JP2005301067A - Projection lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection lens, equipped with a diaphragm mechanism capable of making a light-shielding member move substantially linearly, using a simple structure. <P>SOLUTION: The diaphragm mechanism 1 is equipped with a fixed diaphragm 2 where an aperture 3 is formed, a movable diaphragm 4 for changing the shielding area of the aperture 3, and a pair of coupling members 5 and 6, attached to the movable diaphragm 4 and at a position outside the movable diaphragm 4 and supporting the movable diaphragm 4. A pair of coupling members 5 and 6 can rotate with the center at fulcrums 7 to 10 at respective attached positions, and the respective fulcrums 7 to 10 are positionally arranged so that four lines 11 to 13 linking the respective fulcrums 7 to 10 form a parallelogram or a rectangle, then the position of the movable diaphragm 4 is changed, to adjust the shielding area of the aperture 3. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a projection lens having a built-in diaphragm mechanism, and more particularly to a projection lens used in a projection display device that enlarges and projects an optical image formed on a light valve on a screen.

  In order to obtain a large screen image, a method of forming an optical image corresponding to a video signal on a light valve, irradiating the optical image with light, and enlarging and projecting the image on a screen by a projection lens is known (for example, patent document). 1). If a reflective light valve is used as the light valve, both high resolution and high pixel aperture ratio can be achieved, and a high-luminance projection image with high light utilization efficiency can be displayed.

  Patent Document 1 discloses a diaphragm mechanism that can change the light shielding area in the optical path of the illumination optical system in order to prevent the reflected light generated at the interface between the cover glass and the air of the external medium from entering the projection lens. Proposed configurations have been proposed. Japanese Patent Application Laid-Open No. 2004-228561 also proposes arranging such a diaphragm mechanism directly on the entrance pupil of the projection lens.

Patent Documents 2 to 4 propose a specific structure of a shutter opening / closing mechanism used for a camera body as a technique related to the diaphragm mechanism.
International Publication No. 02/088841 Pamphlet Japanese Patent Publication No. 44-24066 JP-A-56-4128 Japanese Patent Laid-Open No. 54-130021

  However, regarding the mechanism for moving the light shielding plate in the diaphragm mechanism, the above-mentioned Patent Document 1 only describes that the position of the light shielding plate is displaced in conjunction with the rotation of the motor, and a specific mechanism is disclosed. There wasn't. In addition, various technologies for converting the rotation of the motor to linear motion by combining various gears are known, but these are complicated in structure and have a large number of parts, and are not effective in terms of effective use of space. .

  The techniques described in Patent Documents 2 to 4 use an opening and a shielding plate in common with the aperture mechanism, but relate to a shutter opening / closing mechanism, and change the position of the shielding plate to shield the opening. It wasn't about adjusting the amount. In addition, the structure is complicated because a continuous opening / closing operation is required instead of simply moving the shielding plate.

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide a projection lens including an aperture mechanism that can move a light shielding member substantially linearly with a simple structure.

  In order to achieve the above object, a first projection lens of the present invention is a projection lens incorporating a diaphragm mechanism, and the diaphragm mechanism changes a fixed diaphragm having an opening and a shielding area of the opening. And a pair of connecting members attached to a position outside the movable diaphragm and supporting the movable diaphragm, the pair of connecting members at each of the attachment positions. The position of each fulcrum is arranged such that the four straight lines connecting the fulcrums form a parallelogram or rectangle, and the position of the movable diaphragm is changed to change the position of the movable diaphragm. The shielding area of the opening can be adjusted.

  The second projection lens of the present invention is a projection lens incorporating a diaphragm mechanism, and the diaphragm mechanism includes a fixed diaphragm in which an opening is formed, a plurality of movable diaphragms that change a shielding area of the opening, Each movable diaphragm, and a pair of connecting members that are attached to positions outside the movable diaphragms and support the movable diaphragms, and the pair of coupling members are centered on a fulcrum at each of the attachment positions. The positions of the respective fulcrums are arranged so that four straight lines connecting the fulcrum of each movable diaphragm and the fulcrum outside each movable diaphragm form a parallelogram or a rectangle, respectively. The shield area of the opening can be adjusted by changing the position of each movable diaphragm while the movable diaphragms overlap each other.

  According to the present invention, it is possible to adjust the shielding area of the opening by moving the light shielding plate substantially linearly with a simple structure, and it is possible to minimize a decrease in brightness while shielding unnecessary light.

