JP2016001270A - Optical unit and image projection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical unit that reduces an increase in temperature of a lens barrel during image projection without requiring an opening to suppress a deterioration of images to be projected.SOLUTION: There is provided an optical unit 200 used for an image projection device 100, the optical unit 200 including: an image display element 21 that modulates incident light beams and provides image information to the light beams; a lens unit 300 that has a projection optical system 22 having at least one lens on which the light beams passed through the image display element 21 are made incident and a lens barrel 30 holding the projection optical system 22; a cooling part 25 for cooling the lens unit 200; and a heat transfer part 15 that connects the cooling part 25 and the lens barrel 30 to transfer heat of the lens barrel 30 to the cooling part 25.

Description

  The present invention relates to an optical unit using an image display element and an image projection apparatus having the optical unit.

  In an image projection apparatus such as a projector (for example, Patent Documents 1 to 7) that applies image information to light emitted from a light source using an image display element and projects an image on a screen via a projection optical system, high brightness It is desirable to use a light source with a large amount of light in order to increase the size of the projection surface.

When a light source with a large amount of light is used in the image projection apparatus, the temperature rise of the lens unit due to absorption of the light beam incident from the light source is a problem.
Specifically, an increase in temperature of an optical member such as a projection optical system or a lens barrel causes a shift in the arrangement, posture, shape, or the like of the optical member, resulting in deterioration of an image projected on the screen. There is a problem.

In order to solve such a problem, a technique is known in which an opening is provided in the lens barrel, and the lens barrel is cooled by taking in outside air from the opening (for example, Patent Document 4).
However, when the opening is provided, there is a possibility that the projected image is deteriorated due to inflow of dust or the like.

  The present invention has been made in view of the above problems, and an optical unit that suppresses deterioration of an image to be projected by reducing a temperature rise of a lens barrel during image projection without requiring an opening. The purpose is to provide.

  In order to solve the above-described problems, an optical unit according to the present invention is an optical unit used in an image projection apparatus, which modulates an incident light beam and gives image information to the light beam, and the image display A lens unit having a projection optical system having at least one lens on which the luminous flux having passed through the element is incident, a lens barrel holding the projection optical system, a cooling unit for cooling the lens unit, and the cooling unit And a heat transfer section that couples the lens barrel and transfers the heat of the lens barrel to the cooling section.

  ADVANTAGE OF THE INVENTION According to this invention, the optical unit which suppresses the temperature rise of the lens barrel at the time of image projection, and suppresses deterioration of the image to project can be provided.

It is a figure which shows an example of a structure of the image projector in the 1st Embodiment of this invention. It is a figure which shows an example of a structure of the optical unit with which the image projector shown in FIG. 1 is equipped. It is sectional drawing which shows an example of a structure of the projection optical system shown in FIG. FIG. 3 is a diagram illustrating an example of an operation at the time of image projection of the optical unit illustrated in FIG. 2. It is a figure which shows the 1st modification of a structure of the optical unit shown in FIG. It is a figure which shows the 2nd modification of a structure of the optical unit shown in FIG. It is a figure which shows the 3rd modification of a structure of the optical unit shown in FIG. It is a figure which shows the 4th modification of a structure of the optical unit shown in FIG.

As a first embodiment of the present invention, an example of the configuration of an image projection apparatus is shown in FIG.
In FIG. 1, the X direction is defined as the optical axis direction of a light beam incident on a projection optical system, which will be described later, and among the directions perpendicular to the X direction, the vertically upward direction is the Z direction, and the direction perpendicular to the X direction and the Z direction is the Y direction. It is determined. The sign of each direction is determined as shown by the arrows in the figure.
The image projection apparatus 100 includes a light source 101 that emits a light beam, a color wheel 122 that gives color information to the light beam, and a light tunnel 123 that equalizes the luminance of the light beam incident from the light source 101. .
The image projection apparatus 100 also includes an optical unit 200 and a control unit 109 that controls information necessary for image projection.

  The light source 101 is a combination of a high-pressure mercury lamp 101 a serving as a light source that emits a radial light beam and a concave mirror 101 b that emits the incident light beam as a light beam that converges near the entrance of the light tunnel 123. Is emitted. Here, a metal halide lamp or a halogen lamp may be used as the radiation light source, or a radiation light source such as an LED light source or a laser light source may be used.

The color wheel 122 is glass that is color-coded in the rotational direction, which is the circumferential direction, and gives color information to the transmitted light beam by being rotated by a driving source (not shown).
The light tunnel 123 is an optical element as an integrator optical system that has a reflection film formed therein and makes the luminance distribution of the transmitted light beam uniform.

