JP5403902B2 - Projection-type image display device - Google Patents

Description

  The present invention relates to a projection type image display apparatus, and more particularly to a projection type image display apparatus having a scintillation reduction function.

  In a projection image display apparatus such as a rear projection television, a lamp or a laser oscillator is used as a light source. When a laser oscillator is used as a light source, it is relatively easy to increase the brightness of the projection type image display apparatus to such an extent that a clear image can be displayed even in a bright room. However, when a laser oscillator is used as the light source, the screen glare phenomenon due to the speckle pattern, so-called scintillation, becomes more prominent than when the lamp is used as the light source, and the image quality is deteriorated.

  As a conventional technique for reducing the above scintillation, a technique described in Patent Document 1 is known. In the method described in Patent Document 1, a laser that vibrates the screen in any of the vertical direction of the image display surface on the screen, the longitudinal direction of the screen, and the width direction of the screen, or reaches the screen surface. Generation of scintillation is suppressed by vibrating light in a direction perpendicular to the optical axis. The screen is vibrated in the above direction by a vibration device using a bimorph, a motor or the like, and the laser light is reflected on the screen side by a vibration mirror attached to the vibration device, or is applied to the vibration device. The laser beam is oscillated in the above-described direction by deflecting the laser beam in front of the screen by the attached deflection device or by vibrating the laser light source itself.

  Another factor that degrades the image quality of the projection type image display apparatus is stray light that is caused by reflection of image light in an undesired direction within the screen. In order to suppress deterioration in image quality due to stray light, for example, in the projection display apparatus described in Patent Document 2, the emission position of stray light is brought close to the emission position of the real image by thinning the Fresnel lens sheet constituting the screen. . Further, if the thinned Fresnel lens sheet is bent, the image is distorted and the image quality is deteriorated. Therefore, in the projection display device described above, the Fresnel lens sheet is framed by a leaf spring while tension is applied to the Fresnel lens sheet. It is fixed to the body.

Japanese Patent Laid-Open No. 55-65940 (pages 4-6, FIGS. 1 and 2) Japanese Patent Laying-Open No. 2005-10730 (pages 18 to 20, FIGS. 20 to 25)

  As described above, the thinning of the Fresnel lens sheet is useful for suppressing deterioration in image quality caused by stray light, and further useful for reducing the weight of the projection-type image display device. In the described projection display device, since the Fresnel lens sheet and the lenticular lens plate constituting the screen are respectively fixed to the frame, the screen cannot be vibrated and it is difficult to suppress the occurrence of scintillation.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to obtain a projection type image display apparatus that can easily achieve weight reduction and high image quality.

  The projection-type image display apparatus of the present invention that solves the above-described problems and achieves the object has an optical engine that emits light according to an image signal, and light incident from the optical engine is made substantially parallel by a Fresnel lens. A screen to be emitted as diffused light by a diffusing member later, an elastic holding unit that uses a Fresnel lens or diffusing member as a driven member and holds the driven member movably in a plane parallel to the screen, and is driven by the elastic holding unit A driving unit that applies a force to move the driven member in a plane parallel to the screen, and an optical engine, a screen, an elastic holding unit, and a housing that houses the driving unit, and the driven member is flexible The drive unit is driven while applying a driving force to the elastic holding unit and keeping the driven member in a stretched state. It is characterized in that to move the timber in a plane parallel to the screen.

  Further, another projection type image display apparatus of the present invention includes an optical engine that emits light according to an image signal, and light that has entered from the optical engine is made to be substantially parallel light by a Fresnel lens and then diffused by a diffusing member. A screen to be emitted, an elastic holding unit that uses a Fresnel lens or a diffusing member as a driven member, and holds the driven member movably in a plane parallel to the screen, and is driven by applying a driving force to the elastic holding unit. A drive unit that moves a member in a plane parallel to the screen, an optical engine, a screen, an elastic holding unit, and a housing that houses the drive unit, and the driven member is a thin member having flexibility. The elastic holding unit is characterized in that tension is always applied to the driven member to keep the driven member in a tensioned state.

  In the projection type image display apparatus of the present invention, since a thin member is used as a driven member among the Fresnel lens and the diffusing member constituting the screen, it is easy to reduce the weight, and the emission position of stray light is a real image. It is easy to suppress the deterioration of the image quality caused by the stray light by being close to the emission position. Also, the driven member is moved in a plane parallel to the screen while the driven member is kept stretched by the driving unit or the elastic holding unit, so that the optical engine uses a laser oscillator as a light source. In addition, it is easy to suppress the occurrence of scintillation and to suppress the deterioration in image quality due to the bending of the thin driven member. Therefore, according to the present invention, it is possible to obtain a projection type image display apparatus that can easily achieve weight reduction and high image quality.

  Embodiments of a projection type image display apparatus according to the present invention will be described below in detail with reference to the drawings. The present invention is not limited to the embodiments described below.

Embodiment 1.
FIG. 1 is a partially cutaway sectional view schematically showing an example of the projection type image display apparatus of the present invention. FIG. 2-1 schematically shows the internal structure of the projection type image display apparatus shown in FIG. FIG. 2-2 is a cross-sectional view schematically showing an example of the state of the Fresnel lens when the projection type image display apparatus shown in FIG. A projection type image display device 80 shown in FIGS. 1 and 2-1 includes an optical engine 10, a screen 20, an elastic holding unit 30A, a drive unit 60, and a casing 70 that accommodates them. In accordance with the image signal, light emitted from the optical engine 10 is projected onto the screen 20 from the back side of the screen 20 to display an image.

