JP2017102322A - Image projection device, optical engine, and image display unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve the shift and rotation of a projection image and to suppress power consumption by reducing a driving force to a DMD (digital micro-mirror device).SOLUTION: An image projection device includes an image display element unit which includes the DMD which generates an image by using light radiated from a light source, an illumination unit which is for guiding the light radiated from the light source to the DMD, and a projection unit which projects the image generated by the DMD. The image display element unit includes a movable unit which holds the DMD, a fixed unit which is fixed to the illumination unit and supports the movable unit, an actuator which moves the movable unit, so as to relatively move the DMD with respect to the illumination unit, and a tension spring 51a and a compression spring 51b which are connected to the movable unit and the fixed unit and support the movable unit, while keeping the DMD in a predetermined position.SELECTED DRAWING: Figure 10

Description

  The present invention relates to an image projection apparatus, an optical engine, and an image display unit.

  Conventionally, in an image projection apparatus such as a projector, as a method for increasing the resolution of a projection image, a method for increasing the number of images of an image display element (DMD: Digital Micro-mirror Device) is used. A method of shifting by half a pixel in an oblique 45 degree direction is known.

  As a method of shifting the projected image by half a pixel, a method of directly shifting DMD is known. This method has an advantage that the projected image can be moved up and down, left and right (shifted), and the projected image can be rotated, in addition to the half-pixel shifting (higher resolution). Further, as a method for cooling the DMD, a method is known in which a heat sink is pressed against the DMD and is cooled using heat conduction.

  For example, Patent Document 1 discloses an image display device that displays an image with a resolution higher than the number of pixels without increasing the number of pixels of the optical modulation element. In this image display device, a method is disclosed in which an intermediate image is created by shifting pixels by moving an optical modulation element by an actuator to form a high-resolution image.

  However, in the case of the structure in which the DMD is cooled by pressing the heat sink described above, it is necessary to shift not only the DMD but also the heat sink pressed against the DMD at the same time in order to move the projection image. The heat sink is often a mass of aluminum with high thermal conductivity and is sufficiently heavy compared to DMD. Therefore, it is more susceptible to gravity than when shifting only the DMD. In addition, in the configuration in which the DMD pressed against the heat sink is shifted, it is necessary to keep the DMD and the heat sink at desired positions even when the pixels are not shifted, so that a driving force that supports the movable weight is always required. .

  In particular, when the DMD and the heat sink drive plane is perpendicular to the horizontal plane, the DMD and the heat sink are shifted against gravity, which requires a larger driving force. In the image display device of Patent Document 1, the optical modulation element is moved by the rotational movement around the axis, so that it is difficult to be affected by gravity, but the relative positional relationship between the optical modulation element and the projection optical system is fixed. Therefore, the projected image could not be rotated.

  The present invention has been made in view of the above, and can realize shift and rotation of a projected image, and also suppresses power consumption by reducing driving force required for driving an element for shifting pixels and maintaining posture. It is an object of the present invention to provide an image projection apparatus, an optical engine, and an image display unit that can be used.

  In order to solve the above-described problems and achieve the object, the present invention is an image projection apparatus, comprising: an image display unit including a light modulation element that generates an image using light emitted from a light source; An illumination optical unit for guiding light emitted from a light source to the light modulation element; and a projection unit that projects an image generated by the light modulation element, and the image display unit includes the light modulation element. A movable part to be held, a fixed part fixed to the illumination optical part and supporting the movable part, and moving the movable part to move the light modulation element relative to the illumination optical part. A drive unit; and a connection member connected to the movable unit and the fixed unit, and supporting the movable unit while maintaining the light modulation element at a predetermined position.

  According to the present invention, it is possible to realize shift and rotation of a projected image, and it is possible to suppress power consumption by reducing a driving force required for driving a DMD or maintaining a posture for pixel shifting.

