JP3568346B2 - Rear projection display - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a rear projection display device that prevents a so-called ghost phenomenon.
[0002]
[Prior art]
FIG. 4 is a schematic configuration diagram showing a conventional rear projection display device. The rear projection display device includes a projection device 102, a projection lens 103, total reflection mirrors 104 and 105, and a transmission screen 106 disposed in a housing 101. The image light emitted from the projection device 102 is reflected by the total reflection mirrors 104 and 105 via the projection lens 103, and the reflected image light is incident on the back side of the screen 106 and diffusely emitted from the front side of the screen 106. This allows the observer to view the video at the position in front of the screen 106. In this type of rear projection display device, the screen 106 and the total reflection mirror 105 are arranged so that the angle θ formed therebetween is as acute as possible, so that the device can be made thinner.
[0003]
[Problems to be solved by the invention]
However, the screen 106 slightly reflects the image light from the total reflection mirror 105 (see the dotted line in FIG. 4). When the reflected image light reaches the total reflection mirror 105 and is reflected again and is incident on the screen 106 at a position different from the original incident position, a so-called ghost phenomenon in which the displayed image appears double appears. was there.
[0004]
The present invention has been made in view of the above circumstances, and has as its object to provide a rear projection display device that can prevent a ghost phenomenon.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a rear projection display device according to the present invention is configured such that image light from a projection unit is reflected by a reflection unit and is incident on a rear surface of a screen. The angle between the screen and the reflection means is θ, the image light reflected by the reflection means, when incident on the screen at the intersection of the reflection means and the screen with a line perpendicular to the screen as a boundary Where i (f) is the incident angle of the image light and the image light reflected by the reflecting means is incident on the screen at the intersection of the reflecting means and the screen on a line perpendicular to the screen. Let i (b) be such that all rays incident on the screen satisfy the relationship i (f) ≧ 90 ° −2θ and satisfy the relationship i (b) ≦ 2θ−90 °. Constitution It is characterized by having been done.
[0008]
With the above configuration, the image light slightly reflects on the screen, and the image light reaches the reflection unit and is reflected again, but the reflected image light is parallel to the screen or the screen. The ghost phenomenon can be prevented because the display is not displayed on the screen since the display is moved away from the screen.
[0009]
On the back side of the screen, there is provided first optical means for transmitting the first polarized light and reflecting the second polarized light, and the reflecting means converts the first polarized light into the second polarized light. The projector has a function of converting the second polarized light into the first polarized light, and the projection unit emits the image light of the second polarized light so as to reach the back side of the screen, or has the first polarized light. The image light may be configured to be emitted so as to reach the reflection unit.
[0010]
With the above configuration, when the image light of the second polarized light is emitted from the projection unit so as to reach the back side of the screen, the second polarized light is converted into the first optical means (the second polarized light). An optical path such as light reflection) → reflecting means (first polarized light) → first optical means (first polarized light transmission) → screen is realized. Further, when the image light of the first polarized light is emitted from the projection unit so as to reach the reflecting means, the first polarized light is reflected by the reflecting means (second polarized light) → the first optical means ( An optical path such as a second polarized light reflection) → reflecting means (first polarized light conversion) → first optical means (first polarized light transmission) → screen is realized. Therefore, it is possible to shorten the arrangement distance between the screen and the reflection means to reduce the depth of the apparatus, and to increase the optical path from the image light to the screen. Then, even if the image light of the first polarized light reaching the first optical means is slightly reflected, and this image light reaches the reflecting means and is reflected again, the reflected image light is directed in a direction away from the screen. The ghost phenomenon can be prevented.
[0011]
As described above, the first optical unit is configured to reflect the second polarized light, but cannot completely reflect the second polarized light, and the image of the second polarized light is displayed on the screen. A ghost phenomenon caused by being displayed may occur.
[0012]
Therefore, it is noted that the direction in which the image light of the second polarized light is directed to the screen and the direction in which the image light of the first polarized light obtained through the reflecting means is directed to the screen are different from each other. And a light control film having a louver effect having a light-transmitting property in a direction in which the first polarized light arrives and a light-impermeable property in another direction on a back side of the screen. . According to this, it is possible to prevent the ghost phenomenon due to the image of the second polarized light being displayed on the screen.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0014]
FIG. 1 is a schematic configuration diagram showing a rear projection display device according to this embodiment. The rear projection display device 1 includes a housing 2, a transmissive diffusion screen 3 provided on the front side of the housing 2, and a projection device 4 that emits image light.
