JPH11102022A - Method for correcting optical path of liquid crystal projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correctly condense each light beam at a prism body by correcting the deviation of an optical path caused by the distortion of a chassis. SOLUTION: A liquid crystal projector possesses a light source 35, the chassis 3 housing total reflection mirrors 75, 76, 77 and 78 and dichroic mirrors 45 and 46 so as to make them inclined to the optical path and a fitting protrusion 8 which is positioned on the side of the light source 35 of respective total reflection mirrors 75 and 76 along the optical path in the inside of the chassis 3 and in which an adjustment mirror 5 reflecting light from the light source 35 is fitted, and the chassis 3 is molded of a synthetic resin. The adjustment mirror 5 is firstly fitted in the fitting protrusion 8 on the side of the light source 35, and initial adjustment of the light from the light source 35 to a position so as to follow a normal optical path is executed based on the light reflected by the adjustment mirror 5. Next, the adjustment mirror 5 is pulled out, and is fitted in the fitting protrusion 8 positioned on the side of the advancing direction of a one-stage optical path, so that the deviation of the total reflection mirrors 75, 76, 77 and 78 and the dichroic mirrors 45 and 46 from a normal position is detected from the deviation between incident light and outgoing light at the optical path entrance of the chassis 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for correcting an optical path of a liquid crystal projector having a total reflection mirror for reflecting light therein and a dichroic mirror for reflecting light of a specific color.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 8, three liquid crystal panels (7) corresponding to the three primary colors of light, R, G and B, are used.
A liquid crystal projector comprising (7a) and (7b), irradiating them with intense light from a light source (35), and combining the luminous flux passing through a liquid crystal panel to project an image has been proposed (Japanese Patent Application Laid-Open No. Hei 9 (1998)).
-61782). Inside the cabinet (6), total reflection mirrors (75) and (76) for reflecting light of all colors, dichroic mirrors (45) and (46) for separating each color by wavelength, and dichroic mirrors for synthesis (31) and (32) ) Are arranged obliquely with respect to the optical path direction. The blue light B is split by the dichroic mirror (45) near the light source (35), reflected by the total reflection mirror (75), irradiates the liquid crystal panel (7b) corresponding to B, and the two combining dichroic mirrors (31). ) (32) and enters the projection lens (67). Similarly, the green light G is split by the dichroic mirror (46), irradiates the liquid crystal panel (7) corresponding to G, and passes through the two combining dichroic mirrors (31) and (32). Red light R is a liquid crystal panel corresponding to R
After irradiating (7a), B, G, and R respectively enter the projection lens (67) through the total reflection mirror (76) and the dichroic mirror for synthesis (32). The image from the projection lens (67) is applied to a screen (68) as is well known.

[0003] The configuration of the liquid crystal projector is widely used, but in recent years, the size of the liquid crystal projector has been required to be reduced, and the liquid crystal panel and the dichroic mirror also need to be reduced in size. However, since the dichroic mirror has a flat plate shape, it tends to be warped when it is reduced in size and thickness. Therefore, while the light passes through a number of dichroic mirrors, each of the R, G, and B may not follow an accurate optical path, and the light may not be accurately combined with the projection lens (67). In view of this point, a liquid crystal projector shown in FIG. 10 has been proposed. FIG. 10 is an overall side view of the liquid crystal projector. Cabinet that covers the top of the LCD projector
A box-shaped chassis (3) for holding three liquid crystal panels is provided in (6), and a barrel of a projection lens (67) provided at a front end of the chassis (3) includes a cabinet ( 6) penetrates the front surface and projects outward. The chassis (3) is generally provided by molding a synthetic resin, and is compatible with mass production.