FIG. 1 is an external view of an image projection apparatus according to an embodiment. FIG. 2 is a diagram showing the arrangement and configuration of the optical engine and the light source unit. FIG. 3 is a diagram illustrating a configuration example of the optical engine. FIG. 4 is a diagram illustrating a configuration example of the image display element unit. FIG. 5 is a diagram for explaining the Lorentz force generated between the voice coil and the magnet. FIG. 6 is a diagram for explaining the Lorentz force generated between the voice coil and the magnet. FIG. 7 is an exploded perspective view of the fixed unit. FIG. 8 is an exploded perspective view of the movable unit. FIG. 9 is a diagram showing the positional relationship between the plates. FIG. 10 is a diagram illustrating a state where the fixed unit and the movable unit are connected by a spring.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. 1A is a perspective view of the image projection apparatus 1 according to this embodiment, and FIG. 1B is a side view of the image projection apparatus 1. 1B shows a state in which the projection light emitted from the image projection apparatus 1 is applied to the screen (projected object) 2 on which the image is projected.

  The image projection apparatus 1 is an apparatus that generates an image based on image data input from a personal computer, a video camera, or the like, and projects and displays the image on a screen 2 or the like. A liquid crystal projector widely known as the image projection apparatus 1 has recently been improved in the resolution, the price, and the like with an increase in the resolution of the liquid crystal panel and the efficiency of the light source lamp. In addition, small and light projectors using DMD (Digital Micro-mirror Device) have become widespread, and these projectors are widely used not only in offices and schools but also at home. In particular, front-type projectors have improved portability and have been used for small meetings of several people.

  The projector that is the image projection apparatus 1 is required to be able to project a large screen image (increasing the projection screen) and to make the “projection space required outside the projector” as small as possible. In recent years, the performance of optical engines has improved, and projectors that can achieve projection sizes of 60 to 80 inches with a projection distance of 1 to 2 m have become mainstream. In the case of a projector having a long projection distance, there is a conference desk between the projector and the screen 2, and the projector is arranged behind the conference desk. It has become possible to place it on the front side of a desk, and the space behind the projector can be used freely.

  Since the projector contains a light source lamp and a large number of electronic boards, the internal temperature of the projector rises as time passes after startup. This is conspicuous in recent years when the projector housing size has been reduced, and as a countermeasure, as shown in FIG. An air cooling method using a forced air flow is generally adopted by providing an exhaust port 12.

  FIG. 2 is a view showing the arrangement and configuration of the optical engine 3 and the light source unit 4 with the exterior cover of the image projection apparatus 1 removed. In the present embodiment, a high pressure mercury lamp is employed as the light source unit 4. As a path for the light emitted from the light source unit 4 to form an image on the screen 2, the light from the light source unit 4 is first applied to an illumination unit 3 a described later of the optical engine 3. In the illumination unit 3a, the emitted white light is split into RGB, and the split light is guided to an image display element unit 8 described later. Thereafter, the light guided to the image display element unit 8 forms an image according to the modulation signal, and is enlarged and projected by a projection unit 3b described later to reach the screen 2. In addition, the air cooling method inside the image projection apparatus 1 shown in FIG. 1A is performed by forced air flow by the intake fan 13 disposed near the intake port 11 and the exhaust fan 14 disposed near the exhaust port 12. ing.

  FIG. 3 is a diagram illustrating a configuration example of the optical engine 3. As shown in FIG. 3, the optical engine 3 according to the present embodiment mainly includes an illumination unit 3a and a projection unit 3b. The illumination unit 3 a is an example of an illumination optical unit, and guides the light emitted from the light source unit 4 to the DMD 16 provided in the image display element unit 8. The projection unit 3b is an example of a projection unit, and enlarges and projects an image generated by the DMD 16 (image display element unit 8) onto the screen 2.

  In the optical engine 3 of the present embodiment, the white light emitted from the light source unit 4 is first converted into RGB colors by the disk-shaped color wheel 5. After that, light emitted from the color wheel 5 is guided into the illumination unit 3a by the light tunnel 6 configured in a cylindrical shape by laminating plate glasses, and chromatic aberration is generated by the two relay lenses 7 arranged immediately after the light tunnel 6. And the light is condensed on the image display element unit 8 having the DMD 16 by the plane mirror 10 and the concave mirror 9.

