JP2008083428A - Rear projector, cabinet for rear projector, and projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin rear projector, having a projector that can be used for both front projection and rear projection, and to provide a cabinet and projector for the rear projector. <P>SOLUTION: The rear projector 1 includes the cabinet 11; a screen 21; the projector 31 that has a wide-angle projection lens 55 detachable from the front face of the cabinet 11; and the mirror 41. Mathematical Formula (1) is satisfied by defining distance g<SB>1</SB>(mm), between the exit pupil of the projection lens 55 and the mirror 41; distance g<SB>2</SB>(mm) between the mirror 41 and the screen 21; the diagonal angle dimension a (inch) of the screen 21, and the width/length ratio of the screen 21 (e/f), and the diagonal field angle (half angle) θ of the projection lens 55. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rear projector, and more specifically, to a thin rear projector including a projector that can be attached and detached from a side of a cabinet provided with a screen.

  Conventionally, a rear projector is known as a technology for realizing a light-weight and inexpensive large-screen television. A general rear projector projects image light from a projector installed behind a transmissive screen provided at the front of the cabinet to a mirror disposed obliquely with respect to the screen at the upper rear of the cabinet, An image is displayed on the screen by the image light reflected by the mirror. If this projector can be taken out of the cabinet and used as a front projector (front projection projector), it is very convenient. In view of this, a rear projector that can use a projector housed in a cabinet for front projection has been proposed (see, for example, Patent Document 1).

Further, the rear projector has been targeted to be thinner and lighter. However, since a normal front projector has a small angle of view, a corresponding projection distance is required to display an image of a certain size. That is, when this is used as it is for a rear projector, a large space inside the cabinet must be provided in order to secure a necessary optical path length in the cabinet, and it is difficult to reduce the thickness. In addition, when the mirror is disposed obliquely immediately behind the screen as in the prior art, the mirror itself becomes large and heavy. Therefore, as one method for achieving a reduction in thickness and weight, there is a rear projector in which a wide-angle lens is used and one or more mirrors are arranged perpendicular to the lens optical axis and parallel to the screen. It has been proposed (see, for example, Patent Document 2).
JP-A-6-138431 JP-T-2006-504120

  However, as shown in FIG. 3 of Patent Document 1, the projector included in the rear projector described in Patent Document 1 performs so-called tilt projection in which the entire projector is directed obliquely upward and projected using the full angle of view. Yes. Therefore, when this projector is mounted on a desk and used for front projection, for example, there is a problem that the lower part of the image light is obstructed by the mounting surface (desk), the image is lost, and a desired image cannot be obtained. In addition, when tilt projection is used for front projection, the image is distorted in the vertical direction (so-called trapezoidal distortion) due to the fact that the projection optical axis of the projector is tilted with respect to the projection plane. In order to project a correct image, distortion correction was necessary.

  On the other hand, since the rear projector described in Patent Document 2 does not perform tilting projection, when image light from the projector is projected onto the screen via one or more mirrors, the image light is projected at an appropriate angle. If the projection is not performed, the projector lens or mirror may obstruct the optical path, and the image may be lost.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a thin rear projector including a projector that can be used for both front projection and rear projection, a cabinet for the rear projector, and a projector. And

In order to achieve the above object, a rear projector according to a first aspect of the present invention includes a cabinet, a screen provided on one side of the cabinet and displaying an image by image light projected from the inside, and the cabinet of the cabinet. A projector that is housed in the cabinet in a detachable state from the side on which the screen is provided, has a wide-angle projection lens, and enlarges and projects image light formed by a light modulation element onto the screen, and the screen X projections (x is an integer equal to or greater than 1) provided in the cabinet in parallel to and perpendicular to the optical axis of the projection lens and reflecting the image light projected by the projector. order the image light is reflected from the exit pupil and the exit pupil of the lens is the distance between the first mirror g _{1 (mm} The order is n-th and n-1 th mirror (n is an integer from 2 to x) the distance of the mirror of _g n (mm), the distance from the last mirror and the screen _g x + 1 (mm), the When the diagonal dimension of the screen is a (inch) and the horizontal: vertical ratio of the screen is e: f, the diagonal angle of view (half angle) θ used by the projector to project the image light is The mathematical formula is satisfied.

  According to a second aspect of the present invention, in addition to the configuration of the first aspect of the invention, the projection lens and the light modulation element have an optical axis of the projection lens and a central axis of the light modulation element. It is characterized by being shifted.

According to a third aspect of the present invention, there is provided a rear projector according to the first or second aspect, wherein the height from the optical axis of the projection lens to the uppermost end of the projector is h, The angle formed by the optical axis and a light beam incident on the center of the lower side of the image projected from the exit pupil to the first mirror is φ ₁ , and the order from the projection lens optical axis and the exit pupil is When the angle formed by the light beam incident on the center of the upper side of the image projected on the first mirror is φ ₂ , when the number x of mirrors is 1, h <2g ₁ · tan φ ₁ is satisfied, and x is 2 At this time, it is characterized in that h <2g ₁ · tan φ ₁ and the following mathematical formula are satisfied.

  A rear projector according to a fourth aspect of the present invention further includes guide means for translating the projector in a vertical direction with respect to the screen in addition to the configuration of the invention according to any one of the first to third aspects. Yes.

  In the rear projector according to the fifth aspect of the invention, in addition to the configuration of the invention according to the fourth aspect, the guide means displays the installation position of the projector corresponding to the size of the image displayed on the screen. A position display means is further provided.

  According to a sixth aspect of the present invention, there is provided a rear projector according to any one of the first to fifth aspects, wherein the projection surface of the projector has the first order according to the size of the projector. A jig is further provided for adjusting the height of the projector so as to overlap the mirror.

  According to a seventh aspect of the present invention, in addition to the configuration of the first aspect of the present invention, in the case where the number of the mirrors is an even number, Further provided is a left / right reversing means for reversing the image displayed on the screen.

  The rear projector according to an eighth aspect of the invention further includes processing mode setting means for setting an image processing mode indicating whether or not the image is reversed left and right in addition to the configuration of the invention according to the seventh aspect, The left-right reversing means is means for performing left-right reversal based on the image processing mode set by the operation means.

  Further, a rear projector according to a ninth aspect of the present invention further includes a detection unit that detects whether the cabinet or the projector is attached to or detached from the cabinet, in addition to the configuration of the invention according to the seventh or eighth aspect. The left / right reversing means is a means for automatically performing left / right reversal based on the detection result of the detecting means.

  The rear projector cabinet of the invention according to claim 10 is equipped with a projector that has a wide-angle projection lens and that is detachable from the front side of the cabinet and that enlarges and projects the image light formed by the light modulation element onto the projection surface. A mounting unit, x mirrors (x is an integer equal to or greater than 1) that are arranged perpendicular to the optical axis of the projection lens and reflect the image light projected by the projector, and the x mirrors And a screen for displaying an image by the image light reflected by the x mirrors, and means for electrically connecting to the projector when the projector is mounted.

  The rear projector cabinet according to an eleventh aspect of the invention further includes guide means for translating the projector in a direction perpendicular to the screen in addition to the configuration of the invention according to the tenth aspect.

  In the rear projector cabinet according to the twelfth aspect of the invention, in addition to the configuration of the invention of the eleventh aspect, the guide means determines the installation position of the projector corresponding to the size of the image displayed on the screen. Position display means for displaying is provided.

