JP2008033291A - Projection device - Google Patents

Abstract

To provide a projection device capable of disposing optical members necessary to suppress various aberrations while ensuring miniaturization and thinning.
A projection device generates an image and projects it toward a screen, and a first deflection that deflects a light beam emitted from the projection optical system in a direction away from the screen in the depth direction of the projection device. Means, a second deflecting means for deflecting the light beam deflected by the first deflecting means toward the top plate surface of the projection apparatus while correcting the aberration, and a second deflecting device arranged along the top plate surface. And a third deflecting unit that deflects the light beam deflected by the deflecting unit toward the screen, and includes a straight line that passes through the center of the screen of the projection apparatus in a normal use state and extends in the vertical direction. In the cross section, the optical path of the lowermost incident light beam that is incident on the lowermost part of the screen among the light beams reflected by the second deflecting means is substantially parallel to the screen It was on the configuration.
[Selection] Figure 1

Description

  The present invention relates to an oblique projection type projection apparatus that projects a display image of a display body obliquely on a screen.

  2. Description of the Related Art Conventionally, an oblique projection type projection apparatus that projects an image displayed on a display body obliquely on a screen without causing trapezoidal distortion is known. Such an oblique projection type projection apparatus has a configuration suitable as a so-called rear projector capable of projecting a display image from behind the screen and observing the image from the front of the screen, for example. Note that when simply referred to as a projection device in the present specification, it means an oblique projection type projection device.

  In general, a projection apparatus includes a projection optical system that generates a projection image, and a mirror that deflects a light beam emitted from the projection optical system and guides it to a screen. The mirror can be installed inside the apparatus at a position facing the screen (front of the apparatus), that is, on the back side of the apparatus. However, when a mirror is provided on the back side of the apparatus, light incident from the outside of the apparatus through the screen may be reflected by the mirror and become a stray light component. Therefore, in order to avoid the generation of the stray light component, it has been proposed to dispose the mirror on the top plate side of the apparatus, in other words, above the image projected on the screen. Such a projection apparatus is described in Patent Document 1 below, for example.

JP 2005-43681 A

  Here, in the projection apparatus, it is necessary to properly correct various aberrations such as distortion. In order to satisfactorily correct the above aberrations while using an existing projection optical system, it is preferable to provide an aspherical mirror in the optical path from the projection optical system to the screen. However, in the conventional projection apparatus described in Patent Document 1, there is no spatial margin for arranging additional components. More specifically, when an additional constituent member is added, the constituent member enters an optical path that is hindered in the arrangement of other constituent members or bent multiple times. For this reason, the entire apparatus has inevitably been enlarged.

  SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a projection apparatus in which an optical member necessary for suppressing various aberrations can be provided while ensuring miniaturization and thinning.

  In order to solve the above-described problem, the projection device according to claim 1 is a projection device that projects an image obliquely on the back side of the screen, generates an image, and projects a light beam toward the screen; and A first deflecting unit that deflects the light beam emitted from the projection optical system in a direction away from the screen in the depth direction of the projection device, and the light beam deflected by the first deflecting unit corrects the aberration while correcting the aberration. A second deflecting means for deflecting toward the plate surface, a third deflecting means disposed along the top plate surface and deflecting the light beam deflected by the second deflecting means toward the screen, In the cross section including a straight line that passes through the center of the screen of the projection apparatus in a normal use state and extends in the vertical direction, the lowermost incident light incident on the lowermost part of the screen among the light beams Of the optical path between the second deflection means and the third deflection means, characterized in that it is substantially parallel to the screen.

  In this description, in describing the projection device, for convenience, each direction will be described with reference to a state (normal use state) in which the projection device is installed so that the ground plane is horizontal to the ground.

  By disposing and configuring each member as described in claim 1, a projection apparatus is provided in which the entire apparatus is guaranteed to be reduced in size and thickness while correcting various aberrations including distortion.

