JP3754444B2 - Projection display device - Google Patents

Description

  The present invention relates to a projection image display apparatus provided with a lens shift mechanism.

  FIG. 5 is a diagram illustrating an optical system of a three-plate color liquid crystal projector. The light emitting part of the light source 101 is composed of an ultra-high pressure mercury lamp, a metal halide lamp, a xenon lamp or the like, and the irradiated light is emitted as parallel light by a parabolic reflector and guided to the integrator lens 102.

  The integrator lens 102 is composed of a pair of lens groups, and each pair of lenses guides light emitted from the light source 101 to the entire surface of the liquid crystal light valves 111, 112, 113. The light that has passed through the integrator lens 102 is guided to the first dichroic mirror 103.

The first dichroic mirror 103 transmits light in the red wavelength band and reflects light in the cyan (green + blue) wavelength band. The light in the red wavelength band that has passed through the first dichroic mirror 103 is reflected by the total reflection mirror 104 to change the optical path. The red light reflected by the total reflection mirror 104 is light-modulated by passing through the condenser lens 108 and the transmissive liquid crystal light valve 111 for red light. On the other hand, the light in the cyan wavelength band reflected by the first dichroic mirror 103 is guided to the second dichroic mirror 105.

  The second dichroic mirror 105 transmits light in the blue wavelength band and reflects light in the green wavelength band. The light in the green wavelength band reflected by the second dichroic mirror 105 is guided through the condenser lens 109 to the transmissive liquid crystal light valve 112 for green light, and is modulated by being transmitted therethrough. Further, the light in the blue wavelength band that has passed through the second dichroic mirror 105 is guided to the blue-light transmissive liquid crystal light valve 113 through the total reflection mirrors 106 and 107 and the condenser lens 110 and is transmitted therethrough. Is modulated by light.

  Each of the liquid crystal light valves 111, 112, and 113 includes an incident-side polarizing plate, a panel portion in which liquid crystal is sealed between a pair of glass substrates (pixel electrodes and alignment films are formed), an outgoing-side polarizing plate, Comprising. The modulated light (each color video light) modulated by passing through the liquid crystal light valves 111, 112, 113 is synthesized by the dichroic prism 114 to become color video light. The color image light is enlarged and projected by the projection lens unit 115 and projected and displayed on the screen.

  FIG. 6 is a perspective view showing a lens shift mechanism for moving the projection lens unit 115 in the vertical direction. With this lens shift mechanism, it is possible to move the projected image up and down while keeping the liquid crystal projector main body as it is or to reduce the trapezoidal shape of the image.

  Sliding bearings 121 a are provided at the four corners of the moving base 121 to which the projection lens unit 115 is fixed. A guide shaft 122 is inserted into the sliding bearings 121 a, and the moving base 121 is guided along the guide shaft 122 in the vertical direction. Is done. A plate member 121 b is fixed to the side portion of the moving base 121. A screw hole is formed in the plate member 121b, and the male screw portion 123a of the elevating shaft 123 is screwed into the screw hole. The screw shaft 123 is only allowed to rotate, and the upper and lower portions are supported by bearings 124 so as not to move up and down. The bearing 124 and the guide shaft 122 are fixed to a fixed base 129. A worm gear 125 is fixed to the lower end portion of the screw shaft 123, and a worm screw 126 fixed to the rotating shaft of the motor 127 is screwed to the worm gear 125. As the rotation shaft of the motor 127 rotates, the screw shaft 123 rotates and the plate member 121b moves up and down, and the moving base 121 connected to the plate member 121b moves up and down.

  In the lens shift mechanism, in order to smoothly move the moving base 121 up and down, the guide shaft 122 is made of a metal such as stainless steel and is smoothly ground, and the bearing 121a is polyacetal (POM) or the like. Resin and oilless bearings are used. However, in order to reduce the shaft runout when the moving base 121 moves up and down, it is necessary to reduce the gap between the guide shaft 122 and the bearing 121a, and the dimension from the reference surface of the moving base 121 to the four bearings 121a. High accuracy is required for the parallelism, and the dimension and parallelism from the reference surface of the fixed base 129 to the guide shaft 122. If these tolerances are reduced, they move due to component variations and cumulative errors. The base 121 may not be lifted and lowered smoothly.

  Further, as the projection lens unit increases in size and weight, the center of gravity of the projection lens unit becomes, for example, about 100 mm to 200 mm forward from the guide shaft 122, the load is concentrated on the bearing 121a, and the resin is very worn and has a large diameter. The play of the movement base 121 increases with the year. In addition, when the bearing 121a is made of metal, the oil film of grease applied to the guide shaft 122 may be cut and malfunction may occur.

