JP2007047753A - Projection display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection display device whose overall depth and height-directional dimension are suppressed small relatively to the size of a screen and which can prevent a phenomenon such that light from a light source outside the device, such as an electric lamp in a room, is reflected in the device to hinder view and a ghost phenomenon. <P>SOLUTION: A first reflector and a second reflector are provided on an optical path between an image formation unit and the screen, and light passing through an image formed by the image formation unit is reflected by the second reflector and then by the first reflector before being incident on the screen. The first reflector is arranged such that an angle formed between the first reflector and the screen is equal to or greater than 45 degrees and less than 90 degrees, and the second reflector is arranged such that an angle formed between the second reflector and the screen is an obtuse angle. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a projection display device that projects an image on a transmissive screen on the front surface of the device.

  A light source and image forming means (such as a transmissive liquid crystal) and an imaging optical system are provided inside the apparatus, and light from the light source is supplied to the image forming means so that an image is displayed on a translucent screen provided on the front of the apparatus. Projection display devices capable of projecting and observing images projected and displayed on the screen from the front of the device are widely used.

  As this projection display device, for example, as disclosed in Patent Document 1, a light source and an image forming unit are arranged at the lower rear of the screen, and a second reflection that forms an angle near the screen at the lower part of the screen. Means (relay mirrors) are provided, and the first reflecting means (final projection mirror) is provided behind the screen with its upper end slightly inclined toward the screen. After the light from the light source passes through the image forming means, it is sequentially reflected by the second reflecting means and the first reflecting means, and then enters the screen and forms an image there.

  According to said structure, it is possible to ensure the optical path length for displaying the image of a predetermined | prescribed magnitude | size, suppressing the dimension of the depth direction of a projection display apparatus by the light path being folded back several times by the reflection means. . That is, a thin display device with a shorter depth than the screen size is realized.

  However, in the above configuration, since the second reflecting member and the light source need to be arranged on the lower side of the screen, there is a problem that the dimension in the height direction of the entire projection display device increases.

  As a configuration that can solve the above problem, for example, as disclosed in Patent Document 2, the light source and the image forming means are arranged in the lower part of the apparatus, and the reflecting means provided on the upper surface of the apparatus case and the back side of the rear panel. It is conceivable that light transmitted through the image forming means is sequentially reflected to display an image on the screen. In this configuration, the optical path goes around the rear of the apparatus, the upper end of the apparatus, and the front of the apparatus, and the required optical path length can be secured while the light source, the image forming means, and the imaging optical system are arranged behind the screen. It is possible to suppress both the depth and the height of the projection display device.

  However, in the configurations of the above-mentioned Patent Documents 1 and 2, since the reflecting means is provided at an angle close to parallel to the screen, some external light source (in the room, such as a high position behind the screen observer) If an electric lamp is installed, the light from the external light source is transmitted from the front to the back of the screen and enters the projection display device, reflected by the reflecting means provided on the back side of the back panel, and observed on the screen. There was a possibility that it would interfere with screen observation. Further, in the above configuration, there is a possibility that light for forming an image is reflected by the inner surface of the screen and is incident on the reflecting means, and then is reflected by the reflecting means and is incident on the screen again. In this case, there is a possibility that a so-called ghost phenomenon occurs in which an image appears on the screen twice.

  As a configuration for avoiding the above problem, for example, configurations disclosed in Patent Literature 3 and Patent Literature 4 are conceivable. In the configuration disclosed in Patent Document 3, the light transmitted through the image forming unit is directly incident on the reflecting unit provided on the back side of the upper surface of the apparatus case. In this configuration, although the ghost phenomenon is avoided, it is necessary to dispose the image forming unit behind the reflecting unit, so that the depth of the image display device becomes larger than the configuration of Patent Document 1. There was a problem.

