lens is provided with a plurality of projection lenses having different focal lengths corresponding to display modes. .

A liquid crystal projector comprising a light source, a liquid crystal panel and a projection lens includes a plurality of sets of light sources and a liquid crystal panel, one projection lens, and a reflecting mirror for changing the direction of the optical path of the projection light. Was.

In a liquid crystal projector comprising a light source, a liquid crystal panel and a projection lens, a plurality of liquid crystal panels having different resolutions are arranged in cascade.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS With the above-described configuration, an image having a large magnification is projected for each display mode, for example, using a projection lens having a small focal length in a low resolution display mode. , So that the angle of view is substantially the same in all display modes.

In another configuration, by setting a reflecting mirror at a required position, light output from a combination of a light source and a liquid crystal panel corresponding to a display mode is selected and supplied to a projection lens, so that substantially the same image is obtained. Project at the corner.

In another configuration, a liquid crystal panel having an appropriate resolution is selected for each display mode to perform a modulation operation, and the other liquid crystal panels are not selected and only transmit light.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a liquid crystal projector according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a conceptual view showing an embodiment of a liquid crystal projector according to the present invention, which is a side sectional view (A) and a front view (B). Reference numeral 11 denotes a projection lens using a combination lens having a focal length corresponding to the display mode. Reference numeral 15 denotes a disc-shaped holder pivotally supported by the main body of the liquid crystal projector so as to rotate about the center axis. The projection lens 11 is provided with the center thereof along the same circumference 12, in other words, on the disc-shaped holder 15. For example, two projection lenses are provided so that the center of the projection lens overlaps the locus of the optical axis 6 passing through the liquid crystal panel. Reference numeral 3 denotes a light source unit, which includes a lamp and a reflecting mirror that reflects light from the lamp forward as parallel rays. Reference numeral 2 denotes a TN (Twisted Nema) provided with a color filter provided in front of the light source unit 3.
tic) type liquid crystal panel or TFT (Thin Film Transist)
or) A liquid crystal panel section in which a liquid crystal panel is sandwiched between polarizing plates. Reference numeral 6 denotes an optical axis of the liquid crystal projector. 13
Is a motor for rotating and driving the central axis of the disc-shaped holder 15. The same parts as those in the conventional example (FIG. 5) are given the same numbers.

The operation of the liquid crystal projector according to the present invention will be described with reference to FIG. Note that a duplicate description of the same operation as in the related art will be omitted. For example, when a low-resolution display mode such as VGA is selected, the motor 13 is controlled to
5 is rotated to a predetermined position, and the projection lens 11 having a small focal length is set so as to project an image at a high magnification.
At this time, since the center of the projection lens 11 is disposed on the same circumference 12 in the disk-shaped holder 15, for example, at the intersection with the diameter, the optical axis 6 of the image is rotated at a position after a half rotation (180 degrees).
Can be made to coincide with the center of the projection lens 11. When a high-resolution display mode such as SVGA is selected, the motor 13 is similarly controlled to further rotate the disc-shaped holder 15 by half a turn (180 degrees), stop at another predetermined position, and increase the focal length. The projection lens 11 is set so as to project an image at a low magnification. In any of the display modes, the projection lens 1 is set in advance so as to have substantially the same angle of view.
6 by setting the focal length of FIG.
The small screen shown in (B) is enlarged and displayed on the large screen in FIG. It is also possible to provide three or more projection lenses 11 corresponding to three or more display modes.
In this case, the center position of the lens may be arranged on the same circumference 12 in the disc-shaped holder 15 and at every 120 degrees.

FIG. 2 is a conceptual view showing a second embodiment of the liquid crystal projector according to the present invention, which is a side sectional view (A) and a front view (B). The description will focus on the points different from the invention of FIG. A rail 14 is provided on the main body of the liquid crystal projector in a direction perpendicular to the optical axis 6, a plate-like holder 16 that moves along the rail 14 is provided, and two projection lenses 1 are provided.
1 is set on the plate-like holder 16 so that the center of the projection lens 11 coincides with the optical axis 6 by the movement, in other words, the center of the projection lens 11 follows the locus of the optical axis 6 passing through the liquid crystal panel. It was attached to overlap. Projection lens 11
Is selected in advance for each display mode, the plate-like holder 16 is moved left and right so that the center of the corresponding projection lens 11 coincides with the optical axis 6 and the required projection lens 11 is selected. I do.

FIG. 3 is an enlarged view of a liquid crystal panel used in a third embodiment of the liquid crystal projector according to the present invention. In this case, a structure in which the liquid crystal panel unit is formed by superposing liquid crystal panels 21 and 22 that transmit light when pixels are not driven and a polarizing plate 23 that is disposed in a polarization direction that transmits light at this time, In other words, the structure is such that two liquid crystal panels and the like are cascaded. For example, if the liquid crystal panel 21 is a VGA
By setting the resolution of the liquid crystal panel 22 to the resolution of SVGA, as shown in FIG.
If the liquid crystal panel 21 is driven and the liquid crystal panel 21 is not driven, an SVGA image in which white light (arrow) is modulated by the liquid crystal panel 22 is transmitted according to the aperture ratio of the liquid crystal panel 21, and a projection lens (not shown) Is enlarged and projected. When the liquid crystal panel 21 is driven and the liquid crystal panel 22 is not driven as shown in FIG. 3B, the liquid crystal panel 22 transmits white light (arrow) according to the aperture ratio, and Is modulated into VGA image light and enlarged and projected by a projection lens (not shown). By setting the outer dimensions of the liquid crystal panels 21 and 22 having different resolutions to be the same, projected images having the same angle of view are obtained.