FIG. 9 is a plan view of the chassis (3). In the chassis (3), with the optical axis of the projection lens (67)
And liquid crystal panels (7a) and (7b) corresponding to B are provided facing each other, and a prism body (3) is provided between the liquid crystal panels (7a) and (7b).
0) is deployed. The prism body (30) has a reflective surface (31) (3
2) are provided orthogonal to each other, and a liquid crystal panel (7) corresponding to G is provided on the side of the prism body (30) opposite to the projection lens (67). The prism body (30) is formed by abutting the vertices of four triangular prisms, and the reflecting surfaces (31) (3)
2) is made by coating. A light source (35) is provided at an optical path entrance to the chassis (3), and a total reflection mirror (7) is provided on the optical path.
5) (76) (77) (78), dichroic mirrors (45) (46)
Like the liquid crystal projector of the above, it is arranged to be inclined in the optical path direction. The dichroic mirror (45) passes R, and the dichroic mirror (46) reflects G and passes B. At the back of the light source (35), a condenser lens (7
9) is deployed.

After the light from the light source (35) is reflected by the total reflection mirror (75), R passes through the dichroic mirror (45), and G and B are reflected by the dichroic mirror (45). R is reflected by the total reflection mirror (76) and irradiates the liquid crystal panel (7a) corresponding to R. R irradiating the liquid crystal panel (7a) is reflected by the reflecting surface (32) in the prism body (30).
The light is emitted toward the projection lens (67). 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
(67). B is reflected by the reflection surface (31) in the prism body (30) after being reflected by the total reflection mirrors (77) and (78), and is incident on the projection lens (67). Therefore, light can follow the optical path correctly as compared with the liquid crystal projector shown in FIG.

[0006]

Since the chassis (3) is provided by molding a synthetic resin, distortion and deformation may occur. Therefore, total reflection mirror (75) (76) (77) (78)
The mounting angle may deviate from the regular angle. As a result, the R, G, and B lights are not accurately collected on the prism body (30), and there is a possibility that illumination unevenness may occur in an image on the screen (68). SUMMARY OF THE INVENTION It is an object of the present invention to correct a deviation of an optical path due to a distortion of a chassis and accurately condense each light on a prism body.

[0007]

A method according to the present invention comprises a light source (35) and a total reflection mirror (7) for reflecting light from the light source (35).
5) A chassis in which dichroic mirrors (45) and (46) permitting the passage of any one of the three primary colors R, G, and B of the light (76), (77), (78) are inclined with respect to the optical path ( 3) and located near the light source (35) of each total reflection mirror (75) (76) (77) (78) along the optical path in the chassis (3), and reflects the light from the light source (35) And a fitting projection (8) into which an adjusting mirror (5) is fitted.
In (3), a liquid crystal projector formed by injection molding of a synthetic resin is provided. First, the adjusting mirror (5) is fitted to the fitting projection (8) closest to the light source (35), and reflected by the adjusting mirror (5). Based on the adjusted light, an initial adjustment for correcting the light from the light source (35) to a position where the light follows a regular optical path is performed.
(5) is pulled out, the adjusting mirror (5) is fitted into the fitting projection (8) located on the optical path traveling direction side with respect to the pulled-out fitting projection (8), and the adjustment mirror (5) is inserted at the optical path entrance of the chassis (3). The amount of deviation of the total reflection mirrors (75) (76) (77) (78) and the dichroic mirrors (45) (46) from the correct positions is detected based on the deviation between the incident light and the outgoing light, and adjusted according to the deviation amount. The total reflection mirrors (75) (76) (77) (78) and the dichroic mirrors (4
5) Modify the mounting location of (46).

[0008]

According to the present invention, once the adjusting mirror
(5) is fitted to the fitting projection (8), and the adjustment mirror is adjusted by a shift between the incident light and the outgoing light at the optical path entrance of the chassis (3).
The amount of deviation of the total reflection mirrors (75), (76), (77), (78) and the dichroic mirrors (45), (46) corresponding to (5) from the normal positions is detected. That is, the amount of deviation from the regular position is calculated for each of the total reflection mirrors (75) (76) (77) (78) and the dichroic mirrors (45) (46), and the chassis (3) is corrected. Reflective mirror (75) (76) (77) (78) and dichroic mirror (45) (4
The light reflected or passed through 6) can follow an accurate optical path.

