JP2007249171A - Rear projector - Google Patents

Abstract

To provide a rear projector capable of displaying a high-quality image by ensuring high optical performance in a thin configuration.
An optical engine unit 11 that supplies light modulated in accordance with an image signal, a flat mirror 15 that is a mirror that causes light from the optical engine unit 11 to be incident on a screen 16 by reflection, an optical engine unit 11, and The fixing unit 17 that fixes the flat mirror 15 integrally and a housing 18 that houses at least the optical engine unit 11 and the flat mirror 15 are provided. The fixing unit 17 is provided in the housing 18.
[Selection] Figure 1

Description

  The present invention relates to a technology of a rear projector that displays an image by transmitting light corresponding to an image signal to a screen.

  Conventionally, a rear projector has a configuration of an optical system that makes light modulated in accordance with an image signal incident on a screen, and thus it is difficult to make the projector thin compared to other large displays such as a liquid crystal television and a plasma television. It is said that there is. On the other hand, in order to reduce the thickness of the rear projector, a technique has been proposed in which light is incident obliquely on the screen (for example, Patent Document 1).

JP 2005-84576 A

  Patent Document 1 discloses a configuration in which light from an optical engine unit disposed in a lower part of a casing is incident on a screen by a mirror disposed on a ceiling surface of the casing. In the case of such a configuration, the optical engine unit and the mirror are arranged at a long distance as compared with the conventional rear projector. The longer the distance between the optical engine unit and the mirror, the greater the loss of optical performance when the positional relationship between the optical engine unit and the mirror is broken. In order to reduce such a decrease in optical performance, it is conceivable to make the housing strong in order to maintain the positional relationship between the optical engine unit and the mirror with high accuracy. However, if a large depth of the casing is secured in order to strengthen the casing, it is difficult to reduce the thickness of the casing even if the optical system can be thinned. In addition, it is difficult to assemble the optical system and adjust the positional relationship of the optical elements, so that it is difficult to ensure high optical performance. Thus, the conventional technique has a problem that it is difficult to ensure high optical performance in a thin configuration. The present invention has been made in view of the above-described problems, and an object thereof is to provide a rear projector capable of displaying a high-quality image by ensuring high optical performance in a thin configuration. .

  In order to solve the above-described problems and achieve the object, according to the present invention, an optical engine unit that supplies light modulated according to an image signal, and light from the optical engine unit is incident on a screen by reflection. It is possible to provide a rear projector including a mirror, and an optical engine unit and a fixing unit that integrally fixes the mirror.

  By fixing the optical engine unit and the mirror with the fixing unit, the relative positions of the optical engine unit and the mirror can be accurately determined with reference to the fixing unit. The optical engine unit and the plane mirror can be positioned with higher accuracy than the case where the casing is configured by combining the part to which the optical engine unit is fixed and the part to which the plane mirror is fixed. In addition, since the fixed portion has a strong configuration, the positional relationship between the optical engine portion and the mirror can be maintained with high accuracy, and high optical performance can be ensured. Accordingly, a rear projector capable of displaying a high-quality image by securing high optical performance in a thin configuration can be obtained. By incorporating the optical engine unit and the mirror whose relative positions are determined by the fixing unit into the housing, it becomes easy to adjust the positions of the optical engine unit and the mirror and other optical elements. Therefore, the optical system can be assembled easily and accurately. Further, by fixing the fixing portion, it is possible to reduce the bending of the housing even when the optical engine portion, which is considered to be heavy among the optical elements, is arranged at the top of the housing. For this reason, it is possible to increase the degree of freedom in the configuration of the rear projector.

  Moreover, as a preferable aspect of the present invention, it is desirable to have a housing that houses at least the optical engine unit and the mirror, and it is desirable that the fixing unit is provided in the housing. By providing the fixing portion in the housing, the optical engine portion and the mirror can be positioned with high accuracy in the housing, and high optical performance can be ensured. Since only the fixing portion needs to have a strong configuration, the casing can be made thinner and lighter than when the entire casing is configured to be strong. Thereby, high optical performance can be ensured in a thin and lightweight configuration.

