Projector

Abstract

This projector comprises: an optical modulation element that modulates light from a light source into image light on the basis of an input video signal; a projection lens that projects the image light; a projection lens holding member that holds the projection lens; an optical modulation element holding member that holds the optical modulation element; an intermediate member arranged between the projection lens holding member and the optical modulation element holding member; a first connection member that connects the projection lens holding member and the intermediate member; and a second connection member that connects the optical modulation element holding member and the intermediate member. The second connection member is located closer to the projection lens than the first connection member is. The intermediate member and the projection lens holding member thermally deform in an optical axis direction of the projection lens.

Description

Projector

[0001] The present disclosure relates to a projector.

[0002] Since a projector includes components that generate heat during operation, it is known that focus deviation occurs due to thermal deformation of the members. Therefore, techniques for suppressing focus deviation due to such thermal deformation have been studied (for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2015-28655

[0004] However, the study of techniques for suppressing focus deviation caused by thermal deformation is insufficient, and there is room for further improvement.

[0005] An object of the present disclosure is to provide a technique for suppressing focus deviation caused by thermal deformation.

[0006] A projector according to one aspect of the present disclosure includes a light modulation element that modulates light from a light source into image light based on an input video signal, a projection lens that projects the image light, a projection lens holding member that holds the projection lens and extends in a first direction that is the optical axis direction of the projection lens, a light modulation element holding member that holds the light modulation element, an intermediate member that is disposed between the projection lens holding member and the light modulation element holding member in a second direction that intersects the first direction and extends in the first direction, a first connecting member that connects the projection lens holding member and the intermediate member in the first direction, and a second connecting member that connects the light modulation element holding member and the intermediate member in the first direction. In the first direction, the second connecting member is located closer to the projection lens than the first connecting member, and the intermediate member and the projection lens holding member thermally deform in the first direction.

[0007] These general or specific aspects may be implemented by a system, an apparatus, a method, an integrated circuit, a computer program, or a recording medium, or may be implemented by any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium.

[0008] According to the present disclosure, it is possible to provide a technique for suppressing focus deviation caused by thermal deformation.

[0009] Perspective view showing an example of the configuration of a projector according to Embodiment 1 Perspective cross-sectional view showing an example of the configuration of a projector according to Embodiment 1 Schematic side cross-section showing a first example of the configuration of a projector according to Embodiment 1 Schematic side cross-section showing a second example of the configuration of a projector according to Embodiment 1

[0010] Embodiments of the present disclosure will be described in detail below, with appropriate reference to the drawings. However, unnecessary details may be omitted. For example, detailed explanations of already well-known matters and redundant explanations of substantially identical configurations may be omitted. This is to avoid the following explanation becoming unnecessarily verbose and to facilitate understanding by those skilled in the art. The accompanying drawings and the following explanation are provided to enable those skilled in the art to fully understand the present disclosure and are not intended to limit the subject matter of the claims.

[0011] (Embodiment 1) Figure 1 is a perspective view showing an example of the configuration of the projector 1 according to Embodiment 1. Figure 2 is a perspective cross-sectional view showing an example of the configuration of the projector 1 according to Embodiment 1. Figure 2 corresponds to the cross-sectional view taken along line A-A in Figure 1. Figure 3 is a schematic diagram of a side cross-section showing a first example of the configuration of the projector 1 according to Embodiment 1. Figure 3 corresponds to the cross-sectional view taken along line B-B in Figure 1. Figure 4 is a schematic diagram of a side cross-section showing a second example of the configuration of the projector 1 according to Embodiment 1. Figure 4 corresponds to the cross-sectional view taken along line B-B in Figure 1 and has a configuration without the rattle suppression member 51.

[0012] For the sake of explanation, as shown in Figure 1, the axis extending in the height direction of the location where the projector 1 is placed will be defined as the Z-axis. The location where the projector 1 is placed can be, for example, the floor, a desk, or a table. The axis perpendicular to the Z-axis and extending from the back of the projector 1 to the front will be defined as the X-axis. The front of the projector 1 is the surface on which the projection lens 4 is located. The axis perpendicular to the X-axis and Z-axis will be defined as the Y-axis. Furthermore, for the sake of explanation, the positive direction of the Z-axis may be referred to as "up," the negative direction of the Z-axis as "down," the positive direction of the X-axis as "forward," the negative direction of the X-axis as "backward," the positive direction of the Y-axis as "left," and the negative direction of the Y-axis as "right." Moreover, these directional expressions are used for the sake of explanation and are not intended to limit the orientation of the structure during actual use.

