Projection-type image display device

Abstract

This projection-type image display device comprises: a projection lens; a lens holder that holds the projection lens; a first base member; first and second guide shafts that are provided to one of the lens holder and the first base member, and that extend parallel to each other in a first direction intersecting the direction in which the optical axis of the projection lens extends; and first and second guide bushes that are provided to the other one of the lens holder and the first base member, and that respectively slide on the first and second guide shafts. Two first guide bushes are provided with respect to the first guide shaft. One second guide bush is provided with respect to the second guide shaft.

Description

Projection type image display device

[0001] The present disclosure relates to a projection-type image display device in which lenses can be shifted in a direction intersecting an optical axis.

[0002] For example, Patent Document 1 discloses a projection-type image display device equipped with a lens shift mechanism that shifts a projection lens in a direction intersecting its optical axis. Specifically, the projection lens is shifted by sliding (translating) a lens holder that holds the projection lens.

[0003] JP 2015-4699 A

[0004] When a lens holder that holds a projection lens is slid, as in the projection image display device described in Patent Document 1, manufacturing variations can cause large variations in the sliding resistance of the lens holder.

[0005] Therefore, an object of the present disclosure is to suppress the variation in the sliding resistance of a lens holder that occurs when the lens holder that holds the projection lens is slid in a projection-type image display device that can shift the projection lens.

[0006] In order to solve the above-mentioned problems, according to one aspect of the present disclosure, there is provided a projection type image display device having: a projection lens; a lens holder that holds the projection lens; a first base member; first and second guide shafts that are provided on one of the lens holder and the first base member and extend parallel to each other in a first direction that intersects with the extension direction of the optical axis of the projection lens; and first and second guide bushes that are provided on the other of the lens holder and the first base member and slide on the first and second guide shafts, respectively, wherein two first guide bushes are provided for the first guide shaft and one second guide bush is provided for the second guide shaft.

[0007] According to the present disclosure, in a projection image display device capable of shifting a projection lens, it is possible to suppress the variation in sliding resistance of the lens holder that occurs when the lens holder that holds the projection lens is slid.

[0008] 1 is a schematic perspective view of a projection type image forming apparatus according to an embodiment of the present disclosure; 2 is a front perspective view of a lens holding mechanism in a state in which a projection lens is held; 3 is a rear perspective view of the lens holding mechanism in a state in which a projection lens is held; 4 is an exploded perspective view of the lens holding mechanism; 5 is a perspective view of a lens shift mechanism; 6 is a front view of the lens shift mechanism;

[0009] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, more detailed explanation than necessary may be omitted. For example, detailed explanation of well-known matters or redundant explanation of substantially the same configuration may be omitted. This is to avoid unnecessary redundancy in the following explanation and to facilitate understanding by those skilled in the art.

[0010] The inventor(s) provide the accompanying drawings and the following description to enable those skilled in the art to fully understand the present disclosure, and do not intend for them to limit the subject matter described in the claims.

[0011] Hereinafter, an imaging device according to an embodiment of the present disclosure will be described with reference to the drawings.

[0012] Fig. 1 is a schematic perspective view of a projection type image forming apparatus according to an embodiment of the present disclosure. Fig. 2 is a front perspective view of a lens holding mechanism holding a projection lens. Fig. 3 is a rear perspective view of the lens holding mechanism holding a projection lens. Fig. 4 is an exploded perspective view of the lens holding mechanism.

[0013] Note that the X-Y-Z Cartesian coordinate system shown in the figures is intended to facilitate understanding of the embodiments of the present disclosure and does not limit the embodiments of the present disclosure. The X-axis direction is the front-to-rear direction of the projection-type image display device, the Y-axis direction is the left-to-right direction, and the Z-axis direction is the height direction. The optical axis of the projection lens extends in the X-axis direction. Furthermore, in this specification, the image projection direction of the projection-type image display device, i.e., the side of the projection-type image display device where the screen exists, is referred to as the "front side," and the opposite side is referred to as the "rear side."

