JP4906042B2 - Image projection optical unit and image projection apparatus - Google Patents

Description

  The present invention relates to an image projecting optical unit used in an image projecting apparatus, and more particularly to an image projecting optical unit capable of inserting and removing an optical element with respect to an optical path.

In an image projection apparatus such as a liquid crystal projector, an apparatus capable of switching display characteristics such as optimal brightness and color reproducibility in accordance with the purpose of use has been proposed (see Patent Documents 1 and 2). Such an image projection apparatus often employs a configuration in which an optical filter such as a dichroic filter or a trimming filter can be taken in and out of the optical path.
JP 2000-275730 A (paragraphs 0010 to 0017, FIGS. 1 to 7) JP 2001-13585 (paragraphs 0017 to 0019, FIGS. 1 and 3)

  However, in the image projection apparatuses proposed in Patent Documents 1 and 2, the optical filter is put in and out of the optical path in the color separation system. Along with the miniaturization of image projection apparatuses, miniaturization of color separation systems in image projection optical units is also progressing. For this reason, in the color separation system, the spatial margin for taking in and out the optical filter is becoming smaller. In addition, when the optical filter is taken in and out by driving the actuator, the arrangement space for the actuator is required, which hinders downsizing of the apparatus.

  Furthermore, the image projection apparatus also requires a structure for cooling and dustproofing the light source lamp, liquid crystal panel, polarizing plate and other optical elements, and an optical filter that can be taken in and out is arranged so as not to obstruct the cooling / dustproof structure. There is a need.

  An object of the present invention is to dispose an optical element that can be taken in and out of an optical path without hindering miniaturization of an image projection optical unit or an image projection apparatus.

An image projection optical unit according to one aspect of the present invention compresses unpolarized light from a light source into light having a predetermined polarization direction and a light beam emitted from the polarization conversion element in a first direction. A first optical system including the first optical element; The optical system further includes a second optical system that color-separates the light beam from the first optical system and guides it to a plurality of image forming elements. In addition , the movable optical element is disposed between the first optical element and the constituent member closest to the first optical element in the second optical system, and is movable in the first direction . The first optical element has a higher light beam compression degree in the first direction than in the second direction orthogonal to the first direction .

  In the present invention, in the first optical system before reaching the second optical system that performs color separation, the position where the width of the light beam emitted from the polarization conversion element is narrowed (compressed) by the first optical element. Is provided with a movable optical element, and the movable optical element is moved in the compression direction (first direction). Thereby, according to this invention, the movable optical element for switching a display characteristic can be arrange | positioned, without enlarging an image projection optical unit.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows the configuration of an image projection apparatus that is Embodiment 1 of the present invention. In FIG. 1, 1 is a light source lamp, 2 is a lamp holder that holds the lamp 1, 3 is an explosion-proof glass that is attached to the front surface of the lamp holder 2, and 4 is a glass press that sandwiches the explosion-proof glass 3 with the lamp holder 2. is there.

  α denotes an illumination optical system that guides light from the lamp 1 to a color separation / synthesis optical system described later. β is a color separation / synthesis optical system that separates the light emitted from the illumination optical system α into three RGB colors, guides them to three liquid crystal panels, which will be described later, and synthesizes three image lights from the liquid crystal panels. Reference numeral 5 denotes a projection lens that projects light emitted from the color separation / synthesis optical system β onto a screen (projected surface) (not shown).

  Reference numeral 6 denotes an optical box (image projection optical unit) that houses the lamp 1, the illumination optical system α, and the color separation / synthesis optical system β and to which a projection lens barrel (hereinafter simply referred to as a projection lens) 5 is fixed. The optical box 6 is provided with a lamp case member 6 a as a lamp peripheral member surrounding the periphery of the lamp 1.

  Reference numeral 7 denotes an optical box lid that covers the optical box 6 with the illumination optical system α and the color separation / synthesis optical system β housed therein, 8 a power source, and 9 a power filter. Reference numeral 10 denotes a ballast power source for lighting the lamp 1 together with the power source 8. Reference numeral 11 denotes a circuit board that drives the liquid crystal panel with power from the power supply 8 and outputs a lighting command for the lamp 1.

  Reference numerals 12A and 12B denote an optical system cooling fan A and a cooling fan B that cool elements such as a liquid crystal panel in the color separation / synthesis optical system β by sucking air from an air inlet 21a of an exterior cabinet 21 described later. Reference numeral 13 denotes an RGB duct A for sending cooling air from the optical system cooling fans 12A and 12B to an element such as a liquid crystal panel in the color separation / synthesis optical system β.