[0013] The projector 1 comprises a housing containing a light modulation element 3, a projection lens 4, a projection lens holding member 10, a light modulation element holding member 20, an intermediate member 30, a first connecting member 41, a second connecting member 42, and a rattle suppression member 51. However, the projector 1 does not necessarily have to include the rattle suppression member 51. In addition to these, the projector 1 also includes various other components (for example, a light source device, lenses, prisms, power supply, etc.), but these will not be described in this embodiment.

[0014] The optical modulation element 3 modulates light emitted from a light source (not shown) into image light. The optical modulation element 3 is, for example, a DMD (Digital Micromirror Device). The projector 1 may have one optical modulation element 3 or multiple optical modulation elements 3 (for example, three).

[0015] The projection lens 4 receives the image light modulated by the optical modulation element 3 and projects the input image light onto a screen, for example. The projection lens 4 has the X-axis direction as the optical axis direction (first direction), and the optical modulation element 3 and the projection lens 4 are positioned opposite each other in the optical axis direction.

[0016] The projection lens holding member 10 holds the projection lens 4. For example, as shown in Figure 3, the projection lens holding member 10 includes a first bottom member 11 along the bottom surface of the housing and a first front member 12 along the front of the projector 1. The first bottom member 11 extends at least in the X-axis direction. The projection lens 4 is held by the first front member 12 so as to protrude outward from the housing. The projection lens holding member 10 is made up of, for example, a metal member. The projection lens holding member 10 may be made of other materials.

[0017] The optical modulation element holding member 20 holds the optical modulation element 3. For example, as shown in Figure 3, the optical modulation element holding member 20 includes a second bottom member 21 along the first bottom member 11 of the projection lens holding member 10 and a second front member 22 along the first front member 12 of the projection lens holding member 10. The optical modulation element 3 is held by the second front member 22 so as to face the projection lens 4.

[0018] The intermediate member 30 is positioned between the projection lens holding member 10 and the optical modulation element holding member 20 in a direction (second direction) that intersects the optical axis direction of the projection lens 4, for example, in the Z-axis direction. The intermediate member 30 extends at least in the X-axis direction. For example, as shown in Figure 3, the lower surface 31 of the intermediate member 30 is in contact with the first bottom surface member 11 of the projection lens holding member 10, and the upper surface 32 of the intermediate member 30 is in contact with the second bottom surface member 21 of the optical modulation element holding member 20. The intermediate member 30 is made of, for example, POM resin. The intermediate member 30 may be made of other materials.

[0019] The first connecting member 41 connects the projection lens holding member 10 and the intermediate member 30 in at least the X-axis direction. In other words, the first connecting member 41 plays a role in positioning the intermediate member 30 relative to the projection lens holding member 10 in the X-axis direction. The first connecting member 41 may be configured as an upwardly extending pin (projection) on the first bottom member 11 of the projection lens holding member 10. The projection lens holding member 10 and the intermediate member 30 may be connected by the first connecting member 41 fitting into a hole 33 formed at a predetermined position in the intermediate member 30. In addition to the X-axis direction, the first connecting member 41 may also play a positioning role in other directions (for example, the Y-axis direction).

[0020] The second connecting member 42 connects the optical modulation element holding member 20 and the intermediate member 30, at least in the X-axis direction. In other words, the second connecting member 42 plays a role in positioning the optical modulation element holding member 20 relative to the intermediate member 30 in the X-axis direction. The second connecting member 42 may be configured as an upwardly extending pin (projection) on the upper surface 32 of the intermediate member 30. The optical modulation element holding member 20 and the intermediate member 30 may be connected by the second connecting member 42 fitting into a hole 23 formed at a predetermined position in the second bottom surface member 21 of the optical modulation element holding member 20. As shown in Figure 3, in the X-axis direction, the second connecting member 42 is positioned closer to the projection lens 4 (or first front member 12) than the first connecting member 41. The second connecting member 42 may also play a positioning role in other directions (for example, the Y-axis direction) in addition to the X-axis direction.

[0021] The focus of the image light projected from the projection lens 4 is determined by the distance L between the projection lens 4 and the light modulation element 3. Therefore, it is preferable that the distance L between the projection lens 4 and the light modulation element 3 does not change after focusing. However, since there are components that generate heat during operation (e.g., light source, integrated circuit, light modulation element 3, power supply, etc.) inside the housing of the projector 1, the projection lens holding member 10 may be thermally deformed due to this heat. If the projection lens holding member 10 and the light modulation element holding member 20 are in direct contact, the projection lens holding member 10 may be thermally deformed after focusing, and the distance L between the projection lens 4 and the light modulation element 3 may change. In other words, focus drift (out of focus) may occur.