  According to the first projection lens of the present invention, it is possible to adjust the shielding area of the aperture by moving the light shielding plate substantially linearly with a simple structure, and minimize the decrease in brightness while shielding unnecessary light. Can be suppressed. According to the second projection lens of the present invention, the light blocking plate can be moved substantially linearly with a simple structure, and it is advantageous for downsizing the diaphragm mechanism.

  In the first projection lens, the movable diaphragms are provided separately so as to face each other with the opening portion of the opening interposed therebetween, and the pair of connecting members is provided by the separately provided movable diaphragms. It is preferable to provide them separately so as to support them.

  In the second projection lens, the movable diaphragms are provided separately so as to face each other with the opening portion of the opening interposed therebetween, and a plurality of the individually provided movable diaphragms are provided. It is preferable that the connecting members are provided separately so as to support the movable diaphragms provided separately.

  As described above, according to the configuration in which the movable diaphragm is provided so as to face each other with the opening portion of the opening interposed therebetween, the opening can be shielded from both sides. For this reason, the cross-sectional shape of the light beam passing through the opening of the opening can be made symmetric with respect to the optical axis, and the optical performance can be improved. Further, since the amount of light to be shielded is shared by each movable diaphragm, the amount of light to be shielded by each movable diaphragm can be reduced.

  In the second projection lens, there are two movable diaphragms supported by the pair of connecting members, the first movable diaphragm and the second movable diaphragm, and in the state where the shielding area is maximized, The opening is shielded by the first and second movable diaphragms, and the movable diaphragm on the side of the opening facing the unshielded opening is the first movable diaphragm, and the pair of connections In any of the members, LA is a length of a straight line connecting the fulcrum outside the movable diaphragm and the fulcrum of the first movable diaphragm, and the fulcrum outside the movable diaphragm and the fulcrum of the second movable diaphragm. If the length of the straight line connecting the two is LB, it is preferable to satisfy the relationship of LB <LA <2 × LB.

  According to this configuration, it is possible to prevent the first movable diaphragm from protruding from the second movable diaphragm in the open state and the diaphragm mechanism from becoming large, and in a state where the shielding area of the opening is maximized, It is possible to prevent a gap from being formed between the first movable diaphragm and the second movable diaphragm.

  The movable diaphragms supported by the pair of connecting members are the first movable diaphragm and the second movable diaphragm. When the shielding area is maximized, the first and second movable diaphragms are supported. When the movable diaphragm is configured to shield the opening, and the movable diaphragm on the side facing the open portion that is not shielded is the first movable diaphragm, the first movable diaphragm is the second movable diaphragm. It is preferable that a chamfered portion is formed on the movable diaphragm side, and the second movable diaphragm is formed with an extending portion corresponding to the chamfered portion. According to this configuration, the extension amount of the movable diaphragm can be suppressed in the open state of the opening, which is advantageous for downsizing the diaphragm mechanism.

  In the first projection lens, it is preferable that the opening is circular, and the shape of the movable diaphragm is a substantially meniscus shape formed by an arc and a straight line.

  In the second projection lens, the opening is circular, and in a state where the shielding area is maximized, the shape formed by each of the movable diaphragms is a substantially meniscus shape formed by an arc and a straight line. Is preferred.

  According to the movable diaphragm having a straight line as described above, the shielding area of the aperture can be adjusted while the linear portion of the movable diaphragm moves in parallel, so that it is unnecessary to reduce the contrast while minimizing the decrease in brightness. Suitable for shielding light.

  In each projection lens, the position of the movable diaphragm can be set within a range from an open position where the movable diaphragm does not shield the opening to a position where the shielding area of the opening is maximized. Is preferred. According to this configuration, it is possible to arbitrarily adjust the contrast performance and light output of the projected image.

  Moreover, it is preferable that the shape of the part which faced the opening part of the said opening among the said movable diaphragms in the state which the said movable diaphragm blocked the said opening contains a curve. According to this configuration, when the unnecessary light cannot be sufficiently shielded by the linear shape, the unnecessary light can be shielded more completely to prevent a decrease in contrast.

  Further, the first and second projection lenses include a power source that rotates any one of the pair of connecting members around a fulcrum at a position outside the movable diaphragm among the fulcrums. Is preferred.

  Preferably, a gear mechanism in which gears are engaged with each other is provided, the power source is a motor, and the rotation of the connecting member is driven by the gear mechanism driven by the rotation of the motor. According to this configuration, the connecting member can be reliably rotated, and the rotation angle can be easily controlled.