  In view of the above circumstances, it is an object of the present invention to provide a projection display apparatus including a lens shift mechanism that can smoothly move a projection lens unit.

Means for solving the above-described problems includes a projection image unit including a projection lens unit that performs image projection, a moving base to which the projection lens unit is fixed, and a lens shift mechanism in which the movement base moves with respect to the fixed base. In the display device, the fixed base is disposed so as to face the moving base, and has support pieces bent toward the moving base on both side portions orthogonal to the lens shift direction. A rolling support mechanism is disposed between the pair of rail portions facing each other along the moving direction of the moving base and a plurality of rolling elements held by a cage between the pair of rail portions. The rail portion faces the inner wall of the support piece of the fixed base and is fixed to the fixed base, and the other rail portion is fixed to the moving base and is moved by the rolling support mechanism. It is characterized by being movably supported relative to the fixed base.

  According to the present invention, the moving base is movably supported by the fixed base by the rolling support mechanism, and the projection lens unit can be smoothly moved while reducing the tolerance of the member so as to reduce the shake during the movement of the moving base. It is possible to secure a smooth movement.

  Hereinafter, a lens shift mechanism and a projection display apparatus according to the present invention will be described with reference to FIGS. Note that the projection display apparatus is a liquid crystal projector using three transmissive liquid crystal display panels, and the image generation optical system is the same as the liquid crystal projector of FIG. 5 used in the description of the conventional example. Description of the optical system is omitted, and the lens shift mechanism will be mainly described.

  FIG. 1 is a perspective view showing a lens shift mechanism of this embodiment for moving the projection lens unit 115 in the vertical direction. A mounting plate 20 is fixed to the rear end portion of the projection lens unit 115. Insertion holes into which the screws 14 are inserted are formed at the four corners of the mounting plate 20. The mounting plate 20 is bonded to the moving base 21, and the projection lens unit 115 is fixed to the moving base 21 by screwing the screws 14 into screw holes formed at the four corners of the moving base 21.

  The moving base 21 is disposed so as to face the fixed base 29. The fixed base 29 has a concave shape by having support pieces 29a that are bent at both side portions and face each other. The moving base 21 has a convex shape by having step portions 21a on both side portions thereof. When the fixed base 29 having a concave shape and the movable base 21 having a convex shape face each other, the facing portions of the support piece 29a and the stepped portion 21a are separated from each other. 30 is mounted. The moving base 21 is guided by the bearing mechanism 30 and moves up and down.

  As shown in FIG. 2, the bearing mechanism 30 is provided between the one rail portion 30a having a semi-cylindrical groove, the other rail portion 30b having a semi-cylindrical groove, and the rail portions 30a and 30b. The plurality of balls 30c, and the cage 30d that holds the balls 30c. The one-side rail portion 30 a is fixed to the support piece 29 a of the fixed base 29, and the other-side rail portion 30 b is fixed on the surface forming the stepped portion 21 a of the moving base 21. A bearing cover 30e serving as a stopper for the holding plate 30d is fixed to the upper end surface (and the lower end surface) of the fixed base 29. In the lens shift mechanism 30 configured as described above, the load of the projection lens unit 115 is applied in a direction parallel to the facing surfaces of the rail portions 30a and 30b. The lens shift mechanism 30 receives the force in this direction by the balls 30c, so that the rail portion 30a and the rail portion 30b are not displaced. In the direction perpendicular to the facing surface, the support piece 29a and the stepped portion 21a serve as movement restriction bodies for the rail portions 30a and 30b.

  The rail portions 30a and 30b are selected from quench-ground steel, aluminum die-cast products, sheet metal, resin, etc., depending on the weight of the projection lens unit 115 and the required movement accuracy. The ball 30c is selected from steel, resin, and the like.

  A plate member 21 b is fixed to the side portion of the moving base 21. A screw hole is formed in the plate member 21b, and the male screw portion 23a of the elevating shaft 23 is screwed into the screw hole. The screw shaft 23 is only allowed to rotate, and the upper and lower portions are supported by the bearing portion 24 so as not to move up and down. The bearing portion 24 is fixed to the side surface of the fixed base 29. A worm gear 25 is fixed to the lower end portion of the screw shaft 23, and a worm screw 26 fixed to the rotating shaft of the motor 27 is screwed to the worm gear 25. As the rotation shaft of the motor 27 rotates, the screw shaft 23 rotates and the plate member 21b moves up and down, and the moving base 21 connected to the plate member 21b moves up and down. As a result, the vertical shift operation of the projection lens unit 115 can be performed. When the left / right shift operation of the projection lens unit 115 is also performed, such a lens shift mechanism may be configured and combined for left / right shift.