  A lamp cooling fan 14 cools the lamp 1 by blowing cooling air to the lamp 1. A lamp duct A 15 sends the cooling air to the lamp 1 while holding the lamp cooling fan 14. Reference numeral 16 denotes a lamp duct B that sandwiches the lamp cooling fan 14 with the lamp duct A and constructs a duct together with the lamp duct A15.

  Reference numeral 17 denotes a power supply cooling fan that draws air from an air inlet 21b provided in the exterior cabinet 21 so that cooling air flows through the power supply 8 and the ballast power supply 10 and cools them simultaneously.

  Reference numeral 18 denotes an exhaust fan. The exhaust fan 18 is blown from the lamp cooling fan 14 to the lamp 1 and discharges hot air after the lamp 1 is cooled.

  19 is a lamp exhaust louver A, and 20 is a lamp exhaust louver B. These have a light shielding function so that light from the lamp 1 does not leak outside the apparatus.

  The exterior cabinet (lower exterior case) 21 houses the optical box 6 and the like. The exterior cabinet 21 is attached with an exterior cabinet lid (upper case top) in a state where the optical box 6 and the like are stored.

  23 is a side plate A and 24 is a side plate B. The exterior cabinet 21 has the above-described intake ports 21a and 21b, and the side plate B24 has the above-described exhaust port 24a.

  Reference numeral 25 denotes an interface board on which a connector for capturing various signals is mounted. Reference numeral 26 denotes an interface reinforcing plate attached to the inside of the side plate A23.

  Reference numeral 27 denotes a lamp exhaust box for guiding the exhaust from the lamp 1 to the exhaust fan 18 so as not to dissipate the heat of the exhaust inside the apparatus. The lamp exhaust box 27 holds a lamp exhaust louver A19 and a lamp exhaust louver B20.

  Reference numeral 28 denotes a lamp lid. The lamp cover 28 is detachably provided on the bottom surface of the exterior cabinet 21 and is fixed by screws (not shown). Reference numeral 29 denotes a set adjustment leg. The set adjustment leg 29 is fixed to the exterior cabinet 21, and the height of the leg portion 29a can be adjusted. The inclination angle of the apparatus main body can be adjusted by adjusting the height of the leg 29a.

  Reference numeral 30 denotes an RGB intake plate for holding a filter (not shown) attached to the outside of the intake port 21 a of the exterior cabinet 21.

  A prism base (base member) 31 holds the color separation / synthesis optical system β. Reference numeral 32 denotes a box side cover having a duct-shaped portion for guiding cooling air from the cooling fans 12A and 12B in order to cool the optical elements constituting the color separation / synthesis optical system β and the reflective liquid crystal panel. Reference numeral 33 denotes an RGB duct B which forms a duct together with the box side cover 32.

  Reference numeral 34 denotes an RGB substrate disposed in the color separation / synthesis optical system β, and the RGB substrate 34 is connected to the reflective liquid crystal panel via a flexible substrate. The RGB board 34 is also connected to the circuit board 11. Reference numeral 35 denotes an RGB substrate cover having an electromagnetic shielding function for preventing electrical noise from entering the RGB substrate 34.

  Next, FIG. 2 is used for the optical configuration of the image projection optical unit including the lamp 1, the illumination optical system α, the color separation / synthesis optical system β, the reflective liquid crystal panel as the image forming element, and the projection lens 5. I will explain. FIG. 2A is a plan view of the image projection optical unit, and FIG. 2B is a side view. Hereinafter, the direction orthogonal to the paper surface of FIG. 2A and the left-right direction of FIG. 2B are referred to as the vertical direction, and the direction parallel to the paper surface of FIG. 2A and orthogonal to the paper surface of FIG. The direction is called the horizontal direction.

  2A and 2B, 41 is an arc tube that emits white light with a continuous spectrum, and 42 is a reflector that collects light from the arc tube 41 in a predetermined direction. A lamp 1 as a light source is formed by the arc tube 41 and the reflector 42.

  Reference numeral 43a denotes a first cylinder array composed of a plurality of cylindrical lenses having refractive power in the horizontal direction. Reference numeral 43b denotes a second cylinder array having a plurality of cylindrical lenses corresponding to the individual cylindrical lenses constituting the first cylinder array 43a. 44 is an ultraviolet absorption filter, and 45 is a polarization conversion element for aligning non-polarized light with predetermined polarized light.

  A front compressor 46 is constituted by a cylindrical lens having a refractive power in the vertical direction. Reference numeral 47 denotes a total reflection mirror for converting the optical axis by 88 degrees.