  The DMD 16 has a substantially rectangular mirror surface composed of a plurality of micromirrors, and each micromirror is driven in a time-sharing manner based on video data, thereby processing and reflecting the projection light into a predetermined video. It has a structure. Here, it can be considered that the DMD 16 which is an example of the light modulation element generates an image using light emitted from the light source unit 4. The image projection apparatus 1 according to the present embodiment is a projector in which the DMD 16 faces the screen 2.

  There are two types of directions in which the DMD 16 reflects, and light used when forming video data is reflected to the projection lens, and light that is discarded without being used is reflected to the OFF light plate. The light used in forming the video data is reflected toward the projection unit 3b, enlarged when passing through a plurality of projection lenses, and projected onto the screen 2 as enlarged video light. The incident side of the relay lens 7, the concave mirror 9, the flat mirror 10, the image display element unit 8, and the projection unit 3b inside the illumination unit 3a is held by the housing so as to cover each component, and the housing The mating surfaces have a dustproof structure sealed with a sealing material.

  The image projection apparatus 1 of the present embodiment includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The CPU controls the operation of the image projection apparatus 1 by developing and executing a program stored in the ROM or the like on the RAM.

  Next, a specific configuration of the image display element unit 8 will be described. FIG. 4 is a diagram illustrating an example of the configuration of the image display element unit 8. As shown in FIG. 4, the image display element unit 8 includes two units, a fixed unit 31 fixed to the illumination unit 3a and a movable unit 41 that can move. The image display element unit 8 is an example of an image display unit.

  A voice coil 43 (coil), which will be described later, is disposed on the movable unit 41 side, and receives a Lorentz force generated with a magnet 37 (magnet), which will be described later, disposed on the fixed unit 31 side. 31 is configured to move relative to 31. At this time, in order to reduce the resistance that the movable unit 41 receives from the fixed unit 31, a sphere 34 is provided between the fixed unit 31 and the movable unit 41 to reduce sliding friction between the two units. . The position of the sphere 34 will be described later.

  The combination of the voice coil 43 and the magnet 37 generates a driving force for moving the DMD 16 relative to the illumination unit 3a, and may be referred to as an “actuator” in the following description. As will be described later, the image projection apparatus 1 according to the present embodiment has four actuators, and each of the four voice coils 43 is provided at a position facing the magnet 37 paired with the voice coil 43. Yes. The four actuators function as a drive unit that moves the DMD 16 relative to the illumination unit 3 a by moving the movable unit 41 that holds the DMD 16.

  For example, when the relationship between the direction of the magnetic field by the magnet 37 and the current flowing through the voice coil 43 is as shown in FIG. 5, Lorentz force acts in the direction of the arrow shown in FIG. If the direction of the current flowing through the voice coil 43 is reversed, Lorentz force acts in the direction opposite to that in FIG. 5, as shown in FIG.

  FIG. 7 is an exploded perspective view of the fixed unit 31. FIG. 8 is an exploded perspective view of the movable unit 41. As the role of the fixed unit 31, it can be said that two points of supporting the movable unit 41 and supporting the movement of the movable unit 41 are the major roles. Specifically, the movable unit 41 is supported by sandwiching the heat sink 18 in the movable unit 41 with a plurality of spheres 34 provided in the fixed unit 31.

  The sphere 34 is disposed between the top plate 32 and the heat sink 18 and between the base plate 33 and the heat sink 18. The sphere 34 arranged on the top plate 32 side is in a sphere holding part 35 provided on the top plate 32, and the sphere 34 arranged on the base plate 33 side is on a sphere receiving part 36 provided on the base plate 33 side. It is configured to be stored. Although it can be said that the relationship between friction and backlash varies depending on the clearance between each plate and the sphere 34, the clearance is adjusted by a sphere position adjusting screw 39 provided on the top plate 32 side. Further, a support column 38 is provided between the top plate 32 and the base plate 33 to keep the distance between the plates.

