JP2000075409A - Rear projection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin-shaped small-sized display device. SOLUTION: In order to efficiently contain light projected from a liquid crystal projector 3 in a box member 1, such a relationship is established that a 1st plane defined by an optical axis part OA1 and an optical axis part OA2 is orthogonal to a 2nd plane SP defined by the optical axis part OA2 and an optical axis part OA3. Besides, the optical axis part OA2 from a 1st deflection mirror 4 to a 2nd deflection mirror 5 is made orthogonal to the optical part OA1 from the liquid crystal projector 3 to the 1st deflection mirror 4. Besides, an angle β is formed by the 1st plane FP with reference to the projection plane PP of a screen 2. Besides, an angle βis formed by the vertical axis VA of the liquid crystal projector 3 with reference to an X axis, and an angle β is formed by an horizontal axis HA with reference to a Z axis, and the axis HA is included in the 1st plane FP.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear projection display device using a transmission screen.

[0002]

2. Description of the Related Art As a rear projection display apparatus using a transmission screen, a rear projection television apparatus having a structure in which a television image is projected on a transmission screen after passing through a plurality of bending mirrors by a projection lens. And a rear projection type device that projects a projection image of a liquid crystal projector onto the screen via a plurality of bending mirrors in the same manner as described above.

The above two types of devices have the same basic configuration as the whole device, although the device for forming a projected image is different from a television and a liquid crystal projector.

FIGS. 6 and 7 show the structure of two types of rear-projection type display devices described in Japanese Patent Publication No. 63-22267 relating to a television device.

[0005] These drawings are sectional views of the rear projection type display device as viewed from the side. In FIG. 6, a projection image projected from the projection device A5 of the television image with a predetermined spread is transmitted through a folding mirror A1 and a mirror A6 arranged on a plane perpendicular to the paper surface. It is projected on the screen A7. The display device shown in FIG. 7 is an improved version of the device shown in FIG. 6, in which the arrangement of the bending mirror A1 is devised by using dead space. The display device can be made thinner, and the space occupied by the display device in the room can be reduced.

[0006]

However, the above-mentioned effect of making the conventional device thinner is that a small dead space which is inevitable in relation to the arrangement of the adjusting knob is used, and the device is greatly reduced. It cannot be made thin.

In order to further reduce the thickness of the conventional display device, it is conceivable to increase the emission angle from the projection device 5. By doing so, the device itself can be made thinner, but the height becomes larger. I will.

An object of the present invention is to provide a thinner display device in a rear projection display device formed by projecting a projector or television output onto a transmission screen.

[0009]

In order to solve the above-mentioned problems, a rear projection type display device according to the present invention transmits a projection light emitted from a projector device through a first bending mirror and a second bending mirror. A first plane formed by an optical axis portion extending from the projector device to the first folding mirror and an optical axis portion extending from the first folding mirror to the second folding mirror; An optical axis portion extending from the mirror to the second folding mirror and a second plane formed by the optical axis portion extending from the second folding mirror to the transmissive screen form a predetermined angle greater than 0 degrees and 90 degrees or less. Features.

In the above rear projection display device,
Since the first plane and the second plane form a predetermined angle, the optical axis from the projector device to the transmission screen is not in the same plane. As a result, the degree of freedom in designing the arrangement of the projector device and the like is increased, and the display device can be reduced in size.

Further, according to a preferred aspect, the second plane is perpendicular to each of the first plane and a projection plane formed by the screen, and the second plane extends from the projector to the first folding mirror. The optical axis portion is parallel to the projection plane.

In the above rear projection type display device,
Since the vertical dimension of the rear projection type display device is sufficient from the lower end of the first folding mirror to the upper end of the second folding mirror, the projector device and the like can be efficiently housed and the display device can be downsized.

According to a preferred aspect, when the angle between the projection plane and the second folding mirror is α °, the first plane is 90 ° −2α ° with respect to the projection plane. It is characterized by being arranged to be inclined at an angle.

In the above rear projection display device,
Image light from the projector device can be perpendicularly incident on the screen, and a good projected image can be obtained.

Further, according to a preferred aspect, the projection light is a light beam having a spread angle of approximately 180 ° -4α ° in the second plane between the first bending mirror and the second bending mirror. In addition, a ray of the luminous flux that travels closest to the projection plane in the second plane is substantially parallel to the projection plane and is arranged close to the projection plane. And

In the above rear projection display device,
The display device can be further miniaturized while efficiently utilizing the spread of the projection light from the projector device.