  According to the projection device of claim 2, if the angle (unit: deg) formed between the lowest incident light ray incident on the screen and the screen is θ, the angle formed between the normal of the screen and the third deflecting means. The (unit: deg) is preferably (θ / 2) ± 1.

  More specifically, according to the projection apparatus of the third aspect, the first deflecting means is disposed between the screen and the second deflecting means in the cross section.

ただし、ｉは、光束のうちスクリーン最上部に入射する最上部入射光線に関し、投影光学システムの射出瞳から第三の偏向手段までの光路長（単位：ｍｍ）、
ｍは、最下部入射光線に関し、投影光学システムの射出瞳から第三の偏向手段までの光路長（単位：ｍｍ）、
ωは、スクリーンに入射した最上部入射光線と該スクリーンとがなす角度、および、スクリーンに入射した最下部入射光線と該スクリーンとがなす角度、の角度差（単位：ｄｅｇ）、
ｈは、スクリーンの高さ（単位：ｍｍ）、をそれぞれ表す。 According to the projection device of the fourth aspect, it is preferable that the following condition is satisfied in the cross section.

However, i is the optical path length (unit: mm) from the exit pupil of the projection optical system to the third deflecting unit with respect to the uppermost incident light beam incident on the uppermost screen portion of the light flux.
m is the optical path length (unit: mm) from the exit pupil of the projection optical system to the third deflecting means with respect to the lowest incident light beam,
ω is an angle difference (unit: deg) between an angle formed by the uppermost incident light beam incident on the screen and the screen, and an angle formed by the lowermost incident light beam incident on the screen and the screen,
h represents the height of the screen (unit: mm).

  By satisfying the above conditions, the second deflecting means having an aberration correcting function can be suitably arranged without increasing the size of the projection apparatus, particularly the vertical size.

  According to the projection device of the fifth aspect, the first deflecting unit is configured such that, in the cross section, the lowermost incident light beam is lower than the position where the uppermost incident light beam is incident on the first deflecting unit. The position where the light incident on the deflecting means is inclined with respect to the screen is arranged to be inclined, and the second deflecting means is a position where the uppermost incident light beam enters the second deflecting means in the cross section. Rather, the position where the lowermost incident light beam enters the second deflecting means is disposed so as to be inclined with respect to the screen.

ただし、αは、上記断面において、第二の偏向手段で反射した最下部入射光線と、第二の偏向手段とがなす角度、を表す。 Moreover, according to the projection apparatus of Claim 6, it is desirable to satisfy the following conditions further.

However, α represents an angle formed by the second deflecting unit and the lowest incident light beam reflected by the second deflecting unit in the cross section.

  By further satisfying the above conditions, the size of the apparatus is increased without entering the light beam from the second deflecting unit to the third deflecting unit and the light beam from the third deflecting unit to the screen. It becomes possible to arrange | position a 1st deflection | deviation means appropriately, without this.

  According to the projection device of the seventh aspect, the projection optical system includes a light source, an image generation unit that generates an image using a light beam emitted from the light source, and a light beam emitted from the image generation unit toward the screen. And a projection optical system for projecting.

  The first and third deflecting means are preferably configured as plane mirrors. The second deflecting means is preferably configured as an aspherical mirror.

  According to the projection device of the tenth aspect, the second deflecting unit has a substantially flat shape in the cross section in a region where the light beam incident through the first deflecting unit is incident, and is parallel to the screen. The cross-sectional shape on the surface is preferably a convex surface. By configuring the second deflection unit in this way, it is possible to satisfactorily correct distortion that is relatively likely to occur in an oblique projection type projection apparatus.

  According to the projection device of the eleventh aspect, the second deflecting unit has a substantially flat shape in the cross section in a region where the light beam incident through the first deflecting unit is incident, and is parallel to the screen. The cross-sectional shape on the surface may be concave. By configuring the second deflecting means in this way, the astigmatic difference caused by the second deflecting means can be kept small.