The configuration of the optical unit 200 will be described with reference to FIG.
The optical unit 200 includes an illumination lens 24, a mirror M1, and an image display element 21 that gives image information to an incident light beam.
The optical unit 200 also includes a projection optical system 22 that magnifies and projects the light beam that has passed through the image display element 21, a lens barrel 30 that supports the projection optical system 22, and a housing 20 that holds the image display element 21. And a cooling unit 25 for cooling the optical unit 200.
The optical unit 200 also includes a heat transfer unit 15 that connects the lens barrel 30 and the cooling unit 25 to transmit heat of the lens barrel 30 to the cooling unit 25.
The lens barrel 30 and the projection optical system 22 are combined to form a lens unit 300.

  The image display element 21 is a DMD (Digital Micromirror Device), which is a reflective image display element in which minute pixel mirrors are formed on the surface and image information is given by performing ON / OFF switching for each pixel mirror. .

As shown in FIG. 3, the projection optical system 22 is an optical system including at least one lens disposed inside the lens barrel 30, and includes lens groups 32, 33, and 34 and a diaphragm 31. Yes.
The projection optical system 22 may include a prism, a mirror, a dichroic filter, and the like in addition to the lens and the diaphragm.

  The diaphragm 31 is a hole provided in a plate-like member in order to limit the amount of light beam transmitted through the lens barrel 30.

The lens barrel 30 is an aluminum alloy cylindrical member that holds the projection optical system 22.
The lens barrel 30 can use an aluminum alloy such as A5052, and has a thermal conductivity of 100 W / m · K to 150 W / m · K at this time.
The lens barrel 30 has a cam groove (not shown) that is a groove provided in the lens barrel 30 with an inclination with respect to the X-axis direction. At least one lens group is supported so as to be movable in the X-axis direction.
With this configuration, the lens barrel 30 has a lens moving function for zoom adjustment and focus adjustment by moving at least one of the lens groups 32, 33, and 34.
Here, the aluminum alloy used for the lens barrel 30 is A5052, but other aluminum alloys such as A7075 and A2017 may be used, and other metal members and resin materials may be used.

The housing 20 is a magnesium alloy support member that is a housing member that supports the image display element 21 and forms the outer wall of the optical unit 200, and has a thermal conductivity of about 100 W / m · K.
The housing 20 is blackened on the inner surface to prevent reflection inside the optical unit 200 in order to prevent stray light from entering the optical unit 200.
The casing 20 is preferably configured by combining a plurality of plate-like members such as an upper wall, a bottom wall, and a side wall in consideration of ease of assembly of the optical unit 200, but is configured integrally. A box-shaped member may be used.
The metal used for the housing 20 is a magnesium alloy in consideration of weight reduction, thermal conductivity, workability, etc., but may be an aluminum alloy or other metal material.

The cooling unit 25 is a so-called sword mountain-shaped heat radiation fin that is integrally formed on one surface of the housing 20 and serves as a cooling means.
With this configuration, the cooling unit 25 cools the image display element 21 that is a heat radiation source of the optical unit 200 and also cools the lens unit 300 via the heat transfer unit 15 described later.
The cooling unit 25 is not limited to such a configuration, and for example, a heat radiating fin may be provided separately from the housing 20, or the housing 20 itself may be handled as the cooling unit 25.
Moreover, it is good also as a structure which attaches a cooling fan to the cooling part 25, and cools it still more efficiently.

The heat transfer unit 15 is a member made of copper alloy as a cooling auxiliary unit that is a heat transfer unit that couples the cooling unit 25 and the lens barrel 30 and transfers heat of the lens barrel 30 to the cooling unit 25.
The heat conductivity of the heat transfer section 15 is approximately 200 W / m · K, and is designed to be larger than the heat conductivity of the lens barrel 30. Further, in consideration of heat transfer to the cooling unit 25, it is desirable that the thermal conductivity of the heat transfer unit 15 is larger than the thermal conductivity of the cooling unit 25.

The control unit 109 has a function as image pattern generation means for giving image information to be projected to the image display element 21.
The control unit 109 is also a control unit that controls the lens moving operation of the lens barrel 30.

  A method for projecting an image in the image projecting apparatus 100 having such a configuration will be described.

  White light emitted in all directions from the halogen lamp 101 a is reflected by the concave mirror 101 b and enters the color wheel 122 as a light beam that converges near the entrance of the light tunnel 123.

In the color wheel 122, the luminous flux is transmitted by wavelength according to the region of the color wheel 122 that is color-coded in the rotation direction that is the circumferential direction, and is temporally decomposed into R, G, and B color information.
Here, the color wheel 122 operates as color information decomposing means for decomposing the light beam into R, G, and B color information.