Further, according to a preferred aspect, an emission axis and a horizontal axis of the projector device are included in the first plane.

In the above rear projection display device,
An image from the projector device can be projected on a screen without rotation.

According to a preferred aspect, the second plane is perpendicular to each of the first plane and a projection plane formed by the screen, and the first plane is:
When an angle between the projection plane and the second bending mirror is α ゜, 90 ° -2α with respect to the projection plane
It is characterized by being arranged to be inclined with an angle of ゜.

In the above rear projection display device,
The projector device can be stored efficiently,
Vertical incidence on the screen is possible.

Further, according to a preferred aspect, the projection light is a light beam projected from the projector device with a predetermined spread angle, and is most likely to be located between the first bending mirror and the second bending mirror. Of the light rays traveling outside, the light rays traveling closest to the projection plane formed by the screen are substantially parallel to the projection plane and are arranged close to the projection plane. It is characterized by.

In the above rear projection display device,
The spread of the projection light from the projector device can be used efficiently.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] FIG. 1 is a diagram showing the overall configuration of a rear projection display device according to a first embodiment. In addition, coordinate axes X, Y, and Z orthogonal to each other are defined as shown in the figure for convenience of explanation of directions.

The illustrated display device comprises a box member 1,
A projection type screen 2 formed at the upper part of the front surface of the box member 1 and fixed to the opening, a liquid crystal projector 3 arranged at a lower part in the box member 1, and a pair of liquid crystal projectors 3 arranged at appropriate positions in the box member 1 Folding mirrors 4 and 5 are provided.

In the illustrated display device, the projection light emitted from the liquid crystal projector 3 enters the first folding mirror 4 and is reflected, and then enters the second folding mirror 5 and is reflected, and is projected on the screen 2. Is done.

Here, the projection plane including the surface of the screen 2 is a plane parallel to the YZ plane. The second bending mirror 5 is perpendicular to the XZ plane, and is disposed at a predetermined angle α (degree) with respect to the screen 2. Further, the first folding mirror 4 is provided with an XY plane and an X
They are arranged at a predetermined angle with respect to the Z plane.

The arrangement of the optical axis of the projection light from the liquid crystal projector 3 to the screen 2 will be described. Projection light emitted from the liquid crystal projector 3 toward the first bending mirror 4 travels in parallel to a projection plane including the surface of the screen 2. That is, in this area, the optical axis portion OA of the projection light
1 is arranged parallel to the Y axis. Next, the reflected light emitted from the first bending mirror 4 toward the second bending mirror 5 travels with a predetermined inclination with respect to the projection plane of the screen 2. That is, in this region, the optical axis portion OA2 of the reflected light is arranged so as to form a predetermined angle β (degree) with respect to the Z axis. Next, the reflected light emitted from the second bending mirror 5 toward the screen 2 travels perpendicular to the projection plane of the screen 2. That is, in this region, the optical axis portion OA3 of the reflected light is arranged parallel to the X axis.

Next, the arrangement of the first and second bending mirrors 4 and 5 and the arrangement of the liquid crystal projector 3 will be described with reference to FIGS.

FIG. 2 is a view of the display device shown in FIG. 1 as viewed in the Y direction.
4 illustrates the arrangement of members inside the display device when it is assumed that the folding mirror 4 is not used.

In the case where the second folding mirror 5 is arranged so as to be perpendicular to the plane of the paper and has an angle α (degree) with respect to the screen 2, the liquid crystal projector 103 is arranged at the position of the mirror image of the second folding mirror 5. become. The liquid crystal projector 103 is a conjugate image related to the first bending mirror 4 of the liquid crystal projector 3 shown in FIG. When only one second folding mirror 5 is used as shown in the figure, the thickness of the display device in the X direction can be reduced, but the height in the Z direction increases.