  As described above, according to the projection apparatus of the present invention, the lowermost incident light beam of the light beam reflected by the second deflecting unit proceeds to the third deflecting unit in a state substantially parallel to the screen. By providing this deflection means, it is possible to achieve a reduction in size and thickness of the apparatus while providing an aberration correcting optical member.

  FIG. 1 is a cross-sectional view illustrating a schematic configuration of a projection apparatus 100 according to an embodiment in a normal use state. The projection apparatus 100 includes a projection optical system 1, a first plane mirror 2, an aspherical mirror 3, a second plane mirror 4, and a screen 5 in a housing 50.

  As shown in FIG. 1, in the following description, in the projector 100 in the normal use state, the thickness direction of the screen is referred to as the X direction, the vertical direction of the screen 5 is referred to as the Y direction, and the horizontal direction of the screen 5 is referred to as the Z direction. The length in the X direction is called the depth (of the device or each member), the length in the Y direction is called the height (of the device or each member), and the length in the Z direction is called the width (of the device or each member). That is, FIG. 1 is a cross-sectional view in the XY plane. 1 and all the drawings shown later are cross-sectional views on an XY plane including a virtual straight line that passes through the center of the screen 5 and extends in the Y direction. Therefore, unless otherwise specified, all of the following description is made in a cross section in the XY plane.

  For convenience of explanation, the screen 5 is defined as the front surface of the projection device 100, and the surface of the housing 50 that faces the screen 5 is defined as the device back surface. Similarly, the grounding surface of the housing 50 in a state where the projection apparatus 100 is installed is defined as the apparatus bottom surface, and the surface of the housing 50 facing the bottom surface is defined as the top plate surface.

  The projection optical system 1 includes a light source 11, an image generation unit 12 including a liquid crystal element (not shown), and a projection optical system 13. The projection optical system 1 is arranged in the lower rear part of the apparatus, that is, close to the apparatus bottom surface and the apparatus back surface. Then, the projection optical system 1 irradiates the light beam toward the upper side of the screen 5. Although the projection optical system 13 shown in the figure is composed of two lenses, this is only schematically shown, and actually includes a larger number of lenses.

  The light beam irradiated from the projection optical system 1 enters the first plane mirror 2 while diverging. The first plane mirror 2 reflects the incident light beam in a direction away from the screen 5 and guides it to the aspherical mirror 3. Here, a configuration in which the light beam irradiated from the projection optical system 1 is directly incident on the aspherical mirror 3 is also conceivable. However, in this configuration, in order to maintain the miniaturization of the apparatus, the distance between the projection optical system 1 and the aspherical mirror 3 must be set short. For this reason, the aberration correction effect of the aspherical mirror 3 and the problem that it becomes difficult to secure a sufficient optical path length for projecting an image over the entire screen 5 are not preferable. In this embodiment, in the X direction, the first plane mirror 2 is disposed between the screen 5 and the aspherical mirror 3 to appropriately bend the optical path, thereby solving the above problem.

  The aspherical mirror 3 corrects various aberrations such as a trapezoidal distortion component and distortion aberration that cannot be sufficiently corrected by the projection optical system 13 of the projection optical system 1 in a range where the light beam is incident (so-called effective diameter). It has a suitable surface shape. A suitable surface shape is determined according to how much the above-mentioned various aberrations remain in the projection optical system 13. However, generally, in the oblique projection type like the projection apparatus 100, a barrel-type distortion tends to be largely generated. Based on this, the aspherical mirror 3 of the present embodiment has a shape obtained by partially cutting a peripheral portion of a convex mirror (see reference numeral 3 ′ shown in FIG. 3 described later). In other words, the aspherical mirror 3 is substantially flat in a cross section on the XY plane, and a light beam is incident on a plane orthogonal to the XY plane and parallel to the Y direction (that is, a YZ plane parallel to the screen 5). It exhibits a cross-sectional shape that is convex in the direction of coming. The aspherical mirror 3 reflects the incident light beam toward the upper side of the apparatus, that is, toward the top plate surface. The arrangement of the mirrors 2 and 3 will be described in detail later.

