JP3326373B2 - Projection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a projection device for projecting an image displayed on a liquid crystal panel or the like onto a screen.

[0002]

2. Description of the Related Art Conventionally, there has been proposed an apparatus for projecting an image on a screen by using a convex lens body in which a plurality of convex lenses are arranged vertically and horizontally (see JP-A-5-346557 G02B27 / 00). FIG. 3 is a plan view of the device. This is a liquid crystal panel (10) in a cabinet (20) on a substantially rectangular shape.
(10a) (10b) and various lenses, the liquid crystal panel (10) (1
0a) and (10b) are projected on a screen by the light of a lamp (1) as a light source. Light from the lamp (1) is reflected by a reflector (2), which is a concave mirror, and passes through a filter (3) for removing infrared rays and ultraviolet rays, and the two convex lens bodies (4) and (5) and a condenser lens Light is collected by (6). The convex lens bodies (4) and (5) are formed by arranging a plurality of convex lenses (50) vertically and horizontally (see FIG. 4), and the light collected by the condenser lens (6) is reflected by a total reflection mirror (7). Flip 90 degrees. The total reflection mirror (7) is arranged at an angle to the optical path on the inner surface of the cabinet (20) of the apparatus, and only red light is allowed to pass through the first dichroic mirror (8). The red light is reflected by a total reflection mirror (70) located at the back of the cabinet (20), is collected by a condenser lens (9), and irradiates a liquid crystal panel (10) for red light. Similarly, the green light is reflected by the second dichroic mirror (80) and irradiates the liquid crystal panel (10a) for green light, and the blue light passes through the relay lenses (11) and (11a) and is totally reflected by the mirror ( 72) and then reflected by the liquid crystal panel for blue light (1
0b). The light illuminating each of the liquid crystal panels (10), (10a), and (10b) is transmitted by a green light and is synthesized by a dichroic prism (12) that reflects blue light and red light.
At (13), the image is enlarged and projected on the screen (30).

In the above projector, the convex lens body (4)
FIG. 5 shows the principle of obtaining a projection image without luminance unevenness by combining two (5). For convenience of explanation, the description of a dichroic mirror or the like is omitted. In FIG. 5, the convex lens body (4) on the lamp (1) side is a first convex lens body, and the convex lens body (5) on the projection lens (13) side is a second lens body. The convex lens (5) located at the center of the first convex lens body (4)
0) is incident on the second convex lens body as shown by the solid line.
The light enters the convex lens (50) located at the center of (5). Also, the convex lens (5) distant from the center of the first convex lens body (4)
0) is incident on the second convex lens body as indicated by the dotted line.
Focusing is performed by the convex lens (50) located away from the center of (5). After all of the light passes through the condenser lens (6), the entire surface of the liquid crystal panel (10) is illuminated, whereby a projection image without uneven brightness is obtained.

The following relationship holds for the optical system of this projection device. As shown in FIG. 6, the distance from the liquid crystal panel (10) to the entrance pupil of the projection lens (13) is L1,
Assuming that the distance from (10) to the condenser lens (6) is L2 and the radius of the entrance pupil is R1, the radius R2 of the range of light rays that can enter the entrance pupil is as follows. R2 = a × R1 × L2 / L1 (a is a constant of about 0.85 to 0.95 and is a value in consideration of the refractive index of the condenser lens) (1) To make many rays incident on the entrance pupil, the equation (1) is used. To L2
It turns out that the longer is better. FIG. 7 shows the relationship between L2 and the light beam entering the entrance pupil.

However, when L2 becomes large, the liquid crystal panel (1
The amount of light incident on 0) decreases. This is shown below. As shown in FIG. 8, the vertical half distance of the display section of the liquid crystal panel (10) is DL, and one convex lens (5) of the first convex lens body (4) is provided.
0) is the radius of D1, and the focal length of the one convex lens (50) is F.
1. The distance between the condenser lens (6) and the second convex lens body (5) is L3
Then, D1 / F1 = b × DL / (L2 + L3) (b is a constant of about 1.1 to 1.25 and a value in consideration of the refractive indexes of the condenser lens (9) and the condenser lens (6)). The relationship is established. Here, D1 / F1 is the tangent amount (tan) of the inclination angle (θ in FIG. 8) of the light incident on the second convex lens body (5).
θ), all of the light incident on the second convex lens body (5) does not perpendicularly enter the second convex lens body (5), and some light enters obliquely. That is, if D1 / F1 is large, the range in which light incident obliquely can be used is expanded. Therefore,
From equation (2), it is sufficient that L2 is small. FIG. 9 shows the relationship between the distance L2 and the light beam incident on the liquid crystal panel (10).