[0022] Therefore, in this embodiment, as shown in Figure 3, an intermediate member 30 is provided between the projection lens holding member 10 and the optical modulation element holding member 20. The intermediate member 30 has an arrangement, configuration, and coefficient of thermal expansion that cancels out the thermal expansion of the projection lens holding member 10. As a result, for example, as shown in Figure 3, the intermediate member 30 also expands forward (in the optical axis direction (X axis direction) of the projection lens 4) due to thermal expansion (see arrow 62) by the amount that the projection lens holding member 10 expands backward (in the optical axis direction (X axis direction) of the projection lens 4) due to thermal expansion (see arrow 63), thereby maintaining the distance L between the projection lens 4 and the optical modulation element 3. In other words, the occurrence of focus drift (focus shift) can be suppressed. Note that this is not limited to the case where the thermal expansion of the projection lens holding member 10 is canceled out by the thermal expansion of the intermediate member 30, but may also be the case where the effect of thermal expansion due to the thermal expansion of the projection lens holding member 10 is reduced by the thermal expansion of the intermediate member 30. A detailed explanation follows below.

[0023] The positions where the first connecting member 41 and the second connecting member 42 are provided may be based on the thermal expansion coefficients of the intermediate member 30 and the projection lens holding member 10, respectively. For example, the distance of the section D1 between the first connecting member 41 and the second connecting member 42 may be determined such that the rearward extension of the first bottom member 11 of the projection lens holding member 10 in the section D2 between the first front member 12 and the first connecting member 41, based on the thermal expansion coefficient of the projection lens holding member 10, is offset by the forward extension of the intermediate member 30 in the section D1 between the first connecting member 41 and the second connecting member 42 of the intermediate member 30, based on the thermal expansion coefficient of the intermediate member 30. Furthermore, in order to realize this configuration, the thermal expansion coefficient of the intermediate member 30 may be greater than that of the projection lens holding member 10.

[0024] The first connecting member 41 fits into the hole 33 of the intermediate member 30, but if a gap occurs in the fitting portion, a rattle suppression member 51 may be provided to suppress rattle of the first connecting member 41 in the fitting portion. In other words, the rattle suppression member 51 suppresses rattle between the projection lens holding member 10 and the intermediate member 30. As a result, the displacement of the distance D1 between the first connecting member 41 and the second connecting member 42 due to rattle is suppressed, and the accuracy of the cancellation of thermal expansion as described above is improved.

[0025] Furthermore, as illustrated in Figure 4, if there is no gap in the mating portion between the first connecting member 41 and the hole 33 of the intermediate member 30, and there is almost no looseness, the looseness suppressing member 51 may not be provided.

[0026] Furthermore, as illustrated in Figures 3 and 4, a lubricating layer 61 may be provided between the lower surface 31 of the intermediate member 30 and the projection lens holding member 10 to reduce the frictional resistance of the contact surfaces between the intermediate member 30 and the projection lens holding member 10. The coefficient of friction of the lubricating layer 61 is smaller than the coefficient of friction when the lower surface 31 of the intermediate member 30 and the projection lens holding member 10 are in direct contact. The lubricating layer 61 is, for example, a Teflon® coating, a fluororesin coating, or a Teflon® washer. This reduces the frictional force when the projection lens holding member 10 and the intermediate member 30 expand due to thermal expansion, and promotes thermal deformation in a direction that suppresses focus drift.

[0027] (Summary of Embodiment 1) The following technology is disclosed based on the description of Embodiment 1 above.

[0028] <Technology 1> The projector (1) includes an optical modulation element (3) that modulates light from a light source into image light based on an input video signal, a projection lens (4) that projects the image light, a projection lens holding member (10) that holds the projection lens and extends in a first direction (X-axis direction) which is the optical axis direction of the projection lens, an optical modulation element holding member (20) that holds the optical modulation element, an intermediate member (30) that is positioned between the projection lens holding member and the optical modulation element holding member in a second direction (Z-axis direction) intersecting the first direction and extends in the first direction, a first connecting member (41) that connects the projection lens holding member and the intermediate member in the first direction, and a second connecting member (42) that connects the optical modulation element holding member and the intermediate member in the first direction, wherein in the first direction, the second connecting member is located closer to the projection lens than the first connecting member, and the intermediate member and the projection lens holding member are thermally deformed in the first direction. This reduces the effect of thermal deformation in the optical axis direction of the projection lens holding member by thermal deformation in the optical axis direction of the intermediate member. As a result, the displacement of the distance (L) between the optical modulation element held by the optical modulation element holding member and the projection lens held by the projection lens holding member is reduced, thereby suppressing focus shifts during projector operation.