  As a preferred embodiment of the present invention, the mirror is preferably provided in the vicinity of the outer edge portion of the screen, and the optical engine portion is preferably provided on the opposite side of the screen from the side where the mirror is provided. For example, when the mirror is provided in the upper part of the casing, the optical engine unit is provided in the lower part of the casing. In this case, the casing can be thinned by arranging the optical engine unit and the mirror in the vertical direction substantially orthogonal to the thickness direction of the casing. In addition, since the mirror is smaller than the conventional configuration, it is considered that the reduction in the positional accuracy of the mirror has a great influence on the optical performance. Therefore, a decrease in optical performance can be effectively reduced by increasing the positional accuracy of the mirror.

  Further, as a preferred aspect of the present invention, it is desirable to have a projection lens that projects the light from the optical engine unit, and it is desirable for the projection lens to shift the light from the optical axis of the projection lens to a specific side. The rear projector can be made thinner as light travels in the direction along the screen surface in the housing. In this embodiment, it is possible to align the traveling direction of light by employing a shift optical system that shifts light from the optical axis to a specific side. By aligning the light in the direction along the screen surface, the casing can be made thin. Further, since the angle of light is widened by the projection lens as compared with the conventional configuration, it is considered that the decrease in the positional accuracy of the optical engine unit has a great influence on the optical performance. Therefore, a decrease in optical performance can be effectively reduced by increasing the positional accuracy of the optical engine unit.

  As a preferred embodiment of the present invention, the mirror desirably has an aspherical curved surface. Here, the aspherical curved surface may be a curved surface having a substantially rotationally symmetric shape with respect to the central axis, such as a paraboloid or an elliptical surface, or a free-form surface having a non-rotating symmetric shape. And An aspherical mirror having an aspherical curved surface can bend and widen light at the same time. When an aspherical mirror is used, the optical system is a so-called non-coaxial system in which optical axes of optical elements are not matched. In the case of a non-coaxial optical system, it is considered that the decrease in positional accuracy of the optical engine unit and the aspherical mirror has a great influence on the optical performance. Therefore, by increasing the positional accuracy of the optical engine unit and the aspherical mirror, it is possible to effectively reduce a decrease in optical performance.

  Moreover, as a preferable aspect of the present invention, the first mirror that reflects the light from the optical engine unit, and the second mirror that causes the light from the first mirror to be widened by reflection and incident on the screen, are provided. It is desirable that the first mirror and the second mirror are provided on the opposite side of the center of the screen from the side where the optical engine unit is provided, and the fixing unit fixes the optical engine unit and the second mirror integrally. . In this aspect, the light that has been widened by the second mirror is incident on the screen. By increasing the positional accuracy of the optical engine unit and the second mirror, it is possible to reduce a decrease in optical performance.

  Moreover, as a preferable aspect of the present invention, it is desirable that the fixing portion further fixes the first mirror. Optical performance can be further improved by increasing the positional accuracy of the first mirror.

  Moreover, as a preferable aspect of the present invention, it is desirable that the optical engine unit is arranged vertically above the center of the screen. By arranging the optical engine unit on the upper part of the housing, it is possible to easily maintain the periphery of the optical engine unit, and to obtain the advantages of effectively discharging the heat without circulating the heat from the optical engine unit in the housing. . By strengthening the fixing portion, it is possible to reduce the bending of the housing even when the optical engine portion is disposed on the top of the housing.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  FIG. 1 shows a schematic configuration of a rear projector 10 according to an embodiment of the present invention. The configuration shown in FIG. 1 is a YZ cross-sectional configuration in which the rear projector 10 is cut at the center in the X direction. The rear projector 10 displays an image by transmitting light modulated in accordance with the image signal to the screen 16. The optical engine unit 11 supplies light modulated according to the image signal. The optical engine unit 11 is disposed on the vertical lower side which is the minus Y side from the center position O of the screen 16. A projection lens 12 is attached to the emission side of the optical engine unit 11.