    According to a thirteenth aspect of the present invention, there is provided a front projector that projects image light formed by a light modulation element that is housed in the cabinet in a detachable state from the front side of the rear projector cabinet and has a wide-angle projection lens. A front projector for enlarging and projecting the image to the cabinet includes a left / right reversing means for reversing the image displayed on the screen in the left / right direction when being attached to or detached from the cabinet.

  The front projector of the invention according to claim 14 is further provided with processing mode setting means for setting an image processing mode indicating whether or not the image is horizontally reversed in addition to the configuration of the invention of claim 13. The left-right reversing means is means for performing left-right reversal based on the image processing mode set by the operation means.

  Further, the front projector of the invention according to claim 15 is further provided with means for detecting attachment / detachment of the projector to / from the cabinet in addition to the configuration of the invention of claim 13 or 14, wherein Based on the detection result, it is means for automatically performing left-right reversal.

  According to the rear projector of the first aspect of the invention, since the projector is detachable from the cabinet, it can be taken out and used as a front projector for front projection. At this time, since the projector can be taken out from the side where the screen is installed, that is, the front side facing the operator, the taking-out operation is simple. Further, the projection lens of the projector is a wide-angle lens, and at least one mirror and screen are arranged perpendicular to the optical axis of the lens and parallel to each other, so that the entire rear projector can be reduced in thickness. In addition, trapezoidal distortion that becomes a problem when the projection optical axis of the projector is tilted with respect to the projection plane (when tilting projection is performed) does not occur. Further, by specifying the diagonal field angle (half angle) θ of the projection lens as described in claim 1, the image light is emitted only from the upper half region of the projection lens of the projector, and at the lower end of the image light. The light beam is positioned above the projection optical axis. Thus, even when the projector is taken out and placed on a desk and used for front projection, the image is not lost due to being hindered by the placement surface. Further, it is possible to reduce the area of the image light that is obstructed by the projector and the intermediate mirror before the image light reflected by at least one mirror reaches the screen.

  In the rear projector of the invention according to claim 2, in addition to the effect of the invention of claim 1, an offset can be provided by shifting the optical axis of the projection lens from the central axis of the light modulation element.

  Further, according to the rear projector of the invention of claim 3, in addition to the effect of the invention of claim 1 or 2, image light emitted from the projection lens of the projector and reflected by at least one mirror is screened. Thus, it is possible to reliably prevent the image from being lost due to being obstructed by the projector or the intermediate mirror.

  According to the rear projector of the invention according to claim 4, in addition to the effect of the invention according to any one of claims 1 to 3, when changing the size of the projected image by shifting the position of the projector, The projector can be arranged at a position where the image light always forms an appropriate optical path.

  Further, according to the rear projector of the invention according to claim 5, in addition to the effect of the invention of claim 4, the position where the image of the predetermined size can be obtained is specified by the position display means. It can be performed simply.

  Further, according to the rear projector of the invention according to claim 6, in addition to the effect of the invention according to any one of claims 1 to 5, the position of the projection lens of the projector is low, and the optical path of the image light is used as a mirror as it is. Even if they do not overlap, the projector can be lifted and placed in an appropriate position.

  According to the rear projector of the invention according to claim 7, in addition to the effect of the invention according to any one of claims 1 to 6, when an even number of mirrors are provided, an image can be displayed when the projector is attached to or detached from the cabinet. Right-and-left inversion is performed, and an appropriate image can be displayed in both cases of front projection and rear projection. That is, when an even number of mirrors are provided, the left and right sides of the image viewed from the viewer are reversed between the case where the same image light is projected in front and the case where it is rear-projected. Thus, by providing the left / right reversing means and performing appropriate processing, it is possible to always obtain an image that is always right and left as viewed from the viewer.

  Further, according to the rear projector of the invention according to claim 8, in addition to the effect of the invention of claim 7, by setting an image processing mode indicating whether the operator reverses the image horizontally, It is possible to easily instruct left-right reversal as necessary.

  Further, in the rear projector of the invention according to claim 9, in addition to the effect of the invention of claim 7 or 8, when the projector is attached to or detached from the cabinet, the image is reversed left and right, and either front projection or rear projection is performed. In this case, an appropriate image can be displayed.

  The rear projector cabinet of the invention according to claim 10 is electrically connected to the projector when the projector is mounted. By detecting this connection and the projector automatically performs the left / right reversing process, an appropriate image can be obtained without requiring another operation.

  Further, according to the rear projector cabinet of the invention of claim 11, in addition to the effect of the invention of claim 10, when changing the size of the projected image by shifting the position of the projector, the image light is always displayed. The projector can be arranged at a position that forms an appropriate optical path.

  Furthermore, according to the rear projector cabinet of the twelfth aspect of the invention, in addition to the effect of the invention of the eleventh aspect, the position where the image of a predetermined size can be obtained is specified by the position display means. Positioning can be performed easily.

  Further, according to the front projector of the invention according to claim 13, when the projector is attached to or detached from the cabinet, the attachment / detachment is automatically detected and the left / right reversal is performed. Appropriate images can be obtained.

  Furthermore, in the front projector of the invention according to claim 14, in addition to the effect of the invention according to claim 13, it is necessary by setting an image processing mode indicating whether or not the image is reversed horizontally. Accordingly, it is possible to easily instruct the left / right inversion.

  In the front projector according to the fifteenth aspect, in addition to the effect of the thirteenth or fourteenth aspect, when the projector is attached to or detached from the cabinet, the attachment or detachment is automatically detected and the left and right are reversed. Therefore, an appropriate image can be obtained without requiring other operations.

  Embodiments of a rear projector, a rear projector cabinet, and a projector embodying the present invention will be described below with reference to the drawings. In addition, in each drawing, the same code | symbol is attached | subjected about the common component. Further, these drawings are used to explain technical features that can be adopted by the present invention, and there are no specific descriptions of the dimensions, shapes, relative arrangements, and the like of the described components. As long as it is not limited to that, it is merely an illustrative example.

<First Embodiment>
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a partial longitudinal sectional view showing a schematic configuration of a rear projector 1 according to the first embodiment. FIG. 2 is a schematic diagram showing an internal structure of the projector 31 according to the first embodiment. 3 and 4 are explanatory diagrams for explaining the positional relationship between the optical axis and the screen when there is no offset and when there is no offset. FIG. 5 is an explanatory diagram for explaining the relationship between the diagonal angle of view θ of the projection lens 55 and the length Y2 shown in FIG. FIG. 6 is a block diagram showing an electrical configuration of the projector 31.

  First, a schematic configuration of the rear projector 1 according to the present embodiment will be described with reference to FIGS. As shown in FIG. 1, a rear projector 1 includes a box-shaped cabinet 11 having a hollow interior, a screen 21 provided on one side of the cabinet 11, a projector 31 accommodated in the cabinet 11, and a cabinet interior. And a single mirror 41 installed on the side facing the one side on which the screen 21 is provided. Hereinafter, in the cabinet 11, the side surface on which the screen 21 is provided is “front surface 11 </ b> A”, the side surface on which the mirror 41 is provided is “back surface 11 </ b> B”, and the side surface located on the right side when the viewer faces the screen 21. Is referred to as “right side surface 11C”, the opposite side surface is referred to as “left side surface 11D”, the mounting surface of the cabinet 11 on a flat surface such as the ground is referred to as “bottom surface 11E”, and the surface facing the bottom surface is referred to as “top surface 11F”.