[0029] <Technology 2> In the projector described in Technology 2, the positions where the second connecting member and the first connecting member are provided are based on the thermal expansion coefficients of the intermediate member and the projection lens holding member, respectively. As a result, the thermal deformation of the projection lens holding member is offset by the thermal deformation of the section (D1) between the first connecting member and the second connecting member in the intermediate member, and as a result, the distance (L) between the optical modulation element held by the optical modulation element holding member and the projection lens held by the projection lens holding member is maintained, thereby suppressing focus shifts when the projector is in operation.

[0030] <Technology 3> In the projector described in Technology 1, the distance in the first direction between the holding position of the projection lens by the projection lens holding member and the connecting position by the first connecting member is greater than the distance in the first direction between the connecting position by the first connecting member and the connecting position by the second connecting member in the intermediate member, and the thermal expansion coefficient of the intermediate member is greater than the thermal expansion coefficient of the projection lens holding member. As a result, the effect of thermal deformation of the projection lens holding member can be reduced by thermal deformation of the section (D1) between the first connecting member and the second connecting member in the intermediate member. As a result, the distance (L) between the optical modulation element held by the optical modulation element holding member and the projection lens held by the projection lens holding member is maintained, so that focus shifts during projector operation are suppressed.

[0031] <Technology 4> In the projector described in any one of Techniques 1 to 3, the first connecting member fits into a hole (33) provided in the intermediate member. As a result, the projection lens holding member and the intermediate member are connected by the first connecting member.

[0032] <Technical 5> The projector described in Technical 4 is further provided with a rattle suppression member (51) that suppresses the first connecting member from shifting within the hole. As a result, rattle between the projection lens holding member and the intermediate member is suppressed, and the accuracy of the cancellation between the thermal deformation of the projection lens holding member and the thermal deformation of the section (D1) between the first connecting member and the second connecting member in the intermediate member is improved.

[0033] While embodiments have been described above with reference to the attached drawings, this disclosure is not limited to such examples. It is clear to those skilled in the art that various modifications, alterations, substitutions, additions, deletions, and equivalents can be conceived within the scope of the claims, and these are also understood to fall within the technical scope of this disclosure. Furthermore, the components of the embodiments described above can be combined in any way without departing from the spirit of the invention.

[0034] The technology disclosed herein is useful for projectors.

[0035] 1 Projector 3 Light modulation element 4 Projection lens 10 Projection lens holder 11 First bottom member 12 First front member 20 Light modulation element holder 21 Second bottom member 22 Second front member 23 Hole 30 Intermediate member 31 Bottom surface 32 Top surface 33 Hole 41 First connecting member 42 Second connecting member 51 Play suppression member 61 Lubrication layer

Claims

1. A projector comprising: an optical modulation element that modulates light from a light source into image light based on an input video signal; a projection lens that projects the image light; a projection lens holding member that holds the projection lens and extends in a first direction which is the optical axis direction of the projection lens; an optical modulation element holding member that holds the optical modulation element; an intermediate member that is disposed between the projection lens holding member and the optical modulation element holding member in a second direction intersecting the first direction and extends in the first direction; a first connecting member that connects the projection lens holding member and the intermediate member in the first direction; and a second connecting member that connects the optical modulation element holding member and the intermediate member in the first direction, wherein in the first direction, the second connecting member is located closer to the projection lens than the first connecting member, and the intermediate member and the projection lens holding member are thermally deformed in the first direction.

2. The projector according to claim 1, wherein the positions where the second connecting member and the first connecting member are provided are based on the thermal expansion coefficients of the intermediate member and the projection lens holding member, respectively.

3. The projector according to claim 1, wherein the distance in the first direction between the holding position of the projection lens by the projection lens holding member and the connecting position by the first connecting member is greater than the distance in the first direction between the connecting position by the first connecting member and the connecting position by the second connecting member in the intermediate member, and the thermal expansion coefficient of the intermediate member is greater than the thermal expansion coefficient of the projection lens holding member.

4. The projector according to claim 1, wherein the first connecting member fits into a hole provided in the intermediate member.

5. The projector according to claim 4, further comprising a rattle suppression member that prevents the first connecting member from shifting within the hole.

6. The projector according to claim 1, further comprising a lubricating layer between the intermediate member and the projection lens holding member, which reduces the frictional resistance of the surfaces in contact between the intermediate member and the projection lens holding member.

Images