[0014] 1, a projection-type image display device 10 according to this embodiment has a housing 12 and a projection lens 100 mounted on the housing 12. The projection-type image display device 10 projects an image onto a screen or the like via the projection lens 100.

[0015] 2 and 3, in this embodiment, the projection lens 100 is held by a lens holding mechanism 14 mounted in the housing 12. The lens holding mechanism 14, which will be described in detail later, is configured to hold the projection lens 100 so that the projection lens 100 can be attached and detached and can be shifted in directions (Y-axis direction and Z-axis direction) intersecting the direction in which the optical axis C of the projection lens 100 extends (X-axis direction).

[0016] 4, the lens holding mechanism 14 has a lens mount mechanism 16 that detachably holds the projection lens 100, and a lens shift mechanism 18 that shifts the lens mount mechanism 16 in directions (Y-axis direction, Z-axis direction) that intersect with the extension direction (X-axis direction) of the optical axis C of the projection lens 100. The lens mount mechanism 16 is fixed to the front end of the lens shift mechanism 18.

[0017] Fig. 5 is a perspective view of the lens shift mechanism, Fig. 6 is a front view of the lens shift mechanism, and Fig. 7 is an exploded perspective view of the lens shift mechanism.

[0018] As shown in FIGS. 5 to 7 , the lens shift mechanism 18 according to this embodiment includes a lens holder 20 that holds the projection lens 100 and a first base member 22 that supports the lens holder 20 slidably in a first direction (Z-axis direction) that intersects with the direction in which the optical axis C of the projection lens 100 extends (X-axis direction). In this embodiment, the lens shift mechanism 18 further includes a second base member 24 that supports the first base member 22 slidably in a second direction (Y-axis direction) that intersects with both the direction in which the optical axis C extends (X-axis direction) and the first direction (Z-axis direction). The base member 24 functions as a bracket for fixing the lens shift mechanism 18 to the housing 12. The lens holder 20, the first base member 22, and the second base member 24 are frame-shaped members so that the projection lens 100 passes through the lens shift mechanism 18, as shown in FIG. 3 .

[0019] In order for the lens holder 20 to slide relative to the first base member 22, the lens shift mechanism 18 has a first guide shaft 26 and a second guide shaft 28 that extend in a first direction (Z-axis direction) that intersects with the extension direction (X-axis direction) of the optical axis C of the projection lens 100. The lens shift mechanism 18 also has a first guide bush 30 and a second guide bush 32 that slide on the first and second guide shafts 26, 28, respectively.

[0020] Specifically, the first and second guide shafts 26, 28 are rod-shaped members made of, for example, a metal material and extending linearly. In this embodiment, the first and second guide shafts 26, 28 are attached to the first base member 22 parallel to each other and spaced apart in the second direction (Y-axis direction). For example, both ends of the first and second guide shafts 26, 28 are fixed to the first base member 22 via fixing screws 34.

[0021] The first and second guide bushes 30, 32 are cylindrical members that slide on the outer circumferential surfaces of the first and second guide shafts 26, 28. For example, the first and second guide bushes 30, 32 are members that include a cylindrical sleeve made of a metal material and a plurality of metal balls that are provided in the sleeve and roll on the outer circumferential surfaces of the first and second guide shafts 26, 28.

[0022] In this embodiment, the first and second guide bushes 30, 32 are provided on the lens holder 20. Specifically, the first guide bush 30 is inserted into a mounting hole 20a formed in the lens holder 20 and penetrating in a first direction (Z-axis direction). The second guide bush 32 is inserted into a mounting hole 20b formed in the lens holder 20 and penetrating in the first direction (Z-axis direction). The first and second guide bushes 30, 32 are fixed to the lens holder 20 via adhesive filled between their outer peripheral surfaces and the inner peripheral surfaces of the mounting holes.

[0023] Furthermore, for reasons that will be explained later, two first guide bushes 30 are provided for the first guide shaft 26, and one second guide bush 32 is provided for the second guide shaft 28.

