JP2000039591A - Projection device provided with polarizing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform turning adjustment of a polarizing plate with a simple mechanism in a projection device provided with the mechanism turning/adjusting the polarizing plate opposite to a liquid crystal panel. SOLUTION: This projection device is provided with liquid crystal panels 7, 7a, 7b respectively corresponding to three primary colors R, G, B of light and polarizing plates 73 opposite to the respective liquid crystal panels 7, 7a, 7b in a chassis 3. The lower end part of the polarizing plate 73 is pivoted on the chassis 3, and a moving member 9 orthogonally crossing the optical axes of the liquid crystal panels 7, 7a, 7b and horizontally moving in the surface perpendicular to the chassis 3 surface is brought in contact with both side surfaces of the polarizing plate 73.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection device having a mechanism for rotating and adjusting a polarizing plate facing a liquid crystal panel.

[0002]

2. Description of the Related Art Conventionally, three primary colors of light, R, G, B
A liquid crystal projector that is equipped with three liquid crystal panels (7), (7a), and (7b) corresponding to, irradiates them with strong light from a light source (35), and combines the luminous flux passing through the liquid crystal panel to display an image Has been proposed. FIG. 4 is a plan view of the projection device. In the chassis (3), liquid crystal panels (7a) and (7b) corresponding to R and B are provided with the optical axis of the projection lens (67) interposed therebetween, and between the liquid crystal panels (7a) and (7b). A prism body (30) is provided. A liquid crystal panel (7) corresponding to G is provided on the opposite side of the projection lens (67) across the prism body (30). A light source (35) is provided at the light path entrance to the chassis (3), and a total reflection mirror (75) (76) (77) (78) and a dichroic mirror (45) (46) are provided on the light path. It is deployed inclined to it.

After the light from the light source (35) is reflected by the total reflection mirror (75), the dichroic mirror (45) permits the passage of R and reflects G and B. R is a total reflection mirror (76)
The liquid crystal panel (7a) corresponding to R is reflected by the liquid crystal panel, and is radiated toward the projection lens (67) by the prism body (30). G is reflected by the dichroic mirror (46) and enters the prism body (30), and the incident light passes through the prism body (30) as it is and enters the projection lens (67). After being reflected by the total reflection mirror (77), B is reflected by the combining mirror (31) in the prism body (30) and enters the projection lens (67).

[0004] Two polarizing plates (73) and (74) are opposed to each other with the liquid crystal panels (7), (7a) and (7b) interposed therebetween. As is well known, the polarizing plates (73) and (74) allow one of two polarized light beams orthogonal to each other to pass, and both polarizing plates (73) and (74) have a vibration plane of the polarized light that allows the passing. They are shifted 90 degrees from each other. Fig. 5 (a), (b)
FIG. 4 is an exploded perspective view of two polarizing plates (73) and (74) and a liquid crystal panel (7). LCD panel
(7) is an alignment groove formed by enclosing liquid crystal in transparent display substrates (70) and (71), and recessed in opposing surfaces of both display substrates (70) and (71).
(55) and (56) are shifted from each other by 90 degrees. Both display boards (70)
When (71) is overlapped, a large number of small spaces partitioned by the alignment grooves (55) and (56) are formed, and the liquid crystal molecules (57) are confined in a twisted state in each small space.

If there is no electric field between the display substrates (70) and (71), FIG.
As shown in (a), the polarized light that has passed through the polarizing plate (73) on the incident side passes through the polarizing plate (74) on the emitting side while being bent by 90 degrees due to the twist of the liquid crystal molecules (57). Accordingly, the image is displayed brightly, that is, white on the liquid crystal panel (7). Display board (70)
When an electric field is applied between (71), the liquid crystal molecules (57) are aligned vertically as shown in FIG.
The polarized light that has passed through passes through the gap between the liquid crystal molecules (57). Since the polarized light is blocked by the polarizing plate (74) on the emission side, it is displayed in black on the liquid crystal panel (7). The liquid crystal panel (7) displays an image by switching the presence or absence of an electric field for each small space. still,
As shown in FIG. 6, in general, the polarizing plates (73) and (74) often have a polarizing plate (58) attached to a glass plate (59).