  FIG. 2 illustrates the configuration of the optical engine unit 11. The ultra-high pressure mercury lamp 101 serving as the light source unit includes red light (hereinafter referred to as “R light”) as the first color light, green light (hereinafter referred to as “G light”) as the second color light, and third light. Light including blue light (hereinafter referred to as “B light”) that is colored light is supplied. The integrator 102 makes the illuminance distribution of light in the spatial light modulator substantially uniform. The light that has passed through the integrator 102 is converted by the polarization conversion element 103 into polarized light having a specific vibration direction, for example, s-polarized light.

  The light converted into the s-polarized light is bent 90 degrees in the optical path by the reflection mirror 104 and then incident on the R light transmitting dichroic mirror 105R. The R light transmitting dichroic mirror 105R transmits R light and reflects G light and B light. The R light transmitted through the R light transmitting dichroic mirror 105R has its optical path bent by 90 degrees by the reflecting mirror 105 and is incident on the R light spatial light modulator 107R. The spatial light modulator 107R for R light is a transmissive liquid crystal display device that modulates R light according to an image signal. Since the polarization direction of the light does not change even if it passes through the dichroic mirror, the R light incident on the R light spatial light modulator 107R remains as s-polarized light.

  The s-polarized light that has entered the spatial light modulator for R light 107R enters a liquid crystal panel (not shown). In the liquid crystal panel, a liquid crystal layer for image display is sealed between two transparent substrates. The s-polarized light incident on the liquid crystal panel is converted into p-polarized light by modulation according to the image signal. The spatial light modulator 107R for R light emits R light converted into p-polarized light by modulation. In this way, the R light modulated by the R light spatial light modulator 107R is incident on the cross dichroic prism 108 which is a color synthesis optical system.

  The G light and B light reflected by the R light transmitting dichroic mirror 105R are incident on the B light transmitting dichroic mirror 105G after the optical path is bent 90 degrees. The B light transmitting dichroic mirror 105G reflects G light and transmits B light. The G light reflected by the B light transmitting dichroic mirror 105G enters the G light spatial light modulator 107G. The G light spatial light modulation device 107G is a transmissive liquid crystal display device that modulates the G light according to an image signal. The s-polarized light incident on the G light spatial light modulator 107G is converted into p-polarized light by modulation in the liquid crystal panel. The spatial light modulation device 107G for G light emits G light converted into p-polarized light by modulation. In this way, the G light modulated by the G light spatial light modulator 107 </ b> G enters the cross dichroic prism 108.

  The B light transmitted through the B light transmitting dichroic mirror 105G enters the B light spatial light modulator 107B via the two relay lenses 106 and the two reflection mirrors 105. The B light spatial light modulation device 107B is a transmissive liquid crystal display device that modulates B light according to an image signal. The reason why the B light passes through the relay lens 106 is that the optical path of the B light is longer than the optical paths of the R light and the G light. By using the relay lens 106, the B light transmitted through the B light transmitting dichroic mirror 105G can be directly guided to the B light spatial light modulation device 107B.

  The s-polarized light incident on the B light spatial light modulator 107B is converted into p-polarized light by modulation in the liquid crystal panel. The B light spatial light modulator 107B emits B light converted into p-polarized light by modulation. In this way, the B light modulated by the B light spatial light modulator 107B is incident on the cross dichroic prism 108 which is a color synthesis optical system. Each of the spatial light modulators 107R, 107G, and 107B may convert p-polarized light into s-polarized light in addition to converting s-polarized light into p-polarized light by modulation.