As shown in FIG. 1, the optical engine 10 includes a laser module 11 including a laser oscillator, a relay lens 13 that controls the optical path of the laser beam LB emitted from the laser module 11, and a laser beam according to an image signal. It includes a spatial modulation element 15 that spatially modulates LB to form image light IL, and a projection optical system 17 that enlarges and projects the image light IL formed by the spatial modulation element 15 onto a screen 20. As the spatial modulation element 15, for example, a micromirror device that has a large number of aligned micromirrors and spatially modulates the laser beam LB by adjusting the angle of each micromirror according to an image signal is used. It is done. In FIG. 1, for convenience, the projection optical system 17 is represented by one lens. Also, the alternate long and short dash lines OA ₁ and OA ₂ in the figure represent the optical axes.

  The screen 20 is disposed on the projection optical system 17 side and the Fresnel lens 23 on which the image light IL from the optical engine 10 is incident, and the light emitted from the Fresnel lens 23 is disposed on the viewer side of the Fresnel lens 23. And an incident diffusion member 25.

  The Fresnel lens 23 is a thin member made of, for example, acrylic resin and having a width of 1.6 m, a height of 1.0 m, and a maximum thickness of about 0.4 mm, and has flexibility. The Fresnel lens 23 is held by an elastic holding unit 30A described later, and emits the image light IL incident from the optical engine 10 as substantially parallel light. In order to move the Fresnel lens 23 in a plane parallel to the screen 20, a clearance C having a predetermined width is provided between the Fresnel lens 23 and the housing 70.

  The diffusing member 25 is composed of, for example, a lenticular lens sheet, a scattering layer, a light shielding layer, and the like, and is fixed to a groove-like diffusing member holding portion 73 formed in the housing 70, and becomes substantially parallel light by the Fresnel lens 23. The incident image light IL is emitted as diffused light. The image light IL emitted from the optical engine 10 is finally diffused by the diffusing member 25 and emitted, so that the viewing angle of the image on the screen 20 is expanded.

  As shown in FIG. 1 or FIG. 2A, the elastic holding unit 30A includes an upper rail 31a which is an upper support member to which the upper side of the Fresnel lens 23 is fixed, and a lower support member to which the lower side of the Fresnel lens 23 is fixed. A lower rail 31b, two elastic support members 35a and 35b for attaching the upper rail 31a to the housing 70, and two elastic support members 35c and 35d for attaching the lower rail 31b to the housing 70. Each of the upper rail 31a and the lower rail 31b has sufficient mechanical strength that does not deform even when the Fresnel lens 23 is moved in a plane parallel to the screen 20.

  Fixing portions 33 for fixing the elastic support members 35a and 35b are provided at both longitudinal ends of the upper rail 31a. One fixing portion 33 has one end of the elastic support member 35a and the other fixing portion 33. One end of each elastic support member 35b is fixed to each other. Similarly, fixing portions 33 for fixing the elastic support members 35c and 35d are provided at both longitudinal ends of the lower rail 31b. One fixing portion 33 has one end of the elastic supporting member 35c and the other fixing portion. One end of the elastic support member 35d is fixed to 33. The ends of the individual elastic support members 35a to 35d on the side of the housing 70 are fixed to fixing portions 75 provided on the inner surface of the housing 70 corresponding to one elastic support member one by one. The elastic support members 35a to 35d are symmetrical with respect to the left and right axes (hereinafter referred to as “X axis”) and the vertical axis (hereinafter referred to as “Y axis”) of the screen 20, and the X axis direction and the Y axis. It is installed so that the spring constant becomes the same value in any direction.

  Thus, the elastic holding unit 30A in which the upper rail 31a, the lower rail 31b, and the elastic support members 35a to 35d are arranged holds the Fresnel lens 23 so as to be movable in a plane parallel to the screen 20. However, since the Fresnel lens 23 is prevented from being deformed in the X-axis (see FIG. 2) direction by the upper beam 31a and the lower beam 31b, it can be deformed to some extent in the Y-axis (see FIG. 2) direction. When the projection-type image display device 80 is not operating (when no image is being projected. Hereinafter, abbreviated as “when the display device is not operating”), for example, bending occurs as shown in FIG. Sometimes. This bending (warping) occurs due to the influence of temperature and humidity, or due to a shape error during molding.

  In the illustrated example, the Fresnel lens 23 is bent so that the central portion of the Fresnel lens 23 swells in the direction of the front-rear axis (hereinafter referred to as “Z-axis”) of the screen 20 (see FIG. 1). Such bending of the Fresnel lens 23 occurs when the projection-type image display device 80 operates (when an image is projected. Hereinafter, abbreviated as “when the display device operates”). 1) to be eliminated by the driving force applied to the elastic holding unit 30A. In FIG. 2B, the Y axis and the Z axis are also shown.

  The drive unit 60 moves the Fresnel lens 23 in a plane parallel to the screen 20 (see FIG. 1) while eliminating the above-described bending and maintaining the Fresnel lens 23 in a stretched state during the operation of the display device. Therefore, as shown in FIG. 2A, the drive unit 60 is connected to a pair of drive sources 40A and 40B that apply a drive force to the elastic holding unit 30A during the operation of the display device, and to these drive sources 40A and 40B. And a control circuit unit 55 for driving each of the drive sources 40A and 40B with a predetermined drive waveform.

  As each of the drive sources 40A and 40B, for example, a linear actuator configured by a linear motor or the like is used. By using the non-contact drive type linear actuator, it becomes easy to substantially eliminate the operation sound when the Fresnel lens 23 held by the elastic holding unit 30A is moved in a plane parallel to the screen 20.

  The control circuit unit 55 supplies predetermined drive signals to the drive sources 40A and 40B. Each of the drive sources 40A and 40B, when supplied with the drive signal from the control circuit unit 55, applies a drive force in a direction crossing each other to the elastic holding unit 30A to keep the Fresnel lens 23 stretched. A downward resultant force in the Y-axis (see FIG. 2) direction is applied. Further, the Fresnel lens 23 is moved in a plane parallel to the screen 20 by superimposing a predetermined driving force on the driving force.