  Also, a hole or groove is formed in one of the pair of connecting members, the power source is a motor, and a protrusion that engages with the hole or groove is provided to be rotatably attached to the motor. Preferably, a lever is further provided, and the rotation of the connecting member is caused by the rotation of the lever while the protrusion is engaged with the hole or groove by the rotation of the motor. According to this configuration, the components for rotational driving can be reduced in size, which is advantageous for securing a space when the diaphragm mechanism is mounted.

  Further, the projection lens is used for a projection display device, the power source is a motor, a signal corresponding to the intensity of the luminance signal of the video signal is sent to the motor, and the shielding area is set to the video signal. It is preferable to change the luminance signal according to the intensity of the luminance signal. According to this configuration, the contrast can be adjusted according to the luminance signal.

  The pair of connecting members are bent or curved so that when the position of the movable diaphragm changes, a part of the pair of connecting members protrudes from the movable diaphragm and is not exposed to the opening. It is preferable that there is.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1A shows a schematic configuration diagram of a main part of a diaphragm mechanism of a projection lens according to Embodiment 1 of the present invention. This figure is the figure which looked at the aperture mechanism 1 from the optical axis side. The fixed aperture 2 is disposed at the aperture position of the projection lens and is fixed to the lens barrel body of the projection lens. The fixed aperture 2 is formed with a circular opening 3 having a center 3a. In the present embodiment, the shielding area of the opening 3 of the fixed diaphragm 2 changes as the substantially half-moon shaped movable diaphragm 4 formed by a circular arc and a straight line moves.

  FIG. 1A shows a state where the shielding area by the movable diaphragm 4 is maximum. 1B shows a state in which the shielding area of the opening 3 is reduced in the diaphragm mechanism 1 shown in FIG. 1A, and FIG. 1C shows an open state of the opening 3.

  In FIG. 1A, the movable diaphragm 4 is supported by a pair of coupling members 5 and a coupling member 6, and is attached to the fixed diaphragm 2 via the coupling members 5 and 6. One ends of the connecting members 5 and 6 are fixed to the fixed diaphragm 2 at the positions of fulcrums 7 and 8, respectively. The fulcrums 7 and 8 are points that become the rotation centers of the connecting members 5 and 6, respectively. The fulcrums 7 and 8 are fixed points whose positions with respect to the fixed aperture 2 do not move. The fulcrums 7 and 8 are points on the central axis of the shaft when the connecting members 5 and 6 are attached to the fixed aperture 2 via a shaft, for example. The same applies to the following fulcrums 9, 10.

  The other ends of the connecting members 5 and 6 are attached to the movable diaphragm 4 at the positions of fulcrums 9 and 10, respectively. The fulcrums 9 and 10 are the points of rotation, and the connecting members 5 and 6 can rotate around the fulcrums 9 and 10. The fulcrums 9 and 10 move together with the movement of the movable diaphragm 4, but the position with respect to the movable diaphragm 4 is a fixed point that does not move.

  In the state of FIG. 1A, the straight line 11 connecting the fulcrums 7 and 8 and the straight line 12 connecting the fulcrums 9 and 10 are equal in length to L1 and parallel to each other. Further, the straight line 13 connecting the fulcrums 7 and 9 and the straight line 14 connecting the fulcrum 8 and the fulcrum 10 have the same length L2 and are parallel. Therefore, a parallelogram or rectangle is formed by the four straight lines 11 to 14, and the fulcrum 7 to 10 are at the positions of the apexes of the parallelogram or rectangle.

  A gear mechanism is attached to the connecting member 5, and a gear 15 whose center of rotation is the position of the fulcrum 7 is attached. A gear 16 is engaged with the gear 15. A motor (not shown) that is a power source is attached to the gear 16. By driving the gear mechanism by the rotation of the motor, the connecting member 5 can be driven to rotate about the fulcrum 7 via the gears 16 and 15.

  As the connection member 5 rotates about the fulcrum 7, the movable diaphragm 4 attached to the connection member 5 also moves at the position of the fulcrum 9. In this case, the center of rotation of the fulcrum 9 is the fulcrum 7. Since the distance of the straight line 13 connecting the fulcrum 7 and the fulcrum 9 is L2, the fulcrum 9 moves on the arc 17 having the radius L2 with the fulcrum 7 as the center.

  As the movable diaphragm 4 moves, the connecting member 6 also moves when attached to the movable diaphragm 4 at the fulcrum 10. Since the connecting member 6 is attached to the fixed aperture 2 at the fulcrum 8, the fulcrum 10 moves on an arc centered on the fulcrum 8. That is, since the distance of the straight line 14 connecting the fulcrum 8 and the fulcrum 10 is L2, the fulcrum 10 moves on the arc 18 having the radius L2 with the fulcrum 8 as the center.