In the configuration disclosed in Patent Document 4, in addition to the configuration of Patent Document 3, the reflecting means is arranged so as to form an acute angle with the screen. In such a configuration, as the optical path length from the image forming unit to the screen becomes longer, the depth direction dimension of the reflecting unit can be shortened. However, when the optical path length from the image forming unit to the screen becomes long, the arrangement position of the light source and the image forming unit is greatly shifted from the lower end of the screen to the lower side, so that the height dimension of the projection display device is large. There was a problem of becoming.
JP 2003-287813 A JP-A-6-186498 JP 2002-207190 A JP 5-88264

  In view of the above problems, the present invention suppresses the depth and height of the entire apparatus with respect to the screen size, and reflects light from a light source outside the apparatus, such as an indoor lamp, inside the apparatus. It is an object of the present invention to provide a projection display device that can prevent a phenomenon that hinders viewing and a ghost phenomenon.

  In order to solve the above problems, the projection display device of the present invention is a first and second reflecting means disposed on the optical path between the image forming means and the screen, and is formed by the image forming means. The light that has passed through the image is sequentially incident on the second reflecting means and the first reflecting means, and the first reflecting means has a reflecting surface of the first reflecting means and a screen 45. The second reflecting means is provided in a state where the reflecting surface of the second reflecting means is inclined so as to form an obtuse angle with the screen.

  With such a configuration, the image forming unit can be arranged at a position on the back side of the screen and closer to the screen than the distal end of the first reflecting unit with respect to the screen. For example, when the first reflecting means is substantially in contact with the upper end of the screen, it is below the first reflecting means at a position that does not block light from the first reflecting means toward the screen. Image forming means can be arranged. For this reason, the depth dimension of the apparatus can be set to a very small value, which is slightly larger than the distance from the first reflecting means to the screen. Further, since the image forming means can be arranged behind the screen, the height direction dimension of the apparatus is slightly larger than the height direction of the screen. That is, according to said structure, it becomes possible to suppress the depth direction and height direction dimension of a projection display apparatus small. Further, since both the first and second reflecting means are inclined from the screen, the light from the external light source is reflected by the reflecting means and directed to the screen, or the light beam reflected on the screen is reflected by the reflecting means. Never go to the screen again. Therefore, according to the present invention, it is possible to prevent a phenomenon in which light from an external light source is reflected to hinder viewing, a ghost phenomenon, and the like.

Here, the angle formed between the reflection surface of the first reflecting means and the normal line of the screen is θ, and the light beam having the smallest incident angle to the screen out of the light traveling from the first reflecting means to the screen is the screen and W ₁ is an angle formed by a line segment projected on a plane perpendicular to both of the reflecting means and the normal line of the screen, and the light ray having the maximum incident angle to the screen out of the light traveling from the first reflecting means to the screen. the screen and the first both corners formed between the normal of the projected line segment and the screen is a plane perpendicular to the reflecting means is defined as w _2, wherein _{45 ° -w 2/2 ≦ θ} ≦ 45 ° -w _1/2 and the formula _{sin (2θ + w 2 -90 °} ) ≦ (tan w 2 cos (2θ + w 1) + sin (2θ + w 2 -90 °) sin (w 2 -w 1)) / sin ( 2θ + w ₁ + w ₂ ) is set to hold, it is the position on the far side of the screen and closer to the screen than the distal end of the first reflecting means with respect to the screen Image forming means can be arranged at the position.

In particular, the formula sin (2θ + w ₂ -90 °) = (tan w ₂ cos (2θ + w ₁ ) + sin (2θ + w ₂ -90 °) sin (w ₂ -w ₁ )) / sin (2θ + If w ₁ + w ₂ ) is set to hold, the depth dimension of the device can be minimized.

In addition, the projection display device includes a reflection unit that is disposed on an optical path between the image forming unit and the screen and reflects light that has passed through the image formed by the image forming unit in a predetermined direction. Is provided such that the reflection surface forms an angle of 45 degrees or more and less than 90 degrees with the screen, and the angle formed by the reflection surface of the reflection means and the normal line of the reflection means is θ, Of these, the angle formed by the normal line of the screen and the line segment obtained by projecting the light beam with the smallest incident angle on the screen onto the plane perpendicular to both the screen and the reflecting means is w ₁ , and the screen out of the light traveling from the reflecting means to the screen. both corners formed between the normal of the projected line segment and the screen is a plane perpendicular to the screen and reflection means a ray is the maximum incident angle to define with w _2, wherein 45 ° -w _2/2 θ ≦ 45 ° -w _1/2 and the formula _{sin (2θ + w 1) ≦} cos w 1 tan w 2 - sin w 1 may be set to true. Even in this case, the image forming means can be arranged at a position on the back side of the screen and closer to the screen than the distal end of the reflecting means with respect to the screen, and the depth direction dimension of the apparatus can be reduced. is there. Furthermore, in this configuration, the number of reflecting means may be one.