  The movement of the Fresnel lens 23 in a plane parallel to the screen 20 may be a motion in which a temporary stop state appears intermittently, such as a reciprocating motion along the X axis or the Y axis of the screen 20, From the viewpoint of suppressing the occurrence of scintillation, it is preferably a continuous motion performed without interruption, such as an elliptical motion (including a circular motion). When the drive unit 60 is configured such that the line of action of the drive force by the drive sources 40A and 40B passes through the center of gravity O of the Fresnel lens 23 held by the elastic holding unit 30A, the Fresnel lens 23 is placed in a plane parallel to the screen 20. When continuously moving without interruption, it becomes easy to eliminate the influence of the moment.

  The “centroid of the Fresnel lens held by the elastic holding unit” means the center of gravity of the structure including the elastic holding unit and the Fresnel lens held by the elastic holding unit. In the present specification, the center of gravity is hereinafter simply referred to as “the center of gravity of the Fresnel lens”.

  In the projection type image display device 80 configured as described above, since the Fresnel lens 23 is a thin member, it is easy to reduce the weight, and the emission position of the stray light is brought close to the emission position of the real image so that the image quality caused by the stray light can be obtained. It is easy to suppress the decline. Further, during the operation of the display device, the drive unit 60 applies a driving force to the elastic holding unit 30A to move the Fresnel lens 23 in a plane parallel to the screen 20 while keeping the Fresnel lens 23 stretched. It is easy to suppress the occurrence of scintillation, and it is easy to suppress deterioration in image quality caused by the bending of the thin Fresnel lens 23. For these reasons, the projection-type image display device 80 can easily reduce the weight and the image quality.

  The projection-type image display device 80 having the above-described technical effect is characterized in that the Fresnel lens 23 is held by the elastic holding unit 30A in a state where the Fresnel lens 23 can be deformed in the Y-axis direction, and the Fresnel by the drive unit 60. It has a feature in the lens moving method. Since the holding mode of the Fresnel lens 23 by the elastic holding unit 30A has already been described, the moving method of the Fresnel lens 23 by the drive unit 60 will be described in detail below with reference to FIGS.

  FIG. 3 is an exploded perspective view schematically showing an example of a drive source used in the drive unit. A drive source 40 </ b> A shown in the figure is a linear actuator composed of a linear motor including a stator 45 and a mover 50.

  The stator 45 is made of resin that holds two yoke plates 41a and 41b, two magnets 42a and 42b fixed to one yoke plate 41a, and each yoke plate 41a and 41b at a predetermined interval. And a yoke holder 43. The individual yoke plates 41a and 41b have a flat plate shape, and the individual magnets 42a and 42b also have a flat plate shape. The yoke plate 41a is mounted on the yoke holder 43 with the magnets 42a and 42b facing inside, and the yoke plate 41b is mounted on the yoke holder 43 in a state of being separated from the magnets 42a and 42b and facing the yoke plate 41a. Mounting holes 44a and 44b are formed in the yoke holder 43. The stator 45 is fixed to the housing 70 (see FIG. 2) by fixing parts (not shown) such as screws inserted into the mounting holes 44a and 44b.

  On the other hand, the mover 50 includes a coil 46, a resin coil holder 47 molded integrally with the coil 46, and power supply terminals 48 a and 48 b provided on the coil holder 47 while being connected to the coil 46. have. Mounting holes 49a and 49b are formed in the coil holder 47. The mover 50 is attached to the stator 45 with the coil 46 interposed between the two yoke plates 41a41b of the stator 45, and is a fixing component (such as a screw) inserted into the mounting holes 49a and 49b ( It is fixed to the Fresnel frame 31 (see FIG. 2) by a not shown.

  When the mover 50 is mounted on the stator 45 and the coil 46 is energized, a force in a predetermined direction is generated according to Fleming's left-hand rule. By controlling the direction and strength of the current flowing through the coil 46, a tensile force or a pushing force (hereinafter referred to as “driving force”) having a predetermined direction and strength from the driving source 40A to the elastic holding unit 30A (lower rail 31b). Yes). Even when the coil 46 is energized, the mover 50 can slide in a direction perpendicular to the magnetic flux in the magnetic circuit of the stator 45 and perpendicular to the direction in which the driving force is generated.

  Although not shown, the drive source 40B (see FIG. 2) can also have the same configuration as the drive source 40A described above. When the drive source 40B has the same configuration as the drive source 40A, for the same reason as described above, by controlling the direction and strength of the current flowing through the coil, the drive source 40B is given a predetermined force from the drive source 40B to the elastic holding unit 30A. The driving force of the direction and strength can be applied.

  During the operation of the display device, as described above, the driving force for keeping the Fresnel lens 23 stretched (hereinafter referred to as “initial driving force”) and the Fresnel lens 23 are superposed on the initial driving force on the screen 20. And a driving force that moves in a plane parallel to the driving force 40A, 40B is applied to the elastic holding unit 30A. The driving force for moving the Fresnel lens 23 in a plane parallel to the screen 20 is superimposed on the initial driving force at the same time as the initial driving force, or after the predetermined time has elapsed since the initial driving force is applied. It is superimposed on the force and applied to the elastic holding unit 30A.

  FIG. 4 is a schematic diagram showing an example of the drive waveform of each of the pair of drive sources. The drive is preferable when the drive sources are arranged so that the directions of the drive force with respect to the elastic holding unit form an angle of 90 degrees with each other. An example of a waveform is shown. The horizontal axis is time, and the vertical axis is the driving force applied to the elastic holding unit 30A (see FIG. 2) from the individual driving sources 40A and 40B. In this driving force, the tensile force applied to the elastic holding unit 30A from the driving sources 40A and 40B is a positive value, and the pressing force is a negative value.