  As shown in FIG. 1, a door 16 that opens outward is provided below the screen 21 of the front surface 11 </ b> A of the cabinet 11. The door 16 is an opening through which a projector 31 (to be described later) is taken in and out of the cabinet 11. Further, as shown in FIGS. 1 and 2, a substantially rectangular parallelepiped positioning protrusion 15 is provided on the bottom surface 11 </ b> E of the cabinet 11 and protrudes toward the inside of the cabinet 11. The positioning projection 15 is used when the projector 31 is installed in the cabinet 11. A method for attaching and detaching the projector 31 to the cabinet 11 will be described later.

  The screen 21 is a transmissive screen on which image light projected from the projector 31 housed in the cabinet 11 and reflected by the mirror 41 is projected from the back. That is, the viewer views the image on the screen 21 from the back side of the surface on which the image is projected because the viewer views the image while facing the front surface 11A of the cabinet 11.

  As shown in FIG. 2, the projector 31 includes a casing 51 having a hollow inside, a lamp 52 accommodated therein, an illumination lens 53 that collimates illumination light emitted from the lamp 52, and “ A transmissive liquid crystal panel (Liquid Crystal Display: hereinafter abbreviated as LCD) 54 and a projection lens 55 corresponding to the “light modulation element” are provided. In the projector 31, the side on which the exit pupil 55 </ b> A of the projection lens 55 is located is “front surface 31 </ b> A”, the side surface facing this is “back surface 31 </ b> B”, and the right side when the operator faces the exit pupil 55 </ b> A of the projection lens 55. The side surface located on the right side is 31C, the opposite side surface is the left side surface 31D, the bottom surface 11E of the projector 11 is placed on the bottom surface 11E or on a flat surface such as a desk, the bottom surface 31E is opposed to the bottom surface The surface to be referred to is referred to as “upper surface 31F”.

  As shown in FIGS. 1 and 2, the bottom surface 31 </ b> E of the casing 51 of the projector 31 is provided with a substantially rectangular parallelepiped fixing hole 57 that fits into the positioning protrusion 15 of the cabinet 11 described above. The projector 31 can be installed at an appropriate position in the cabinet 11 by fitting the fixing hole 57 to the positioning protrusion 15 provided on the bottom surface 11E of the cabinet 11 described above.

  As the lamp 52, a light source used in a normal projector, such as a xenon lamp, a metal halide lamp, or an ultrahigh pressure mercury lamp, is used. Among these, a high-intensity and long-life ultra-high pressure mercury lamp is particularly excellent.

  The LCD 54 is a transmissive color liquid crystal panel incorporating a color filter. The LCD 54 modulates the illumination light emitted from the lamp 52 and incident through the illumination lens 53, and as described later, is reflected by the mirror 41 according to a separately input video signal and is shown in FIG. The image light projected on is formed.

  The projection lens 55 is a wide-angle lens, and can project a large size image at a short distance. In other words, the projection distance for obtaining an image of the same size can be made shorter than that of a normal lens. In the present embodiment, in order to provide an offset described later, the LCD 54 and the projection lens 55 are arranged so that the optical axis of the projection lens 55 and the center axis of the LCD 54 are shifted as shown in FIG.

  A mirror 41 that reflects the image light projected from the projector 31 and projects it onto the screen 21 is installed on the back surface 11B of the cabinet 11, as shown in FIG. The reflection surface is parallel to the screen 21 provided on the front surface 11 </ b> A of the cabinet 11 and is perpendicular to the optical axis of the projection lens 55. With such a configuration, it is possible to reduce the thickness of the cabinet 11 and solve the problem of trapezoidal distortion that occurs when the projection surface is inclined with respect to the projection optical axis.

Further, in the rear projector 1, the diagonal angle of view θ of the projection lens 55 shown in FIG. 1, the diagonal dimension a (inch) and the aspect ratio (e: f) of the screen 21, the mirror from the exit pupil 55 A of the projection lens 55. The following relational expression (1) is established between the distance g ₁ (mm) to 41 and the distance g ₂ (mm) from the mirror 41 to the screen 21.
tan ⁻¹ [25.4a√ {{(e / 2) ² + f ² } / (e ² + f ² )} / (g ₁ + g ₂ )] <θ <90 ° (1)

  Hereinafter, the above formula (1) will be described with reference to FIGS. Here, consider a case where a screen is arranged in front of the projector 31 and an image is projected onto the virtually arranged screen. In FIG. 3, the optical axis of the projection lens 55 extends perpendicularly to the projection surface of the screen S from the front of the figure, and intersects with a straight line L that is the central axis in the left-right direction of the screen S at a point P1. A straight line that is in the same plane as the screen S and is orthogonal to the straight line L at the point P1 is defined as a straight line M. As shown in FIG. 3, when the distance between the optical axis of the projection lens 55 (projection optical axis) and the lower end of the screen S is zero (0), that is, when the lower side of the screen S is in contact with the straight line M, the offset is It is said that there is no state. On the other hand, as shown in FIG. 4, when there is a distance between the projection optical axis and the lower end of the screen S, that is, when the lower side of the screen S is above the straight line M, there is an offset. This distance HD is called an offset value. In the present embodiment, the projection optical axis of the projector 31 is perpendicular to the mirror 41 and the actual screen 21. That is, so-called tilt projection is not performed in which the entire projector 31 is tilted upward or downward and the projection optical axis is tilted with respect to the projection surface. Therefore, if no offset is provided, the light rays below the image light emitted from the exit pupil 55A of the projection lens 55 are reflected by the mirror 41 and then blocked by the projector 31 before reaching the screen 21, and the image Will be missing.

Therefore, the length of the line segment connecting the intersection P1 between the projection optical axis and the screen center axis L and the vertex P2 on the left side of the upper side of the screen S shown in FIG. 3 (state without offset) is Y1 (mm). When the length of the line segment connecting the intersection P1 shown in FIG. 4 (offset state) and the vertex P3 moved upward by the offset value HD from P2 in FIG. 3 is Y2 (mm), the offset It is necessary to satisfy the following formula (2), which is a condition having
Y2> Y1 (2)

Here, since 1 inch = 25.4 mm and the actual aspect ratio of the screen 21 is e: f, the following equation (3) is derived.
Y1 = 25.4a√ {{(e / 2) ² + f ² } / (e ² + f ² )} (3)
Further, as shown in FIG. 5, the distance from the projection pupil 55A to point P1 on the screen S in the same plane of the projection lens 55, from the distance g ₁ and the mirror 41 and the exit pupil 55A and the mirror 41 to the screen 21 equal to the sum of the distance _{g 2.} Furthermore, since the angle formed by the straight line connecting the projection pupil 55A and the point P3 and the projection optical axis is the diagonal field angle θ, the following equation (4) is derived.
Y2 = (g ₁ + g ₂ ) · tan θ (4)

  Therefore, since the expressions (3) and (4) are substituted into (2) and rearranged, and the diagonal angle of view θ does not exceed 90 degrees, the above-described expression (1) is obtained.

  By providing the offset in this way, the light beam below the image light emitted from the projection lens 55 is blocked by the projector 31 before being reflected by the mirror 41 and reaching the screen 21, and the image may be lost. Can be reduced.