  As described above, according to the present invention, the depth of the entire apparatus with respect to the size of the screen and the height direction dimension can be kept small, and light from an external light source is reflected to prevent viewing or ghost phenomenon. A projection display device capable of preventing the above is realized.

  Hereinafter, a projection display apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of the projection display device 1 of the present embodiment cut along a vertical plane perpendicular to the screen. The projection display device 1 includes a case 10 whose depth direction dimension is sufficiently short with respect to the width direction dimension and the height direction dimension. A screen 100 on which an image is displayed is provided on the front surface of the case 10. The screen 100 is made of a translucent material, and an image is formed on the screen 100 by projecting an image from the inside of the case 10. An optical element for projecting an image on the screen 100 is incorporated.

  Inside the case 10 is a liquid crystal panel as an image forming apparatus, a light source that transmits light to the liquid crystal panel, and an image displayed on the liquid crystal panel arranged so that light transmitted through the liquid crystal panel is incident on the screen 100. A projection unit 300 including an imaging optical system that forms an image is provided. As shown in the figure, the projection unit 300 is disposed at the center of the rear part of the case 10, and the light transmitted through the liquid crystal panel is relayed as a second reflecting means disposed in the lower front part inside the case 10. Irradiation toward the mirror 210. In this embodiment, a transmissive projection unit that transmits light from the light source to the liquid crystal panel is used. However, a reflective projection unit that uses a DMD (digital micromirror device) or the like is used instead. You may do it.

  The relay mirror 210 is disposed so as to be inclined from the horizontal plane so that its front edge is slightly higher than its rear edge, and its reflection surface 212 is disposed on the upper surface side. The light emitted from the projection unit 300 is reflected by this reflecting surface and enters the final projection mirror 220 as the first reflecting means disposed on the upper side inside the case 10.

  The final projection mirror 220 is attached to the lower surface of the top plate of the case 10, and a reflection surface 222 is formed on the lower surface. In addition, the front edge of the final projection mirror 220 is in contact with the upper edge of the screen 100. Further, the final projection mirror 220 is disposed so as to be inclined from the horizontal plane so that the front edge thereof is slightly higher than the rear edge. The light reflected on the relay mirror 210 and incident on the final projection mirror 220 is reflected on the reflection surface 222 and incident on the screen 100. The screen 100 is formed from a translucent material, and as a result, an image is displayed on the screen 100. Note that the upper end of the front edge of the final projection mirror 220 is cut horizontally, and the height of the upper end of the projection display device 1 is suppressed to be as low as the upper end height of the screen 100 + the thickness of the case 10. .

  In FIG. 1, the reach of light incident on the screen 100 from the projection unit 300 through the relay mirror 210 and the final projection mirror 220 is indicated by a one-dot chain line. As shown in the drawing, in the present embodiment, the light reflected on the final projection mirror 220 is incident on the screen 100 at a high incident angle exceeding 45 °. For this reason, a bending mechanism is provided on the inner surface of the screen 100 for bending incident light so that the light is emitted from the outer surface of the screen 100 substantially horizontally.

  The configuration of this bending mechanism will be described below with reference to the drawings. FIG. 2 is an enlarged cross-sectional view of the screen 100 cut along a vertical plane perpendicular to the screen 100. As shown in the drawing, a large number of protrusions 112 are formed in a sawtooth shape on the inner surface 110 of the screen 100, and the light incident on the upper surface of the protrusion is refracted to change its direction to a substantially horizontal direction. The light is emitted from the outer surface of the screen 100. In other words, the inner surface 110 of the screen 100 on which the protrusions 112 are formed functions as a kind of Fresnel lens.