[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 perspective view showing the bottom surface of the liquid crystal projector upside down. The LCD projector consists of a receiving base (60) and a cabinet (6).
As is well known, a projection lens (6) is provided from the cabinet (6).
7) is protruding. In the following description, the side provided with the projection lens (67) is referred to as the front, and the opposite side is referred to as the rear. At the front end of the lower surface of the receiving base (60), a hand-turnable adjustment tool (65) (65)
When the turning angle of the adjusters (65) and (65) is adjusted in the state shown in FIG. 2 in which the liquid crystal projector is placed on a desk,
(68) The irradiation state on the top can be changed. As shown in FIG. 1, three elongated projections (66), (66), (66) protrude from the rear end of the lower surface of the receiving base (60), and the projections (66), (66), (66) are a liquid crystal projector. It is arranged on a bulging arc facing the rear end. The liquid crystal projector has the protrusions (65) and (65)
It is supported on the tip surface of (66). Incidentally, the projections (66), (66), (66) may be connected integrally.

FIG. 3 is an overall perspective view of the cabinet (6). Inside the cabinet (6), a box-shaped chassis (3) is provided as before, and a projection lens (67) attached to the front end of the chassis (3) connects the front end of the cabinet (6). It penetrates and projects outside. Chassis (3) is mold
This is provided by injection molding of a synthetic resin using (25) (see FIG. 7). In FIG. 3, the description of the components in the chassis (3) is omitted. An opening (61) is formed on the top surface of the cabinet (6), and a lid (9) is detachably attached to the opening (61).

FIG. 4 is a plan view of the chassis (3). Total reflection mirror (75) (76) (77) (78), dichroic mirror (4
5) (46) and the arrangement of the prism body (30) are the same as those of the conventional liquid crystal projector shown in FIG. 9, and the total reflection mirror (75) (76)
(77) and (78) are attached inside the side surface of the chassis (3).
Through the reflecting surfaces (31) and (32) in the prism body (30), R, G,
Light transmitted through the B liquid crystal panel is accurately combined. In front of the condenser lens (79), between the dichroic mirror (45) and the total reflection mirror (76), the dichroic mirror
Between the (46) and the total reflection mirror (77) and between the total reflection mirror (77) and the total reflection mirror (78), a fitting projection (8) for attaching an adjustment mirror (5) described later is provided. It is provided on the side surface of the chassis (3). The fitting projection (8) forms a recess (80) at the center, and the side edge of the plate-shaped adjusting mirror (5) fits into the recess (80). The concave portion (80) of the fitting projection (8) is finished to an extremely accurate width and position by performing cutting or the like after forming the chassis (3). Therefore, there is almost no play in mounting the concave portion (80) and the adjusting mirror (5), and the relative position of the concave portion (80) with respect to the optical path hardly changes. Also, a fitting projection (8) is provided on the back side of each of the liquid crystal panels (7), (7a), (7b), but is omitted in FIG. 4 for convenience of explanation.

In FIG. 4, the liquid crystal panels (7), (7a), (7)
b) is indicated by a dashed line. Each liquid crystal panel (7) (7a) (7b)
Corresponds to a high number of pixels, and unless the R, G, and B lights passing through each liquid crystal panel are accurately combined, a correct image cannot be projected on the screen (68). However, since the chassis (3) is provided by injection molding of a synthetic resin, warping or distortion occurs after molding, and the total reflection mirror (75) is formed.
(76) (77) (78) and the dichroic mirrors (45) (46) may not be mounted at an accurate angle to the optical path. In view of this point, in this example, after the chassis (3) is formed, the adjusting mirror (5) is attached to the fitting projection (8), and the total reflection mirrors (75), (76), (77) are formed. ) (78), dichroic mirror (4
5) The amount of deviation of the mounting angle of (46) is detected, and the chassis (3) is corrected. The detailed procedure is shown below.

First, the mounting angle of the total reflection mirror (75) is detected. As shown in FIG. 5 (a), on the chassis (3), the adjusting mirror (5) is fitted to the fitting projection (8) located on the incident side of the mounting position of the condenser lens (79), and the total reflection mirror is mounted. (75) is attached to the chassis (3). Adjustable mirror
(5) is a total reflection mirror for reflecting all the received light, and its thickness is equal to the width of the recess (80). Thereafter, the light source (35a) is set at the entrance of the optical path of the chassis (3), and the light is irradiated. still,
In this case, the light source (35a) to be installed is a laser light source,
It is not a lamp light source used when using a liquid crystal projector.
If the light source (35a) is shifted from the proper mounting position, the light is reflected with a shift as shown in FIG. 5 (a), and the amount of deviation of the light source (35a) can be determined from the angle of reflection. Thereby, initial adjustment for correcting the original mounting position of the lamp light source (35) is performed.