Further, it is possible to easily determine the arrangement of the components of the rear projector 1 based on the above formula (1). For example, when the rear projector 1 includes a screen of 56 inches wide (aspect ratio 16: 9), a = 56, e = 16, and f = 9 in the above formula (1). Further, g ₂ is set to a desired value as the depth from the front surface 11A to the back surface 11B of the cabinet 11. Therefore, if the installation position of the projector 31 in the cabinet, that is, the distance g ₁ between the exit pupil 55A of the projection lens 55 and the mirror 41 is determined, the range of the angle of view θ of the projection lens 55 of the projector 31 can be easily determined. Can do. Alternatively, after the angle of view θ of the projection lens 55 is determined, the installation position of the projector 31 corresponding to this in the cabinet 11 may be determined. Alternatively, the angle θ of the projection lens 55 set to a desired value initially, it is also possible to adjust the g ₁ corresponding to the installation position of the inside cabinet 11 in the depth g ₂ and the projector 31 of the cabinet 11.

  Since the screen size of a normal rear projector is limited to some specific combinations of diagonal dimensions and aspect ratios, in order to achieve thinning of the device, a desired depth is first determined, as described above. In addition, the angle of view of the projection lens 55 and the installation position of the projector 31 inside the cabinet 11 may be determined sequentially. As described above, in the rear projector 1 according to the present embodiment, the arrangement of each component can be easily determined.

Furthermore, in the present embodiment, the height from the projection optical axis shown in FIG. 1 to the uppermost end of the projector 31 is h, the center of the lower side of the image projected on the mirror 41 from the projection optical axis and the exit pupil of the projection lens 55 When the angle formed by the light ray incident on is φ ₁ , the following relational expression (5) is established.
h <2 · g ₁ · tanφ ₁ (5)

Hereinafter, the equation (5) will be described with reference to FIG. As described above, since the projector 31 has an offset, as shown in FIG. 1, the light beam at the lower end of the image light emitted from the exit pupil 55A of the projection lens 55 travels obliquely upward and is reflected by the mirror 41. Thus, the light enters the screen 21 located behind the projector 31. However, when the angular phi ₁ formed between the lower end of a beam of image light incident on the projection optical axis and the mirror 41 is too small, light rays reflected by the mirror 41 is inhibited at the top of the projector 31, the lower portion of the image is missing End up. Therefore, in order to prevent this, the position where the light beam at the lower end of the image light emitted from the exit pupil 55A of the projection lens 55 is at least higher than ½ of the height h from the projection optical axis to the uppermost end of the projector 31. Therefore, it is necessary to enter the mirror 41. That is, the following relational expression (6) is established between the angle φ ₁ formed by the projection optical axis and the above-mentioned light beam and the above-described height h.
h / 2 <g ₁ · tan θ (6)
If this is rearranged, the aforementioned equation (5) is obtained.

  Next, the electrical configuration of the projector 31 will be described with reference to the block diagram of FIG. As shown in FIG. 6, the projector 31 includes a power switch 61 for switching on / off the power of the projector 31, an operation panel 62 for an operator to operate the projector 31, a CPU, ROM, and RAM (not shown). A microcomputer 63, a video signal input circuit 64 to which a video signal is input, an image processing circuit 65 that converts the video signal into a signal necessary for driving the LCD 54, an LCD drive circuit 66 that drives the LCD 54, and a lamp 52. And a lamp driving circuit 67 for performing. These are connected via a data bus 60 as shown in FIG.

  Next, with reference to FIG. 1 and FIG. 6, the attachment / detachment operation | movement to the cabinet 11 of the projector 31 and an image projection operation | movement are demonstrated.

  As described above, the projector 31 can be attached to and detached from the cabinet 11 via the door 16 provided on the front surface 11A of the cabinet 11 described above. Normally, as shown in FIG. 1, the projector 31 is configured such that the fixing hole 57 of the bottom surface 31 </ b> E is fitted into the positioning protrusion 15 provided on the bottom surface 11 </ b> E of the cabinet 11 described above, and the front surface of the projector 31 with respect to the back surface 11 </ b> B of the cabinet 11. 31A is accommodated in the cabinet 11 so as to face each other, and the rear projector 1 is configured as a whole. By fixing the fixing hole 57 of the projector 31 to the positioning protrusion 15 of the cabinet 11 and fixing it at that position, the distance between the projector 31 and the mirror 41 is set appropriately, and the projection optical axis is set to the mirror 41 and the screen 21. It becomes perpendicular to it.

  Cables are connected to various input terminals provided in the projector 31 (not shown). When an operator turns on the power by the power switch 61 of the projector 31 and the projector 31 is activated, a video signal and sound are externally received. Various signals such as signals are input. Among these, the video signal of the image projected on the screen 21 is input to the video signal input circuit 64 and transferred to the image processing circuit 65 as shown in FIG. The image processing circuit 65 processes the video signal transferred from the video signal input circuit 64 in accordance with a command from the CPU of the microcomputer 63 and converts it into a video signal necessary for driving the LCD 54. When the converted video signal is input to the LCD drive circuit 66, the LCD drive circuit 66 drives the LCD 54 based on the input converted video signal. As a result, an image projected on the screen 21 is displayed on the LCD 54. As described above, the LCD 54 is illuminated by the lamp 52 via the illumination lens 53. The LCD 54 modulates the illumination light and forms image light of the displayed image. The formed image light is emitted from the projection lens 55, reflected by the mirror 41, and projected onto the screen 21 from the back surface. At this time, an image of the correct orientation as viewed from the viewer is displayed on the front surface of the screen 21 facing the viewer.

  On the other hand, when the projector 31 is used as a front projector, the operator opens the door 16 provided on the front surface 11A of the cabinet 11 to the outside as shown in FIG. As described above, since the door 16 is provided on the front surface 11A facing the operator, the operator does not need to go around the cabinet 11 and can easily attach and detach the projector 31.

  When an operator connects cables to various input terminals provided on the projector 31 (not shown) and the power is turned on by the power switch 61, the projector 31 is activated, and video signals, audio signals, and the like are input from the outside. . Thereafter, the image light formed by the LCD 54 and emitted from the projection lens 55 is projected directly from the front onto a separately provided screen, wall surface, or the like in the same manner as described above, and is an image in the correct orientation as viewed from the viewer. Is displayed.

  When the projector 31 according to the present embodiment is used as a front projector, the projector 31 and the viewer are both directed toward the projection plane of the image such as a screen or a wall surface. The left and right sides of the image projected on the screen coincide with the left and right sides of the viewer. When the projector 31 is housed in the cabinet 11 and used as a component of the rear projector 1, the viewer is the same as viewing the image reflected on the mirror 41 through the transmissive screen 21. Also in this case, the image and the left and right of the viewer match. Therefore, in the present embodiment, when the projector 31 is taken out from the cabinet 11 and used as a front projector, it is not necessary to perform the horizontal reversal processing of the image.

  As described above, the rear projector 1 according to the present embodiment employs a wide-angle lens as the projection lens 55 of the projector 31, and makes the mirror 41 and the screen 21 perpendicular to the optical axis of the projection lens 55 and to each other. By arranging them in parallel, the thickness is reduced. Furthermore, by defining the positional relationship between the screen 21, the projector 31, and the mirror 41 and the angle of the image light projected from the projection lens 55 as described above, it is possible to prevent the image from being lost. Further, by making the projector 31 detachable from the cabinet 11, it can be used for both rear projection and front projection.