In the illustrated example, the driving source 40A at time T _1, 40B starts operating each from time T ₁ to time T ₂ are, each of which imparts the initial driving force Fi to the elastic retaining unit 30A. Thereafter, each of the drive waveform DW ₁ of the drive source 40A and the drive waveform DW ₂ of the drive source 40B becomes a sine waveform in which a predetermined drive force is superimposed on the initial drive force Fi. The drive waveforms DW ₁ and DW ₂ have the same amplitude and wavelength, but the drive waveform DW ₁ and the drive waveform DW ₂ have a phase difference Δφ of 90 degrees. The magnitude of the driving force superimposed on the initial driving force Fi varies between the driving force value F ₀ shown in FIG. 4 and its negative value −F ₀ . By this driving force is applied to the elastic retaining unit 30A, time T _2, since the Fresnel lens 23 is continuous motion in a plane parallel to the screen 20, it performs circular motion specifically.

  FIG. 5 is a schematic diagram showing a Fresnel lens when an initial driving force is applied from each driving source. As shown in the figure, by applying an initial driving force Fi to the Fresnel lens 23 from each of the driving sources 40A and 40B, a resultant force Fr downward in the Y-axis direction acts on the center of gravity O of the Fresnel lens 23, and the Fresnel lens 23 It becomes a stretched state. The magnitude of the initial driving force Fi is set so that the Fresnel lens 23 can be stretched, the elastic force of the elastic support members 35a to 35d constituting the elastic holding unit 30A, and elastic holding from the driving source 40A. The angle θ formed by the direction of the driving force applied to the unit 30A and the direction of the driving force applied from the driving source 40B to the elastic holding unit 30A and the flexibility of the Fresnel lens 23 are selected as appropriate. The

Note that the above-mentioned “angle θ” is obtained by assuming each coordinate line in the first quadrant when assuming a coordinate system in which the direction of the tensile force by each drive source 40a, 40B is a positive direction and the line of action of each drive force is an axis. Means an angle formed by each other, and the angle θ corresponds to the phase angle of each of the drive waveforms DW ₁ and DW ₂ shown in FIG. Hereinafter, this phase angle is referred to as “phase angle θ”. In FIG. 5, an alternate long and short dash line AL ₁ indicates a line of drive force applied from the drive source 40A to the elastic holding unit 30A, and an alternate long and short dash line AL ₂ indicates a drive force applied from the drive source 40B to the elastic holding unit 30A. The action line is shown.

Figure time T _2, since as shown in 4, a driving force Fa applied from the driving source 40A to the elastic holding unit 30A (theta) is a function of the phase angle theta, the driving force Fa (theta) is the following formula (i)
Fa (θ) = Fi + F ₀ · sin (θ + 90 °) = Fi + F ₀ · cos θ (i)
It is represented by Similarly, the driving force Fb (θ) applied from the driving source 40B to the elastic holding unit 30A is also a function of the phase angle θ, and the driving force Fb (θ) is expressed by the following equation (ii)
Fb (θ) = Fi + F ₀ · sinθ (ii)
It is represented by The resultant force of these driving forces Fa (θ) and Fb (θ) actually acts on the center of gravity O of the Fresnel lens 23 (see FIG. 2 or FIG. 4).

Note that “F ₀ ” in the above formulas (i) and (ii) indicates a force that serves as a reference for the driving forces Fa (θ) and Fb (θ), and the magnitude thereof is F in FIG. Same as ₀ . The magnitude of the force F ₀ depends on the elastic force of each of the elastic support members 35a to 35d (see FIG. 2) constituting the elastic holding unit 30A, or the surface of the Fresnel lens 23 parallel to the screen 20 (see FIG. 1). Is selected in advance in consideration of the size of the range of movement of the center of gravity O that is allowed to move within, the magnitude of the correction force required to correct the deflection of the Fresnel lens 23, and the like.

FIG. 6 is a conceptual diagram showing an example of the relationship between the phase angle after time T ₂ and the force acting on the center of gravity of the Fresnel lens when each drive source is driven with the drive movement waveform shown in FIG. In the figure, when the drive source 40A is driven by the X axis and the Y axis on the screen 20 (see FIG. 1) and the drive waveform DW ₁ shown in FIG. 4, the Fresnel lens 23 is passed through the elastic holding unit 30A. Drive applied to the Fresnel lens 23 via the elastic holding unit 30A when the drive source 40B is driven by the X ′ axis corresponding to the line of action of the applied drive force and the drive waveform DW ₂ shown in FIG. The Y ′ axis corresponding to the force action line is shown.

In FIG. 6, the position of the center of gravity O (see FIG. 2) of the Fresnel lens 23 when the display device is not operating is a point P ₀ , and the reference position of the center of gravity O when an image is displayed is a point P _0. Each is indicated by ₁ . The distance between the point P ₀ and the point P ₁ corresponds to the amount of displacement of the center of gravity O when each of the driving sources 40A and 40B applies only the initial driving force Fi to the elastic holding unit 30A. In the illustrated example, each of the X axis, the Y axis, the X ′ axis, and the Y ′ axis passes through the point P ₁ . Further, the X ′ axis and the Y ′ axis are orthogonal to each other, and the X axis and the Y axis are also orthogonal to each other. Each of the X′-axis and the Y′-axis has the direction of the tensile force by the drive sources 40A and 40B as the positive direction, and the azimuth angle of the X′-axis and the azimuth angle of the X-axis are shifted from each other by 135 degrees.