The luminous flux decomposed into the R, G, and B color information has its luminance distribution made uniform by the light tunnel 123, and becomes a luminous flux having substantially uniform luminance divided in time.
The light beam that has passed through the light tunnel 123 enters the optical unit 200 and enters the image display element 21 while changing its traveling direction through the mirror M1 and the illumination lens 24.
The image display element 21 reflects an incident light beam to an angle corresponding to each ON / OFF state by a pixel mirror adjusted to each pixel size.
That is, when the pixel mirror is in the ON state, as shown in the ON light A in FIG. 4, the light beam is reflected in the X direction, which is the direction of the projection optical system 22, and when the pixel mirror is in the OFF state, the OFF is shown in FIG. Like the light B, the incident light is reflected in the opposite direction across the ON light A.
In other words, the image display element 21 has a reflection surface switching member having a reflection surface switching function capable of switching whether the light beam that has passed through the image display element 21 is incident on the projection optical system 22 or is incident on a position different from the projection optical system 22. It is.
By the operation of switching the reflection position, the image display element 21 controls the reflection direction of the light beam obtained by temporally dividing the color information, and reflects the light beam having specific color information to a specific position, whereby the image is displayed. Image information is given to the ON light A reflected by the display element 21.
The OFF light B that does not contribute to the application of image information, in other words, that does not enter the projection optical system 22 irradiates the inner surface of the housing 20 at a position different from the projection optical system 22. The OFF light B is absorbed by the inner surface of the blackened casing 20 and is discharged by the cooling unit 25 as heat.
The luminous flux to which the image information is given is reduced by the lens group 32 on the reduction side of the projection optical system 22, the amount of light is limited by the diaphragm 31, and then the lens groups 33 and 34 on the enlargement side of the projection optical system 22. It is enlarged and transmitted in the positive direction of the X axis.
Image projection is performed by projecting and forming an image of a light beam to which image information is provided by such a configuration on the projection surface 104.

By the way, in the image projector 100, it is desirable that the light amount of the light source 101 is large in order to increase the brightness and the size of the projection surface.
However, when the light source 101 with a large amount of light is used in the image projection apparatus 100, the temperature rise of the optical unit 200 due to the absorption of the light beam incident from the light source 101 can be a problem.
Specifically, the temperature rise due to the above-described OFF light B being absorbed as heat inside the housing 20, and the ON light A is irradiated to the optical member such as the lens barrel 30 and the diaphragm 31. Due to the temperature rise due to the above, there is a possibility that displacement of the arrangement, posture, shape, etc. of the lens barrel 30 may be caused.
In particular, during the image projection, the influence of the temperature rise due to the ON light A being applied to the lens barrel 30 is particularly large.
As a result, the image projected on the screen may be deteriorated due to the displacement of the arrangement, posture, shape, or the like of the lens groups 32, 33, and 34.
In addition, a rise in temperature of the image display element 21 due to the incident light flux on the image display element 21 may affect the deterioration of these images.

Therefore, the optical unit 200 includes a cooling unit 25 for cooling the lens unit 300, and a heat transfer unit 15 that couples the cooling unit 25 and the lens barrel 30 to transmit heat of the lens barrel 30 to the cooling unit 25. have.
Here, the heat transfer unit 15 reduces the temperature rise of the lens barrel 30 by transmitting heat generated by the irradiation of the ON light A to the lens barrel 30 and the like to the cooling unit 25.
With this configuration, the temperature rise of the lens barrel during image projection is reduced without forming an opening in the lens barrel 30, and deterioration of the projected image is suppressed.

The cooling unit 25 reduces the temperature rise of the image display element 21, reduces the temperature rise of the housing 20 due to absorption of the OFF light B, and further reduces the temperature rise of the lens barrel 30 via the heat transfer unit 15. It functions as a cooling means.
With this configuration, the housing 20, which is a plurality of heat exhausting units, the lens barrel 30, and the image display element 21 of the optical unit 200 are connected to the cooling unit 25, respectively. While reducing the rise, the cooling means can be saved in space, and the cost and size can be easily reduced.

Further, the heat conductivity of the heat transfer section 15 is larger than the heat conductivity of the lens barrel 30.
With this configuration, heat transfer is improved, and the temperature rise of the lens barrel during image projection is more efficiently reduced, and deterioration of the projected image is suppressed.
At this time, if the thermal conductivity of the heat transfer section 15 is greater than the thermal conductivity of the housing 20, the temperature rise of the optical unit 200 during image projection can be reduced more efficiently, and the projected image Reduce deterioration.