<Second Embodiment>
Next, with reference to FIG. 7 and FIG. 8, the difference from the first embodiment will be mainly described for the rear projector 2 according to the second embodiment of the present invention. FIG. 7 is a partial longitudinal sectional view showing a schematic configuration of the rear projector 2. FIG. 8 is an explanatory diagram showing a state in which the rear projector 2 is moved from the position shown in FIG. 7 to the mirror 41 side.

  In the rear projector 1 according to the first embodiment, the positioning projection 15 and the fixing hole 57 are used to fix the projector 31 at a specific position in the cabinet 11, but the rear projector 2 according to the present embodiment is a projector. The guide plate 17 is provided in the cabinet 12 to move the plate 32 in parallel with the mirror 41. The details of this feature will be described below.

  As shown in FIG. 7, the rear projector 2 according to the present embodiment is similar to the rear projector 1 of the first embodiment, in the cabinet 12, the screen 21 provided on the front surface 12 </ b> A of the cabinet 12, and the cabinet 12. The projector 32 accommodated and the mirror 41 provided on the back surface 12B of the cabinet 12 are provided. Further, on the bottom surface 12E of the cabinet 12 of the rear projector 2, a plate-shaped guide plate 17 having the same lateral width and constant thickness as the bottom surface 32E of the projector 32 with the horizontal axis in the horizontal direction of the bottom surface 12E as the center. It is laid between 12A and the back surface 12B. The guide plate 17 in the present embodiment corresponds to the “guide means” of the present invention.

  As shown in FIG. 7, three positioning holes 171 having a substantially rectangular parallelepiped shape are provided on the guide plate 17 along the central axis in the width direction of the guide plate 17 with a predetermined interval. On the other hand, to the bottom surface 32E of the projector 32, a fixed piece 59 that can be folded and stored in a concave storage portion (not shown) provided on the bottom surface 32E is connected in the vicinity of the center of the lower end portion of the front surface 32A. The base portion of the fixed piece 59 is rotatably supported by a rotating shaft (not shown) provided between the side surfaces of the storage portion. Therefore, by rotating about the rotation axis, the fixed piece 59 can be protruded from the bottom surface 32E or folded and stored in the storage unit. And when making it protrude from the bottom face 32E, it is comprised so that the protrusion part of the fixed piece 59 may become a substantially rectangular parallelepiped shape fitted to the above-mentioned positioning hole 171. FIG. The positioning hole 171 in this embodiment corresponds to the “position display means” of the present invention.

It should be noted that in the rear projector 2, the projection image is the same as in the first embodiment both in the case of FIG. 7 where the projection image has the maximum size that matches the size of the screen 21 and in the case of FIG. Similarly, the diagonal angle of view θ of the projection lens 55, the diagonal dimension a (inch) and aspect ratio (e: f) of the screen 21, the distance g ₁ (mm) from the exit pupil of the projection lens 55 to the mirror 41, The following relational expression (1) described above holds between the distance g ₂ (mm) from the mirror 41 to the screen 21.
tan ⁻¹ [25.4a√ {{(e / 2) ² + f ² } / (e ² + f ² )} / (g ₁ + g ₂ )] <θ <90 ° (1)

Further, the height h from the projection optical axis to the uppermost end of the projector 2, and the angle φ ₁ formed by the projection optical axis and the light ray incident on the lower side center of the image projected on the mirror 41 from the exit pupil of the projection lens 55. The following relational expression (5) is satisfied.
h <2 · g ₁ · tanφ ₁ (5)

  Hereinafter, the moving operation and the attaching / detaching operation of the projector 32 in the cabinet 12 will be described with reference to FIGS. 7 and 8. First, the operator pulls out the fixing piece 59 of the projector 32 described above from the storage portion of the bottom surface 32E, and fits the fixing piece 59 into any one of the positioning holes 171 on the guide plate 17 having the same width as the projector 32. 32 is fixed on the guide plate 17. As a result, the optical axis of the projection lens 55 of the projector 32 is parallel to the mirror 41 and the screen 21. FIG. 7 shows a state in which the fixing piece 59 of the projector 32 is fitted into the positioning hole 171 closest to the screen 21. At this time, the size of the image projected on the screen is maximized. Then, when the operator removes the fixing piece 59 from the positioning hole 171, fits it in the positioning hole 171 farthest from the screen 21, and fixes the projector 32 on the guide plate 17, projection is performed as shown in FIG. 8. The size of the image can be reduced. In this embodiment, the size of the projection image can be changed according to the fixed position of the projector 32 in this way.

  Further, when the operator takes out the projector 32 from the cabinet 12 and uses it as a front projector, the operator folds the fixed piece 59 and stores it in the storage unit, and the projection is removed from the bottom surface 32E. What is necessary is just to mount in planes, such as a desk.

  As described above, according to the rear projector 2 according to the present embodiment, the guide plate 17 is disposed perpendicular to the cabinet front surface 12A and the back surface 12B, and the positioning hole 171 extends along the central axis of the guide plate 17 in the width direction. Therefore, the projector 32 is simply moved in parallel along the guide plate 17 and the fixing piece 59 is fitted into one of the positioning holes 171 and fixed. The 32 projection optical axes can always be kept perpendicular to the mirror 41. Thereby, the image can be adjusted to a predetermined size without causing trapezoidal distortion in the image.

  Next, a modification of the rear projector 2 according to the second embodiment will be described with reference to FIG. FIG. 9 is a partial vertical cross-sectional view showing a schematic configuration of a rear projector 2A that is a modification of the rear projector 2. As shown in FIG. 9, the rear projector 2 </ b> A according to the modification is characterized in that a height adjusting jig 19 for the projector 321 that can be fixed on the guide plate 17 of the rear projector 2 is provided.

  As shown in FIG. 9, if the height of the projector 321 accommodated in the rear projector 2 </ b> A is low and installed directly on the bottom surface 12 </ b> E of the cabinet 12, the lower part of the image light may not enter the mirror 41. That is, the lower part of the image projected on the screen 21 is missing. In such a case, the height adjusting jig 19 is installed under the projector 321 and lifts up to an appropriate height.

  The height adjustment jig 19 has a substantially rectangular shape, and one of the six surfaces of the height adjustment jig 19 is provided with a fixing projection 191 that fits into the positioning hole 171 of the guide plate 17. A fixing hole 192 that fits into the fixing piece 59 of the projector 321 is provided on the surface facing this. Further, the shape of the bottom surface of the height adjusting jig 19 provided with the fixing protrusion 191 and the shape of the upper surface provided with the fixing hole 192 are the same as the shape of the bottom surface of the projector 321.

  Next, a method for using the height adjusting jig 19 will be described. First, the operator fits and fixes the fixing protrusion 191 of the height adjusting jig 19 into the positioning hole 171 of the guide plate 17 corresponding to the desired image size. Then, the fixing piece 59 of the projector 321 is fitted into the fixing hole 192 of the height adjusting jig 19, and the projector 321 is installed on the height adjusting jig 19.

  By using the height adjustment jig 19 in this way, the position of the projection optical axis of the projector 321 is increased by the height of the height adjustment jig 19, so that the image light is appropriately incident on the mirror 41 and the image It is possible to avoid the inconvenience that the lower part of the chip is missing.