[0006]

In recent years, there has been a demand for higher density images. In such an apparatus for projecting a high-density image, it is necessary to sharpen the contrast between the black and white of the projected image and to clearly project the image. However, FIG.
In some of the polarizing plates (73) and (74), a polarizing film (58) is attached to the glass plate (59) by being erroneously inclined. As shown in FIG. 7, the polarizing film (58) is cut out from the film sheet (54) to a required size. There are things. Such a polarizing plate (73) (7
In 4), since the polarization directions are not exactly orthogonal to each other, light that should be cut off is allowed to pass therethrough. Is projected. By rotating and adjusting at least one of the polarizing plates in a plane perpendicular to the optical axis and perpendicular to the chassis (3), an image with a clear contrast between black and white is projected and rotated. The idea was to simplify the adjustment mechanism. An object of the present invention is to perform rotation adjustment of a polarizing plate with a simple mechanism.

[0007]

[MEANS FOR SOLVING THE PROBLEMS] A liquid crystal panel of a projection device (7)
(7a) The lower end of at least one of the polarizing plates (73) facing the (7b) is pivotally supported by the chassis (3) and is rotatably supported in the plane of the polarizing plate (73). On both sides of the plate (73),
Perpendicular to the optical axes of the liquid crystal panels (7), (7a) and (7b),
(3) A moving member (9) that moves horizontally in a plane perpendicular to the upper surface is in contact with the upper surface.

[0008]

Since the moving member (9) moves only in the horizontal direction, at least one of the polarizing plates (73) pivotally supported by the chassis (3) is pushed by the moving member (9), and the optical axis is moved. In a plane perpendicular to the upper surface and perpendicular to the upper surface of the chassis (3). By rotating the polarizer (73) in a plane perpendicular to the optical axis and perpendicular to the upper surface of the chassis (3), the polarization directions of the polarizers (73) and (74) are exactly orthogonal to each other, and The cut-off and passage of is switched exactly. Thereby, an image with a clear contrast between black and white is emitted. Further, since the rotation of the polarizing plate (73) can be adjusted only by moving the moving member (9) horizontally, the adjustment work becomes easy.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an example of the present invention will be described in detail with reference to the drawings. The same components as those of the related art are denoted by the same reference numerals, and detailed description thereof is omitted. FIG. 1 is a plan view of the chassis (3). Light source (35), total reflection mirror (75) (76) (77) (7
8), the arrangement of the dichroic mirrors (45) and (46), and the arrangement of the prism body (30) are the same as in the prior art. Liquid crystal panel (7) (7a) (7b)
A first polarizing plate (73) is provided on the incident side, and a second polarizing plate is provided on the outgoing side.
(74) are respectively provided, and the second polarizing plate (74) is a prism body (30).
Is pasted on. In this example, the first polarizing plate (7
There is a feature in the structure that adjusts the rotation of 3).

The first polarizing plate (73) is attached to a partition wall (36) of the chassis (3), and a moving member (9) is fitted on an upper end portion. In FIG. 1, the moving member (9) is attached only to the first polarizing plate (73) through which the R light passes, but the moving member (9) is also moved to the first polarizing plate (73) through which the G light and B light pass. The member (9) is attached. FIG. 2 is an exploded perspective view of the first polarizing plate (73) and the moving member (9). An opening (37) is opened in the partition wall (36), and the first polarizing plate (73) covers the opening (37). A hook piece (34) projects outward from the lower end of the opening (37), and the hook piece (34) contacts the lower edge of the first polarizing plate (73). Accordingly, the downward movement of the first polarizing plate (73) is restricted, and the first polarizing plate (73) can rotate around the contact point with the hooking piece (34) in the plane including the first polarizing plate (73). On both sides of the opening (37), the receiving wall (3
8) and (38) are provided, and the opposing inner surfaces of the receiving walls (38) and (38) are inclined such that the lower ends approach each other.

The moving member (9) is formed by bending a metal plate, and the holding pieces (91) (91) contacting both side surfaces of the first polarizing plate (73).
And a sliding plate (90) in contact with the top surface of the partition wall (36), and an elastic piece (92) extending obliquely downward from the sliding plate (90). The sliding plate (90) is provided with a through hole (93) through which the fixing screw (8) penetrates with a margin, and a long hole (94). Partition wall
A screw hole (39) into which the fixing screw (8) is screwed is formed on the top surface of (36), and a protruding shaft (33) that fits into the long hole (94) protrudes.