  Since the fulcrum 7 and the fulcrum 8 are points on the fixed aperture 2, even when the gear 16 rotates, the positional relationship thereof does not change, and the position of the straight line 11 connecting the fulcrum 7 and the fulcrum 8 does not change. Further, even if the movable diaphragm 4 rotates, the distance L2 between the straight line 13 and the straight line 14 does not change. Furthermore, since the connecting member 6 moves in conjunction with the connecting member 5, the rotation angle around the fulcrum 7 of the connecting member 5 (straight line 13) and the rotation angle around the fulcrum 8 of the connecting member 6 (straight line 14) are The same.

  For this reason, in the state where the movable diaphragm 4 is moving, the parallelogram or rectangle formed by the four straight lines 11 to 14 changes the angle between the sides, but the shape is a parallelogram or rectangle. Will be maintained.

  FIG. 1B shows a state in which the movable diaphragm 4 has moved from the state of FIG. 1A. As the movable diaphragm 4 moves, the straight line 12 moves while maintaining a parallel relation with the straight line 11 whose position is fixed. For this reason, although the position of the straight line 12 changes, the direction thereof does not change, and the angle of the side 4a of the movable diaphragm 4 with respect to the straight line 12 does not change. Therefore, the parallel relationship between the side 4a before the movement and the side 4a after the movement indicated by a broken line is also maintained. In this case, the shielding amount of the opening 3 decreases while the straight side 4a moves in parallel.

  Since the amount of movement of the movable diaphragm 4 changes according to the amount of rotation of the motor that drives the gear 16, the shielding area of the opening 3 can be adjusted by controlling the amount of rotation of the motor.

  Here, the straight line 12 moves while maintaining a parallel relationship with the straight line 11, but the fulcrum 9 moves on the arc 17 and the fulcrum 30 moves on the arc 18 as described above. For this reason, the movement of the straight line 12 is not a movement on the same straight line. That is, the side 4a moves in the direction orthogonal to the side 4a and also moves in the direction of the side 4a. In this case, if the length of the side 4 a is sufficiently large, the outer periphery of the opening 3 does not protrude from the outer periphery of the movable diaphragm 4. Therefore, the shielding of the opening 3 is substantially the same as moving the movable diaphragm 4 so that the straight line 12 moves on the same straight line.

  FIG. 1C shows a state in which the movement of the movable diaphragm 4 has further advanced compared to the state of FIG. 1B. In FIG. 1C, when the opening 3 is in an open state and the opening 3 is not required to be shielded, the movable diaphragm 4 is held in this state. In addition, the connecting member 6 and the connecting member 5 each have a bent portion between a pair of fulcrums, and are bent so as to be recessed toward the opening 3 side. This prevents the connecting member 6 and the connecting member 5 from protruding from the movable aperture 4 and being exposed to the opening 3 during the movement of the movable aperture 4 as shown in FIGS. 1A to 1C. The bent portions of the connecting member 6 and the connecting member 5 may be curved portions.

  According to the present embodiment, the side 4a of the movable diaphragm 4 can be translated in a simple configuration. In this case, by controlling the amount of rotation of the motor that drives the gear 16, the amount of movement of the movable diaphragm 4 can be controlled, and the shielding area can be adjusted. That is, the position of the movable diaphragm 4 is a position that maximizes the shielding area of the opening 3 as shown in FIG. 1A from the open position where the movable diaphragm 4 does not shield the opening 3 as shown in FIG. 1C. It can be set within the range up to. As a result, the contrast performance and light output of the projected image can be arbitrarily adjusted.

(Embodiment 2)
FIG. 2A shows a schematic configuration diagram of a main part of the aperture mechanism of the projection lens according to Embodiment 2 of the present invention. This figure is the figure which looked at the aperture mechanism from the optical axis side. The fixed aperture 21 is disposed at the aperture position of the projection lens and is fixed to the lens barrel body of the projection lens. The fixed aperture 21 is formed with a circular opening 22 having a center 22a. FIG. 2A shows a state where the shielding area by the movable diaphragms 23 and 24 is maximum.

  In this embodiment, the movable diaphragm is composed of two movable diaphragms 23 and 24. In the state shown in FIG. 2A, the two movable diaphragms 23 and 24 are formed in a substantially half-moon shape formed by arcs and straight lines. Is forming. Although details will be described later, the shielding area of the circular opening 22 changes as the two movable diaphragms 23 and 24 move while overlapping.

  2B shows a state in which the shielding area of the opening 22 is reduced in the diaphragm mechanism 20 shown in FIG. 2A, and FIG. 2C shows an open state of the opening 22.