If the isotropic in the plane parallel to the screen 20 (the elastic force due to the elastic holding members 35a to 35d) above the center of gravity O is elastic force of the elastic holding unit 30A under a state of being displaced to point P _1, When each of the drive sources 40A and 40B is driven by the drive waveforms DW ₁ and DW ₂ shown in FIG. 4 and the drive forces Fa (θ) and Fb (θ) are applied to the elastic holding unit 30A after time T _2. As shown in FIG. 6, the resultant force Fr (θ) that forms an angle θ with the X ′ axis acts on the center of gravity O of the Fresnel lens 23. The angle θ at this time corresponds to the phase angle θ of the drive waveforms DW ₁ and DW ₂ shown in FIG. 4 as described above. Further, the magnitude of the resultant force Fr (θ) becomes the same value as F ₀ shown in FIG. 4 if the initial driving force Fi is ignored. The magnitudes of the driving forces Fa (θ) and Fb (θ) are selected so that the Fresnel lens 23 is always kept in tension regardless of the phase angle θ.

The resultant force Fr (0 °) when the phase angle θ of the drive waveforms DW ₁ and DW ₂ of the drive sources 40A and 40B is (0 + 360 · n) degrees (n represents an integer) is the center of gravity O at the point P becomes the direction and magnitude displaced from ₁ to a point P ₂ on the X 'axis, (45 + 360 · n) of the resultant force Fr when the (45 °), the point P ₃ on the Y-axis center of gravity O is from the point P ₁ The resultant force Fr (135 °) at (135 + 360 · n) degrees is the direction and magnitude at which the center of gravity O is displaced from the point P ₁ to the point P ₄ on the X axis. Further, the resultant force Fr (225 °) when the phase angle θ is (225 + 360 · n) degrees has a direction and a magnitude at which the center of gravity O is displaced from the point P ₁ to the point P ₅ on the Y axis, and (315 + 360 · n). ) Degrees, the resultant force Fr (315 °) is the direction and magnitude of displacement of the center of gravity O from the point P ₁ to the point P ₆ on the X axis.

When elastic force of the elastic holding unit 30A in a state where the center of gravity O of the Fresnel lens 23 is displaced to the point P ₁ is isotropic in the plane parallel to the screen 20, the above-mentioned resultant force Fr (theta) is any direction If the driving sources 40A and 40B are driven by the driving waveforms DW ₁ and DW ₂ as a result of the elastic force in the direction opposite to the resultant force Fr (θ) acting by the elastic supporting members 35a to 35d, The center of gravity O of the Fresnel lens 23 moves substantially on the circumference of the circle Cr having the radius F ₀ . The Fresnel lens 23 performs a circular motion in a plane parallel to the screen 20. At this time, the Fresnel lens 23 is not substantially affected by the moment.

  Each of FIG. 7 to FIG. 9 is a schematic diagram illustrating an example of the relationship between the force acting on the Fresnel lens and the position of the Fresnel lens in the projection type image display apparatus. Since each member shown in these figures has already been described with reference to FIG. 2, the same reference numerals as those used in FIG.

As shown in FIG. 7, at time T ₃ in FIG. 4, since the phase angle θ of the drive waveforms DW ₁ and DW ₂ is 45 degrees, the downward resultant force Fr (45 °) is applied to the screen 20 (FIG. 7). It occurs along the Y-axis of the first reference), as a result, the center of gravity O of the Fresnel lens 23 is moved beneath viewed from the initial position direction, i.e. in the direction of the point P ₃ shown in FIG. Also, at time T ₄ in FIG. 4, the phase angle θ of the drive waveforms DW ₁ and DW ₂ described above is 135 degrees, so that as shown in FIG. 8, the Fresnel lens 23 faces rightward when viewed from the back. A resultant force Fr (135 °) is generated along the X axis of the screen 20. As a result, the center of gravity O of the Fresnel lens 23 is in the right direction (right direction when viewed from the back) as viewed from the initial position, that is, the point P shown in FIG. Move in the direction of ₄ . At time T ₅ in FIG. 4, the phase angle θ of the drive waveforms DW ₁ and DW ₂ is 225 degrees, so that the upward resultant force Fr (225 °) is applied to the screen 20 as shown in FIG. This occurs along the Y axis, and as a result, the center of gravity O of the Fresnel lens 23 moves directly upward, that is, in the direction of the point P ₅ shown in FIG.

  As described above, as a result of the center of gravity O of the Fresnel lens 23 moving in a predetermined direction according to the phase angle θ, the Fresnel lens 23 moves continuously (circular motion) in a plane parallel to the screen 20 (see FIG. 1). To do. Since the driving forces Fa (θ) and Fb (θ) are applied in the direction passing through the center of gravity O, the elastic supporting members 35a to 35d in the elastic holding unit 30A (see FIG. 2) holding the Fresnel lens 23 are provided. By setting the elastic force (spring constant) to the same value in both the X-axis direction and the Y-axis direction, it becomes easy to eliminate the influence of the moment.

  In the projection type image display device 80 (see FIG. 1 or FIG. 2) having the above-described configuration, as described above, the Fresnel lens 23 is a thin member, so that it is easy to reduce the weight and image quality due to stray light. It is easy to suppress degradation of image quality due to degradation or scintillation, and degradation of image quality due to flexing of the Fresnel lens 23. For these reasons, the projection-type image display device 80 can easily reduce the weight and the image quality.

Embodiment 2. FIG.
The driven member that is moved in a plane parallel to the screen during the operation of the projection type image display device may be kept in a tensioned state only during the operation of the display device, or may be kept in a constantly tensioned state. In maintaining the driven member in a tensioned state, for example, the elastic force of each elastic holding member constituting the elastic holding unit can be used.

  FIG. 10-1 is a cross-sectional view schematically showing an example of a projection type image display apparatus in which a Fresnel lens is always kept in tension, and FIG. 10-2 is a projection type image display shown in FIG. It is sectional drawing which shows the Fresnel lens in an apparatus roughly.