  A second plane mirror 4 is disposed on the apparatus top plate surface. The second flat mirror 4 is attached to the housing 50 (device top plate) in a state where it is inclined by a predetermined amount with respect to the XZ plane. The second plane mirror 4 reflects the incident light beam and guides it to the screen 5. The light beam reflected by the second plane mirror 4 forms an image on the back side of the screen 5. The user can observe the image by facing the screen 5 from the front, that is, from the left side in FIG.

  Next, the arrangement configuration of the first flat mirror 2 and the aspherical mirror 3 in the apparatus, which is one of the main features of the present invention, will be described in detail. FIG. 2 is an explanatory diagram for explaining a preferred arrangement of the mirrors 2 and 3 that can ensure a reduction in size and thickness of the projection apparatus 100, and is an optical path of a light beam emitted from the projection optical system 1. It is a figure which expands and shows a part of. FIG. 3 is an explanatory view similar to FIG. 2, in which all the optical paths of the light flux are developed. In each of the drawings including FIG. 1 described above, among the light beams irradiated from the projection optical system 1, a light beam that is finally incident on the lowermost part of the screen 5 (referred to as a lowermost incident light beam) is indicated by a dashed line. . Of the luminous flux, a light beam that is finally incident on the uppermost part of the screen 5 (referred to as an uppermost incident light beam) is indicated by a broken line.

Each symbol shown in FIGS. 2 and 3 is defined as follows.
A ... Bottom of screen 5.
B: The top of the screen 5.
C: The end of the second plane mirror 4 closest to the screen. The end corresponds to the incident position of the uppermost incident light beam in the second plane mirror 4.
D: The end of the second plane mirror 4 farthest from the screen. The end corresponds to the incident position of the lowest incident light beam on the second plane mirror 4.
E: intersection of a perpendicular to the screen 5 extending from the point B, the optical path of the lowest incident light beam reflected by the aspherical mirror 3 and incident on the second plane mirror 4 and a line extending the optical path.
F: Intersection of the perpendicular to the screen 5 extending from the point A, the optical path of the lowest incident light beam reflected by the aspherical mirror 3 and incident on the second flat mirror 4 and a line extending the optical path.
P: Exit pupil position of the projection optical system 13 when the mirrors 2 and 3 are provided.
P ′: a position corresponding to a point P when the optical path bent by the mirrors 2 and 3 is developed when the aspherical mirror 3 is assumed to be a plane.
Q: The incident position of the lowest incident light beam on the aspherical mirror 3. Further, as shown in FIG. 3, the aspherical mirror 3 is also a point farthest from the optical axis AX of the projection optical system 13.
R: The incident position of the uppermost incident light beam on the aspherical mirror 3. Further, as shown in FIG. 3, the aspherical mirror 3 is also a point closest to the optical axis AX of the projection optical system 13. In FIG. 3, the triangle PQR and the triangle P′QR are in a line-symmetric relationship with respect to the line segment QR (aspherical mirror 3).
S: An incident position of the lowest incident light beam in the first plane mirror 2.
T: The incident position of the uppermost incident light beam in the first plane mirror 2.
θ is an angle formed by the screen 5 and the lowest incident light beam incident on the screen.
ω: An angle difference between the angle θ formed by the screen 5 and the uppermost incident light beam incident on the screen 5 and the angle θ. Always take a positive value.
α: An angle formed by the aspherical mirror 3 and the lowest incident light ray incident on the aspherical mirror 3.

  In addition, the definition regarding an angle among the above shall be an acute angle (unit: deg). That is, in FIGS. 2 and 3, the angle θ is ∠BAD, the angle ω is ∠BP'D, and the angle α is ∠SQR. Here, as described above, FIG. 2 is a partially developed view of the optical path. Therefore, the line segment QD and the line segment FQ are considered to be on the same straight line. Therefore, in FIG. 2, the angle α is indicated as ∠FQR. In addition, when the angle α is equal to the angle formed by the aspherical mirror 3 and the screen 5, the lowest incident light beam that is reflected by the aspherical mirror 3 and incident on the second flat mirror 4 is substantially parallel to the screen 5. Proceed to Thereby, further thinning of the apparatus is achieved. The angles described below are all acute angles as well. The optical axis AX of the projection optical system 13 is indicated by a two-dot chain line.