  As for the support of movement of the movable unit 41, which is another role of the fixed unit 31, a magnet 37a is disposed on the fixed unit 31 side, and a voice coil 43 is disposed on the movable unit 41 side. A control circuit (which may be the above-described CPU or a circuit different from the CPU) performs a control to flow a current through the voice coil 43, thereby generating a Lorentz force and moving the movable unit 41. . As described above, the direction of the Lorentz force varies depending on the direction of current flow, and the magnitude of the Lorentz force varies depending on the magnitude of the current. Therefore, the movable unit 41 having the DMD 16 is moved in a desired direction by a desired amount. be able to.

  A hall element 42 is attached to the heat sink 18 on the movable unit 41 side, and the position of the movable unit 41 is detected by a change in the magnetic field received from the magnet 37b on the fixed unit 31 side.

  On the other hand, the role of the movable unit 41 includes holding the DMD 16. In general, the DMD 16 is sandwiched between the illumination housing and the heat sink 18. However, as shown in the exploded perspective view of FIG. 8, in this configuration, the DMD holding bracket 47 which is one of the components of the movable unit 41. In this way, the DMD 16 is held without being pressed against the illumination housing. Here, the heat sink 18 presses the DMD 16 to diffuse and cool the heat of the DMD 16.

  Further, as described above, the heat sink 18 in which the Lorentz force works is supported by being sandwiched between the spheres 34 in the fixed unit 31, so that the heat sink 18 itself is disposed between the top plate 32 and the base plate 33 of the fixed unit 31. Will be. Further, the DMD holding bracket 47, the coupling plate 46 that holds the DMD 16, and the heat sink 18 are fixed from the heat sink 18 side by a step screw 48 provided with a spring 49. FIG. 9 is a diagram showing the positional relationship between the plates. In FIG. 9, the DMD holding bracket 47 and the coupling plate 46 are disposed on the opposite side of the top plate 32 from the heat sink 18.

  As shown in FIG. 9, in this embodiment, a magnet 37 a is arranged in the fixed unit 31. On the other hand, a voice coil 43 is disposed at a position of the plate of the heat sink 18 in the movable unit 41 facing the magnet 37a. When a driving force (Lorentz force) is generated by the actuator composed of the magnet 37a and the voice coil 43, the Lorentz force is directly applied to the heat sink 18 including a part of the actuator to drive it. Thereby, DMD16 currently pressed by the heat sink 18 currently driven can be driven indirectly.

  Next, the case where the fixed unit 31 and the movable unit 41 are connected by a spring which is an example of an elastic member will be described. FIG. 10 is a diagram illustrating a state where the fixed unit and the movable unit are connected by a spring. In FIG. 10, the image display element unit 8 in which the fixed unit and the movable unit are arranged is viewed from the direction of arrow A in FIG. In the present embodiment, the image display element unit 8 is disposed perpendicular to the horizontal plane. For this reason, the drive plane (surface including the movable direction) of the movable unit 41 including the DMD 16 and the heat sink 18 is also perpendicular to the horizontal plane.

  Here, the example shown in FIG. 10 shows a configuration in which the movable unit 41 is connected to the fixed unit 31 by three springs (two tension springs 51a and one compression spring 51b), but the number of springs is arbitrary. The two units may be connected by 1, 2, or 4 or more springs. However, when the fixed unit 31 and the movable unit 41 are connected by one or two springs, there is a possibility that the movable unit 41 rotates by generating a moment. preferable.

  As shown in FIG. 10, in this embodiment, the spring post 36a that hooks and connects one end of the tension spring 51a to the top plate 32, and the spring post 36b that hooks and connects one end of the compression spring 51b. Is provided. Two spring posts 36 a are provided on the upper left and right sides of the top plate 32, and one spring post 36 b is provided near the center of the lower portion of the top plate 32.