FIG. 4 is a conceptual diagram showing a fourth embodiment of the liquid crystal projector according to the present invention, in which (A) two light source units and a liquid crystal panel unit are provided, and (B) three light source units and a liquid crystal panel unit are provided. ). First, the example of FIG. 4A will be described. Light source 3a
And the image light generated from the liquid crystal panel unit 2a, since the reflecting mirror 4 is rotated to the (b) side, goes straight on to the projection lens 1 and is enlarged and projected. The reflecting mirror 4 is freely rotated by a hinge portion 5 provided on one side. The light source unit 3b
And the image light generated from the liquid crystal panel unit 2b, since the reflecting mirror 4 is rotated to the (a) side,
For example, the light is reflected in a right angle direction, reaches the projection lens 1, and is enlarged and projected.

Next, an example of FIG. 4B will be described. Since the image light generated from the light source unit 3a and the liquid crystal panel unit 2a has the reflecting mirrors 4b and 4c on the (B) side and the (A) side, respectively, it proceeds straight and directly reaches the projection lens 1 and is enlarged and projected. You. The hinge 5 provided on one side of the reflecting mirrors 4b, 4c
To rotate freely. Each image light generated from the combination (b system, c system) of the light source units 3b, 3c and the liquid crystal panel units 2b, 2c is turned by the reflecting mirrors 4b, 4c to turn the respective liquid crystal panel units 2b, 2c. Is set at an angle of, for example, 45 degrees with respect to the optical axis passing therethrough, the light is reflected at right angles by the corresponding reflecting mirrors 4b and 4c, reaches the projection lens 1, and is enlarged and projected. The reflecting mirror 4b shown in FIG.
The position 4c is an example showing a case where an image on the liquid crystal panel unit 2b is reflected and supplied to the projection lens 1.

[0019]

As described above, the present invention provides a liquid crystal projector in which a plurality of display modes are all displayed at the same angle of view on a large screen. Therefore, a plurality of display modes of a personal computer using one liquid crystal projector, for example, VG
A (Video Graphics Array), SVGA (Super Video
Graphics Array) and XGA (eXtended Graphics)
Array) etc. are conventionally displayed in XGA, SVGA, V
Although the size of the display screen becomes smaller in the order of GA and it is difficult to see, there is a merit that an image of the same size can be obtained even if the display mode is changed.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an embodiment of a liquid crystal projector according to the present invention, which is a side sectional view (A) and a front view (B).

FIG. 2 is a conceptual view showing a second embodiment of the liquid crystal projector according to the present invention, which is a side sectional view (A) and a front view (B).
It is.

FIG. 3 is an enlarged view of a liquid crystal panel used in a third embodiment of the liquid crystal projector according to the present invention.

FIG. 4 is a conceptual diagram showing a fourth embodiment of the liquid crystal projector according to the present invention, in which an example (A) including two sets of a light source unit and a liquid crystal panel unit and an example (B) including three sets of the same. It is.

FIG. 5 is a conceptual diagram showing a configuration of an optical system of a conventional liquid crystal projector using one liquid crystal panel.

FIG. 6 is a diagram illustrating a projection principle of a liquid crystal projector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Projection lens 2, 2a, 2b, 2c Liquid crystal panel part 3, 3a, 3b, 3c Light source part 4, 4b, 4c Reflecting mirror 5 Hinge part 6 Optical axis 11 Projection lens 12 Same circumference 13 Motor 14 Rail 15 Disc-shaped holder 16 Plate holder 21, 22 Liquid crystal panel 23 Polarizing plate

Claims (9)

[Claims] 1. A liquid crystal projector comprising a light source, a liquid crystal panel and a projection lens, comprising a plurality of projection lenses having different focal lengths corresponding to display modes. 2. The liquid crystal projector according to claim 1, wherein the display modes are VGA, SVGA, and XGA. 3. A center of the projection lens on a disc-shaped holder pivotally supported by the liquid crystal projector main body so as to rotate about the central axis so that the plurality of projection lenses overlap a locus of an optical axis passing through the liquid crystal panel. 2. The liquid crystal projector according to claim 1, wherein the liquid crystal projector is installed in the projector. 4. The liquid crystal projector according to claim 3, wherein a central axis of said disc-shaped holder is driven by a motor. 5. A plurality of projection lenses are provided on a plate-shaped holder provided on a liquid crystal projector main body and moving in a direction perpendicular to an optical axis such that a center of the projection lens overlaps a locus of an optical axis passing through a liquid crystal panel. The liquid crystal projector according to claim 1. 6. A liquid crystal projector comprising a light source, a liquid crystal panel, and a projection lens, comprising a plurality of sets of the light source and the liquid crystal panel, and one projection lens.
A liquid crystal projector having a reflector for changing the direction of the optical path of the projection light. 7. The liquid crystal projector according to claim 6, wherein two sets of the light source and the liquid crystal panel are provided, and the reflecting mirror is pivotally supported on a side surface of the reflecting mirror. 8. The liquid crystal projector according to claim 6, wherein three sets of the light source and the liquid crystal panel are provided, and two reflecting mirrors are provided, and each of the reflecting mirrors is pivotally supported at a side surface. 9. A liquid crystal projector comprising a light source, a liquid crystal panel, and a projection lens, wherein a plurality of liquid crystal panels having different resolutions are cascaded.