  The projection type image display device 85 shown in FIG. 10A includes the projection type image shown in FIGS. 1 and 2-1, except that the projection type image display device 85 includes an elastic holding unit 30B that keeps the Fresnel lens 23 always stretched. The display device 80 has the same structure. Among the constituent members shown in FIG. 10A, the remaining constituent members excluding the elastic holding unit 30B are denoted by the same reference numerals as those used in FIG. Further, reference symbol “O” in the drawing indicates the center of gravity of the Fresnel lens 23 held by the elastic holding unit 30B.

  The elastic holding unit 30B has the same structure as the elastic holding unit 30A shown in FIG. 2A, but the elastic support members 35a and 35b are always elastic in the Y-axis direction upward with respect to the upper rail 31a. The elastic support members 35a to 35d are arranged such that each of the elastic support members 35c and 35d always applies a downward elastic force in the Y-axis direction to the lower rail 31b. Different from the elastic holding unit 30A shown in 2-1. As a result of the elastic holding unit 30B holding the Fresnel lens 23 in this way, as shown in FIG. 10-2, the Fresnel lens 23 is always kept in a tensioned state.

  FIG. 11 is a schematic diagram illustrating an example of the drive waveforms of each of the pair of drive sources in the projection type image display apparatus illustrated in FIG. 10A. The directions of the drive force with respect to the elastic holding unit form an angle of 90 degrees with each other. It is an example of a drive waveform suitable when each drive source is arranged as described above. The horizontal axis is time, and the vertical axis is the driving force applied to the elastic holding unit 30B (see FIG. 10-1) from the individual driving sources 40A and 40B. In this driving force, the tensile force applied from the driving sources 40A and 40B to the elastic holding unit 30B is a positive value, and the pressing force is a negative value.

In the illustrated example, to start the driving source 40A, 40B are operated at time T _11, the driving waveforms DW ₁₂ of the drive waveforms DW ₁₁ and the driving source 40B at time T ₁₁ after the drive source 40A, respectively, the same amplitude each other And a sinusoidal waveform having a wavelength. Further, the drive waveform DW ₁₁ and the drive waveform DW ₁₂ have a phase difference Δφ of 90 degrees. The magnitude of the driving force by each driving source 40A, 40B varies between the driving force value F ₀ shown in FIG. 11 and its negative value −F ₀ . By this driving force is applied to the elastic retaining unit 30B, the time T ₁₁ later, the Fresnel lens 23 is continuous motion in a plane parallel to the screen, performing circular motion specifically.

At this time, the driving force Fa (θ) applied from the driving source 40A to the elastic holding unit 30B is a function of the phase angle θ of the driving waveforms DW ₁₁ and DW ₁₂ , and the following equation (iii)
Fa (θ) = F ₀ · sin (θ + 90 °) = F ₀ · cos θ (iii)
It is represented by Similarly, the driving force Fb (θ) applied from the driving source 40B to the elastic holding unit 30B is also a function of the phase angle θ of the driving waveforms DW ₁₁ and DW ₁₂ , and the following equation (iv)
Fb (θ) = F ₀ · sinθ (iv)
It is represented by The resultant force of these driving forces Fa (θ) and Fb (θ) actually acts on the center of gravity O (see FIG. 10-1) of the Fresnel lens 23.

Note that “F ₀ ” in the above formulas (iii) and (iv) indicates a force that serves as a reference for the driving forces Fa (θ) and Fb (θ), and the magnitude thereof is F in FIG. Same as ₀ . The magnitude of the force F ₀ depends on the elastic force of each of the elastic support members 35a to 35d (see FIG. 2) constituting the elastic holding unit 30A, or the surface of the Fresnel lens 23 parallel to the screen 20 (see FIG. 1). Is selected in advance in consideration of the size of the range of movement of the center of gravity O that is allowed to move within, the magnitude of the correction force required to correct the deflection of the Fresnel lens 23, and the like.

FIG. 12 is a conceptual diagram showing an example of the relationship between the phase angle and the force acting on the center of gravity of the Fresnel lens when each drive source is driven with the drive movement waveform shown in FIG. As apparent from the comparison with FIG. 6, the above relationship shown in FIG. 12 indicates that the force acting on the phase angle and the center of gravity of the Fresnel lens in the drive waveform of each drive source after time T ₂ described in the first embodiment. This is the same as the relationship with (the resultant force Fr (θ)). The magnitudes of the driving forces Fa (θ) and Fb (θ) are selected so that the Fresnel lens 23 is always kept in tension regardless of the phase angle θ. Of course, the Fresnel lens 23 is always kept in tension even when the display device is not in operation.

The resultant force Fr (0 °) when the phase angle θ of the drive waveforms DW ₁₁ and DW ₁₂ of the drive sources 40A and 40B is (0 + 360 · n) degrees (n represents an integer) is the center of gravity O from the point P ₁ The resultant force Fr (45 °) when displaced to the point P ₂ on the X ′ axis and (45 + 360 · n) degrees is the center of gravity O displaced from the point P ₁ to the point P ₃ on the Y axis. The resultant force Fr (135 °) at (135 + 360 · n) degrees is the direction and magnitude at which the center of gravity O is displaced from the point P ₁ to the point P ₄ on the X axis. Then, the resultant force Fr (225 °) when the phase angle θ is (225 + 360 · n) degrees has a direction and a magnitude at which the center of gravity O is displaced from the point P ₁ to the point P ₅ on the Y axis, and is (315 + 360 · n). ) Degrees, the resultant force Fr (315 °) is the direction and magnitude of displacement of the center of gravity O from the point P ₁ to the point P ₆ on the X axis.