  Reference numeral 43c denotes a third cylinder array composed of a plurality of cylindrical lens arrays having refractive power in the vertical direction. 43d is a fourth cylinder array having a plurality of cylindrical lenses corresponding to individual cylindrical lenses constituting the third cylinder array 43c.

  Reference numeral 50 denotes a color filter as a movable optical element for returning the color in a specific wavelength range to the lamp 1 in order to adjust the color coordinates to a predetermined value. Reference numeral 48 denotes a condenser lens. Reference numeral 49 denotes a rear compressor composed of a cylindrical lens having a refractive power in the vertical direction. The illumination optical system α is configured as described above.

  Reference numeral 58 denotes a dichroic mirror that reflects light in the blue (B) and red (R) wavelength regions and transmits light in the green (G) wavelength region. 59 is an incident side polarizing plate for G in which a polarizing element is bonded to a transparent substrate, and transmits only P-polarized light. Reference numeral 60 denotes a first polarization beam splitter that transmits P-polarized light and reflects S-polarized light, and has a polarization separation surface.

  61R, 61G, and 61B are a red reflective liquid crystal panel, a green reflective liquid crystal panel, and a blue reflective liquid crystal panel that reflect incident light and modulate the image, respectively. These liquid crystal panels are also referred to as image forming elements and image modulating elements. The liquid crystal panels 61R, 61G, and 61B are connected to a drive circuit 110 that drives them. An image information supply device 120 such as a personal computer, a DVD player, a video deck, or a TV tuner is connected to the drive circuit 110. It is connected. The drive circuit 110 receives video (image) information from the image information supply device 120 and causes the liquid crystal display elements 61R, 61G, and 61B to form original images according to the video information.

  62R, 62G, and 62B are a quarter wavelength plate for red, a quarter wavelength plate for green, and a quarter wavelength plate for blue, respectively. A trimming filter 64a returns orange light to the lamp 1 in order to increase the color purity of the R light. Reference numeral 64b denotes an incident-side polarizing plate for RB in which a polarizing element is attached to a transparent substrate, and transmits only P-polarized light.

  65 is a color selective phase difference plate that converts the polarization direction of the R light by 90 degrees and does not convert the polarization direction of the B light. Reference numeral 66 denotes a second polarization beam splitter that transmits P-polarized light and reflects S-polarized light, and has a polarization separation surface.

  Reference numeral 68B denotes an exit side polarizing plate (polarizing element) for B, which rectifies only S-polarized light of B light. 68G is an exit side polarizing plate for G that transmits only S-polarized light. Reference numeral 69 denotes a dichroic prism that transmits R and B light and reflects G light. The dichroic mirror 58 and the dichroic prism 69 constitute a color separation / synthesis optical system β.

  Here, P-polarized light and S-polarized light will be described. The polarization conversion element 45 converts P-polarized light into S-polarized light. The P-polarized light and the S-polarized light here are polarized light with the polarization conversion element 45 as a reference. On the other hand, the light incident on the dichroic mirror 58 is P-polarized light because it is considered based on the polarization beam splitters 60 and 66. Although the light emitted from the polarization conversion element 45 is S-polarized light, the same S-polarized light will be described as P-polarized light as light incident on the dichroic mirror 58 in this embodiment.

  Next, the optical action will be described. Light emitted from the arc tube 41 is collected in a predetermined direction by the reflector 42. The reflector 42 has a paraboloid shape, and light from the focal position of the paraboloid becomes a light beam parallel to the symmetry axis of the paraboloid. However, since the light source from the arc tube 41 is not an ideal point light source but has a finite size, the condensed light flux contains many light components that are not parallel to the symmetry axis of the paraboloid. Yes. These light beams are incident on the first cylinder array 43a. The light beam incident on the first cylinder array 43a is divided into a plurality of light beams (a plurality of strip-shaped light beams extending in the vertical direction) corresponding to the respective cylindrical lenses, and is condensed. These split light beams pass through the second cylinder array 43 b via the ultraviolet absorption filter 44 and form a plurality of light source images in the vicinity of the polarization conversion element 45.

  The polarization conversion element 45 has a polarization separation surface, a reflection surface, and a half-wave plate. Light beams from a plurality of light source images are incident on a polarization separation surface corresponding to each light beam, and are separated into a P-polarized component that is transmitted through the polarization separation surface and an S-polarized component that is reflected by the polarization separation surface. The reflected S-polarized component is reflected by the reflecting surface and is emitted in the same direction as the P-polarized component. On the other hand, the transmitted P-polarized light component is transmitted through the half-wave plate and converted into the same polarized light component as the S-polarized light component. As a result, light having the same polarization direction (S-polarized light) is emitted from the polarization conversion element 45.