[0015]
FIG. 2 is a configuration diagram illustrating an example of the projection device 4. The projector 4 includes a reflector 41, a metal halide lamp 42 as a light source, a UV / IR filter 43, a condenser lens 44, an LCD panel 45, a color filter 46, and a projection lens 47 arranged in this order. It consists of The white light emitted from the metal halide lamp 42 passes through the UV / IR filter 43, is collected by the condenser lens 44, and then enters the LCD panel 45. The LCD panel 45 is provided with an incident-side polarizing plate and an outgoing-side polarizing plate so as to sandwich a liquid crystal layer. When light incident on the LCD panel 45 passes through the LCD panel 45 and becomes image light, a specific vibration occurs. It becomes image light by the polarization component of the direction.
[0016]
The color filter 46 includes a red light filter portion and a green light filter portion corresponding to the red (R) pixel, the green (G) pixel, and the blue (B) pixel formed in a matrix on the LCD panel 45. , And a blue light filter section, and converts white image light transmitted through the LCD panel 45 into color image light. The projection lens 47 projects the color image light obtained by the color filter 46 in an enlarged manner.
[0017]
In this embodiment, the projection device 4 emits the image light of the S-polarized light (the S-polarized light is indicated by a dashed line in FIG. 1) toward the back side of the screen 3. I have.
[0018]
On the light incident surface side (back side) of the screen 3, a light separating means 8 as a first optical means is provided. The light separating means 8 is constituted by a plane polarizing mirror that transmits only the P-polarized light and projects it on the back side of the screen 3 while reflecting other polarized light. Therefore, the image light of the S-polarized light from the projection device 4 is reflected by the light separating means 8 and does not reach the screen 3.
[0019]
The reflecting means 7 includes a quarter-wave plate 71 and a total reflection mirror 72, and reflects the S-polarized image light reflected by the light separating means 8 toward the screen 3. Are located. When the S-polarized light image light reflected by the light separating means 8 passes through the 波長 wavelength plate 71 of the reflecting means 7, the vibration direction is rotated by 45 ° with respect to the S-polarized light. Then, when this light is reflected by the total reflection mirror 72 and passes through the quarter-wave plate 71 again, the vibration direction is further rotated by 45 ° to become P-polarized light (see the solid line in FIG. 1). In other words, the S-polarized light image light is converted into P-polarized light image light by being reflected by the reflection means 7.
[0020]
The P-polarized image light travels toward the screen 3. The light separating means 8 provided on the light incident surface side (back side) of the screen 3, as described above, Since the polarized light is transmitted, the P-polarized image light reaches the screen 3 and an image is displayed.
[0021]
The light separating means 8 transmits the P-polarized image light, but cannot completely transmit the image light. The image light is slightly reflected (see the dotted line in the drawing), and proceeds to the reflecting means 7. It is reflected again by the means 7. If the angle x between the reflection optical path and the reflection means 7 at this time is equal to or smaller than the angle θ between the reflection means 7 and the screen 3 (x ≦ θ), the reflected image light (see the dotted line in FIG. 1) Since the light travels in a direction parallel to or away from the screen 3, the reflected image light is not displayed on the screen 3, and the occurrence of a ghost phenomenon can be prevented.
[0022]
Here, as shown in FIG. 1, the image light reflected by the reflection means 7 (see the solid line in the figure) intersects the reflection means 7 with the screen 3 at a line Y perpendicular to the screen 3. In the case where the light is incident on the screen 3 on the side, the incident angle is i (f) , and the above-mentioned x ≦ θ is expressed by using the i (f) and the θ. The arrangement of the reflection means 7, the screen 3, and the projection device 4 is set so as to satisfy the first expression. Since the image light reaches the screen 3 with a predetermined spread angle, the incident angle i (f) is not the same at any position of the screen 3.
[0023]
(Equation 1)
i (f) ≧ 90 ° −2θ ( 1)
On the other hand, as shown in FIG. 3, the image light reflected by the reflection means 7 is incident on the screen 3 on the opposite side of the reflection means 7 and the screen 3 at a line Y perpendicular to the screen 3. When the incident angle is i (b) and x ≦ θ is expressed by using i (b) and the θ, the following expression (2) is obtained. The arrangement of the reflection means 7, the screen 3, and the projection device 4 is set so as to satisfy the condition.