  A dotted line 3 ′ virtually indicates the cross-sectional shape of the convex mirror that is the base of the aspherical mirror 3 in the XY cross section. It can be seen from FIG. 3 that the aspherical mirror 3 has a shape obtained by partially cutting the peripheral edge of the convex mirror indicated by the dotted line 3 ′.

  In order to achieve a reduction in size and thickness of the projection apparatus 100, a space (hereinafter referred to as an arrangement space) in which the mirrors 2 and 3 can be arranged in the projection apparatus 100 so as not to enter the optical path of the light beam. It is necessary to secure the maximum without changing the size of the entire apparatus. In order to secure the maximum arrangement space, each member is arranged and configured such that the lowest incident light beam reflected by the aspherical mirror 3 and the screen 5 are substantially parallel.

Specifically, assuming that the lowermost incident light beam reflected by the aspherical mirror 3 and the screen 5 are parallel, the following formula (1)
∠ADQ = ∠BAD = θ (1)
Is established. From equation (1),
∠ECD = 1/2 ∠ADQ = θ / 2 (2)
Is derived. That is, the second plane mirror 4 is disposed so that the angle formed with the perpendicular CE is θ / 2, in other words, the angle formed between the second plane mirror 4 and the screen 5 is (90−θ / 2) °. The In the actual apparatus, the second flat mirror 4 is arranged so that the angle formed with the perpendicular CE is (θ / 2) ± 1 ° in view of the individual difference of each mirror, the influence of the thickness, ribs and the like. .

  In FIG. 2, the point R is arranged on the line segment AF, the point S is arranged on the line segment CR (or the line segment CP ′), and the extended line of the line segment ST is matched with the point A. This configuration means a state in which the bottom end of each mirror 2, 3 is closest to the XZ plane including the bottom of the screen 5. With this configuration, the use area of each mirror 2, 3 can be kept small, in other words, the size of each mirror 2, 3 can be reduced. In addition, there is an advantage that the degree of freedom of the inclination of the first plane mirror 2 is particularly high. That is, FIG. 2 and FIG. 3 are configurations that can be most easily achieved by disposing the mirrors 2 and 3 without entering the optical path on the assumption that the entire apparatus of the projection apparatus 100 is not enlarged. . Therefore, the arrangement configuration in which the mirrors 2 and 3 cannot be arranged without entering the optical path is a configuration that cannot effectively solve the problem of the present invention.

  In the arrangement space, the first flat mirror 2 is arranged to be inclined so that the point S is farther away from the screen 5 in the X direction than the point T. Further, the aspherical mirror 3 is disposed so as to be inclined so that the point Q is farther away from the screen 5 in the X direction than the point R. The arrangement of the mirrors 2 and 3 will be further described.

Here, a line segment QD indicating the lowermost incident light beam reflected by the aspherical mirror 3 and incident on the second flat mirror 4 and a line segment indicating the lowermost incident light beam emitted from the exit pupil and incident on the first flat mirror 2. Let β be the angle formed by PS. In addition, an angle formed by the line segment QR corresponding to the aspherical mirror 3 and the line segment ST corresponding to the first flat mirror 2 is γ. Note that the angles β and γ are positive and reverse C-shaped (that is, the top surface of the apparatus) if the two line segments that define each of the angles are C-shaped (that is, a state where the line segments expand toward the bottom of the apparatus). Negative (thus, zero if parallel). Between the angle β and the angle γ, a relationship such as the following formula (3) is established.
β = 2γ (3)

  When β <−ω, the line segment PS is positioned on the rear side of the apparatus with respect to the line segment SR, and the line segment PS and the line segment RQ intersect each other. This is not preferable because the aspherical mirror 3 enters the optical path of the light beam from the exit pupil position P toward the first plane mirror 2 and vignetting occurs in a part of the light beam.