  The plurality of split light beams (polarized light beams extending in the vertical direction) that have undergone polarization conversion are reflected by the reflection mirror 47 via the front compressor 46 and are incident on the third cylinder array 43c. The light beam incident on the third cylinder array 43c is divided into a plurality of light beams (a plurality of strip-shaped light beams extending in the horizontal direction) corresponding to the respective cylindrical lenses and condensed. Then, these split light beams pass through the fourth cylinder array 43d and reach the rear compressor 49 via the condenser lens 48.

  Here, due to the optical action of the front compressor 46, the condenser lens 48, and the rear compressor 49, the rectangular images of the plurality of divided light beams overlap with each other to form a rectangular uniform illumination area. Liquid crystal panels 61R, 61G, and 61B are arranged in this illumination area.

  Next, the S-polarized light emitted from the rear compressor 46 enters the dichroic mirror 58. The dichroic mirror 58 reflects B (430 to 495 nm) and R (590 to 650 nm) light, and transmits G (505 to 580 nm) light.

  Next, the G optical path will be described. The G light transmitted through the dichroic mirror 58 enters the incident side polarizing plate 59. The G light remains P-polarized light (S-polarized light when the polarization conversion element 45 is used as a reference) even after being decomposed by the dichroic mirror 58. The G light exits from the incident-side polarizing plate 59 and then enters the first polarization beam splitter 60 as P-polarized light, passes through the polarization separation surface, and enters the G reflective liquid crystal panel 61G. It reaches.

  In the reflective liquid crystal panel 61G for G, the G light is image-modulated and reflected. The P-polarized component of the image-modulated G reflected light is transmitted again through the polarization separation surface of the first polarization beam splitter 60 and returned to the light source side, and is removed from the projection light.

  On the other hand, the S-polarized component of the image-modulated G reflected light is reflected by the polarization separation surface of the first polarization beam splitter 60 and travels toward the dichroic prism 69 as projection light. At this time, in a state where all the polarization components are converted to P-polarized light (in a state where black is displayed), a ¼ wavelength provided between the first polarizing beam splitter 60 and the G reflective liquid crystal panel 61G. The slow axis of the plate 62G is adjusted in a predetermined direction. Thereby, it is possible to suppress the influence of the disturbance of the polarization state generated in the first polarizing beam splitter 60 and the G-use reflective liquid crystal panel 61G. The G light emitted from the first polarization beam splitter 60 enters the third polarization beam splitter 69 as S-polarized light, is reflected by the dichroic film surface of the dichroic prism 69, and reaches the projection lens 5.

  On the other hand, the R light and B light reflected by the dichroic mirror 58 are still P-polarized light after being decomposed by the dichroic mirror 58. After the orange light is cut by the trimming filter 64a, the R light and the B light are emitted from the incident-side polarizing plate 64b and are incident on the color selective phase difference plate 65. The color selective phase difference plate 65 has an effect of rotating the polarization direction of 90 degrees only for the R light. As a result, the R light is incident on the second polarization beam splitter 66 as S-polarized light and the B light is incident on P-polarized light. The R light incident on the second polarization beam splitter 66 as S-polarized light is reflected by the polarization separation surface of the second polarization beam splitter 66 and reaches the R reflective liquid crystal panel 61R. The B light incident on the second polarization beam splitter 66 as P-polarized light passes through the polarization separation surface of the second polarization beam splitter 66 and reaches the B-use reflective liquid crystal panel 61B.

  The R light incident on the reflective liquid crystal panel 61R for R is image-modulated and reflected. The S-polarized component of the image-modulated R reflected light is reflected again by the polarization separation surface of the second polarization beam splitter 66, returned to the light source side, and removed from the projection light. On the other hand, the P-polarized component of the image-modulated R reflected light passes through the polarization separation surface of the second polarization beam splitter 66 and travels toward the dichroic prism 69 as projection light.

  Further, the B light incident on the reflective liquid crystal panel 61B for B is image-modulated and reflected. The P-polarized component of the image-modulated B reflected light is again transmitted through the polarization separation surface of the second polarization beam splitter 66 and returned to the light source side, and is removed from the projection light. On the other hand, the S-polarized component of the image-modulated B reflected light is reflected by the polarization separation surface of the second polarizing beam splitter 66 and travels toward the dichroic prism 69 as projection light.

  At this time, by adjusting the slow axis of the quarter-wave plates 62R and 62B provided between the second polarizing beam splitter 66 and the reflective liquid crystal panels 61R and 61B for R and B, G The black display of each of the R and B lights can be adjusted in the same way as the light.