<Third Embodiment>
Hereinafter, the third embodiment of the present invention will be described mainly with respect to differences from the first embodiment with reference to FIGS. FIG. 10 is a partial longitudinal sectional view showing a schematic configuration of the rear projector 3 according to the third embodiment. FIG. 11 is a schematic configuration diagram of the sensor switch 56 provided in the projector 33. FIG. 12 is an explanatory diagram of the operation of the sensor switch 56 when the projector 33 is installed in the cabinet 13. FIG. 13 is a block diagram showing an electrical configuration of the projector 33.

  The rear projector 3 according to the present embodiment includes two mirrors 431 and 432, whereas the rear projector 1 according to the first embodiment includes one mirror 41. In addition, since the image light is reflected by the two mirrors and then projected from the rear surface of the transmissive screen, the viewer sees an image that is reversed from the normal image. Therefore, the present embodiment is characterized in that when the projector 33 is housed in the cabinet 13 and performs rear projection, the projector 33 performs a left-right reversal process on the image.

  As shown in FIG. 10, the rear projector 3 is housed in a cabinet 13 having a box shape and a hollow inside, a screen 21 provided on one side of the cabinet 13, and the cabinet 13, as in the first embodiment. In addition to the projector 33, the cabinet includes a first mirror 431 on the front surface 13A and a second mirror 432 on the back surface 13B.

  A door 16 that opens outward is provided below the first mirror 431 on the front surface 13 </ b> A of the cabinet 13, and the projector 33 can be inserted into and removed from the cabinet 13 through the door 16. As in the first embodiment, the bottom surface 13E of the cabinet 13 is provided with a positioning projection 15 used when the projector 33 is installed in the cabinet 13.

  On the other hand, as shown in FIG. 11, the bottom surface 33E of the projector 33 is provided with a substantially cuboid-shaped fixing hole 57 that fits into the positioning projection 15 described above, and the projector 33 can be attached to and detached from the cabinet 13 therein. A sensor switch 56 to be detected is fitted. As shown in FIG. 11, the sensor switch 56 has a substantially rectangular parallelepiped shape, a main body portion 561 having a built-in switch mechanism therein, a cylindrical sleeve 562, and a switch terminal shaft held by the sleeve 562 so as to be retractable. 563. The base portion of the switch terminal shaft 563 is urged by a spring (not shown) in the main body portion 561, and the switch terminal shaft 563 normally protrudes the longest (state in FIG. 11). The main body 561 includes two terminals (not shown), and wiring is connected to each terminal.

  In the state where the switch terminal shaft 563 protrudes as shown in FIG. 11, the sensor switch 56 is in a blocking state between the two terminals provided on the main body 561, and the switch is off. On the other hand, as shown in FIG. 12, in a state where the switch terminal shaft 563 is pushed in, the terminals are brought into conduction and the switch is turned on. Based on the detection result of the sensor switch 56, an image processing circuit 65, which will be described later, performs an image reversal process. The sensor switch 56 in the present embodiment corresponds to the “detecting means” of the present invention.

  Further, as shown in FIG. 10, a changeover switch that can select one of three types of image processing modes of “automatic”, “inverted”, and “normal” is provided on the upper surface 33F of the projector 33 by switching a knob. 58 is provided. When the changeover switch 58 is set to “automatic”, when the above-described sensor switch 56 detects the installation of the projector 33 in the cabinet 13, the left / right reversing process by the image processing circuit 65 described later is automatically performed. . On the other hand, when “invert” is selected, the image processing circuit 65 forcibly performs the left / right inversion process. When “normal” is selected, the left / right inversion process is not performed at all. Has been. The changeover switch 58 corresponds to the “processing mode setting means” of the present invention.

  The first mirror 431 that reflects the image light emitted from the projection lens 55 (not shown) of the projector 33 is installed on the front surface 13A of the cabinet 13 and further reflects the image light reflected by the first mirror 431. The mirror 432 is installed on the back surface 13 </ b> B of the cabinet 13. The reflecting surfaces are parallel to each other, and the reflecting surface of the second mirror 432 is parallel to the screen 21 provided on the front surface 13A of the cabinet 13. Further, the reflecting surfaces of the first mirror 431 and the second mirror 432 and the screen 21 are both perpendicular to the optical axis of the projection lens 55. With such a configuration, even if a plurality of mirrors are provided on the optical path of the image light, the problem of trapezoidal distortion that occurs when the projection surface is inclined with respect to the projection optical axis can be solved.

In the rear projector 3, the distance from the exit pupil 55A of the projection lens 55 to the first mirror 431 is g ₁ (mm), the distance between the first mirror 431 and the second mirror 432 is g ₂ (mm), 2 When the distance from the mirror 432 to the screen is g ₃ (mm), the diagonal dimension of the screen is a (inch), and the horizontal: vertical ratio of the screen is e: f, the projector 33 The diagonal field angle (half angle) θ used for projection satisfies the following relational expression (7) obtained in the same manner as described in the first embodiment.
tan ⁻¹ [25.4a√ {{(e / 2) ² + f ² } / (e ² + f ² )} / (g ₁ + g ₂ + g ₃ )] <θ <90 ° (7)

In addition, the height from the projection optical axis to the uppermost end of the projector 33 is h, the projection optical axis, and a light beam incident on the lower center of the image projected on the first mirror 431 from the exit pupil 55A of the projection lens 55. when the corner with phi _1, as in the first embodiment, emitted from the exit pupil 55A, rays reflected by the first mirror 431, thereby missing the lower portion of the image is inhibited at the top of the projector 33 The above equation (5), which is a condition for avoiding this, is established.
h <2 · g ₁ · tanφ ₁ (5)

Further, in the present embodiment, the projection optical axis, when the angle made by the ray incident on the upper center of the image projected on the first mirror 431 from the exit pupil 55A was phi _2, the following equation ( 8) is satisfied.
g ₁ · tan φ ₂ −g ₁ · tan φ ₁ <(g ₂ + g ₃ ) tan φ ₁ (8)

Hereinafter, the equation (8) will be described with reference to FIG. In the present embodiment, after the first mirror 431, the image light is further reflected by the second mirror 432 and reaches the screen 21. Therefore, as shown in FIG. 10, when the light beam at the lower end of the image light reflected by the first mirror 431 is reflected by the second mirror 432 and enters the screen 21, it is above the height of the first mirror 431. Otherwise, the lower part of the image is obstructed by the first mirror 431 and is missing. The height of the first mirror 431 is g ₁ · tan φ ₂ −g ₁ · tan φ ₁ , and the second mirror 432 (point Q 2) from the position (point Q 1) where the light beam at the lower end of the image light is reflected by the first mirror 431. ) And the height (the length of the line segment connecting the point Q1 and the point Q3) to the position (point Q3) reflected by the screen 21 is (g ₂ + g ₃ ) tanφ ₁ , (8) is obtained.

  Next, the electrical configuration of the projector 33 according to the present embodiment will be described with reference to the block diagram of FIG. As in the first embodiment, as shown in FIG. 13, the projector 33 includes a power switch 61 for switching on / off the power of the projector 33, an operation panel 62 for operating the projector 33 by an operator, A microcomputer 63 having a CPU, a ROM, and a RAM, a video signal input circuit 64 to which a video signal is input, an image processing circuit 65 for converting the video signal into a signal necessary for driving the LCD 54, and an LCD drive circuit for driving the LCD 54 66, and a lamp driving circuit 67 for driving the lamp 52. Further, the above-described sensor switch 56 and changeover switch 58 are provided, which are connected via a data bus 60 as shown in FIG.