[0024] In this embodiment, the lens holder 20 is shifted in a first direction (Z-axis direction) relative to the first base member 22 via a first motor 36 (first drive source) and a first linear motion mechanism 38. The first motor 34 is fixed to the first base member 22. The first linear motion mechanism 38 is composed of a feed screw 38a connected to the first motor 36 and a nut 38b provided on the lens holder 20 and engaging with the feed screw 38a. Note that the present disclosure does not limit the means for shifting the lens holder 20 relative to the first base member 22. For example, the lens holder 20 may be shifted manually by a user. In addition, in this embodiment, a first position detection sensor 40 that detects the position of the lens holder 20 in the first direction is provided on the first base member 22.

[0025] In order for the first base member 22 to slide relative to the second base member 24, the lens shift mechanism 18 has a third guide shaft 42 and a fourth guide shaft 44 that extend in a second direction (Y-axis direction) that intersects both a first direction (Z-axis direction) that intersects with the extension direction (X-axis direction) of the optical axis C of the projection lens 100. The lens shift mechanism 18 also has a third guide bush 46 and a fourth guide bush 48 that slide on the third and fourth guide shafts 42, 44, respectively.

[0026] Specifically, the third and fourth guide shafts 42, 44 are rod-shaped members made of a metal material and extending linearly, similar to the first and second guide shafts 26, 28. In the present embodiment, the third and fourth guide shafts 42, 44 are attached to the second base member 24 parallel to each other and spaced apart in the first direction (Z-axis direction). For example, both ends of each of the first and second guide shafts 26, 28 are fixed to the second base member 24 via fixing screws 50.

[0027] The third and fourth guide bushes 46, 48, like the first and second guide bushes 30, 32, are cylindrical members that slide on the outer circumferential surfaces of the third and fourth guide shafts 42, 44. For example, the third and fourth guide bushes 46, 48 are members that include a cylindrical sleeve made of a metal material and a plurality of metal balls that are provided in the sleeve and roll on the outer circumferential surfaces of the third and fourth guide shafts 42, 44. In the present embodiment, the first, second, third, and fourth guide bushes 30, 32, 46, 48 are the same guide bush.

[0028] In the present embodiment, the third and fourth guide bushes 46, 48 are provided on the first base member 22. Specifically, the third guide bush 46 is inserted into a mounting hole 22a formed in the first base member 22 and penetrating in the second direction (Y-axis direction). The fourth guide bush 48 is inserted into a mounting hole (not shown) formed in the lens holder 20 and penetrating in the second direction (Z-axis direction). The third and fourth guide bushes 46, 48 are fixed to the first base member 22 via adhesive filled between their outer peripheral surfaces and the inner peripheral surfaces of the mounting holes.

[0029] Furthermore, for reasons that will be explained later, two third guide bushes 46 are provided for the third guide shaft 42, and one second guide bush 48 is provided for the fourth guide shaft 44.

[0030] In this embodiment, the first base member 22 is shifted in the second direction (Y-axis direction) relative to the second base member 24 via a second motor 52 (second drive source) and a second linear motion mechanism 54. The second motor 52 is fixed to the second base member 24. The second linear motion mechanism 54 is composed of a feed screw 54a connected to the second motor 52 and a nut 54b provided on the first base member 22 and engaged with the feed screw 54a. Note that the present disclosure does not limit the means for shifting the first base member 22 relative to the second base member 24. For example, the first base member 22 may be shifted manually by a user. In addition, in this embodiment, a second position detection sensor 56 is provided on the second base member 24 to detect the position of the first base member 22 in the second direction.

[0031] 6 and 7, the first and third guide shafts 26 and 42 are provided with two first and third guide bushes 30 and 46, respectively. On the other hand, the second and fourth guide shafts 28 and 44 are provided with one second and fourth guide bush 32 and 48, respectively. The reason for this will be explained below.

[0032] FIG. 8 is a schematic diagram of a lens holder, first and second guide shafts, and first and second guide bushes in a lens shift mechanism of a comparative example.

[0033] 8, two first guide bushes 130 are provided for the first guide shaft 126. Also, two second guide bushes 132 are provided for the second guide shaft 128.