  The cross dichroic prism 108 has two dichroic films 108a and 108b arranged so as to be substantially orthogonal to each other. The first dichroic film 108a reflects B light and transmits R light and G light. The second dichroic film 108b reflects R light and transmits B light and G light. With this configuration, the cross dichroic prism 108 combines the R light, the G light, and the B light. The projection lens 12 projects the light combined by the cross dichroic prism 108 in the direction of the plane mirror 15 (see FIG. 1).

  Returning to FIG. 1, the projection lens 12 widens the light mainly in the X direction. Further, the projection lens 12 shifts the light from the optical axis AX of the projection lens 12 to the vertical upper side, which is a specific side, and advances the light. The flat mirror 15 is provided in the vicinity of the upper outer edge of the screen 16 and at a position close to the ceiling surface of the housing 18. The plane mirror 15 is a mirror that causes light from the optical engine unit 11 to enter the screen 16 by reflection. The flat mirror 15 can be configured by forming a reflective film on a substrate that is a parallel plate. As the reflective film, a highly reflective member layer, for example, a metal member layer such as aluminum, a dielectric multilayer film, or the like can be used. Further, a protective film having a transparent member may be formed on the reflective film.

  The flat mirror 15 may be disposed substantially parallel to the ceiling surface in addition to being disposed obliquely with respect to the ceiling surface as illustrated. The screen 16 is a transmissive screen that displays a projected image on a surface on the viewer side by transmitting light according to an image signal. The screen 16 is provided in front of the housing 18. The housing 18 houses the optical engine unit 11, the flat mirror 15, and the like. The projection lens 12, the flat mirror 15, and the screen 16 all form a so-called coaxial optical system that is arranged so that the optical axes thereof are substantially coincident with each other. Further, the projection lens 12 forms a so-called shift optical system in which the light from the optical engine unit 11 is shifted upward from the optical axis AX to a specific side.

  FIG. 3 shows a cross-sectional configuration of the main part of the screen 16. The screen 16 has a Fresnel lens 310 provided on the side on which light corresponding to an image signal is incident. The Fresnel lens 310 is an angle conversion unit that converts the angle of light from the plane mirror 15. The Fresnel lens 310 is configured by arranging prism portions 303 having a shape obtained by cutting out a convex surface of a convex lens on a plane. The plurality of prism portions 303 are arranged substantially concentrically. The prism portion 303 has a substantially triangular shape formed by the first surface 301 and the second surface 302 in the YZ cross section passing through the center of the concentric circle. The first surface 301 makes light from the plane mirror 15 incident. The second surface 302 reflects light from the first surface 301.

  Light from the plane mirror 15 enters the prism portion 303 from the first surface 301. The light incident on the prism portion 303 is totally reflected by the second surface 302 and then travels in the Z direction, which is the direction of the observer. In this way, the Fresnel lens 310 angle-converts the light incident obliquely from the plane mirror 15 in the direction of the observer. The screen 16 may be provided with a configuration other than the Fresnel lens 310, for example, a lenticular lens array or a microlens array that diffuses light from the Fresnel lens 310, a diffusion plate in which a diffusion material is dispersed, or the like.

  Returning to FIG. 1, the optical engine unit 11 and the plane mirror 15 are integrally fixed by a fixing unit 17. The fixing portion 17 can be formed of a metal member such as aluminum, for example. As shown in the perspective configuration of FIG. 4, the fixing unit 17 fixes the optical engine unit 11 with the optical engine fixing unit 401 formed at the lower end of the column unit 403, and is a flat mirror formed at the upper end of the column unit 403. The plane mirror 15 is fixed by the fixing unit 402. The optical engine fixing unit 401 fixes the optical engine unit 11 on a plane substantially orthogonal to the optical axis AX of the projection lens 12. The plane mirror fixing unit 402 fixes the plane mirror 15 by bonding the plane mirror 15 to a plane substantially parallel to the plane mirror 15. The optical engine unit 11 and the plane mirror 15 are positioned with high accuracy by making the fixing unit 17 have a strong configuration. The fixing unit 17 is fitted in the housing 18 (see FIG. 1) in a state where the optical engine unit 11 and the plane mirror 15 are fixed.