  The arrangement of the relay mirror 210 and the final projection mirror 220 in the projection display apparatus 1 of the present embodiment will be described in detail below with reference to the drawings. FIG. 3 is a cross-sectional view of the screen 100, the relay mirror 210, and the final projection mirror 220 taken along a vertical plane perpendicular to the screen 100. In FIG. 3, only the inner surface 110 of the screen 100 and the reflecting surfaces 212 and 222 of the relay mirror 210 and the final projection mirror 220 are described in order to describe the positions of the relay mirror 210 and the final projection mirror 220 with respect to the screen 100 in more detail. The other elements relating to the screen 100, the relay mirror 210, and the final projection mirror 220 are omitted for simplification of the drawing. Also, the projection unit 300 is shown as a point.

In the following description, an angle formed by the reflection surface 222 of the final projection mirror 220 and the normal line of the screen 100 is defined as θ. Of the light traveling from the projection unit 300 via the relay mirror 210 and the final projection mirror 220 to the screen 100, a light beam having a minimum incident angle on the screen 100 is a vertical plane perpendicular to the screen 100 (that is, the screen 100 and each A line projected onto a plane perpendicular to both of the mirrors is defined as B _1, and a line projected on a vertical plane perpendicular to the screen 100 is defined as B _{2 where the} light beam having the maximum incident angle on the screen 100 is defined as B _2. To do. Here, of the line B ₁ , a line segment from the final projection mirror 220 toward the screen 100 is defined as s ₁ , and a line segment from the relay mirror 210 toward the final projection mirror 220 is defined as s ₅ . Of the line B ₂ , the line segment from the relay mirror 210 to the final projection mirror 220 is s ₂ , the line segment from the projection unit 300 to the relay mirror 210 is s ₄ , and the minute line is from the final projection mirror 220 to the screen 100. A straight line obtained by extending the minutes back and forth is defined as s ₃ . At this time, when reversing the segment _{s 2} the line _{s 2} around the normal line of the final projection mirror 220, overlaps the straight line _{s 3.}

Here, the angle formed by the straight line s ₃ and the normal line of the screen 100 is w ₁ , the angle formed by the line segment s ₁ and the normal line of the screen 100 is w ₂ , the height dimension of the screen 100 is H, and the line B The length of ₂ is defined as L, and the distance from the rear edge of the final projection mirror 220 to the inner surface 110 of the screen 100 is defined as d. In the following description, it is assumed that the dimensions of the projection unit 300 and the thicknesses of the relay mirror 210 and the final projection mirror 220 are sufficiently smaller than the dimensions of the apparatus.

The distance d is calculated by Equation 1 using the length H, the angles θ, w ₁ , and w ₂ .

To the thickness d to approximately one-half of the screen shorter side, when considering the thickness of a mechanism for attaching the relay mirror 210, w ₂ is preferably not less than 50 °. As for the upper limit, 90 ° is unrealistic because the light beam traveling from the relay mirror 210 toward the final projection mirror 220 is too close to the screen inner surface 110, and is at most about 85 °.

Also for w ₁ , the mounting mechanism and the edge of the mirror are positioned on the normal line at the center of the screen, and in order to avoid the possibility of adverse effects such as scattering, it is slightly less than the theoretical value, 60 ° or less It is realistic to set as the installation range. At this time, w ₂ > w ₁ .
Therefore, in order to reduce the depth of the projection display device 1 under the condition that the projection unit 300 and / or the relay mirror 210 does not protrude from the upper and lower ends of the screen 100, w2 and w1 satisfy the above-described conditions, The unit 300 is disposed behind the screen 100, and the distance between the projection unit 300 and the screen 100 and the distance to the rear edge of the relay mirror 210 are smaller than the distance d (that is, it passes through the rear edge of the final projection mirror 220). The projection unit 300 and the relay mirror 210 are disposed between the plane parallel to the screen 100 and the screen 100), and the maximum angle θ is set so that the rear edge of the relay mirror 210 does not protrude from the upper edge of the screen. To do.