  The B light out of the R and B projection lights that are combined into one light beam and emitted from the second polarization beam splitter 66 is detected by the exit-side polarizing plate 68B and enters the dichroic prism 69. Further, the R light passes through the polarizing plate 68 </ b> B as P polarization and enters the dichroic prism 69.

  By being analyzed by the exit-side polarizing plate 68B, the B projection light is ineffective generated by passing through the second polarizing beam splitter 66, the B-use reflective liquid crystal panel 61B, and the quarter-wave plate 62B. The light is cut from the ingredients.

  The R and B projection light incident on the dichroic prism 69 passes through the dichroic film surface of the dichroic prism 69 and is combined with the G light reflected on the dichroic film surface to reach the projection lens 5.

  The combined R, G, B projection light is projected onto a projection surface such as a screen by the projection lens 5.

  Since the optical path described above is for the case where the reflective liquid crystal panel displays white, the optical path for the case where the reflective liquid crystal panel displays black will be described below. First, the G optical path will be described.

  The P-polarized light of the G light that has passed through the dichroic mirror 58 enters the incident-side polarizing plate 59, and then enters the first polarization beam splitter 60, passes through the polarization separation surface, and is reflected by the G reflective liquid crystal panel 61G. It leads to. However, since the reflective liquid crystal panel 61G displays black, the G light is reflected without being image-modulated. For this reason, the G light remains P-polarized light even after being reflected by the reflective liquid crystal panel 61G. Accordingly, the light passes again through the polarization separation surface of the first polarization beam splitter 60, passes through the incident side polarizing plate 59, returns to the light source side, and is removed from the projection light.

  Next, the R and B optical paths will be described. P-polarized light of R light and B light reflected by the dichroic mirror 58 is incident on the incident-side polarizing plate 64b. The R light and the B light are emitted from the incident side polarizing plate 64 b and then incident on the color selective phase difference plate 65. The color selective phase difference plate 65 has an effect of rotating the polarization direction of 90 degrees only for the R light. Thus, the R light is incident on the second polarization beam splitter 66 as S-polarized light and the B light is incident on P-polarized light.

  The R light incident on the second polarization beam splitter 66 as S-polarized light is reflected by the polarization separation surface of the second polarization beam splitter 66 and reaches the R reflective liquid crystal panel 61R. The B light incident on the second polarization beam splitter 66 as P-polarized light passes through the polarization separation surface of the second polarization beam splitter 66 and reaches the B-use reflective liquid crystal panel 61B.

  Here, since the R reflective liquid crystal panel 61R displays black, the R light incident on the R reflective liquid crystal panel 61R is reflected without being image-modulated. For this reason, the R light remains S-polarized light even after being reflected by the reflective liquid crystal panel 61R for R. Therefore, the light is again reflected by the polarization separation surface of the first polarization beam splitter 60, passes through the incident-side polarizing plate 64b, returns to the light source side, and is removed from the projection light. Thereby, black display is obtained.

  On the other hand, the B light incident on the B reflective liquid crystal panel 61B is reflected without being image-modulated because the B reflective liquid crystal panel 61B displays black. For this reason, the B light remains P-polarized light even after being reflected by the reflective liquid crystal panel 61B for B. Therefore, the light is again transmitted through the polarization separation surface of the first polarization beam splitter 60, converted to P-polarized light by the color-selective retardation plate 65, transmitted through the incident-side polarizing plate 64b, and returned to the light source side from the projection light. Removed. The above is the optical configuration of the image projection optical unit using the reflective liquid crystal panel.

  Next, the characteristic configuration of the present embodiment will be described with reference to FIGS. In FIG. 3, θ is a switch for switching the color coordinate by moving the color filter 50 in and out of the optical path of the illumination optical system α in the vertical direction of the drawing, that is, in the vertical direction in which the beam width is compressed by the front compressor 46. Is a unit. The color filter 50 is taken in and out (retracted and inserted) between the third cylinder array 43c and the fourth cylinder array 43d.

  The superiority of the position where the switching unit θ is arranged will be described. In FIGS. 4A and 4B, the illumination optical system α is developed with reference to the optical axis of the total reflection mirror 47 (also referred to as the optical axis of the condenser lens 48) except for the total reflection mirror 47. FIG. 4A is a top view and FIG. 4B is a side view.

  In the illumination optical system α, the light beam emitted from the lamp 1 is basically dominant. The width of the light beam emitted from the polarization conversion element 45 is Y1 in the vertical direction shown in FIG. 4B and X1 in the horizontal direction shown in FIG. 4A. In contrast to these light beam widths, in the color separation / synthesis optical system β, the light beam width is significantly narrowed in both the vertical direction and the horizontal direction, and the optical system is compactly integrated, and therefore has a relatively large space. It is very difficult to provide the switching unit θ.