  FIG. 5 illustrates a schematic configuration of a conventional rear projector 20 as a comparison with the present embodiment. The rear mirror 25 is provided in a rear portion of the housing 28 that is formed obliquely with respect to the ceiling surface. The projection lens 12 advances light from the optical engine unit 11 substantially symmetrically with respect to the optical axis AX of the projection lens 12. The light from the projection lens 12 is reflected by the rear mirror 25 and then enters the screen 16. Generally, the housing 28 of the conventional rear projector 20 is configured by combining a bottom surface portion that fixes the optical engine unit 11, a front surface portion that fixes the screen 16, and a back surface portion that fixes the rear mirror 25. Normally, the rear projector 20 adjusts the optical system by finely adjusting the position of the optical engine unit 11 after the optical engine unit 11, the screen 16, and the rear mirror 25 are positioned with respect to each other by assembling the casing 28. .

  The rear projector 10 of the present invention shown in FIG. 1 has an optical engine unit 11 on the lower side, which is the side opposite to the side on which the plane mirror 15 is provided, with respect to the center position O of the screen 16. . By disposing the optical engine unit 11 and the plane mirror 15 in the Y direction substantially orthogonal to the Z direction, which is the thickness direction of the casing 18, the casing 18 can be made thinner than the conventional rear projector 20. it can.

  FIG. 6 explains the optical system of the rear projector 10 of the present invention. Here, illustration of bending of the optical path by the plane mirror 15 is omitted. In order to display a large image with a thin configuration, it is desired to spread light over a wide range with a short optical path. For this reason, the rear projector 10 causes the projection lens 12 to make the angle of light wider than that of the conventional rear projector 20. In addition, the projection lens 12 projects light onto a part α that is vertically above the optical axis AX in the angular range θ1 centered on the optical axis AX.

  The rear projector 10 can be made thinner as light travels in the direction along the screen 16 in the housing 18. The rear projector 10 employs a shift optical system that shifts light from the optical axis AX to a specific side, whereby the light traveling direction can be aligned to some extent. By aligning the light in the direction along the surface of the screen 16, the casing 18 can be made thin.

FIG. 7 compares the effect of the change in the position of the projection lens 12 on the image size on the screen 16 between the conventional rear projector 20 and the rear projector 10 of the present invention. For example, assume that an image is displayed on a 60-inch screen 16. The diagonal distance S of the 60-inch screen 16 is 1524 mm. For example, if the projection lens 12 of the conventional rear projector 20 advances light in the angle range θ2 = 60 ° from the position P2 on the optical axis AX, the distance L2 from the projection lens 12 to the screen 16 is as follows: Can be expressed as
L2 = (S / 2) / tan30 °

In the conventional rear projector 20, the diagonal distance S ′ when the distance L2 from the projection lens 12 to the screen 16 is reduced by 1 mm is calculated as follows.
S ′ = {(L2) −1} × tan 30 ° × 2 = [{(S / 2) tan30 °} −1] × tan30 ° × 2≈1523 (mm)

Therefore, in the case of the conventional rear projector 20, even if the distance L2 from the projection lens 12 to the screen 16 is reduced by 1 mm, the diagonal distance S of the image is only reduced by 1 mm. Next, assuming that the projection lens 12 of the rear projector 10 of the present invention advances light in the angle range θ1 = 160 ° from the position P1 on the optical axis AX, the distance L1 from the projection lens 12 to the screen 16 is as follows. It can be expressed as
L1 = (S / 2) / tan80 °

In the rear projector 10 of the present invention, the diagonal distance S ″ when the distance L1 from the projection lens 12 to the screen 16 is reduced by 1 mm is calculated as follows.
S ″ = {(L1) −1} × tan 80 ° × 2 = [{(S / 2) tan 80 °} −1] × tan 80 ° × 2≈1513 (mm)