[0034] Comparing this embodiment with the comparative example, in the embodiment shown in Fig. 6, the lens holder 20 is slidably supported on two guide shafts 26, 28 via three guide bushes 30, 32. In the comparative example shown in Fig. 8, the lens holder 120 is slidably supported on two guide shafts 126, 128 via four guide bushes 130, 132.

[0035] Considering the straightness of the lens holder, it is preferable to provide a lens holder with as many guide bushes as possible. However, as the number of guide bushes increases, the sliding resistance that occurs when the lens holder is slid increases. This will be explained in detail.

[0036] 6, first, the two first guide bushes 30 must be provided in the lens holder 20 so that their central axes are aligned on the same line. Then, the second guide bush 32 must be provided in the lens holder 20 so that its central axis is parallel to the central axis of the first guide bush 30.

[0037] 8 , first, two first guide bushes 130 must be provided in the lens holder 120 so that their respective central axes are aligned on the same line. Also, two second guide bushes 132 must be provided in the lens holder 120 so that their respective central axes are aligned on the same line. Then, the second guide bushes 132 must be provided in the lens holder 120 so that their central axes are parallel to the central axis of the first guide bushes 130.

[0038] To meet this requirement, the lens holder is formed with a mounting hole into which the guide bush is inserted, and the guide bush is inserted into the mounting hole with a predetermined tolerance.

[0039] If the guide bushes are tilted within a predetermined tolerance within the corresponding mounting holes, the lens holder of the comparative example, which has a large number of guide bushes, tends to have a larger variation in sliding resistance than the lens holder of the present embodiment, which has a small number of guide bushes. In particular, in the case of the comparative example, the sliding resistance may become too large, making it impossible for the lens holder 120 to slide.

[0040] Specifically, when the central axes of two guide bushes sliding on one guide shaft are aligned on the same straight line, the sliding resistance of each of the two guide bushes sliding on the outer circumferential surface of the guide shaft (i.e., the sliding resistance of the lens holder) is lowest.On the other hand, when the central axes of two guide bushes sliding on one guide shaft are inclined to the maximum within a predetermined tolerance, extend on the same plane, and intersect each other at the maximum angle, the sliding resistance of each of the two guide bushes sliding on the outer circumferential surface of the guide shaft is highest.

[0041] Therefore, the maximum value of sliding resistance that can be exhibited by lens holder 120 of the comparative example, which is equipped with first guide shaft 126 on which two first guide bushes 130 slide and second guide shaft 128 on which two guide bushes 132 slide, as shown in Fig. 8, is greater than the maximum value of sliding resistance that can be exhibited by lens holder 20 of the present embodiment, which is equipped with only first guide shaft 26 on which two first guide bushes 30 slide, as shown in Fig. 6. Therefore, the range of variation in sliding resistance of lens holder 20 of the present embodiment is kept smaller than the range of variation in sliding resistance of lens holder 120 of the comparative example.

[0042] In this embodiment, the sliding resistance of the lens holder 20 is greatest when the central axes of the two first guide bushes 30 are inclined to the maximum within a predetermined tolerance, extend on the same plane, and intersect with each other at the maximum angle. The second guide bush 32 does not substantially contribute to the sliding resistance of the lens holder 20 as long as the inclination of its central axis is within a predetermined tolerance.

[0043] In contrast, in the comparative example, the sliding resistance of the lens holder 120 is at its maximum when the central axes of the two first guide bushes 130 are inclined to the maximum within a predetermined tolerance, extend on the same plane, and intersect with each other at the maximum angle, while the central axes of the two second guide bushes 132 are inclined to the maximum within a predetermined tolerance, extend on the same plane, and intersect with each other at the maximum angle. In this case, there is a possibility that the motor will not be able to drive the lens holder 120.

[0044] In the present embodiment, one second guide bush 32 is provided on the second guide shaft 28, and one fourth guide bush 48 is provided on the fourth guide shaft 44. Therefore, the second and fourth guide shafts 28, 44 can be made shorter than the first guide shaft 26, which is provided with two first guide bushes 30, and the third guide shaft 42, which is provided with two third guide bushes 46. As a result, the lens shift mechanism 18 is made lighter.