Here, of the projection light emitted from the liquid crystal projector 103 with a predetermined spread angle, the light ray traveling the outermost and closest to the projection plane PP of the screen 2 enters the upper part of the second bending mirror 5. The point to be projected is M, and the screen 2
The point at which the light beam traveling the farthest on the projection plane PP of the second folding mirror PP enters the upper part of the second bending mirror 5 is defined as M ′. Also, the point where the projected light on the optical axis is incident, that is, both optical axis portions OA
2. The intersection of OA3 is O '. Points on the screen 2 corresponding to the points M, M ', and O are denoted by S, S', and O, respectively. Further, the emission point of the projection light from the liquid crystal projector 103 is denoted by P. As already described with reference to FIG. 1, the emission axis of the liquid crystal projector 103, that is, the optical axis portion OA2 forms an angle β with the projection plane PP of the screen 2, so that 180 (degrees) = α + β + ∠MO′P (1) ) Holds. Furthermore, since the incident angle and the outgoing angle of the projection light on the second bending mirror 5 are equal, if the optical axis portion OA3 is perpendicular to the screen 2, ∠MO′P = 180− (90−α) .. (2) holds. From the above equations (1) and (2), the relational expression β = 90−2α (3) holds.

Here, in order to efficiently store the projection light from the liquid crystal projector 103 in the box member 1, a line segment SS 'in the Z direction on the projection plane PP on which the screen 2 is provided, and the nearest point to the projection plane PP. The traveling light beam PM is arranged close to and in a substantially parallel state. In this case, the projection light from the liquid crystal projector 103 becomes a light beam having a spread angle of approximately 180 ° -4α ° in the second plane. With the above arrangement, the distance between the point M on the second folding mirror 5 and the screen 2 is shortened, and the display device can be made extremely thin. That is, as shown in the drawing, the point S and the point M are almost close to each other, so that the second folding mirror 5 can be arranged close to the screen 2 and the display device can be made as thin as possible. it can.

The liquid crystal projector 203 is the same as that shown in FIG.
3 shows a conjugate image of the liquid crystal projector 3 when it is assumed that both the first and second bending mirrors 4 and 5 are not used in the display device of FIG. In this case, the configuration of the most basic display device in which a projection image projected from the emission point P ′ of the liquid crystal projector 203 is projected on the screen 2 from the vertical direction is obtained, but the thickness of the device is the thickest.

The liquid crystal projector 203 has an emission axis EA
And a vertical axis VA and a horizontal axis HA, which are orthogonal to. The projection light in the vertical axis VA direction emitted from the liquid crystal projector 203 is projected as an image on the vertical axis of the screen 2, and the projection light in the horizontal axis HA direction emitted from the liquid crystal projector 203 is projected on the horizontal axis of the screen 2. Will be projected as In the case of the liquid crystal projector 103 at the conjugate position of the liquid crystal projector 203, the vertical axis VA is X
The horizontal axis HA is perpendicular to the plane of the paper.

FIG. 3 is a view of the inside of the display device of FIG. 1 viewed in the Y direction, and is an explanatory diagram of the liquid crystal projector 3 as viewed from the rear. Note that the actual liquid crystal projector 3 is disposed at a conjugate position of the liquid crystal projector 103 shown in FIG.

Here, in order to efficiently store the projection light from the liquid crystal projector 3 in the box member 1, the optical axis portion OA 1 of the projection light from the liquid crystal projector 3 and the projection light reflected by the first bending mirror 4 will be described. The first plane FP defined by the optical axis portion OA2 of the optical axis portion OA2 is the optical axis portion O of the projection light reflected by the first bending mirror 4.
A2 is orthogonal to a second plane SP perpendicular to the paper surface defined by A2 and the optical axis portion OA3 of the projection light reflected by the second bending mirror 5. The first plane F
P forms an angle β with the projection plane PP of the screen 2 as is clear from the above description. Also, the second
The plane SP is parallel to the XZ plane and orthogonal to the projection plane PP.

Further, an optical axis portion OA1 from the liquid crystal projector 3 to the first folding mirror 4 and an optical axis portion OA2 from the first folding mirror 4 to the second folding mirror 5
Are orthogonal to each other, so that the optical axis portion OA1 is parallel to the Y axis, and the optical axis portion OA1 from the liquid crystal projector 3 to the first bending mirror 4 does not affect the height of the display device. Can be lowered by the height of the arrangement position.