  If a color separation / synthesis optical system β is provided with a moving mechanism that is movable in the vertical direction, the mechanism protrudes greatly from the vertical dimension of the color separation / synthesis optical system β. The dimensions become large. In addition, when the color separation / combination optical system β is provided with a horizontal movable moving-in / out mechanism, the configuration retracted to the projection lens side interferes with the liquid crystal panel and the projection lens, and also retracts to the illumination optical system α side. Attempts to interfere with the illumination optical system α are both difficult.

  If the distance between the polarization beam splitters 60 and 66 and the dichroic prism 69 is widened so as not to interfere with the projection lens, the liquid crystal panel, and the illumination optical system α, the back focus of the projection lens becomes long, and the total length of the projection lens is increased. become longer. As a result, the overall size of the apparatus is increased. Furthermore, the back focus of the illumination optical system α also becomes long, which causes a reduction in the amount of light.

  In addition, since there is no optical element in the vertical direction of FIG. 4B, it is considered spatially advantageous. However, in reality, a duct structure for cooling the polarizing plate and the liquid crystal panel, and a substrate connected to the liquid crystal panel are provided. Arranged and there is little surplus space. Even if the surplus space exists, by providing the taking in / out mechanism, there is only one portion that protrudes greatly. For this reason, the power supply unit composed of the power supply 8 and the ballast power supply 10 described above cannot be disposed close to the image projection optical unit, and the space utilization efficiency is low.

  Therefore, in this embodiment, the switching unit θ for inserting and removing the color filter 50 in the direction of the light beam width is disposed at a position where the light beam width is extremely narrow in the illumination optical system α. At the position of the switching unit θ, the beam width is X2 in the horizontal direction and larger than Y1 and X1, but becomes Y2 in the vertical direction and is reduced to about １ ／ that is ½ or less of Y1. . This is due to the peculiarity of the illumination optical system α of the present embodiment having the front compressor 46 that greatly compresses the light beam emitted from the polarization conversion element 45 only in the vertical direction. However, the present invention is not limited to the illumination optical system α of the present embodiment, and an optical element that compresses (condenses) a light beam with a higher degree of compression in the vertical direction than in the horizontal direction in the illumination optical system. It is applicable if you have

  As described above, since the vertical light flux width Y2 is as narrow as ½ or less of Y1, even if the color filter 50 having a size substantially similar to Y2 is retracted in the vertical direction, the movable range of the color filter 50 is approximately the same. Fits within Y1. That is, the color filter 50 can be retracted from the optical path without protruding significantly from the maximum vertical width (height) of the illumination optical system α.

  Further, even if an actuator for driving the switching unit θ is arranged, the prisms 60 and 69 are arranged so as not to protrude greatly from the vertical dimension of the so-called vertical arrangement color separation / synthesis optical system β. Is possible.

  Next, details of the switching unit θ will be described with reference to FIG. FIG. 5A shows a state in which the color filter 50 is inserted (moved down) into the optical path, and FIG. 5B shows a state in which the color filter 50 has been retracted out of the optical path (moved up). .

  In FIG. 5, reference numeral 80 denotes a filter holder that holds the color filter 50. Reference numeral 81 denotes a filter press that sandwiches the color filter 50 together with the filter holder 80. A motor gear unit (actuator) 83 drives the filter holder 80 up and down. A motor flange 82 holds the motor gear unit 83. 85B and 85T are sensors for detecting whether the filter holder 80 (that is, the color filter 50) is in the downward movement state or the upward movement state. Reference numeral 84 denotes a sensor substrate to which the sensor 85 is soldered. The sensor substrate 84 is attached to the motor flange 82 by screws 87. Reference numeral 86 denotes a connector for connecting the sensor board 84 and the circuit board 11 described above.

  Next, the position detection and drive control of the switching unit θ will be described. In the filter insertion state shown in FIG. 5A, the filter holder 80 is lowered. At this time, the protrusion 80B provided at the upper end of the filter holder 80 pushes the switch portion of the sensor 85B. At this time, the driving of the motor gear unit 80 is stopped.

  Consider the case where the filter holder 80 is driven downward by a malfunction of the motor gear unit 83 even though the switch portion of the sensor 85B is pushed by the protrusion 80B and the controller (not shown) outputs a stop signal. The following configuration is adopted. That is, the protrusion 80B abuts against a stopper 82B provided on the motor flange 82, and further downward movement is prevented. The motor gear unit 83 is provided with a slip mechanism, and the motor gear unit 83, the filter holder 80, and the motor flange 82 are not damaged.