Next, as shown in FIG. 5 (b), the adjusting mirror (5) is pulled out from the fitting projection (8) located in front of the condenser lens (79), and the dichroic mirror (45) and the total reflection mirror are extracted. The side edge of the adjustment mirror (5) is fitted to the fitting projection (8) between (76). The dichroic mirror (45) has not been installed yet. As described above, the fitting projection (8) between the dichroic mirror (45) and the total reflection mirror (76) is finished with high accuracy, and there is little possibility that the relative position with respect to the optical axis is shifted. The laser light source (35a) is irradiated again. If the total reflection mirror (75) is mounted at a position shifted from the normal position, the light is reflected with a shift as indicated by a chain line. light source
Since the position of (35) is previously adjusted to the regular position as described above, the deviation between the incident light and the outgoing light is a total reflection mirror (75).
It can be seen that this is caused by misalignment. Also, it can be seen that the shift angle θ between the incident light and the output light is twice as large as the mounting shift angle of the total reflection mirror (75). Therefore, the amount of angle to be corrected for the side surface of the chassis (3) on which the total reflection mirror (75) is mounted is obtained from the shift angle θ. Since the chassis (3) is provided by injection molding of a synthetic resin, the mold (25) may be modified in accordance with the obtained angle amount.

Next, the mounting angle of the dichroic mirror (45) is detected. The adjustment mirror (5) fitted in the fitting projection (8) between the dichroic mirror (45) and the total reflection mirror (76) is pulled out, and as shown in FIG. 6, the dichroic mirror (46) and the total reflection mirror ( The adjustment mirror (5) is fitted to the fitting projection (8) provided between the mounting positions of (77). When the laser light source (35a) is irradiated, the light is reflected by the total reflection mirror (75), R passes through the dichroic mirror (45), and G
And B are reflected. However, G and B are reflected by the adjusting mirror (5), and G and B are again returned to the dichroic mirror (45).
And it is reflected by the total reflection mirror (75) and returns to the light source (35a). The shift amount δ between the outgoing light and the incident light returned to the light source (35a) is
The total displacement mirror (75) and the dichroic mirror (45) are added with the amount of misalignment.
Since the mounting displacement of the dichroic mirror (45) is detected, the mounting displacement of the dichroic mirror (45) can be determined. By repeating the above operation, the amount of misalignment of the total reflection mirror (75) (76) (77) (78) and the dichroic mirror (45) (46) is known, and if the mold is corrected according to this, Chassis where the light from the lamp light source (35) used for the liquid crystal projector follows the regular optical path
(3) can be manufactured.

Here, as shown in FIG. 7, the mold (25) is a general one in which a fixed mold (2) and a movable mold (20) are abutted, and is opened in the fixed mold (2). Both types from gate (21)
(2) Pour the molten metal into the space (22) between the (20). After cooling, when the movable mold (20) is lowered, a molded product is created. The above mold (2
The modification of (5) means that the space (22) in the movable mold (20) serving as the side wall of the chassis (3) is modified, and the total reflection mirror (75) (76) (77) (7)
8) and dichroic mirrors (45), (46) refer to the chassis (3) which is mounted in a proper position.

The following method can be used to detect the mounting angle of the dichroic mirror (45). As shown in FIG. 6, a chassis with a total reflection mirror (75) attached
The through hole (36) is opened in the side wall of (3), and the laser light source (35a) is installed outside the side wall without attaching the total reflection mirror (75). The adjusting mirror (5) is fitted to the fitting projection (8) provided between the mounting positions of the dichroic mirror (46) and the total reflection mirror (77).
May be fitted to determine the mounting displacement of the dichroic mirror (45). In this case, the light source (35) is a light source indicated by a solid line in FIG.
It is necessary to set the position correctly shifted by 90 degrees from the position of (35a), that is, the position shown by the dashed line.