The vertical axis VA of the liquid crystal projector 3
Forms an angle β with the X axis, and the horizontal axis HA forms an angle β with the Z axis and is included in the first plane FP. That is, from the above equation (3), the liquid crystal projector 3
Is β = 90−2 with respect to the projection plane PP of the screen 2.
It is arranged to be inclined with an angle of α. Thus, the projected image from the liquid crystal projector 3 is displayed on the screen 2.
Can be projected without rotation.

Here, the progress of the projection light will be described again. Projection light emitted from the liquid crystal projector 3 with a divergence angle of about 2β = 180−4α travels in the Y direction perpendicular to the plane of the drawing (optical axis portion OA1), and is projected onto the plane of the paper by the first folding mirror 4. The light is reflected in a parallel direction and travels with an inclination of β = 90−2α with respect to the Z axis (optical axis portion OA2), and is reflected by the second bending mirror 5 and X
(Optical axis portion OA3), and an appropriate projected image is formed on the screen 2.

FIG. 4 is a view for explaining the internal components of the liquid crystal projector 3 which is a projection device.

The light source light emitted from the light source 31 composed of a lamp and a concave mirror such as an elliptical mirror is composed of a dichroic mirror 32B having reflection characteristics for B light and a dichroic mirror having characteristics for reflecting E light and G light regions. 3
2RG and 2RG are incident on a cross dichroic mirror 32 arranged orthogonal to each other and are respectively reflected. As a result, the light is color-separated into B light, which is orthogonal to the incident optical axis and reflected in the direction opposite thereto, and R, G mixed light.

The B light separated by the cross dichroic mirror 32 travels with the bending mirror 34 changing the optical axis to a right angle, and enters the polarization beam splitter 37B. On the other hand, the remaining R and G mixed light travels by changing the optical axis at a right angle by the bending mirror 35, enters the dichroic mirror 36 having a reflection characteristic for the G light, is reflected and changes the optical axis at a right angle. The color is separated into a traveling G light and a traveling R light. The G light and the R light that have been color-separated are incident on the polarization beam splitters 37G and 37R, respectively.

The polarization beam splitters 37B, 37G, 3
Each color light incident on 7R is polarized and separated into reflected S-polarized light and P-polarized light passing therethrough by the polarization separation unit provided for each, and the S-polarized light is arranged near the exit surface of each polarization beam splitter. Reflective liquid crystal light valve 38B,
38G and 38R, respectively. The P-polarized light is discarded as unnecessary light.

Reflection type light valves 38B, 38G, 38
The S-polarized light of each color light incident on R is modulated by a signal corresponding to each color light, and is reflected and emitted as a mixed light of P-polarized light and non-modulated S-polarized light related to the modulated light,
The light enters the polarization beam splitters 37B, 37G, and 37R, respectively.

The P-polarized light related to the modulated light travels through the polarization splitters of the polarization beam splitters 37B, 37G, and 37R, and the transmitted light of each color enters the cross dichroic prism 39. Inside the cross dichroic prism 39, the B light reflecting dichroic film 39B and the R light
The light reflection dichroic film 39R and the light reflection dichroic film 39R are arranged in an X-shape, and the respective color lights are combined and incident on the projection lens PL. Thereby, a full-color image can be projected.

The vertical axis VA of the illustrated liquid crystal projector 3 is perpendicular to the paper surface, and the horizontal axis HA is the direction in which the polarization beam splitters 37B and 37R are arranged.

[Second Embodiment] FIG. 5 is a diagram showing the overall configuration of a rear projection display device according to a second embodiment. Note that the display device of the second embodiment is the first device.
This is a modification of the embodiment, and the same portions are denoted by the same reference numerals, and redundant description will be omitted.

In the display device of the second embodiment, the first folding mirror 104 in which the arrangement and the posture of the first folding mirror 4 of the first embodiment are changed is arranged below the second folding mirror 5. As a result, the arrangement of the liquid crystal projector 3 of the first embodiment is also changed, and the liquid crystal projector 303 is arranged at the mirror image position of the first bending mirror 104.

Here, the optical axis portion OA1 'of the projection light from the liquid crystal projector 303 is on the XY plane, but forms a predetermined angle larger than 0 ° with respect to the Y axis unlike the case of the first embodiment. I have. As a result, the optical axis portions OA1 ', O
Although the first plane including A2 and the second plane including the optical axis portions OA2 and OA3 are not orthogonal to each other, the liquid crystal projector 3
03 etc. can be stored in the box member 1 relatively efficiently.