  Two limit switches 33 and 33 are provided on the side surface of the fixed base 29. When the limit switch 33 is activated, the motor 27 is stopped. The operating pieces of the limit switches 33 and 33 face the side surface of the moving base 21, and the operating pieces are operated by projections or the like (not shown) formed on the side surface of the moving base 21. By setting the positional relationship between the operating piece and the projection or the like, the projection lens unit 115 can be automatically positioned at a desired position.

  With the lens shift mechanism configured as described above, the moving base 21 is movably supported by the fixed base 29 by the bearing mechanism 30, and the tolerance of the members is reduced in order to reduce the shake and the like during movement of the moving base 21. However, smooth movement of the movement base 21 (smooth movement of the projection lens unit 115) can be ensured.

  Although the above-described bearing mechanism 30 uses the ball 30c, the present invention is not limited thereto, and a roller may be used. When this roller is used, square grooves are formed in the rail portions 30a and 30b. When the rollers are alternately arranged in a cross shape, V-grooves are formed in the rail portions 30a and 30b.

  When a relatively soft material such as resin, aluminum, or soft iron is used as the material of the rail portions 30a and 30b of the bearing mechanism 30, an indentation may be formed in the grooves of the rail portions 30a and 30b due to an impact load. In order to minimize this, balls 30c (or rollers) are made of iron and resin (the resin is made slightly larger in diameter than the iron). A high precision slide is maintained by the iron one, and the impact is absorbed by the resin one.

  The bearing mechanism 30 shown in FIG. 3 uses a soft material such as a resin as a material for the rail portions 30a and 30b, while a reinforcing metal plate 30f (for example, thickness 0) such as stainless steel or phosphor bronze is used for the groove of the rail portions 30a and 30b. .05 mm to 0.5 mm). By providing the reinforcing metal plate 30f, the impact strength is increased, and the rolling body such as the ball 30c or the roller is smoothly rotated, which can solve the disadvantage of being made of resin.

  Further, the lens shift mechanism described above is configured such that the load of the projection lens unit 115 is applied in a direction parallel to the opposing surfaces of the rail portions 30a and 30b. However, the present invention is not limited thereto, and the projection lens unit 115 is not limited thereto. The load may be applied in a direction perpendicular to the opposing surfaces of the rail portions 30a and 30b. For example, as shown in FIG. 4, the mounting plate 20 of the projection lens unit 20 is positioned behind the front piece of the fixed base 29 ′, and between the front piece of the fixed base 29 ′ and the mounting plate 20. A bearing mechanism 30 is provided. The one-side rail portion 30 a is fixed to the back surface of the front piece portion of the fixed base 29 ′, and the other-side rail portion 30 b is fixed to the front surface side of the mounting plate 20. A slit 29'a is formed in the fixed base 29 'in the vertical direction, and the nut member 20a is fixed to the mounting plate 20 (or the other rail portion 30b) via the slit 29'a. . Further, for example, by providing a leaf spring on the back side of the mounting plate 20, rattling of the mounting plate 20 can be prevented. The sliding contact surface with the leaf spring has a low friction coefficient. In addition, if it is a structure shown in FIG. 1, there exists an advantage which can make the said leaf | plate spring for rattling prevention unnecessary.

It is the perspective view which showed the lens shift mechanism of embodiment of this invention. It is the perspective view which expanded and showed the bearing mechanism of FIG. It is the perspective view which showed the other example of the bearing mechanism. It is the perspective view which showed the other example of the lens shift mechanism of embodiment of this invention. It is explanatory drawing which showed the optical system of the general liquid crystal projector. It is the perspective view which showed the conventional lens shift mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 Mounting plate 21 Moving base 29 Fixed base 30 Bearing mechanism 30a One side rail part 30b The other side rail part 30c Ball 30d Cage 115 Projection lens unit

Claims (1)

In a projection display apparatus including a projection lens unit that performs image projection, a moving base to which the projection lens unit is fixed, and a lens shift mechanism in which the moving base moves with respect to the fixed base, the fixed base moves It has a support piece that is arranged to face the base and bends toward the moving base on both side parts orthogonal to the lens shifting direction . Between the fixed base and the moving base, the moving base moves in the moving direction. A rolling support mechanism comprising a pair of rail portions facing each other and a plurality of rolling elements held by a cage between the pair of rail portions is disposed, and the one rail portion is provided on the inner wall of the support piece of the fixed base is fixed to the fixed base facing, the other rail section is fixed to the movable base, the movable base by the rolling support mechanism so as to move freely with respect to the fixed base Projection display device characterized by being lifting.