On the other hand, the angles γ (= β / 2) and ω are the following expressions (4),
γ ≧ −ω / 2 (4)
When satisfying, it is possible to realize a mirror arrangement that does not generate vignetting. Therefore, hereinafter, conditions regarding a specific numerical configuration of the projection apparatus 100 in which the angle γ satisfies Expression (4) will be described.

When the projection apparatus 100 on the XY cross section is expanded to an XY coordinate system with the point A as the origin, the coordinates of the points A, B, and F are assumed where the height of the screen 5 is h and the depth of the apparatus 100 is w. (X, y)
A (0, 0)
B (0, h)
F (w, 0)
Is defined as Here, when the length of the line segment P′C is i, the length of the line segment P′R is m, and the length of the line segment RF is k, the following expressions (5) and (6) are established. However, the unit of each length is mm.

w = i · sin ω (5)
k = m · sin ω (6)

を満たすように構成することにより、特に非球面ミラー３をスクリーン５のサイズによって規定される領域ＡＢＥＦ内に収めることができる。条件（ａ）を満足しない場合、非球面ミラー３の使用領域における端部がスクリーン５最下部を含むＸ−Ｚ平面よりも下方に位置することになる。このことは、装置の大型化を招く要因となるため好ましくない。 Here, the following condition (a),

In particular, the aspherical mirror 3 can be accommodated in the area ABEF defined by the size of the screen 5. If the condition (a) is not satisfied, the end of the aspherical mirror 3 in the use region is positioned below the XZ plane including the lowermost part of the screen 5. This is not preferable because it causes an increase in the size of the apparatus.

Here, the line segment RQ is expressed by the following equation (7),
y = (x− (w−k)) / tan α (7)
It is prescribed by. From equation (7), the point Q is
Q (w, k / tan α)
Is defined as

In FIG. 2, since a part of the optical path is developed, the line segment SQ and the line segment FQ are in a line symmetric relationship with respect to the line segment QR. That is, the following expressions (8) and (9) are established.
∠SQR = ∠FQR = α (8)
∠ SQF = 2α (9)

From equations (8) and (9), the line segment SQ is defined by the following equation (10).
y = (x−w) / tan2α + k / tanα (10)
Further, from each value described above, the line segment CR is defined by the following equation (11).
y = hx / tan ω (11)

By solving the two formulas (10) and (11), the intersections of the line segments SQ and CR, that is, the x-coordinate Sx and y-coordinate Sy of the point S can be obtained as follows.
Sx (w / tan2α−ktanα + h) (1 / tan2α + 1 / tanω)
Sy h-Sx / tan ω

Since the point T coincides with the origin (point A), the slope of the line segment ST is obtained by Sy / Sx. From the values of Sx and Sy, the slope Sy / Sx of the line segment ST is obtained by the following equation (12).
Sy / Sx = h / Sx−1 / tan ω (12)

Here, the following expression (13) is derived based on the above expression (4).
1 / tan (α + γ) ≦ 1 / tan (α−ω / 2) (13)

The left side of Equation (13) is equal to the slope Sy / Sx of the line segment ST. Therefore, the expression (13) is converted into the following expression (14) and further the expression (15).
h / Sx−1 / tan ω ≦ 1 / tan (α−ω / 2) (14)
h / Sx ≦ (1 / tan (α−ω / 2) + 1 / tan ω) (15)

Substituting the value of Sx into equation (15), the following condition (b) is derived.

  By arranging and configuring the respective members so as to satisfy the condition (b), the first flat mirror 2 and the aspherical mirror 3 are maintained in a state where the projection apparatus 100 is kept small and thin, and without causing vignetting. Can be arranged. If the condition (b) is not satisfied, a part of the aspherical mirror 3 enters the optical path of the light beam from the exit pupil position P toward the first flat mirror 2, which is not preferable.