  In addition, the heat sink 18 of the movable unit 41 is provided with a hole 18a that hooks and connects the other end of the tension spring 51a, and a hole 18b that hooks and connects the other end of the compression spring 51b. . Two holes 18a are provided on the left and right upper portions of the plate of the heat sink 18 in correspondence with the spring posts 36a, and the holes 18b are 1 near the center of the lower portion of the plate of the heat sink 18 in correspondence with the spring posts 36b. One is provided.

  The two tension springs 51a are connected to the spring posts 36a and the holes 18a, the one compression spring 51b is connected to the spring posts 36b and the holes 18b, and the heat sink 18 is suspended to suspend the movable unit 41. It has become. In the present embodiment, the tension spring 51a is a spring that pulls the upper portion of the heat sink 18 in a direction opposite to the direction in which gravity is applied by an elastic force. The compression spring 51b is a spring that pushes up the lower portion of the heat sink 18 in the direction opposite to the direction in which gravity is applied.

  Further, in the tension spring 51a and the compression spring 51b, the direction in which the elastic force acts is on the surface including the direction in which the movable unit 41 including the heat sink 18 can move. That is, the tension spring 51a and the compression spring 51b are attached on the surface on which the driving force to the movable unit 41 acts.

  Since the tension spring 51a and the compression spring 51b support the movable unit 41 including the heat sink 18 and apply a force in the direction opposite to the gravity, the actuator acts on the movable unit 41 in the direction opposite to the gravity. The power can be reduced.

  Further, the tension spring 51a and the compression spring 51b set the spring constant so that the DMD 16 is maintained at a predetermined position when the resultant force of the elastic force in the vertical direction is balanced with the gravity applied to the movable unit 41. Here, the predetermined position in the present embodiment indicates a basic position / posture at which the DMD 16 can receive the light emitted from the light source over the entire surface. As a result, when projecting an image without shifting the pixels for high resolution or moving (shifting) or rotating the projected image, it is possible to control the driving force to the movable unit 41 to be suppressed. As a result, it is possible to avoid changing to expensive and large parts in order to generate a large driving force, or a large increase in power consumption due to the constant driving force.

  As described above, since the movable unit 41 including the DMD 16 and the heat sink 18 is suspended by the tension spring 51a and the compression spring 51b in the image projection apparatus 1 of the present embodiment, the movable unit 41 for pixel shifting is used. The driving force required for driving and maintaining the posture can be reduced. Further, by setting the spring constants of the tension spring 51a and the compression spring 51b so that the DMD 16 can balance the light source light at the basic position / posture, it is possible to shift the pixel for high resolution and the projected image. When movement / rotation is not performed, control can be performed to suppress the driving force to the movable unit 41, and power consumption can be suppressed. As a result, the image projection apparatus of the present embodiment can achieve high resolution of the projection image and shift / rotation of the projection image, and can be reduced in size and cost.

  In the image projection apparatus of the present embodiment, the ends of the tension spring 51a and the compression spring 51b (an example of an elastic member) are hooked and connected to the fixed unit 31 and the movable unit 41, but the tension spring 51a and the compression spring 51b are connected. It is good also as a structure which fixes and connects the edge part of this to the fixed unit 31 and the movable unit 41. FIG. In the image projection apparatus of the present embodiment, two tension springs are connected to the left and right of the upper part, and one compression spring is connected to the vicinity of the center of the lower part, but may be connected at other positions. For example, one spring may be connected near the center of the upper part, two springs may be connected to the left and right of the lower part, or two springs may be connected to the left and right of the upper and lower parts by four springs.

  Further, the image projection apparatus according to the present embodiment has a configuration in which the image display element unit 8 is arranged perpendicular to the horizontal plane. However, the image display element unit 8 is arranged so as to intersect the horizontal plane, that is, the horizontal plane. However, it is good also as a structure arrange | positioned in more than 0 degree and less than 90 degree | times with respect to.

  Moreover, it is good also as a structure which arrange | positions the image display element unit 8 in parallel with a horizontal surface. When the fixed unit 31 and the movable unit 41 are connected by three or more springs, the spring constant is set so that the DMD 16 is maintained at a predetermined position when the resultant force of all the springs is in a balanced state. Set.