[0045] According to the present embodiment as described above, in a projection-type image display device capable of shifting a projection lens, it is possible to suppress the variation in the sliding resistance of the lens holder that occurs when the lens holder that holds the projection lens is slid.

[0046] Although the embodiments of the present disclosure have been described above with reference to the above-mentioned embodiments, the embodiments of the present disclosure are not limited to these.

[0047] For example, in the above-described embodiment, as shown in Fig. 7, the first and second guide shafts 26, 28 are provided on the first base member 22, and the first and second guide bushes 30, 32 are provided on the lens holder 20. However, the embodiments of the present disclosure are not limited to this. For example, the first and second guide shafts may be provided on the lens holder, and the first and second guide bushes may be provided on the first base member.

[0048] 7 , in the above-described embodiment, the third and fourth guide shafts 42, 44 are provided on the second base member 24, and the third and fourth guide bushes 46, 48 are provided on the first base member 22. However, the embodiment of the present disclosure is not limited to this. For example, the third and fourth guide shafts may be provided on the first base member, and the third and fourth guide bushes may be provided on the second base member.

[0049] Therefore, a projection type image display device according to an embodiment of the present disclosure broadly comprises a projection lens, a lens holder that holds the projection lens, a first base member, first and second guide shafts that are provided on one of the lens holder and the first base member and extend parallel to each other in a first direction that intersects with the extension direction of the optical axis of the projection lens, and first and second guide bushes that are provided on the other of the lens holder and the first base member and slide on the first and second guide shafts, respectively, wherein two first guide bushes are provided for the first guide shaft and one second guide bush is provided for the second guide shaft.

[0050] As described above, the above-described embodiments have been described as examples of the technology of the present disclosure. For this purpose, drawings and detailed descriptions are provided. Therefore, the components described in the drawings and detailed descriptions may include not only components essential for solving the problem, but also components that are not essential for solving the problem in order to exemplify the above-described technology. Therefore, the fact that these non-essential components are described in the drawings or detailed descriptions should not be interpreted as immediately indicating that these non-essential components are essential.

[0051] Furthermore, since the above-described embodiments are intended to illustrate the technology of the present disclosure, various modifications, substitutions, additions, omissions, etc. may be made within the scope of the claims or their equivalents.

[0052] The present disclosure is applicable to a projection-type image display device in which the projection lens can be shifted.

Claims

1. A projection type image display device comprising: a projection lens; a lens holder that holds the projection lens; a first base member; first and second guide shafts that are provided on one of the lens holder and the first base member and extend parallel to each other in a first direction that intersects with the extension direction of the optical axis of the projection lens; and first and second guide bushes that are provided on the other of the lens holder and the first base member and slide on the first and second guide shafts, respectively; two first guide bushes are provided for the first guide shaft; and one second guide bush is provided for the second guide shaft.

2. The projection type image display device according to claim 1, wherein said second guide shaft is shorter than said first guide shaft.

3. The projection type image display device according to claim 1, further comprising a first drive source that shifts said lens holder in said first direction.

4. A projection type image display device as described in claim 1, further comprising: a second base member; third and fourth guide shafts provided on one of the first base member and the second base member and extending in a second direction intersecting both the extension direction and the first direction; and third and fourth guide bushes provided on the other of the first base member and the second base member and sliding on the third and fourth guide shafts, respectively; two third guide bushes provided for the third guide shafts; and one fourth guide bush provided for the fourth guide shaft.

5. The projection type image display device according to claim 4, wherein said fourth guide shaft is shorter than said third guide shaft.

6. The projection type image display device according to claim 4, further comprising a second drive source for shifting said first base member in said second direction.

7. The projection type image display device according to claim 4, wherein the first, second, third and fourth guide bushes are the same guide bush.

8. The projection type image display device according to claim 1, further comprising a lens mount mechanism provided on said lens holder for detachably holding said projection lens.

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