FIG. 3A shows a first polarizing plate 73 and a moving member.
FIG. 3 is a front view showing a state where (9) is attached to a partition wall (36).
(b) is a plan view thereof. With the sliding plate (90) in contact with the top surface of the partition wall (36) and the holding pieces (91) and (91) positioned in front of the partition wall (36), the fixing screw (8) is attached to the sliding plate ( The screw (39) is screwed into the screw hole (39) through the through hole (93) of the partition (90), and the protruding shaft (33) of the partition wall (36) is fitted in the elongated hole (94). The elastic piece (92) is the first polarizing plate (73)
Downward, and the lower end surface of the first polarizing plate (73) is
It is pressed against the hooking piece (34) of (36). First polarizing plate (73)
A slight gap is formed between the side surface of the first polarizing plate and the receiving walls (38), (38), and a very small amount of rotation of the first polarizing plate (73) is allowed. A notch (95) is formed at the rear end of the sliding plate (90) of the moving member (9), and the notch (95) is formed in a recess (25) formed in the top surface of the partition wall (36). ).

(Rotation Adjustment of Polarizing Plate) When adjusting the rotation of the polarizing plate, the fixing screw (8) is loosened in advance. As shown by a dotted line in FIG. 3B, a jig (26) such as a driver is inserted across the notch (95) and the recess (25), and the moving member (9) is moved right and left. As shown in FIG. 3 (a), the lower end of the polarizing plate (73) and the receiving wall
(38) The gap between the inner surface is small, and the gap between the center of the polarizing plate (73) in the vertical direction and the upper end of the receiving wall (38) is large. Accordingly, when the polarizing plate (73) is moved right and left, the polarizing plate (73) rotates around the contact point with the hooking piece (34) while the lower end contacts one of the receiving walls (38). The polarizing plate (73) is urged toward the hooking piece (34) by the elastic piece (92), and the polarizing plate (73) and the hooking piece are
Contact with (34) will not be lost. The actual rotation adjustment of the polarizing plate is performed while turning on the light source (35) in FIG. 1 and observing the black and white contrast of the screen on the screen. When the rotation adjustment is completed, the fixing screw (8) is tightened. By rotating the polarizing plate (73), the polarization directions of the polarizing plates (73) and (74) can be made orthogonal to each other accurately, and the cutoff and the passage of light can be accurately switched. As a result, an image in which the contrast between black and white is clear is projected.

In the apparatus according to this embodiment, the moving member
Insert the jig (26) from above toward (9) and move the moving member (9).
If the is moved right and left, the rotation of the polarizing plate (73) can be adjusted, so that workability is good. Further, the rotation of the polarizing plate (73) can be adjusted by a simple mechanism. In addition, instead of receiving the lower end of the polarizing plate (73) with the hooking piece (34), a partition wall (not shown) separates the partition wall.
You may pivot on (36).

The description of the above embodiments is for the purpose of illustrating the present invention and should not be construed as limiting the invention described in the appended claims or reducing the scope thereof. Further, the configuration of each part of the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made within the technical scope described in the claims.

[Brief description of the drawings]

FIG. 1 is a plan view of a projection device.

FIG. 2 is an exploded perspective view of a mechanism for adjusting a polarizing plate.

3A is a front view of a mechanism for adjusting a polarizing plate, and FIG. 3B is a plan view of the same.

FIG. 4 is a plan view of a conventional projection device.

5A and 5B are exploded perspective views of a liquid crystal panel, wherein FIG. 5A shows a state where no electric field is applied between display substrates, and FIG. 5B shows a state where an electric field is applied between display substrates.

FIG. 6 is a front view of a display substrate.

FIG. 7 is a plan view of a film sheet, showing cut-out lines of a polarizing film.

[Explanation of symbols]

 (3) Chassis (7) Liquid crystal panel (9) Moving member (38) Receiving wall (73) Polarizing plate (74) Polarizing plate (92) Elastic piece

Claims (2)

[Claims] 1. In a chassis (3), three primary colors of light R, G,
In a projection apparatus comprising a liquid crystal panel (7), (7a) and (7b) corresponding to B, and a polarizing plate (73) and (74) opposed to each liquid crystal panel (7) (7a) (7b), The lower end of at least one polarizing plate (73) is pivotally supported by the chassis (3), and is rotatably supported in the plane of the polarizing plate (73). , Liquid crystal panels (7) (7a) (7b)
And a moving member (9) that moves horizontally in a plane perpendicular to the optical axis and perpendicular to the surface of the chassis (3). 2. A receiving member (38) for restricting excessive tilting and rotation of a polarizing plate (73) is provided on a chassis (3).
(9) has an elastic piece (9) for urging the polarizing plate (73) toward the pivot.
2. The projection device according to claim 1, wherein 2) is provided.