In the method according to the present embodiment, the adjusting mirror (5) is once fitted to the fitting projection (8), and the adjustment is performed by a shift between the incident light and the outgoing light at the optical path entrance of the chassis (3). The amount of deviation of the total reflection mirrors (75) (76) (77) (78) and the dichroic mirrors (45) (46) corresponding to the mirror (5) from their normal positions is detected. That is, the amount of deviation from the regular position is calculated for each of the total reflection mirrors (75) (76) (77) (78) and the dichroic mirrors (45) (46), and the chassis (3) is corrected. Reflective mirror (75) (76) (77) (78) and dichroic mirror (45)
The light reflected or passed by (46) can follow an accurate optical path. Since the concave portion (80) of the fitting projection (8) is finished by cutting or the like, the total reflection mirrors (75), (76), (7)
It is conceivable that the attachment points of 7) (78) and the dichroic mirrors (45), (46) may be finished by cutting or the like. However, in this example, the number of cutting processes etc.
The feature of the modification of (25) is that the light from the lamp light source (35) is accurately traced.

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 perspective view illustrating a bottom surface of a liquid crystal projector when the projector is turned upside down.

FIG. 2 is a side view showing an irradiation state of the liquid crystal projector.

FIG. 3 is an exploded perspective view of a liquid crystal projector and a lid.

FIG. 4 is a plan view of the chassis.

5A and 5B are plan views of a main part of the chassis, in which FIG. 5A shows an initial adjustment, and FIG. 5B shows an adjustment of a total reflection mirror near an optical path entrance of the chassis.

FIG. 6 is a plan view of a main part of the chassis, showing adjustment of a dichroic mirror near an optical path entrance of the chassis.

FIG. 7 is a sectional side view of a mold.

FIG. 8 is a side view of a conventional liquid crystal projector.

FIG. 9 is a front view of a chassis of the liquid crystal projector of FIG.

FIG. 10 is a side view of another conventional liquid crystal projector.

[Explanation of symbols]

 (3) Chassis (5) Adjustment mirror (8) Mating protrusion (25) Mold (35) Light source (45) Dichroic mirror (46) Dichroic mirror (75) Total reflection mirror (76) Total reflection mirror (77) All Reflection mirror (78) Total reflection mirror

Claims (2)

[Claims] 1. A light source (35), a total reflection mirror (75) (76) for reflecting light from the light source (35), and a light of any one of the three primary colors R, G and B. Dichroic mirrors (45) (46)
And a chassis (3) in which the light is tilted with respect to the optical path, and the total reflection mirrors (75) and (76) are located near the light source (35) along the optical path in the chassis (3). A fitting projection (8) into which an adjusting mirror (5) for reflecting light from
In (3), a liquid crystal projector formed by injection molding of a synthetic resin is provided. First, an adjusting mirror (5) is provided on the fitting projection (8) closest to the light source (35).
And based on the light reflected by the adjusting mirror (5), perform initial adjustment to correct the light from the light source (35) to a position where the light follows a regular optical path, and pull out the adjusting mirror (5). Pulled-out mating protrusion
The adjusting mirror (5) is fitted to the fitting projection (8) located on the optical path advancing direction side of (8), and a total reflection mirror is formed by a shift between the incident light and the outgoing light at the optical path entrance of the chassis (3). (75) (7
6) (77) (78) and the amount of deviation of the dichroic mirrors (45) and (46) from their normal positions are detected, and in accordance with the amount of deviation, the total reflection mirrors (75) and (76) of the chassis (3) are detected. (77) (78) An optical path correcting method for a liquid crystal projector for correcting a mounting position of a dichroic mirror (45) (46). 2. The chassis (3) is provided by injection molding of a synthetic resin into a mold (25), and a total reflection mirror of the chassis (3) is provided.
(1) The correction of the mounting position of the (75), (76), (77), (78) and the dichroic mirror (45), (46) is performed by correcting the position of the mold (25) corresponding to the mounting position. 3. The method for correcting an optical path of a liquid crystal projector according to claim 1.