[0025]
(Equation 2)
i (b) ≦ 2θ−90 ° 2nd formula
Further, it is needless to say that it is desirable to satisfy the above-mentioned first and second formulas, but it is not limited to the configuration that satisfies these formulas. Even if the process proceeds to, it is possible to prevent the ghost phenomenon if it is configured to proceed out of the screen 3.
[0027]
Further, in this embodiment, by utilizing the polarization of the image light, the arrangement distance between the screen 3 and the reflection means 7 is shortened to reduce the depth of the apparatus, and the image light reaches the screen 3. The configuration of FIG. 1 is shown as a configuration that can increase the optical path of the image light. However, the configuration using the polarization of the image light is not limited to this. A total reflection mirror for reflecting the light toward the reflection means 7 is provided, and the projection device 4 is configured to emit P-polarized light image light. The total reflection mirror (P-polarized light reflection) → reflection means 7 (S-polarized light) ) → light separating means 8 (reflecting S-polarized light) → reflecting means 7 (converting to P-polarized light) → light separating means 8 (transmitting P-polarized light) → screen 3. In addition, the present invention can of course be applied to a configuration that does not use the polarization of image light.
[0028]
Although the light separating means 8 is configured to reflect the S-polarized light, it cannot reflect the S-polarized light completely, and the image of the S-polarized light is slightly displayed on the screen 3. The resulting ghost phenomenon can occur.
[0029]
Therefore, focusing on the fact that the direction when the image light from the projection device 4 is incident on the screen 3 and the direction when the image light obtained through the reflecting means 7 is incident on the screen 3 are different from each other, On the back side of the screen 3 (between the screen 3 and the light separating means 8 or on the back side of the light separating means 8), has a light transmissivity in a direction in which the image light of the P-polarized light arrives; A light control film having a louver effect having light opacity in other directions is provided. According to this, it is possible to prevent a ghost phenomenon caused by displaying an image of S-polarized light on the screen 3.
[0030]
【The invention's effect】
As described above, according to the present invention, there is an effect that a so-called ghost phenomenon can be prevented.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram illustrating a rear projection display device according to an embodiment of the present invention.
FIG. 2 is a configuration diagram illustrating a projection device according to an embodiment of the present invention.
FIG. 3 is an explanatory diagram showing a case in which image light reflected by the reflecting means of the present invention is incident on the screen at a crossing point between the reflecting means and the screen with respect to a line Y perpendicular to the screen.
FIG. 4 is a schematic configuration diagram showing a conventional rear projection display device.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 rear projection display device 2 housing 3 screen 4 projection device 5 projection lens 7 reflection means 71 quarter-wave plate 72 total reflection mirror 8 light separation means

Claims (3)

In the rear projection display device configured so that the image light from the projection unit is reflected by the reflection unit and is incident on the back of the screen,
The angle between the screen and the reflecting means is θ, and the image light reflected by the reflecting means is incident upon the screen at the intersection of the reflecting means and the screen with a line perpendicular to the screen as a boundary. Let i (f) be the angle, and let i be the incident angle when the image light reflected by the reflection means enters the screen at the intersection of the reflection means and the screen at a line perpendicular to the screen. In the case of (b), all the rays incident on the screen are configured to satisfy the relationship of i (f) ≧ 90 ° −2θ and to satisfy the relationship of i (b) ≦ 2θ−90 °. A rear-projection display device, characterized in that: On the back side of the screen, there is provided first optical means for transmitting the first polarized light and reflecting the second polarized light, and the reflecting means converts the first polarized light into the second polarized light. The projector has a function of converting the second polarized light into the first polarized light, and the projection unit emits the image light of the second polarized light so as to reach the back side of the screen, or has the first polarized light. The rear projection type display device according to claim 1, wherein the rear projection type display device is configured to emit light image light so as to reach the reflection unit. On the back side of the screen, a light control film having a louver effect having a light transmitting property in a direction in which the first polarized light arrives and a light opaque property in other directions is provided. The rear projection type display device according to claim 2, wherein

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