  Therefore, in the case of the rear projector 10 of the present invention, when the distance L1 from the projection lens 12 to the screen 16 is reduced by 1 mm, the diagonal distance S of the image is reduced by about 10 mm. From this, it can be said that in the case of the rear projector 10 of the present invention that widens the angle of light as compared with the conventional rear projector 20, the loss of the optical performance is increased when the positional relationship between the optical elements is broken. If each optical element is fixed to the housing, the positional relationship between the optical performances easily changes due to distortion and bending of the housing. Further, since the positional relationship between the optical elements has a great influence on the optical performance, it is very difficult to adjust the entire optical system only by fine adjustment of the position of the optical engine unit 11 after the housing 18 is assembled. Become. The rear projector 10 of the present invention is desired to be able to hold the positional relationship between the optical elements, in particular, the optical engine unit 11 and the flat mirror 15 with high accuracy.

  According to the present invention, by fixing the optical engine unit 11 and the plane mirror 15 with the fixing unit 17, the relative positions of the optical engine unit 11 and the plane mirror 15 can be accurately determined with reference to the fixing unit 17. The optical engine unit 11 and the plane mirror 15 can be positioned with higher accuracy than the case where the housing is configured by combining the parts to which the optical engine unit 11 is fixed and the parts to which the plane mirror 15 is fixed. In addition, by making the fixing portion 17 have a strong configuration, the positional relationship between the optical engine portion 11 and the flat mirror 15 can be maintained with high accuracy, and high optical performance can be ensured.

  In the optical system of the rear projector 10, after the adjustment of the optical engine unit 11 and the plane mirror 15 is completed by the fixing unit 17, the fixing unit 17 to which the optical engine unit 11 and the plane mirror 15 are fixed is fitted into the housing 18. Can be configured. By incorporating the optical engine unit 11 and the plane mirror 15 whose relative positions are determined by the fixing unit 17 into the housing 18, the positions of the optical engine unit 11 and the plane mirror 15 and other optical elements such as the screen 16 are arranged. It is easy to make adjustments. Therefore, the optical system can be assembled easily and accurately.

  By arranging the flat mirror 15 of the rear projector 10 of the present invention in the vicinity of the ceiling surface of the casing 18, it can be made smaller than the rear mirror 25 of the conventional rear projector 20 (see FIG. 5). Since the plane mirror 15 can be reduced in size, the plane mirror 15 can be held on the fixed portion 17 with a simple configuration. Moreover, it is thought that the influence which the displacement of the plane mirror 15 exerts on the optical performance increases by making the plane mirror 15 small. By holding the plane mirror 15 with high positional accuracy, it is possible to effectively reduce the deterioration of the optical performance of the rear projector 10.

  By adopting a configuration in which the fixing portion 17 is provided in the housing 18, the optical engine unit 11 and the flat mirror 15 can be positioned with high accuracy without securing the housing 18, and high optical performance can be ensured. It becomes. Since only the fixing portion 17 is required to have a strong configuration, the casing 18 can be made thinner and lighter than a case where the entire casing 18 has a strong configuration. As described above, it is possible to display a high-quality image by ensuring high optical performance in a thin and lightweight configuration. The rear projector 10 may use another projection optical system instead of the projection lens 12, for example, a projection optical system that combines a plurality of mirrors, or a projection optical system that combines a mirror and a lens. The mirror and the lens constituting the projection optical system may be appropriately fixed to the fixing unit 17.

  FIG. 8 shows a schematic configuration of the rear projector 30 according to the first modification of the present embodiment. The rear projector 30 of this modification has an aspherical mirror 33. The aspherical mirror 33 is a mirror that causes the light from the optical engine unit 11 to enter the screen 16 by reflection. The aspherical mirror 33 is provided near the upper outer edge of the screen 16 and close to the ceiling surface of the housing 18. The aspherical mirror 33 has an aspherical curved surface. In the present embodiment, the aspherical curved surface is any curved surface that is substantially rotationally symmetric with respect to the central axis, such as a paraboloid or an elliptical surface, and a free-form surface that is non-rotary symmetric. Be good. The aspherical mirror 33 can be configured by forming a reflective film on a base material having an aspherical shape.