In order to prevent the relay mirror 210 and the screen 100 from interfering with each other, the angle β formed between the inner surface 110 of the screen 100 and the line s ₂ needs to be 0 ° or more. Since the angle is 90 ° −2θ−w ₁ , in order for the angle β to be 0 ° or more, the angle θ needs to satisfy the condition of Formula 2.

Further, in order to make the distance between the rear edge of the relay mirror 210 and the screen 100 shorter than the distance d, the rear edge of the reflection surface 212 of the final projection mirror 220 is extended from the rear edge of the reflection surface 212 of the relay mirror 210. and extended lines (one-dot chain line s ₅ in the _figure), (dashed line s ₆ in the _figure) edge from a line drawn vertically downward after reflecting surface 222 of the final projection mirror 220 and is an angle made 0 ° or more to the There must be. Since the size of this angle is 2θ + w ₂ −90 °, in order for this angle to be 0 ° or more, the angle θ needs to satisfy the condition of Equation 3.

  From Equation 2, it is obvious that θ is 45 ° or less. In other words, the angle (90 ° −θ) formed by the reflection surface of the screen 100 and the final projection mirror 220 is 45 ° or more and 90 ° or less. When the angle formed by the screen 100 and the reflecting surface of the final projection mirror 220 satisfies the above conditions, light from an external light source disposed outside the projection display device 1 (particularly the upper rear of the viewer) passes through the screen 100. Then, the light is incident on the final projection mirror 220 and reflected there, and is incident on the viewer's eyes, making it difficult to see the screen, or the light incident on the screen 100 is reflected by the screen and the final projection mirror toward the screen. It is possible to prevent a ghost phenomenon that can occur due to the above.

At this time, if L cos β ≦ H, the projection unit 300 can be provided in the case 10 of the apparatus 1 without providing the relay mirror 210. Here, L can be described as in Expression 4 using H, θ, w ₁ , and w ₂ .

Therefore, when the following formula 5 is established, the relay mirror becomes unnecessary. Further, when all of Equations 2, 3, and 5 are established, the projection unit 300 does not protrude backward from the rear edge of the final projection mirror 220 or protrudes downward from the lower end of the screen 100. A display device that does not require a relay mirror is realized. Here, in the case of H = 747 mm, w ₁ = 19.9 °, and w ₂ = 53 °, if θ = 22.6 °, the projection satisfying Equations 2, 3, and 5 and d = 428 mm. A device is realized.

  Next, the conditions for the relay mirror to be accommodated in the case 10 will be described below with reference to FIG. 4 is a cross-sectional view of the screen 100, the relay mirror 210, and the final projection mirror 220 cut along a vertical plane perpendicular to the screen 100, as in FIG.

Here, the angle formed by the cross section of the reflecting surface 212 of the relay mirror 210 on the vertical plane perpendicular to the screen 100 and the normal line of the screen 100 is α. Further, the length of the cross section of the reflecting surface 212 of the relay mirror 210 on the vertical plane perpendicular to the screen 100 is n. Here, in order for the rear edge of the relay mirror 210 to be higher than the lower end of the screen 100, the normal line of the screen 100 that intersects the front edge of the relay mirror 210 and the screen 100 intersect with each other. The relationship of Equation 6 needs to be established between the distance H ′ to the lower end, the length n, and the angle α. In the following, it is assumed that the front edge of the relay mirror 210 is arranged at the intersection of the lines s ₁ and s ₂ . When the relay mirror 210 is arranged so that the angle between the reflection surface of the relay mirror 210 and the screen is an obtuse angle as described above, the projection unit 300 is placed in a dead space between the relay mirror 210 and the final projection mirror 220. The projector can be arranged, and the projector can be downsized.

Here, when the reflective surface 212 and the line s ₅ relay mirror 210 is perpendicular, the angle α is minimized, also the minimum value of Nsinarufa. The value of the angle α at this time is 2θ + w ₂ −90 °. At this time, the trailing edge of the relay mirror 210 is moved away from the lower end closest to the screen 100, and the projection unit 300 is arranged on the line _{s 5.} When the angle α takes a smaller value, the projection unit 300 moves upward. Therefore, in order to eliminate the possibility that the projection unit 300 is arranged behind the rear edge of the final projection mirror 220 and the depth dimension of the apparatus increases, the value of the angle α may be 2θ + w ₂ −90 °. desirable. In the following description, it is assumed that α = 2θ + w ₂ −90 °.