  Hereinafter, specific examples of the above embodiment will be described. FIG. 4 is an XY sectional view showing the projection apparatus 100 of the embodiment. 4 omits the light source 11, the image generation unit 12, and the housing 50 in order to simplify the illustration. The specific numerical configuration of the projection apparatus 100 of the embodiment shown in FIG. 4 is shown in Table 1 below.

  As shown in Table 1, in the projection apparatus 100 of the example, the angle formed by the second plane mirror 4 and the perpendicular CE was 14 ° obtained by adding 1 ° as a margin to θ / 2. Thus, the aspherical mirror 3 is designed not to interfere with the housing 50 on the rear side of the apparatus due to the rib and thickness of the aspherical mirror 3. Thus, when the margin is set to ± 1 °, the incident angle when the lowermost incident light beam enters the screen 5 changes by ± 2 °. The state where the lowermost incident light beam reflected by the aspherical mirror 3 and incident on the second plane mirror 4 travels substantially parallel to the screen 5 is that the incident angle when the lowermost incident light beam enters the screen 5 is ± 2 °. A state that allows change.

  Also, from Table 1, it can be seen that the left side of the condition (a) is 588.6 and the right side is 745.6, which satisfies the condition. Therefore, the uppermost incident light incident position in the aspherical mirror 3 is located above the XZ plane including the lowermost part of the screen 5, which contributes to downsizing of the entire apparatus.

  Similarly, from Table 1, it can be seen that the left side of the condition (b) is 1.08 and the right side is 1.56, which satisfies the condition. As shown in FIG. 2, in the case where the first plane mirror 2 is arranged so that the point S is substantially in contact with the line segment CR (the optical path of the uppermost incident light beam reflected by the aspherical mirror 3), the condition (b), etc. When the number is established, the exit pupil P ′ is positioned above the plane of the drawing (in the direction close to the second plane mirror 4). This is preferable because it is possible to minimize a portion further below the lowermost portion of the screen 5, generally referred to as a bag of the apparatus, indicated by reference numeral 6 in FIG. 1. However, when the point S is arranged at a distance from the line segment CR as in the present embodiment, vignetting does not occur even if the angle γ is slightly smaller than ω / 2.袴 6 can be minimized (and frameless depending on the configuration).

  The above is the description of the embodiment of the present invention. The projection apparatus according to the present invention is not limited to the configuration of the above embodiment. For example, even a projection apparatus that has been modified as described below can achieve the same effects as those of the above-described embodiment by arranging and configuring the members so as to satisfy the above-described conditions.

  A schematic configuration of the projection apparatus according to the modified example appears in the same manner as FIG. 1 showing the configuration of the projection apparatus according to the above embodiment. FIG. 5 is a diagram corresponding to FIG. 3, and is a diagram in which all the optical paths in the projection device of the modification are developed. As shown in FIG. 5, the projection apparatus of the modification has substantially the same configuration as the projection apparatus of the above embodiment except that the aspherical mirror 3a has a shape obtained by partially cutting the peripheral edge of the concave mirror 3a '.

  The surface shape of the aspherical mirror 3a will be described. The aspherical mirror 3a is substantially flat in the cross section on the XY plane, and faces upward in the apparatus vertical direction on a plane orthogonal to the XY plane and parallel to the Y direction (that is, the YZ plane parallel to the screen 5). Presents a concave cross-sectional shape. By employing such an aspherical mirror 3a, the astigmatic difference caused by the mirror 3a itself can be kept small.