  The fixing unit 37 integrally fixes the optical engine unit 11 and the aspherical mirror 33. The projection lens 12 advances light from the optical engine unit 11 in a vertically upward direction. The aspherical mirror 33 simultaneously performs bending and widening of the light from the projection lens 12. The rear projector 30 widens light mainly in the X direction by the projection lens 12 and the aspherical mirror 33. By widening the light with the aspherical mirror 33 as well as the projection lens 12, the projection lens 12 can be made smaller than when the light is widened only with the projection lens 12. Further, the aspherical mirror 33 itself, which is a mirror that folds the light on the ceiling surface of the housing 18, can be made smaller than when the angle of light is widened only by the projection lens 12.

  When the aspherical mirror 33 is used, the optical system is a so-called non-coaxial system in which optical axes of optical elements do not coincide with each other. When the non-coaxial optical system is adopted, it is considered that the influence of the displacement of each optical element on the optical performance becomes large. Therefore, by increasing the positional accuracy of the optical engine unit 11 and the aspherical mirror 33, it is possible to effectively reduce the decrease in optical performance.

  FIG. 9 shows a schematic configuration of a rear projector 50 according to the second modification of the present embodiment. A rear projector 50 according to this modification includes a first mirror 53 and a second mirror 54 provided in the optical path of the projection lens 12 and the screen 16. The rear projector 50 is configured such that the optical engine unit 11 is disposed on the upper side and the first mirror 53 and the second mirror 54 are disposed on the lower side with respect to the center position O of the screen 16. The first mirror 53 is provided near the lower outer edge of the screen 16 and close to the bottom surface of the housing 18. The first mirror 53 reflects the light from the optical engine unit 11 toward the second mirror 54. The first mirror 53 has a substantially flat planar shape. The first mirror 53 can be configured by forming a reflective film on a parallel plate.

  The second mirror 54 is provided at a position facing the first mirror 53 and close to the back surface and the bottom surface of the housing 18. The second mirror 54 has an aspheric curved surface. The second mirror 54 causes the light from the first mirror 53 to be widened mainly in the X direction by reflection, and also bends the light from the first mirror 53. The second mirror 53 can be configured by forming a reflective film on a base material having an aspherical shape. The projection lens 12 causes the light from the optical engine unit 11 to enter the first mirror 53. The light incident on the first mirror 53 is reflected from the first mirror 53 toward the second mirror 54. The light that has entered the second mirror 54 is bent by the second mirror 54, is widened, and enters the screen 16.

  As shown in the perspective configuration of FIG. 10, the fixing unit 57 integrally fixes the optical engine unit 11, the first mirror 53, and the second mirror 54. By fixing the optical engine unit 11, the first mirror 53, and the second mirror 54 together by the fixing unit 57, high optical performance can be ensured also in this modification. Further, by strengthening the fixing portion 57, even if the optical engine portion 11 that is considered to be heavy among the optical elements is disposed on the upper portion of the housing 18, the bending of the housing 18 can be reduced.

  The rear projector 50 arranges the optical engine unit 11 vertically above the center position O of the screen 16 so that maintenance around the optical engine unit 11 can be easily performed. It is possible to obtain an advantage such as effective discharge of heat without causing any trouble. Other rear projectors of the present embodiment can be modified so that the optical engine unit 11 is arranged on the upper portion of the casing 18. Further, the rear projector can be wall mounted by fixing the fixing portion to a wall surface or the like. Thus, according to the present invention, it is possible to increase the configuration of the rear projector and the degree of freedom of usage.