When the elastic force of the elastic holding unit 30B is isotropic in a plane parallel to the screen, the resultant force Fr (θ) is in the opposite direction to the resultant force Fr (θ) regardless of the direction. as a result of forces exerted by the elastic supporting members 35a to 35d, the driving source 40A, when driving the 40B at driving waveforms DW _11, DW _12, the center of gravity O of the Fresnel lens 23 is substantially of a circle Cr with a radius F ₀ It will move on the circumference. The Fresnel lens 23 performs a circular motion in a plane parallel to the screen 20.

  Each of FIGS. 13 to 15 is a schematic diagram illustrating an example of the relationship between the force acting on the Fresnel lens and the position of the Fresnel lens in the projection type image display apparatus. Since each member shown in these figures has already been described with reference to FIG. 10A, the same reference numerals as those used in FIG. .

As shown in FIG. 13, since the phase angle θ of the drive waveforms DW ₁₁ and DW ₁₂ is 45 degrees at time T ₁₂ in FIG. 11, the downward resultant force Fr (45 °) is the Y axis of the screen. As a result, the center of gravity O of the Fresnel lens 23 moves in the downward direction from the initial position, that is, in the direction of the point P ₃ shown in FIG. Further, since the phase angle of the above-described driving waveforms DW _11, DW ₁₂ theta is 135 degrees at time T ₁₃ in FIG. 11, as shown in FIG. 14, the right when the Fresnel lens 23 and the back surface view A resultant force Fr (135 °) is generated along the X axis of the screen. As a result, the center of gravity O of the Fresnel lens 23 is in the right direction (right direction when viewed from the back) as viewed from the initial position, that is, the point P ₄ shown in FIG. Move in the direction of. Then, since the phase angle θ of the above-described driving waveforms DW _11, DW ₁₂ is 225 degrees at time T ₁₄ in FIG. 11, an upward force Fr (225 °) as shown in FIG. 15 is a screen Y As a result, the center of gravity O of the Fresnel lens 23 moves in the directly upward direction from the initial position, that is, in the direction of the point P ₅ shown in FIG.

  As described above, as a result of the center of gravity O of the Fresnel lens 23 moving in a predetermined direction according to the phase angle θ, the Fresnel lens 23 continuously moves in a plane parallel to the screen. At this time, since each driving force Fa (θ), Fb (θ) is applied in a direction passing through the center of gravity O, each elastic support in the elastic holding unit 30B (see FIG. 10-1) holding the Fresnel lens 23. By setting the elastic force (spring constant) of the members 35a to 35d to the same value in both the X-axis direction and the Y-axis direction, it becomes easy to eliminate the influence of the moment.

  In the projection type image display apparatus 85 (see FIG. 10-1) having the configuration described above, the same reason as in the projection type image display apparatus 80 (see FIGS. 1 and 2-1) described in the first embodiment. Therefore, it is easy to reduce the weight, and it is also easy to suppress the deterioration of the image quality due to stray light, the deterioration of the image quality due to scintillation, and the deterioration of the image quality due to the flexure of the Fresnel lens 23. It is easy to plan.

  The projection image display apparatus of the present invention has been described with reference to the embodiment. However, as described above, the present invention is not limited to the above-described embodiment. For example, the driven member to be moved in a plane parallel to the screen by the driving unit may be the diffusion member 25 (see FIG. 1) instead of the Fresnel lens 23.

  In addition, the pair of drive sources 40A and 40B shown in the embodiment can be arranged so that the directions of the drive force form a desired angle of 180 degrees or less, and the angles are 90 described in the embodiment. It is not limited to degrees. Here, when the directions of the driving forces by the respective driving sources are not parallel to each other, the “angle formed by the directions of the driving forces by the respective driving sources” means that the direction of the tensile force by each driving source is a positive direction. When the coordinate system which makes the action line of each driving force an axis line is assumed, it means the angle which each axis line makes in the first quadrant.

If the above angle is α degrees, the drive waveforms of the drive sources are sine waveforms having the same amplitude and wavelength, and the phase difference Δφ between the drive waveform of one drive source and the drive waveform of the other drive source is By setting it to (180−α) degrees, it becomes easy to continuously move the driven member in a plane parallel to the screen. At this time, the driving force Fa (θ) applied from one drive source to the elastic holding unit is a function of the phase angle θ, and the following equation (v) is applied when the initial driving force Fi is applied.
Fa (θ) = Fi + F ₀ · sin (θ + 90) (v)
When the initial driving force Fi is not applied, the following formula (vi)
Fa (θ) = F ₀ · sin (θ + 90) (vi)
It is represented by

Similarly, the driving force Fb (θ) applied to the elastic holding unit from the other driving source is also a function of the phase angle θ, and when the initial driving force Fi is applied, the following formula (vii)
Fb (θ) = Fi + F ₀ · sin (θ−90 + α) (vii)
When the initial driving force Fi is not applied, the following formula (viii)
Fb (θ) = F ₀ · sin (θ−90 + α) (viii)
expressed.

  The driving forces Fa (θ) and Fb (θ) represented by the expressions (v) to (viii) pass through the center of gravity of the driven member (the center of gravity of the structure including the elastic holding unit and the driven member). If the drive source is arranged, it becomes easy to eliminate the influence of the moment. And when it arrange | positions so that the direction of the driving force by a pair of drive source 40A, 40B may make the desired angle of less than 90 degree | times, since it is easy to narrow the space | interval of the drive source 40A and the drive source 40B, It is also easy to realize a slim design with a narrow width in front view of the lower part of the apparatus.