Further, H ′ can be described using the length H, the angles θ, w ₁ , and w ₂ as in the following Expression 7.

A line segment obtained by projecting a light beam traveling from the front edge of the relay mirror 210 toward the front edge of the final projection mirror 220 onto the vertical plane perpendicular to the screen from the projection unit 300 toward the front edge of the relay mirror 210 (the dashed line s in FIG. The length of ₂ ) is defined as L ′. Therefore, the length of the line segment (dashed line s ₄ in the figure) obtained by projecting the light beam from the projection unit 300 toward the front edge of the relay mirror 210 onto the vertical plane perpendicular to the screen is LL ′. At this time, the value of L ′ is the value shown in Equation 8.

  Furthermore, from the equations 7 and 8, the result of the equation 9 is obtained.

Further, the angle formed by the line segment (dotted line s ₆ in the figure) obtained by projecting the light beam from the projection unit 300 toward the rear edge of the relay mirror 210 onto the vertical plane perpendicular to the screen and the line segment s ₄ is w ₂ −w _1. It is. Since α = 2θ + w ₂ −90 °, the line s ₆ is perpendicular to the reflecting surface 212 of the relay mirror 210, and the dimension n is a value that satisfies the equation (10).

  Further, from the formulas 9 and 10, n is defined as the following formula 11.

  Further, from Equations 6 and 7, the possible range of n is defined by the following Equation 12.

  Furthermore, the relationship shown in Equation 13 is derived from Equations 4, 11, and 12.

By setting θ so that Expression 13 is satisfied within the range where Expressions 2 and 3 are satisfied, the projection unit 300 is arranged behind the screen 100, the distance between the projection unit 300 and the screen 100, and the relay mirror 210. A projection display device is realized in which the distance to the rear edge is smaller than the distance d and the rear edge of the relay mirror 210 does not protrude from the upper edge of the screen. For example, when H = 747 mm, w ₁ = 19.9 °, and w ₂ = 50 °, if θ = 32.9 °, the projection apparatus satisfying Equations 2, 3, and 13 and d = 406 mm Is realized. As θ increases, the difference between the left side and the right side in Equation 13 decreases. Therefore, if Equations 2 and 3 are satisfied and θ can be set so that the left side and the right side are equal in Equation 13, The angle θ at that time is a value that minimizes the distance d (that is, the depth dimension of the apparatus).

  In the present embodiment, the relay mirror 210 is configured to fold light emitted from the projection unit 300 provided obliquely upward and rearward in an obliquely upward and forward direction. The configuration is not necessarily limited to the above as long as the configuration does not come behind the rear edge of the final projection mirror. For example, a projection unit 300 and a relay mirror 210 are respectively provided at both lower portions of the projection display device 1 in the width direction, and the relay mirror 210 folds light emitted along the device width direction upward. It is good.

It is sectional drawing which cut | disconnected the projection display apparatus of embodiment of this invention by the vertical plane perpendicular | vertical to a screen. It is the expanded sectional view which cut | disconnected the screen in the perpendicular plane perpendicular | vertical to a screen. It is sectional drawing which cut | disconnected the screen, the relay mirror, and the final projection mirror by the vertical plane perpendicular | vertical to a screen. It is sectional drawing which cut | disconnected the screen, the relay mirror, and the final projection mirror by the vertical plane perpendicular | vertical to a screen.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Projection display apparatus 10 Case 100 Screen 110 Screen inner surface 112 Protrusion 210 Relay mirror 212 Relay mirror reflective surface 220 Final projection mirror 222 Final projection mirror reflective surface 300 Projection unit

Claims (9)