  In the filter insertion state, the chromaticity of the projected image is adjusted to a predetermined state. The chromaticity can be adjusted electrically by controlling the driving of the liquid crystal panels 61R, 61G, 61B. However, for example, when electrical adjustment is performed in order to realize an ideal color balance, the color reproducibility of intermediate gradation becomes poor. Therefore, in this embodiment, the color reproducibility is optically enhanced by removing light having an unnecessary wavelength with the color filter 50 constituted by a dichroic filter or the like.

  When the user selects a mode that prioritizes brightness over the color reproduction priority mode by operating a mode selector (not shown), the motor gear unit 83 is driven. Thereby, the gear part 83a of the motor gear unit 83 pushes up the filter holder 80 via the rack part 80a, and raises it to the filter retracted state of FIG. When the protrusion 80T provided on the filter holder 80 presses the switch portion of the sensor 85T, the driving of the motor gear unit 83 is stopped by a controller (not shown). If the filter holder 80 continues to rise due to an inertial force or the like after the stop signal is output from the controller, the upper surface of the filter holder 80U of the filter holder 80 is the inner wall surface of the optical box lid 7 (see FIG. 1). The filter holder 80 is prevented from further rising. When the color reproduction priority mode is selected by operating the mode selector, the motor gear unit 83 reverses and the filter holder 80 moves downward until the protrusion 80B presses the switch portion of the sensor 85B.

  When the filter holder 80 is displaced from the position in the filter insertion state or the filter retracted state due to vibration or a drop impact, the signals from the sensors 85B and 85T change. As a result, the controller detects an error and drives the filter holder 80 to the original position.

  According to the configuration described above, even in the filter retracted state shown in FIG. 5B, the protrusion 80B at the upper end of the filter holder 80 only slightly protrudes from the upper end of the motor flange 82. Therefore, the switching unit θ can be arranged without substantially increasing the overall size (height) of the image projection optical unit.

  6 shows a state in which the lamp 1, the projection lens 5 and other components are attached to the illumination optical system α and the color separation / synthesis optical system β shown in FIG. 3, that is, image projection optics referred to as a so-called optical engine. The appearance of the unit is shown.

  As shown in FIG. 6, even when the switching unit θ is mounted, the switching unit θ does not protrude so much from the upper surface of the optical box lid 7. In other words, the switching unit θ is mounted without changing the basic silhouette of the image projection optical unit, that is, the size. Specifically, the motor gear unit 83 and the motor flange 82 are only attached to the upper outer surface of the optical box lid 7 so that it is not apparent that the switching unit θ exists in the optical box 6. The space utilization efficiency in the optical box 6 is increased. The height of the portion of the optical box 6 that houses the lamp 1 and the portion of the prism base 31 that houses the color separation / combination optical system is originally higher than the portion where the switching unit θ is provided. Is big. In the present embodiment, a space that is sandwiched between these high portions and originally becomes a dead space is effectively used as an arrangement space for the switching unit θ.

  FIG. 7 shows a second embodiment of the present invention. Reference numeral 90 denotes a fixed diaphragm made of sheet metal. In the present embodiment, the fixed diaphragm 90 is held in the filter holder 80 of the switching unit θ described in the first embodiment. Other configurations are the same as those of the first embodiment (FIG. 5).

  The fixed diaphragm 90 is manufactured from sheet metal for the following reason. That is, the position where the luminous flux is narrowed is a position where the degree of condensing is high, the light energy density is high, and it is considered that the temperature of the diaphragm 90 rises to a considerably high temperature due to light absorption. For this reason, a measure for preventing deformation of the diaphragm 90 is required. Therefore, the diaphragm 90 is made of a metal that is more resistant to temperature than plastic that is susceptible to temperature deformation.

  The contrast of the projected image can be changed by inserting and removing the fixed diaphragm 90 with respect to the optical path. By inserting the fixed aperture 90 in the optical path, it is possible to project a good cinema mode image with high contrast but low brightness.

  FIG. 8 shows the configuration of the image projection optical unit according to the third embodiment of the present invention as viewed from above. α is an illumination optical system, β is a color separation / synthesis optical system, and θ is a switching unit. The basic configurations of the illumination optical system α, the color separation / synthesis optical system β, and the switching unit θ are the same as those in the first embodiment. However, in the image projection optical unit shown in the first embodiment (FIG. 3), the light beam is compressed in the vertical direction by the front compressor 46, but in this embodiment, the horizontal direction (first direction: parallel to the drawing sheet). Direction). In the first embodiment, the prisms 60 and 69 of the color separation / combination optical system β are arranged in the vertical direction. However, in this embodiment, the prisms 60, 66, and 69 are arranged in the horizontal direction.