It is a figure showing the schematic structure of the projection apparatus of embodiment of this invention. It is a figure which expands and shows a part of optical path inside the projection device of this embodiment. It is a figure which expands and shows the optical path inside the projector of this embodiment. It is a figure which shows schematic structure of the projection apparatus of an Example. It is a figure which expands and shows the optical path inside the projection device of a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Projection optical system 11 Light source 13 Projection optical system 2 1st plane mirror 3, 3a Aspherical mirror 4 2nd plane mirror 5 Screen 100 Projection apparatus

Claims (11)

In a projection device that projects an image obliquely on the back side of the screen,
A projection optical system that generates the image and projects a light beam toward the back of the screen;
First deflecting means for deflecting the light beam emitted from the projection optical system in a direction away from the screen in a depth direction of the projection device;
Second deflecting means for deflecting the light beam deflected by the first deflecting means toward the top plate surface of the projection apparatus while correcting aberrations;
A third deflecting unit disposed along the top plate surface and deflecting the light beam deflected by the second deflecting unit toward the back surface of the screen;
In a cross section of a plane that includes a straight line that passes through the center of the screen of the projection device in the normal use state and extends in the vertical direction and that is perpendicular to the screen, An optical path between a second deflecting unit and the third deflecting unit is substantially parallel to the screen. The projection device according to claim 1,
Assuming that the angle (unit: deg) formed by the lowermost incident light beam incident on the screen and the screen is θ, the angle (unit: deg) formed by the perpendicular of the screen and the third deflecting means is (θ / 2) A projection apparatus characterized by being ± 1. The projection apparatus according to claim 1 or 2,
The projection device according to claim 1, wherein the first deflection unit is disposed between the screen and the second deflection unit in the cross section. The projection apparatus according to any one of claims 1 to 3,
In the cross section, the following conditions:

However, i is the optical path length from the exit pupil of the projection optical system to the third deflecting unit with respect to the uppermost incident light beam that is incident on the uppermost screen portion of the light flux in the cross section,
m is the optical path length from the exit pupil of the projection optical system to the third deflecting means with respect to the lowest incident light beam,
ω is the angle difference between the uppermost incident light beam incident on the screen and the screen, and the angle difference between the lowermost incident light beam incident on the screen and the screen,
h represents the height of the screen,
The projection apparatus characterized by satisfy | filling. The projection apparatus according to any one of claims 1 to 4,
In the cross section, the first deflecting unit has a position where the lowermost incident light beam enters the first deflecting unit, rather than a position where the uppermost incident light beam enters the first deflecting unit. Inclined to be away from the screen,
In the cross section, the second deflecting unit has a position where the lowermost incident light beam enters the second deflecting unit, rather than a position where the uppermost incident light beam enters the second deflecting unit. A projection apparatus, wherein the projection apparatus is disposed so as to be away from the screen. The projection apparatus according to any one of claims 1 to 5,

Where i is an optical path length (unit: mm) from the exit pupil of the projection optical system to the third deflecting unit with respect to the uppermost incident light ray incident on the uppermost part of the screen in the cross section in the cross section,
m is the optical path length (unit: mm) from the exit pupil of the projection optical system to the third deflecting unit with respect to the lowest incident light beam;
ω is an angle difference (unit: deg) between an angle formed by the uppermost incident light beam incident on the screen and the screen and an angle formed by the lowermost incident light beam incident on the screen and the screen;
h is the height of the screen (unit: mm),
α represents an angle formed by the lowermost incident light beam incident on the second deflection unit and the second deflection unit in the cross section, respectively.
The projection apparatus characterized by satisfy | filling. The projection apparatus according to any one of claims 1 to 6,
The projection optical system includes a light source, an image generation unit that generates an image using a light beam emitted from the light source, a projection optical system that projects the light beam emitted from the image generation unit toward the screen, A projection apparatus comprising: The projection apparatus according to any one of claims 1 to 7,
The projection apparatus, wherein the first and third deflecting means are plane mirrors. The projection apparatus according to any one of claims 1 to 8,
The projection apparatus, wherein the second deflecting means is an aspherical mirror. The projection apparatus according to claim 9, wherein
The second deflecting unit has a substantially flat shape in a cross section and a convex surface in a plane parallel to the screen in a region where a light beam incident through the first deflecting unit is incident. A projection apparatus characterized by that. The projection apparatus according to claim 9, wherein
The second deflecting means has a substantially flat shape in a cross section and a concave shape in a plane parallel to the screen in a region where a light beam incident through the first deflecting means is incident. A projection apparatus characterized by that.

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