[0006]

The relationship between the brightness of the projected image on the screen (30) and the distance L2 is shown in FIG. 10 which is a graph obtained by combining the graphs of FIGS. 7 and 9 and FIG.
There is a peak of the illuminance of the screen (30) in a certain section indicated by A and B. The applicant has prototyped a projection device in which a total reflection mirror (7) for inverting and reflecting light by 90 degrees is installed between the lamp (1) and the first dichroic mirror (8) (see FIG. 3).
In the prototype device, a 1.3-inch liquid crystal panel (10) was used, the F number (the value obtained by dividing the focal length by the diameter of the entrance pupil) of the projection lens (13) was 2.8, and the lamp (1) was used. ) In the optical path direction is 3.5 mm, and the focal length of the reflector (2) is 12 m.
When simulated as m, L2 is 150-16
The screen illuminance becomes maximum at about 0 mm. In other words,
A in FIG. 10 was 150 mm and B was 160 mm.

However, in designing such a projection device,
The size of each component on the optical path is almost determined by the size of the lamp (1). That is, when the total reflection mirror (7) and the dichroic mirror (8) are too small, a so-called phenomenon of causing a part of light to fall off the mirror occurs. When a lamp (1) having the same size as the projection device prototyped by the applicant is used, the optimum value of L2 is about 190 to 230 mm, which is longer than the value at which the screen illuminance is maximized. That is, in the projection device shown in FIG. 3, the position of the liquid crystal panel (10) at which the screen illuminance is maximized is the position of the cabinet (20).
The position of the liquid crystal panel (10) where the screen illuminance is maximized does not coincide with the position of the liquid crystal panel (10) where light is not shaken because it is on the total reflection mirror (70) located at the back of the panel. Here, the applicant has conceived of making L2 small and L3 large so that the position where the screen illuminance is maximum and the position where light is not blurred are close to each other. Increasing L3 requires a condensing lens in the projector of FIG.
(6) is to be installed at a position to cover the total reflection mirror (7). However, the total reflection mirror (7) is the equipment cabinet.
Since it is provided inside (20), it is a total reflection mirror.
(7) cannot be eliminated. The present invention relates to a projection apparatus having a total reflection mirror that reflects light 90 degrees between a condenser lens and a liquid crystal panel, in which a position where the screen illuminance is maximized and a position where light is not shaken are approached. To obtain a bright projected image.

[0008]

[Means for Solving the Problems] In a cabinet (20), a lamp (1) as a light source and a plurality of convex lenses (50) (50) arranged in a depth side of the lamp (1) are arranged vertically and horizontally. And first and second convex lens bodies (4) for condensing light from the lamp (1).
(5), a total reflection mirror (7) provided on the inner side surface of the cabinet (20) for inverting the light transmitted through the biconvex lens bodies (4) and (5) by 90 degrees, and the total reflection mirror (7) Dichroic mirror (8) for dispersing reflected light and cabinet
A liquid crystal panel (10) located at the back of (20) and irradiated with light dispersed by the dichroic mirror (8),
A projection device in which a condenser lens (6) is provided between the convex lens body (5) located near the total reflection mirror (7) and the total reflection mirror (7) among the biconvex lens bodies (4) and (5). In the total reflection mirror
A condenser lens (60) is provided on the optical path between (7) and the dichroic mirror (8), and both condenser lenses (6) are formed by the condenser lens (60) and the condenser lens (6). 6) One condenser lens (6) at the installation position of the total reflection mirror (7) located between (60)
Is supposed to be provided, and the convex reflection near the total reflection mirror (7) is assumed.
The length L3 from the lens body (5) to the condenser lens (6) is substantially
Has the effect of extending .

[0009]

[Operation and effect] Between the convex lens body (5) and the total reflection mirror (7) located near the total reflection mirror (7) and between the total reflection mirror (7) and the dichroic mirror (8), respectively. By arranging condenser lenses (6) and (60), total reflection mirror
There is an effect that it is assumed that a condenser lens is provided at the installation position of (7). That is, even in a projection device in which the total reflection mirror (7) cannot be moved, the convex lens body shown in FIG.
Since the length of L3, which is the length from (5) to the condenser lens (6), can be substantially extended, the value of L2 at which the screen illuminance is maximized is brought close to the value of L2 at which light is not blurred. And a bright projection image can be obtained.

[0010]

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 projection device. As in the prior art, the light from the lamp (1) is reflected by an arc-shaped reflector (2) and passes through a filter (3) for removing infrared rays and ultraviolet rays, thereby forming two convex lens bodies (4).
The light is condensed by (5) and the condenser lens (6). Condenser lens
The light collected by (6) is reflected by the total reflection mirror (7) to 9
Flip 0 degrees. The total reflection mirror (7) is disposed at an angle with respect to the optical path on the inner surface of the cabinet (20) of the apparatus, and the reflected light passes through the condenser lens (60) and is converted into red light by the first dichroic mirror (8). Only allowed to pass.

The red light is reflected by a total reflection mirror (70) located at the back of the cabinet (20) and is reflected by a prism (12).
Incident on. Green light is the second dichroic mirror (80)
Irradiates the liquid crystal panel (10a) for green light and is incident on the prism body (12), and the blue light is reflected by the relay lens.
(11) After passing through (11a) and being reflected by the total reflection mirror (72), the liquid crystal panel (10b) for blue light is irradiated. Each light is combined by the prism body (12) and reflected toward the projection lens (13). The projection direction of the projection lens (13) is the same as the direction in which the light passing through the second convex lens body (5) is reflected by the total reflection mirror (7).