  Next, the attaching / detaching operation of the projector 33 to / from the cabinet 13 and the image projecting operation will be described with reference to FIGS.

  Normally, as shown in FIG. 10, the projector 33 is accommodated in the cabinet 13 by fitting the fixing hole 57 of the bottom surface 31E to the positioning protrusion 15 provided on the bottom surface 13E of the cabinet 13, and the rear projector as a whole. 3 is constituted. By fixing the fixing hole 57 of the projector 31 to the positioning protrusion 15 of the cabinet 13 and fixing it at that position, the distance between the projector 33 and the first mirror 431 is set appropriately, and the projection optical axis is set to the first mirror 431. , Perpendicular to the second mirror 432 and the screen 21. Note that unlike the first embodiment, the projector 33 is installed such that the front surface 33A faces the front surface 13A of the cabinet 13.

  At this time, as shown in FIG. 12, the sensor switch 56 is in an ON state in which the switch terminal shaft 563 is pushed in by the positioning protrusion 15. In this state, when the power is turned on by the power switch 61 of the projector 33 and “automatic” is selected by the changeover switch 58, an electrical signal from the sensor switch 56 indicating the ON state is transmitted to the data bus 60 shown in FIG. To the microcomputer 63.

  On the other hand, various signals such as video signals and audio signals are input from the outside via various input terminals (not shown) provided in the projector 33. Among these, the video signal of the image projected on the screen 21 is input to the video signal input circuit 64 and transferred to the image processing circuit 65 as shown in FIG. As described above, the CPU of the microcomputer 63 to which the signal from the sensor switch 56 is input via the data bus 60 instructs the image processing circuit 65 to drive the LCD 54 by performing the horizontal reversal processing of the image. The image processing circuit 65 processes the video signal transferred from the video signal input circuit 64 in accordance with a command from the CPU of the microcomputer 63 and converts it into a video signal necessary for driving the LCD 54. When the converted video signal is input to the LCD drive circuit 66, the LCD drive circuit 66 projects an image with the left and right reversed with respect to a normal image based on the input converted video signal. Thus, the LCD 54 is driven. Then, after the image light with the left and right reversed is formed by the LCD 54, it is emitted from the projection lens 55 and first incident on the first mirror 431. Then, the image light reflected by the first mirror 431 is further reflected by the second mirror 432, and then projected from the back onto the transmissive screen 21. As a result, an image in the correct orientation as viewed from the viewer is displayed on the front surface of the screen 21 facing the viewer. In the present embodiment, the image processing circuit 65 and the LCD driving circuit 66 that perform the above-described left-right inversion processing of the image correspond to the “left-right inversion means” of the present invention.

  On the other hand, when “invert” is selected by the changeover switch 58, the CPU of the microcomputer 63 recognizes this signal and instructs the image processing circuit 65 to perform the above-described left-right inversion processing. When “normal” is selected by the changeover switch 58, the CPU of the microcomputer 63 recognizes this signal and instructs the image processing circuit 65 to drive the LCD 54 without performing the left-right reversing process. As a result, on the screen 21 of the rear projector 3, when viewed from the viewer, an image in which the right and left are reversed from the normal image is displayed.

  When the projector 33 is used as a front projector, the operator opens the door 16 provided on the front surface 13A of the cabinet 13 to the outside as shown in FIG. When a cable is connected to various input terminals provided on the projector 33 and the power is turned on by the power switch 61, the projector 33 is activated and a video signal, an audio signal, and the like are input from the outside. At this time, as shown in FIG. 11, the switch terminal shaft 563 of the sensor switch 56 is in an off state protruding from the sleeve 562. Therefore, when “automatic” is selected by the changeover switch 58, the CPU of the microcomputer 63 recognizes the signal indicating the off state and drives the LCD 54 without performing the left-right reversing process. To Then, the image light formed by the LCD 54 and emitted from the projection lens 55 is directly projected onto a separately provided screen, wall surface, or the like, and an image in the correct direction as viewed from the viewer is displayed.

  On the other hand, when “normal” is selected by the changeover switch 58, the CPU of the microcomputer 63 recognizes this signal and instructs the image processing circuit 65 to drive the LCD 54 without performing the left-right reversing process. As a result, as in the case where “automatic” is selected, an image with the correct orientation as viewed from the viewer is displayed on a screen, wall surface, or the like provided separately. When “reverse” is selected by the changeover switch 58, the CPU of the microcomputer 63 recognizes this signal and forcibly performs the left-right reversal process described above. Therefore, in this case, when viewed from the viewer, an image in which the left and right are reversed from a normal image is displayed on a separately provided screen, wall surface, or the like.

  As described above, since the rear projector 3 according to the present embodiment has the optical path folded back inside the cabinet 13 by the two mirrors 431 and 432, the rear projector 3 can be further reduced in thickness. In addition, by providing the sensor switch 56, it is detected that the projector 33 is attached to or detached from the cabinet 13, and the image processing circuit 65 performs left / right reversal processing of the image as necessary, so that an image always oriented correctly for the viewer is obtained. Can be displayed. Further, since the changeover switch 58 can also instruct the left / right reversal processing, even when the image cannot be automatically handled, such as when an image is projected directly from the back onto a separately provided transmissive screen, appropriate image processing is possible. It can be performed.

  Next, a modification of the rear projector 3 according to the third embodiment will be described with reference to FIG. FIG. 14 is a schematic diagram illustrating a schematic configuration of a rear projector 3 </ b> A that is a modification of the rear projector 3.

  As shown in FIG. 14, the cabinet 14 of the rear projector 3 </ b> A includes a door 16 </ b> B that opens to the left and right sides below the screen 21, and is configured so that the projector 34 can be attached and detached therefrom. Further, the cabinet 14 includes a USB terminal 18 corresponding to the “electrical connection means” of the present invention. On the other hand, the projector 34 also includes a USB connection terminal 38 instead of the sensor switch 56 of the projector 33 according to the third embodiment. In the present embodiment, the two are electrically connected to detect that the projector 34 is installed in the cabinet 14, and as described above, the image is horizontally reversed. Thereby, it is possible to detect attachment / detachment of the projector 34 with a simple configuration of the USB terminals 18 and 38. The USB terminal provided in the projector 34 corresponds to the “detecting means” of the present invention.

  The configurations of the rear projector, the rear projector cabinet, and the projector shown in the first to third embodiments are merely examples, and it goes without saying that the present invention can be variously modified.

  For example, in the first and third embodiments, the positioning protrusion 15 and the fixing hole 57 are used to appropriately install the projector 31 (33) in the cabinet 11 (13). Is appropriately set, and the projection optical axis may be perpendicular to the mirror 41 and the screen 21. Therefore, for example, an appropriate position may be set by providing a shallow concave installation portion having the same shape as the bottom surface 31E of the projector 31 on the bottom surface 11E of the cabinet 11 and placing the projector 31 in the installation portion.