  The movement form of the driven member during the operation of the display device is not limited to the circular motion or the elliptical motion, and is, for example, a reciprocating motion along the X-axis or the Y-axis (for example, see FIG. 2-1) of the screen. May be. However, from the viewpoint of suppressing the occurrence of scintillation, it is preferable to cause the driven member to perform a motion whose speed is greater than 0 even when the motion direction changes, such as a circular motion. The structure, the total number, and the arrangement of the driving source can be changed as appropriate according to the moving form of the driven member when performing image display.

  When the driven member is kept stretched when a driving force is applied from the driving source, the elastic holding unit substantially deforms the driven member in either the X-axis direction or the Y-axis direction. A pair of left and right support members can be used as long as they can be held in a deformable manner and can be deformed in the other direction, instead of the upper rail 31a and the lower rail 31b (see FIG. 2-1) described in the first embodiment. Can also be used. When using the pair of left and right support members, a drive source is connected to one of the support members.

  Further, in the case where the driven member is always kept in tension regardless of whether or not the driving force is applied from the driving source, the elastic holding unit is driven from at least one of the X-axis direction and the Y-axis direction. As long as the driven member is kept in a tensioned state by applying tension to the belt, it has a pair of left and right support members instead of the upper beam 31a and the lower beam 31b described in the first embodiment. May be. In addition, support members can be disposed on each of the four sides of the driven member. The projection type image display apparatus of the present invention can be variously modified, modified, combined, etc. in addition to those described above.

  The present invention can be applied to a projection image display device for home use or business use, and is particularly suitable for a large screen projection image display device.

1 is a partially cutaway sectional view schematically showing an example of a projection type image display apparatus of the present invention. It is sectional drawing which shows roughly the internal structure of the projection type image display apparatus shown in FIG. It is sectional drawing which shows roughly an example of the state of the Fresnel lens at the time of the non-operation of the projection type image display apparatus shown to FIGS. It is a disassembled perspective view which shows roughly an example of the drive source used with the drive unit of the projection type image display apparatus shown in FIG. It is the schematic which shows an example of the drive waveform of each of a pair of drive source used with the drive unit of the projection type image display apparatus shown in FIG. FIG. 2 is a schematic diagram showing a Fresnel lens when an initial driving force is applied from each driving source in the projection type image display apparatus shown in FIG. 1. FIG. 5 is a conceptual diagram showing an example of a relationship between a phase angle and a force acting on the center of gravity of a Fresnel lens when each drive source is driven with the drive movement waveform shown in FIG. 4. FIG. 2 is a schematic diagram illustrating an example of a relationship between a force acting on a Fresnel lens and a position of the Fresnel lens in the projection type image display apparatus illustrated in FIG. 1. FIG. 6 is a schematic diagram showing another example of the relationship between the force acting on the Fresnel lens and the position of the Fresnel lens in the projection type image display apparatus shown in FIG. 1. FIG. 6 is a schematic diagram showing still another example of the relationship between the force acting on the Fresnel lens and the position of the Fresnel lens in the projection type image display apparatus shown in FIG. 1. It is sectional drawing which shows roughly an example of what kept the state which always stretched the Fresnel lens among the projection type image display apparatuses of this invention. It is sectional drawing which shows schematically the Fresnel lens in the projection type image display apparatus shown to FIGS. It is the schematic which shows an example of the drive waveform of each of a pair of drive source in the projection type image display apparatus shown to FIGS. It is a conceptual diagram which shows an example of the relationship between the phase angle when driving each drive source with the drive dynamic waveform shown in FIG. 11, and the force which acts on the gravity center of a Fresnel lens. It is the schematic which shows the other example of the relationship between the force which acts on a Fresnel lens, and the position of a Fresnel lens in the projection type image display apparatus shown to FIGS. It is the schematic which shows the other example of the relationship between the force which acts on a Fresnel lens, and the position of a Fresnel lens in the projection type image display apparatus shown to FIGS. It is the schematic which shows the other example of the relationship between the force which acts on a Fresnel lens, and the position of a Fresnel lens in the projection type image display apparatus shown to FIGS.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Optical engine 20 Screen 23 Fresnel lens 25 Diffusion member 30A, 30B Elastic holding unit 31a Upper beam 31b which is an upper support member Lower beam 35a-35d which is a lower support member Elastic support members 40A, 40B Drive source 55 Control circuit unit 60 Drive unit 70 Case 80, 85 Projection-type image display device O Center of gravity of Fresnel lens Fa (θ) Fb (θ) Driving force applied from the driving source to the elastic holding unit Fr (θ) Combined force X Left and right axes of screen Y screen Vertical axis of the screen Z Front / back axis of the screen

Claims (3)

An optical engine that emits light in response to an image signal;
A screen that makes light incident from the optical engine light substantially parallel by a Fresnel lens and then emits it as diffused light by a diffusion member;
An elastic holding unit that holds the driven member movably in a plane parallel to the screen using the Fresnel lens or the diffusion member as a driven member;
A driving unit that applies a driving force to the elastic holding unit to move the driven member in a plane parallel to the screen;
A housing for housing the optical engine, the screen, the elastic holding unit, and the drive unit;
With
The driven member is a flexible member,
The driving unit includes an initial driving force for applying tension to the driven member, and the driven member in a plane parallel to the screen in a state where the driven member is always stretched while being superimposed on the initial driving force. A projection-type image display device, wherein a driving force for movement is applied to the elastic holding unit.   The driven member is bent without receiving the driving force when the projection-type image display device is not projecting an image, and the driving force is applied when the projection-type image display device is projecting an image. The projection image display apparatus according to claim 1, wherein the projection image display apparatus is in a tensioned state. The elastic holding unit is
An upper support member to which an upper side of the driven member is fixed;
A lower support member to which a lower side of the driven member is fixed;
Have
The drive unit is disposed below the elastic holding unit and applies a driving force to the elastic holding unit from the lower support member side.
Projection type image display apparatus according to claim 1 or 2, characterized in that.

Images