  Each of the rear projectors described above uses an ultra-high pressure mercury lamp as the light source unit of the optical engine unit 11, but is not limited thereto. For example, a solid light emitting element such as a light emitting diode element (LED) or a semiconductor laser may be used. Further, the rear projector is not limited to a so-called three-plate type rear projector provided with three transmissive liquid crystal display devices, and may be a rear projector using a reflective liquid crystal display device or a rear projector using a tilt mirror device, for example. The rear projector may use a projection device (for example, GLV (Grating Light Valve)) that controls the direction and color of light using the diffraction effect of light. Further, the rear projector may be a laser projector that scans a laser beam modulated in accordance with an image signal. In the case of a laser projector, a laser light source that supplies laser light modulated in accordance with an image signal and a scanning optical system that scans light from the laser light source are used instead of the optical engine unit 11.

  As described above, the rear projector according to the present invention is useful when displaying a large and high-quality image with a thin configuration.

1 is a diagram showing a schematic configuration of a rear projector according to an embodiment of the invention. The figure explaining the structure of an optical engine part. The figure which shows the principal part cross-section structure of a screen. The figure which shows the perspective structure of the fixing | fixed part which has fixed the optical engine part and the plane mirror. The figure explaining schematic structure of the conventional rear projector. The figure explaining the optical system of a rear projector. The figure explaining the influence which the change of the position of a projection lens has on an image size. The figure which shows schematic structure of the rear projector which concerns on the modification 1 of an Example. The figure which shows schematic structure of the rear projector which concerns on the modification 2 of an Example. The figure which shows the perspective structure of a screen and a fixing | fixed part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Rear projector, 11 Optical engine part, 12 Projection lens, 15 Plane mirror, 16 Screen, 17 Fixing part, 18 Case, AX optical axis, O center position, 101
Ultra high pressure mercury lamp, 102 integrator, 103 polarization conversion element, 104, 105 reflection mirror, 105R R light transmission dichroic mirror, 105GB light transmission dichroic mirror, 106 relay lens, 107R spatial light modulator for R light, 107G for G light Spatial light modulator, spatial light modulator for 107B light, 108 cross dichroic prism, 108a first dichroic film, 108b second dichroic film, 301
First surface, 302 Second surface, 303 Prism section, 310 Fresnel lens, 401 Optical engine fixing section, 402 Flat mirror fixing section, 403 Column section, 20 Rear projector, 25 Rear mirror, 28 Housing, 30 Rear projector, 33 Aspherical mirror, 37
Fixed part, 50 Rear projector, 53 First mirror, 54 Second mirror, 57 Fixed part

Claims (8)

An optical engine that supplies light modulated in accordance with an image signal;
A mirror that reflects the light from the optical engine unit to the screen by reflection;
A rear projector, comprising: a fixing unit that integrally fixes the optical engine unit and the mirror. A housing for housing at least the optical engine unit and the mirror;
The rear projector according to claim 1, wherein the fixing unit is provided in the housing. The mirror is provided near the outer edge of the screen,
The rear projector according to claim 1, wherein the optical engine unit is provided on a side opposite to a side where the mirror is provided with respect to a center of the screen. A projection lens for projecting light from the optical engine unit;
The rear projector according to any one of claims 1 to 3, wherein the projection lens shifts light from the optical axis of the projection lens to a specific side and travels.   The rear projector according to claim 1, wherein the mirror has an aspherical curved surface. A first mirror that reflects light from the optical engine unit;
A second mirror for widening the angle of light from the first mirror by reflection and making it incident on the screen;
The first mirror and the second mirror are provided on a side opposite to a side where the optical engine unit is provided with respect to a center of the screen,
The rear projector according to claim 3, wherein the fixing unit integrally fixes the optical engine unit and the second mirror.   The rear projector according to claim 6, wherein the fixing unit further fixes the first mirror.   The rear projector according to claim 1, wherein the optical engine unit is arranged vertically above a center of the screen.

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