A first modification of the embodiment of the present invention is shown in FIG.
In the first modification, the cooling unit 25 is a housing 20 for fixing the image display element 21.
The lens barrel 30 includes a first lens barrel 36 made of an aluminum alloy that supports the lens group 32, a second lens barrel 37 that supports the lens group 33 so as to be movable in the X direction, and a lens group 34 that is in the X direction. And a resin-made third lens barrel 38 that is movably supported.
In other words, the lens barrel 30 is configured by combining a plurality of lens barrels each supporting at least one lens group.
In other words, in this modification, the optical unit 200 includes a plurality of lens barrels 36, 37, and 38 that support at least one lens group.
Hereinafter, the plurality of lens barrels 36, 37, and 38 are arranged in order from the −X side in the X-axis direction, in other words, the incident light upstream side of the projection optical system 22, in order, the first lens barrel 36, the second lens barrel 37, and the third lens barrel. 38.
As shown in FIG. 5, the first lens barrel 36 is disposed on the −X side in the X-axis direction of the lens barrel 30, that is, on the incident light side in the projection optical system 22. It is considered that the amount of light energy that rises, in other words, is the highest.
On the other hand, it is considered that the second lens barrel 37 and the third lens barrel 38 are both downstream of the first lens barrel 36 and the temperature rise is smaller than that of the first lens barrel 36. In order to reduce cost and weight, it is desirable to use a resin material for the second lens barrel 37 and the third lens barrel 38.
Accordingly, the second lens barrel 37 and the third lens barrel 38 both have a low thermal conductivity and are made of a resin material of about 1 W / m · K.
As described above, when the second lens barrel 37 and the third lens barrel 38 are made of a resin material having a lower thermal conductivity than the first lens barrel 36, the heat of the first lens barrel 36 is changed to the second lens barrel. There is a concern that the temperature of the first lens barrel 36 is likely to rise due to the difficulty of being transmitted to 37 and the third lens barrel 38.
Therefore, the first lens barrel 36 is disposed in contact with the heat transfer portion 15 that connects the cooling portion 25 and the first lens barrel 36 and transfers the heat of the first lens barrel 36 to the cooling portion 25. .
The first lens barrel 36 is also preferably made of a metal material having a high thermal conductivity, such as an aluminum alloy.
With this configuration, the portion of the lens barrel 30 with the largest temperature rise is efficiently cooled to reduce the temperature rise, while increasing the degree of freedom of material selection for the lens barrel 30 to facilitate low cost and downsizing.
The heat transfer unit 15 in the present modified example connects the first lens barrel 36 located closest to the −X side in the X-axis direction and the cooling unit 25 among the plurality of lens barrels 36, 37, and 38, It arrange | positions so that the heat | fever of the lens-barrel 36 may be transmitted to the cooling part 25. FIG.
With such a configuration, the portion of the lens barrel 30 with the largest temperature rise during image projection is efficiently cooled, so the temperature rise of the lens barrel 30 is reduced and deterioration of the projected image is suppressed.
As already described, the cooling unit 25 may be a heat radiating fin.

A second modification of the embodiment of the present invention is shown in FIG.
In the second modification, the heat transfer unit 15 is disposed on the inner wall of the housing 20 on a surface different from the inner wall irradiated with the OFF light B at a position where the OFF light B is not irradiated.
With this configuration, the temperature increase of the heat transfer unit 15 due to the irradiation of the OFF light B is prevented, and the temperature increase of the lens barrel 30 is reduced to suppress deterioration of the projected image.
As shown in FIG. 4, the heat transfer unit 15 is preferably installed at a position opposite to the OFF light B with the ON light A interposed therebetween. Or when arrange | positioning on the same side as the OFF light B seeing from the ON light A, as shown in FIG. 6, the temperature rise by irradiation of the OFF light B is suppressed by arrange | positioning in the position where the OFF light B is not irradiated. be able to.

FIG. 7 shows a third modification of the embodiment of the present invention.
In FIG. 7, the heat transfer unit 15 is disposed outside the housing 20 at a position where the OFF light B is not irradiated.
With this configuration, the temperature increase of the heat transfer unit 15 due to the irradiation of the OFF light B is prevented, and the temperature increase of the lens barrel 30 is reduced to suppress deterioration of the projected image.