The inclination of the liquid crystal projector 303 will be considered. The horizontal axis HA direction (ie, the −Y axis direction) of the liquid crystal projector 303 when there is no first bending mirror 104 (see FIG. 2) and the first plane including the optical axis portions OA1 ′ and OA2 in FIG. The angle formed is γ. If the angle between the first plane and the Z-axis direction is β ′, the liquid crystal projector 303
Of the horizontal axis HA with respect to the Z axis is represented by an angle (β′−γ)
Given by That is, when the inclination of the liquid crystal projector 303 is given by the angle (β′−γ), the screen 2
No rotation occurs in the projected image of.

Although the present invention has been described with reference to the embodiment, the present invention is not limited to the above embodiment.
For example, instead of the liquid crystal projector 3, a projector having a configuration in which a transmission type light valve is arranged for each of the R, G, and B lights and a polarization beam splitter is not used can be used. Further, three dichroic mirrors each having a predetermined angle inclined with respect to each other are used as a three-color separation optical system, and a light valve is used as a light valve according to the incident angle for each color light from the lens array and the three-color separation optical system. A projector having a configuration using one light valve composed of arranged pixels can be used. Further, the liquid crystal projector 3 can be replaced with a television type projector device.

[0052]

As is apparent from the above description, according to the rear projection display device of the present invention, the first plane and the second plane make a predetermined angle, so that the distance between the projector and the transmission screen can be reduced. Since the optical axes are not on the same plane, the degree of freedom in designing the arrangement of the projector device and the like is increased, and the size of the display device can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a configuration of a display device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an arrangement of a bending mirror and the like.

FIG. 3 is a diagram illustrating an arrangement of a bending mirror and the like.

FIG. 4 is a diagram showing a configuration of a liquid crystal projector used in the display device of FIG.

FIG. 5 is a perspective view illustrating a configuration of a display device according to a second embodiment.

FIG. 6 is a sectional configuration diagram of a conventional display device.

FIG. 7 is a cross-sectional view of another conventional display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Box member 2 Screen 3 Liquid crystal projector 4 1st bending mirror 5 2nd bending mirror

Claims (7)

[Claims] 1. A rear projection display device for projecting projection light emitted from a projector device onto a transmission screen via a first folding mirror and a second folding mirror, wherein the light is projected from the projector device to the first folding mirror. And a first plane formed by the optical axis portion of the first bending mirror and the optical axis portion extending from the first bending mirror to the second bending mirror, and an optical axis portion extending from the first bending mirror to the second bending mirror and the second bending mirror. A rear projection type display device, wherein a second plane formed by the optical axis portion extending to the transmission type screen forms a predetermined angle of more than 0 degree and 90 degrees or less. 2. The second plane is perpendicular to each of the first plane and a projection plane formed by the screen, and the optical axis portion from the projector to the first folding mirror is 2. The rear projection display device according to claim 1, wherein the rear projection display device is parallel to a projection plane. 3. When the angle between the projection plane and the second folding mirror is α °, the first plane is inclined at an angle of 90 ° −2α ° with respect to the projection plane. 3. The rear projection type display device according to claim 2, wherein the rear projection type display device is arranged in a vertical direction. 4. The projection light is a light beam having a spread angle of approximately 180 ° −4α ° within the second plane between the first bending mirror and the second bending mirror, and 4. The light beam which travels closest to the projection plane in the second plane is substantially parallel to the projection plane and is arranged close to the projection plane. Rear projection display device. 5. The rear projection display device according to claim 2, wherein the emission axis and the horizontal axis of the projector device are included in the first plane. 6. The second plane is perpendicular to each of the first plane and a projection plane formed by the screen, and the first plane is defined by the projection plane and the second folding mirror. 2. The rear projection type display device according to claim 1, wherein, when the angle formed is [alpha] [deg.], The device is arranged to be inclined at an angle of 90 [deg.]-2 [alpha] [deg.] With respect to the projection plane. 7. The projection light is a light beam projected from the projector device at a predetermined spread angle,
Of the light beams traveling the outermost between the first bending mirror and the second bending mirror, the light beam traveling closest to the projection plane formed by the screen is substantially parallel to the projection plane, 2. The device according to claim 1, wherein the device is arranged close to the projection plane.
A rear projection display device as described in the above.