  In the present embodiment, the movable unit 41 including the DMD 16 and the heat sink 18 is suspended by a spring which is an elastic member as an example of a connection member. However, as a configuration using a connection member other than an elastic member such as a spring. Also good. For example, one end of a connection member that does not have elasticity is connected to the heat sink 18 of the movable unit 41, a weight is provided on the other end of the connection member, and a protrusion provided at the position of the post in this embodiment. A connecting member is hung on. That is, the weight is adjusted by the weight so that the heat sink 18 and the weight are balanced by the connecting member via the protrusion.

  As mentioned above, although embodiment of this invention was described, the above-mentioned embodiment is shown as an example and is not intending limiting the range of invention. The present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above-described embodiments. For example, some components may be deleted from all the components shown in the embodiment.

DESCRIPTION OF SYMBOLS 1 Image projector 2 Screen 3 Optical engine 3a Illumination unit (illumination optical part)
3b Projection unit (projection unit)
4 Light source unit 5 Color wheel 6 Light tunnel 7 Relay lens 8 Image display element unit 9 Concave mirror 10 Plane mirror 16 DMD (light modulation element)
18 Heat sink 18a, 18b Hole 31 Fixing unit 36a, 36b Spring post 37a, 37b Magnet (magnet)
41 Movable unit 43 Voice coil (coil)
46 Coupling plate 51a Tension spring (elastic member, connecting member)
51b Compression spring (elastic member, connecting member)

JP 2007-248721 A

Claims (8)

An image projection device,
An image display unit including a light modulation element that generates an image using light emitted from a light source;
An illumination optical unit for guiding the light emitted from the light source to the light modulation element;
A projection unit for projecting an image generated by the light modulation element,
The image display unit
A movable part holding the light modulation element;
A fixed part fixed to the illumination optical part and supporting the movable part;
A drive unit that moves the light modulation element relative to the illumination optical unit by moving the movable unit;
An image projection apparatus comprising: a connecting member connected to the movable portion and the fixed portion, and supporting the movable portion while maintaining the light modulation element at a predetermined position.   The image projection apparatus according to claim 1, wherein the connection member is an elastic member.   The image projection apparatus according to claim 2, wherein the elastic member has a direction in which an elastic force acts on a surface including a direction in which the movable part can move.   In the elastic member, when the image display unit is arranged so that a plane including a direction in which the movable unit can move intersects a horizontal plane, the elastic force in the vertical direction is balanced with the gravity applied to the movable unit. The image projection apparatus according to claim 3. A plurality of the elastic members are provided,
The image projection apparatus according to claim 4, wherein the plurality of elastic members are in a state in which a resultant force of an elastic force in a vertical direction is in balance with gravity applied to the movable portion. The elastic member is a spring,
The spring is a tension spring when the movable part is pulled in a direction opposite to a direction in which gravity is applied by an elastic force, and a compression spring when the movable part is pushed up in the opposite direction by an elastic force. The image projection device according to 4 or 5. An optical engine,
An image display unit including a light modulation element that generates an image using light emitted from a light source;
An illumination optical unit for guiding the light emitted from the light source to the light modulation element;
A projection unit for projecting an image generated by the light modulation element,
The image display unit
A movable part holding the light modulation element;
A fixed part fixed to the illumination optical part and supporting the movable part;
A drive unit that moves the light modulation element relative to the illumination optical unit by moving the movable unit;
An optical engine comprising: a connecting member that is connected to the movable part and the fixed part and supports the movable part while maintaining the light modulation element at a predetermined position. An image display unit,
A light modulation element that generates a projected image using light emitted from a light source;
A movable part holding the light modulation element;
A fixed part that supports the movable part;
A drive unit that moves the light modulator relative to the fixed unit by moving the movable unit;
An image display unit comprising: a connecting member connected to the movable portion and the fixed portion, and supporting the movable portion while maintaining the light modulation element at a predetermined position.