A translucent screen placed in front of the device;
Image forming means for forming an image projected on the screen;
A light source for projecting the image formed by the image forming means onto the screen;
First and second reflecting means arranged on an optical path between the image forming means and the screen, and light passing through an image formed by the image forming means is the second reflecting means and One that is sequentially incident on the first reflecting means;
Have
The first reflecting means is provided such that the reflecting surface of the first reflecting means forms an angle of 45 degrees or more and less than 90 degrees with the screen.
The second reflecting means is provided in a state where the reflecting surface of the second reflecting means is inclined so as to form an obtuse angle with the screen.
A projection display device characterized by that.   Of the light traveling from the first reflecting means to the screen, the distance from the incident position to the first reflecting means of the light beam having the smallest incident angle to the screen is the incident angle to the screen. The projection display device according to claim 1, wherein the projection display device is equal to or less than a half of a distance from an incident position of the maximum light ray to the first reflecting means to the screen.   The projection display device according to claim 2, wherein one edge of the first reflecting means is substantially in contact with one edge of the screen. An angle formed by the reflecting surface of the first reflecting means and the normal line of the screen is θ, and a light beam having a minimum incident angle to the screen out of the light traveling from the first reflecting means to the screen is the screen. And an angle formed by a line segment projected on a plane perpendicular to both of the first reflecting means and the normal line of the screen, w ₁ , and out of light traveling from the first reflecting means toward the screen to the screen. If w ₂ is defined as an angle formed by a line segment obtained by projecting a light beam having a maximum incident angle onto a plane perpendicular to both the screen and the first reflecting means, and the normal of the screen, the angles θ and w ₁ are defined. , W _{2
45 ° -w 2/2 ≦ θ} ≦ 45 ° -w 1/2
The projection display device according to claim 1, wherein the relationship is established. Between the angles θ, w ₁ and w ₂ ,
sin (2θ + w ₂ -90 °) ≦
(tan w ₂ cos (2θ + w ₁ ) + sin (2θ + w ₂ -90 °) sin (w ₂ -w ₁ )) / sin (2θ + w ₁ + w ₂ )
The projection display apparatus according to claim 4, wherein the relationship is established. 0 ° ≦ θ ≦ 40 °
0 ° ≦ w ₁ ≦ 60 °
60 ° ≦ w ₂ ≦ 85 °
The projection display device according to claim 4, wherein the projection display device is a projection display device. Between the angles θ, w ₁ and w ₂ ,
sin (2θ + w ₂ -90 °) =
(tan w ₂ cos (2θ + w ₁ ) + sin (2θ + w ₂ -90 °) sin (w ₂ -w ₁ )) / sin (2θ + w ₁ + w ₂ )
The projection display device according to claim 4, wherein the relationship is established. A translucent screen placed in front of the device;
Image forming means for forming an image projected on the screen;
A light source for projecting the image formed by the image forming means onto the screen;
A reflecting unit disposed on an optical path between the image forming unit and the screen, and reflecting light that has passed through the image formed by the image forming unit in a predetermined direction;
Have
The reflection means is provided such that a reflection surface of the reflection means forms an angle of 45 degrees or more and less than 90 degrees with the screen.
The angle formed by the reflecting surface of the reflecting means and the normal line of the screen is θ, and the light beam having the smallest incident angle to the screen out of the light traveling from the reflecting means to the screen is both the screen and the reflecting means. If the angle formed by the line segment projected on the plane perpendicular to the plane and the normal line of the screen is defined as w ₁ , the light ray having the maximum incident angle to the screen out of the light traveling from the reflecting means to the screen is Assuming that an angle formed by a line segment projected on a plane perpendicular to both the screen and the reflecting means and the normal line of the screen is w ₂ , between the angles θ, w ₁ and w ₂ ,
_{45 ° -w 2/2 ≦ θ} ≦ 45 ° -w 1/2
sin (2θ + w ₁ ) ≤ cos w ₁ tan w ₂ -sin w ₁
A projection display device characterized in that the relationship is established. 0 ° ≦ θ ≦ 40 °
0 ° ≦ w ₁ ≦ 60 °
50 ° ≦ w ₂ ≦ 85 °
The projection display device according to claim 8, wherein:

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