  In the present embodiment, the light beam having the horizontal width X1 emitted from the polarization conversion element 45 is compressed by the front compressor 46 'to 1/2 or less (about 1/3) of the horizontal width X2. The switching unit θ is arranged at a position where the horizontal width of the light beam is X2.

  Accordingly, the switching unit θ can be laid out without greatly protruding from the image projection optical unit arranged in a substantially L shape. That is, the switching unit θ can be added without increasing the size of the image projection optical unit when there is no switching unit θ.

  In each of the above-described embodiments, the case where the color filter and the diaphragm are put in and out of the optical path of the illumination optical system has been described. However, the present invention can be applied to the case where other optical elements are put in and out.

  In the above embodiments, the image projection optical unit using the reflective liquid crystal panel has been described. However, the present invention can also be applied to an image projection optical unit using a transmissive liquid crystal panel or a digital micromirror device. it can.

  In each of the above-described embodiments, the image projection optical unit including the color separation / synthesis optical system that performs both color separation and color combination has been described. However, the present invention provides color separation as in the case of using a transmissive liquid crystal panel. The present invention can also be applied to an image projection optical unit in which a system and a color synthesis system are separated.

1 is an exploded perspective view of an image projection apparatus that is Embodiment 1 of the present invention. FIG. 2 is a plan view and a side view of the image projection optical unit according to the first embodiment. FIG. 3 is a perspective view illustrating a layout of an illumination optical system and a color separation / synthesis optical system in the image projection optical unit according to the first embodiment. FIG. 2 is a plan view and a side view showing a switching unit provided in the image projection optical unit of Embodiment 1. FIG. 3 is a diagram illustrating the configuration and operation of the switching unit according to the first embodiment. FIG. 3 is a perspective view illustrating an appearance of an image projection optical unit according to the first embodiment. The front view which shows the structure of the switching unit which is Example 2 of this invention. FIG. 6 is a plan view showing the configuration of an image projection optical unit that is Embodiment 3 of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lamp 5 Projection lens 45 Polarization conversion element 46 Front compressor 60 1st polarizing beam splitter 61R, 61G, 61B Reflective type liquid crystal panel 66 2nd polarizing beam splitter 69 Dichroic prism 50 Color filter 90 Fixed stop (alpha) Illumination optical system (beta) color Decomposition / synthesis optical system θ switching unit

Claims (12)

An image projection optical unit for projecting an image,
A first optical system including a polarization conversion element that converts non-polarized light from a light source into light having a predetermined polarization direction, and a first optical element that compresses a light beam emitted from the polarization conversion element in a first direction; ,
A second optical system for color-separating the light beam from the first optical system and guiding it to a plurality of image forming elements;
Most disposed until the components of the first optical element side, possess a movable optical element movable, to the first direction in the second optical system from the first optical element,
It said first optical element, in the first direction, the image projection optical unit, which comprises have a high light flux compression level than a second direction perpendicular to the first direction. It said first optical element, the image projection optical unit according to claim 1, characterized in that compressing the light beam only in the first direction. The first optical system includes a second optical element that condenses the light beam from the first optical element in the first direction and a second direction orthogonal to the first direction. The image projection optical unit according to claim 1 or 2 . The first optical element narrows the width of the light beam emitted from the polarization conversion element in the first direction to ½ or less,
The image projecting optical unit according to any one of claims 1 to 3 , wherein the movable optical element is disposed in a region having a light flux width equal to or less than the half. The first direction, the image projection optical unit according to claim 1, any one of 4, which is a direction corresponding to the short side direction of the image forming device. The movable optical element, the image projection optical unit according to any one of claims 1 to 5, characterized in that an optical filter. The image projecting optical unit according to claim 6 , wherein the movable optical element has an optical action of converting chromaticity coordinates. The movable optical element, the image projection optical unit according to claim 1, any one of the 5, characterized in that a diaphragm. An actuator for driving the movable optical element;
The actuator is, the image projection optical unit according to any one of claims 1 to 8, characterized in that it is arranged in the first direction relative to the movable optical element. The second optical system includes a plurality of optical elements,
Image projection optical unit according to any one of claims 1 to 9, characterized in that the optical elements of the plurality of are arranged in the first direction. Image projection apparatus characterized by having an image projection optical unit according to claim 1, any one of 10. An image projection apparatus according to claim 11 ;
An image projection system comprising: an image information supply device that supplies image information to the image projection device.