  In the second embodiment, the plate-shaped guide plate 17 provided with the positioning hole 171 is provided. However, as the “guide means” of the present invention, the projection optical axis of the projector 32 includes the mirror 41 and the screen 21. It is only necessary to maintain a state parallel to. Thus, for example, two guide rails may be provided at an interval equal to the horizontal width of the projector 32, and the projector 32 may be moved along the guide rail.

  Further, instead of the fixing piece 59 and the positioning hole 171 of the second embodiment, for example, the installation position of the lower end portion of the front surface 32A of the projector 32 corresponding to an image of a predetermined size is connected to the bottom surface 12E of the cabinet 12. It may be drawn and described as “position display means”.

  Furthermore, instead of the height adjustment jig 19 having a fixed height described in the modification of the second embodiment, a projector having various heights can be provided by providing a jig that can adjust the height in several steps. Can be installed in the cabinet 12 and used as the rear projector 2.

The projectors 31 to 34 according to the first to third embodiments use a transmissive liquid crystal panel as a light modulation element. However, a DLP method using a DMD (Digital Micromirror Device) as the light modulation element. Alternatively, an LCOS (Liquid Crystal On Silicon) method using a reflective liquid crystal may be employed.

1 is a partial longitudinal sectional view showing a schematic configuration of a rear projector 1 according to a first embodiment. FIG. 2 is a schematic diagram showing an internal structure of a projector 31 according to the first embodiment. It is explanatory drawing explaining the positional relationship of an optical axis and the screen 21 when there is no offset. It is explanatory drawing explaining the positional relationship of an optical axis and the screen 21 when there exists offset. FIG. 6 is an explanatory diagram for explaining a relationship between a diagonal angle of view θ of the projection lens 55 and a length Y2 shown in FIG. 3 is a block diagram showing an electrical configuration of a projector 31. FIG. It is a fragmentary longitudinal cross-section which shows schematic structure of the rear projector 2 which concerns on 2nd Embodiment. It is explanatory drawing which shows the state which moved the rear projector 2 to the mirror 41 side from the position shown in FIG. It is a partial longitudinal cross-sectional view which shows schematic structure of the rear projector 2A which is a modification of 2nd Embodiment. It is a fragmentary longitudinal cross-section which shows schematic structure of the rear projector 3 which concerns on 3rd Embodiment. It is a schematic block diagram of the sensor switch 56 with which the projector 33 which concerns on 3rd Embodiment is provided. FIG. 11 is an explanatory diagram of the operation of the sensor switch 56 when the projector 33 is installed in the cabinet 13. 4 is a block diagram showing an electrical configuration of a projector 33. FIG. FIG. 10 is a schematic diagram illustrating a schematic configuration of a rear projector 3A that is a modification of the third embodiment.

Explanation of symbols

1-3, 2A, 3A Rear projector 17 Guide plate 171 Positioning hole 18 USB terminal 19 Height adjustment jig 21 Screens 31-34, 321 Projector 38 USB connection terminals 41, 431, 432 mirror 55 Projection lens 56 Sensor switch 58 Switching Switch 65 Image processing circuit 66 LCD drive circuit

Claims (15)

Cabinet,
A screen provided on one side of the cabinet and displaying an image by image light projected from the inside;
A projector that is housed in the cabinet in a detachable state from the side of the cabinet where the screen is provided, has a wide-angle projection lens, and enlarges and projects image light formed by a light modulation element on the screen;
X mirrors (x is an integer equal to or greater than 1) provided in the cabinet parallel to the screen and perpendicular to the optical axis of the projection lens and reflecting the image light projected by the projector; With
The distance between the exit pupil of the projection lens and the first mirror in the order in which the image light is reflected from the exit pupil is g ₁ (mm), the order is the (n−1) th mirror and the nth (n is 2). (Integer from x to x) is the distance of the mirror g _n (mm), the distance from the last mirror to the screen is g _{x + 1} (mm), the diagonal dimension of the screen is a (inch), the horizontal of the screen: vertical A rear projector characterized in that a diagonal angle of view (half angle) θ used by the projector for projecting the image light satisfies the following formula when the ratio of e: f is:

  The rear projector according to claim 1, wherein the projection lens and the light modulation element are arranged so that an optical axis of the projection lens is shifted from a center axis of the light modulation element. The height from the optical axis of the projection lens to the uppermost end of the projector is h, the optical axis of the projection lens, and the light beam incident on the lower side center of the image projected on the first mirror from the exit pupil. ₁ preparative angle formed by _phi, the optical axis of the projection lens, the injection ₂ an angle phi formed by the light pupil the order from is incident on the upper center of the image projected on the first mirror, and then if In addition,
When the number x of mirrors is 1, h <2g ₁ · tan φ ₁ is satisfied,
3. The rear projector according to claim ₁ , wherein when x is 2 or more, h <2g ₁ · tan φ ₁ and the following formula are satisfied.

  The rear projector according to claim 1, further comprising guide means for translating the projector in a direction perpendicular to the screen.   The rear projector according to claim 4, wherein the guide unit includes a position display unit that displays an installation position of the projector corresponding to a size of an image displayed on the screen.   6. The apparatus according to claim 1, further comprising a jig for adjusting the height of the projector so that the projection surface of the projector overlaps the first mirror in the order according to the size of the projector. The rear projector in any one.   7. The apparatus according to claim 1, further comprising a left / right reversing means for reversing the image displayed on the screen when the projector is attached to or detached from the cabinet when the number of mirrors is an even number. The described rear projector. A processing mode setting means for setting an image processing mode indicating whether to reverse the image horizontally;
The rear projector according to claim 7, wherein the left / right reversing unit is a unit that performs left / right reversal based on the image processing mode set by the processing mode setting unit. The cabinet or the projector comprises a detecting means for detecting attachment / detachment of the projector to / from the cabinet,
9. The rear projector according to claim 7, wherein the left-right reversing unit is a unit that automatically performs left-right reversal based on a detection result of the detection unit. A mounting portion that has a wide-angle projection lens and is detachable from the front side of the cabinet, and is mounted with a projector that enlarges and projects the image light formed by the light modulation element on the projection surface;
X mirrors (x is an integer greater than or equal to 1) mirrors arranged perpendicular to the optical axis of the projection lens and reflecting the image light projected by the projector;
A screen installed in parallel with the x mirrors and displaying an image with the image light reflected by the x mirrors;
And a means for electrically connecting to the projector when the projector is mounted.   The rear projector cabinet according to claim 10, further comprising guide means for translating the projector in a direction perpendicular to the screen.   12. The rear projector cabinet according to claim 11, wherein the guide means includes position display means for displaying an installation position of the projector corresponding to a size of an image displayed on the screen. A front projector that is housed in the cabinet in a detachable state from the front side of the rear projector cabinet, has a wide-angle projection lens, and projects the image light formed by the light modulation element on the projection surface in an enlarged manner,
A front projector, comprising: a left / right reversing means for reversing the image displayed on the screen when the image is attached to or detached from the cabinet. A processing mode setting means for setting an image processing mode indicating whether to reverse the image horizontally;
The front projector according to claim 13, wherein the left-right reversing unit is a unit that performs left-right reversal based on the image processing mode set by the processing mode setting unit.   14. The front projector includes means for detecting attachment / detachment of the projector to / from the cabinet, and the left / right inversion means is means for automatically performing left / right inversion based on the detection result. Or the front projector of 14.

Images