The 4th modification of embodiment of this invention is shown to Fig.8 (a), (b).
The heat transfer part 15 has a fixed part 15a and an elastic part 15b.
The fixing portion 15a is a through-hole serving as an opening for allowing a fixing member such as a screw formed at one end of the heat transfer portion 15 to pass therethrough. In the cooling portion 25 configured integrally with the housing 20, It is fixed integrally with a screw as a fixing member (not shown).
The elastic portion 15b is a portion formed at the other end of the fixed portion 15a in the heat transfer portion 15 and having elasticity depending on the shape, material, and the like. Even when the lens barrel 30 moves, the elastic portion 15b is elastic with the lens barrel 30. It is formed so as to maintain the state of contact with each other.
Specifically, since the elastic portion 15b is pressed against the lens barrel 30 by the elastic force in the -Z direction, the lens barrel 30 moves in the X-axis direction by zoom adjustment or focus adjustment. In addition, it is possible to always maintain the state in which the elastic portion 15b is in elastic contact with the lens barrel 30.
In FIG. 8, the fixing portion 15a is fixed to the cooling portion 25, and the elastic portion 15b elastically contacts the lens barrel 30, but the fixing portion 15a is fixed to the lens barrel 30, and the elastic portion 15b is The cooling unit 25 may be elastically contacted.
With this configuration, even when the lens barrel 30 is moved for zoom adjustment or focus adjustment, the heat transfer unit 15 keeps the lens barrel 30 and the cooling unit 25 connected and in contact with each other so that the image projection can be performed. The temperature rise of the lens barrel 30 is reduced to suppress the deterioration of the projected image.
Note that so-called heat conductive grease or the like is applied to the contact surface between the lens barrel 30 and the elastic portion 15b in order to improve the thermal conductivity by suppressing the change of the contact surface due to the movement of the lens barrel 30. It is desirable.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the specific embodiments, and the present invention described in the claims is not specifically limited by the above description. Various modifications and changes are possible within the scope of the above.

  For example, the image projection apparatus 100 is a color image projection apparatus using a white light source, but may be a monochrome image projection apparatus using a single light source.

Alternatively, a plurality of heat transfer units 15 may be provided, and the lens barrel 30 and the cooling unit 25 may be connected to each other.
Alternatively, any one or a plurality of the first to fourth modifications may be combined to form a plurality of heat transfer units 15.
In addition, the image display element 21 may be an image projection apparatus 100 using a liquid crystal element as a transmissive image display element such as a liquid crystal element disposed on the upstream side of the optical axis of the projection optical system 22.

  The effects described in the embodiments of the present invention are only the most preferable effects resulting from the present invention, and the effects of the present invention are limited to those described in the embodiments of the present invention. is not.

DESCRIPTION OF SYMBOLS 15 Heat-transfer part 20 Case 21 Image display element 22 Projection optical system 25 Cooling part 30 Lens barrel 31 Diaphragm 32 Lens group 33 Lens group 34 Lens group 36 First lens barrel 37 Second lens barrel 38 Third lens barrel 100 Image projection Device 101 Light source 104 Image plane (projection plane)
109 Control unit 200 Optical unit 300 Lens unit Z Vertical upward direction X Optical axis direction

JP 2013-097326 A JP 2011-158862 A JP 2006-227087 A JP 2005-331791 A Japanese Patent No. 5298443 JP2013-109042A JP 2008-292953 A

Claims (8)

An optical unit used in an image projection device,
An image display element that modulates an incident light beam and gives image information to the light beam;
A lens unit having a projection optical system having at least one lens on which the light flux that has passed through the image display element enters, and a lens barrel that holds the projection optical system;
A cooling unit for cooling the lens unit;
An optical unit having a heat transfer section that connects the cooling section and the lens barrel and transfers heat of the lens barrel to the cooling section. The optical unit according to claim 1,
The optical unit according to claim 1, wherein a thermal conductivity of the heat transfer unit is larger than a thermal conductivity of the lens barrel. The optical unit according to claim 1 or 2,
The optical unit according to claim 1, wherein the cooling unit is a heat radiating fin. The optical unit according to any one of claims 1 to 3,
The optical unit, wherein the cooling unit is a housing for fixing the image display element. The optical unit according to claim 4,
The optical unit characterized in that the heat conductivity of the heat transfer section is larger than the heat conductivity of the casing. The optical unit according to any one of claims 1 to 5,
The heat transfer section has elasticity, is fixed and supported by either the cooling section or the lens barrel, and the cooling section and the lens barrel are moved even when the lens barrel is moved. An optical unit characterized in that a state of elastic contact with either one of the two is maintained. The optical unit according to any one of claims 1 to 6,
The image display element can switch whether the light passing through the image display element is incident on the projection optical system or a position different from the projection optical system,
The optical unit, wherein the heat transfer unit is disposed at a position where the light beam is not irradiated even when the light beam is incident on the different position by the image display element.   An image projection apparatus comprising the optical unit according to claim 1.

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