In this embodiment, a first dichroic mirror (8) for splitting red light and a total reflection mirror (7)
A condenser lens (60) is provided. A condensing lens is provided between the birefringent lens body (4) and the second convex lens body (5) near the total reflection mirror (7) and the total reflection mirror (7).
Since (6) is provided, the second convex lens body (5) and the first
Two condensing lenses between the dichroic mirrors (8)
(6) and (60) are provided. The focal lengths of the two condenser lenses (6) and (60) may be the same or different from each other, but are longer than the conventional condenser lens (6) shown in FIG.

When the two condenser lenses (6) and (60) are arranged apart from each other on the optical path, as shown in FIG. 2, the light is condensed between the two condenser lenses (6) and (60). It is known that the same effect as providing the lens (6) can be obtained. That is, the focal points of the two condenser lenses (6) and (60) are
(6) A condenser lens provided at a virtual position indicated by a dotted line between (60) and (60).
The position is the same as the focal point according to (6). This means that in the conventional projector shown in FIG. 3, the condenser lens (6) located near the second convex lens body (5) can be moved to a position where the condenser lens (6) covers the total reflection mirror (7). This means that the same effect is obtained, and the value of L2 in FIG. 8 can be substantially reduced. In other words, in order to prevent the light shading phenomenon, the value of L2 was about 190 to 230 mm in the apparatus prototyped by the applicant, but the two condenser lenses (6) (60) ) Can be used to substantially reduce the value of L2 and approach the ideal value.

[0014] In the apparatus shown in FIG. 3 which is a conventional apparatus, the applicant has a focal length of 155 mm at a position of L2 = 155 mm.
An experiment was conducted with the aim of obtaining the same effect as providing the condenser lens (6). As a result, the focal length becomes 27
It has been found that the effect can be obtained by using two 0 mm lenses and installing them at a distance of 75 mm from each other. It is to be noted that the purpose of this embodiment is to obtain the same effect as installing the condenser lens (6) at the installation position of the total reflection mirror (7) for reversing the optical path by 90 degrees as described above. Therefore, as shown in FIG. 11, the second convex lens body (5) and the dichroic mirror
Total reflection mirror that reverses the optical path by 90 degrees between (8) and
For a projection device not provided with (7), there is no restriction on the movement of the condenser lens (6) on the optical path, so that the technical effect according to this example is small. However, the projection device shown in FIG. 11 has a large depth from the lamp (1) to the projection lens (13),
There is a problem that the size becomes larger than that of the projection device shown in FIG.

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 explanatory diagram showing a state where it is assumed that a condenser lens is provided at a virtual position between two condenser lenses.

FIG. 3 is a plan view of a conventional projection device.

FIG. 4 is a perspective view of a convex lens body.

FIG. 5 is a diagram showing a state of incidence on a projection lens.

FIG. 6 is a diagram showing a state of incidence on a projection lens.

FIG. 7 is a graph showing a relationship between a distance L2 and a light flux amount entering an entrance pupil.

FIG. 8 is a diagram showing an irradiation state of a liquid crystal panel.

FIG. 9 is a graph showing a relationship between a distance L2 and a light beam entering a liquid crystal panel.

FIG. 10 is a graph showing a relationship between a distance L2 and screen illuminance.

FIG. 11 is a plan view of a projection device without a total reflection mirror.

[Explanation of symbols]

 (1) lamp (4) first lens body (5) second lens body (6) condenser lens (7) total reflection mirror (8) total reflection mirror (10) liquid crystal panel (20) cabinet (50) convex lens ( 60) Condensing lens

Claims (2)

(57) [Claims] 1. A lamp (1), which is a light source, and a plurality of convex lenses (50) (50) disposed in the cabinet (20) in a vertical direction and a horizontal direction. First and second convex lens bodies (4) and (5) for condensing light from (1), and light transmitted through the biconvex lens bodies (4) and (5) provided on the inner surface of the cabinet (20). A total reflection mirror (7) for inverting 90 degrees, a dichroic mirror (8) for dispersing light reflected by the total reflection mirror (7), and a dichroic mirror (8) located at the back of the cabinet (20). ) And a liquid crystal panel (10) illuminated with light split by the
(5) A convex lens body located near the total reflection mirror (7)
In a projection device provided with a condenser lens (6) between (5) and a total reflection mirror (7), an optical path is provided between the total reflection mirror (7) and the dichroic mirror (8). A condenser lens (60) is provided, and the condenser lens (60) and the condenser lens (6) are used to position a total reflection mirror (7) located between the condenser lenses (6) and (60). one condenser lens (6) is fictitious and provided, all
Converging lens from convex lens body (5) near reflecting mirror (7)
(6) A projection device having an effect of substantially extending the length L3 up to . 2. A liquid crystal panel (1) is provided in the cabinet (20).
A projection lens (13) for projecting the light irradiated to the screen (30) toward the screen (30) is provided, and the light reflected by the total reflection mirror (7) is directed in the same direction as the projection direction of the projection lens (13). The projection device according to claim 1.