  In FIG. 2A, the movable diaphragm 23 is supported by a pair of coupling members 25 and a coupling member 26, and is attached to the fixed diaphragm 21 via the coupling members 25 and the coupling member 26. One ends of the connecting members 25 and 26 are fixed to the fixed diaphragm 21 at the positions of fulcrums 27 and 28, respectively. The fulcrums 27 and 28 are points on the rotation axis, which are the rotation centers of the connecting members 25 and 26, respectively, and the position with respect to the fixed aperture 21 is a fixed point that does not move. The fulcrums 27 and 28 are points on the central axis of the shaft when the connecting members 25 and 26 are attached to the fixed aperture 21 via a shaft, for example. The same applies to the following fulcrums 29, 30, 31, and 32.

  The other ends of the connecting members 25 and 26 are attached to the movable diaphragm 23 facing the unshielded open portion of the opening 22 at the positions of fulcrums 29 and 30, respectively. The fulcrums 29 and 30 are the points of rotation, and the connecting members 25 and 26 are rotatable around the fulcrums 29 and 30. The fulcrums 29 and 30 move together with the movement of the movable diaphragm 23, but the position with respect to the movable diaphragm 23 is a fixed point that does not move.

  In the state of FIG. 2A, the straight line 33 connecting the fulcrums 27 and 28 and the straight line 34 connecting the fulcrums 29 and 30 are equal in length L3 and parallel. The straight line 35 connecting the fulcrums 27 and 29 and the straight line 36 connecting the fulcrum 28 and the fulcrum 30 are equal in length and parallel to each other. Therefore, a parallelogram or a rectangle is formed by the four straight lines 33 to 36.

  A gear mechanism is attached to the connecting member 25, and a gear 37 whose center of rotation is the position of the fulcrum 27 is attached. A gear 38 is engaged with the gear 37. A motor (not shown) that is a power source is attached to the gear 38. By driving the gear mechanism by the rotation of the motor, the connecting member 25 can be rotated around the fulcrum 27 via the gears 38 and 37.

  The other movable diaphragm 24 is attached to the connecting members 25 and 26 at the positions of the fulcrums 31 and 32. The fulcrums 31 and 32 are points on the rotation axis, and the connecting members 25 and 26 are rotatable around the fulcrums 31 and 32. The fulcrums 31 and 32 move as the movable diaphragm 24 moves, but the position relative to the movable diaphragm 24 is a fixed point that does not move.

  Here, when comparing the diaphragm mechanism of FIG. 1A with the diaphragm mechanism of FIG. 2A, the shapes of the movable diaphragm 4 and the movable diaphragm 23 are different, but the shape of the center side of the opening is the same. Further, in FIG. 1A, a parallelogram or a rectangle is formed by the four straight lines 11 to 14, but in FIG. 2B, a parallelogram or a rectangle is formed by the four straight lines 33 to 36. On the other hand, the configuration of FIG. 2A differs from the configuration of FIG. 1A in that the connecting members 25 and 26 are attached not only to the movable diaphragm 23 but also to the other movable diaphragm 24 at the positions of the fulcrums 31 and 32. It has been.

  However, since the connecting members 25 and 26 are arranged with their positions shifted in the optical axis direction, when the movable diaphragm 23 moves, the movable diaphragm 23 and the movable diaphragm 24 overlap each other, and the movement of the movable diaphragm 23 is It is not obstructed by the movable diaphragm 24. Further, the connecting members 25 and 26 can rotate around the fulcrums 31 and 32, respectively, and the movable diaphragm 24 attached to the positions of the fulcrums 31 and 32 can be moved separately from the other movable diaphragm 23. .

That is, when the gear 38 rotates, the movable diaphragm 23 moves, but this movement is not restricted by the fulcrums 31, 32, and the movement is the same as the movement of the movable diaphragm 4 shown in FIG. 1A. become. Therefore, also in the configuration of FIG. 2A, when the gear 38 rotates, the parallelogram or rectangle formed by the four straight lines 33 to 36 changes the parallelogram or rectangle while changing the angle formed between the sides. It does not change to maintain the shape. For this reason, when the movable diaphragm 23 moves, the shielding amount of the opening 22 decreases while the straight side 23 a moves in parallel. Next, with respect to the movable diaphragm 24, the movable diaphragm 24 includes the fulcrums 31 and 32. Since it is attached to the connecting members 25 and 26 at the position, the movable diaphragm 24 also rotates as the connecting members 25 and 26 rotate. More specifically, in FIG. 2A, a straight line 33 that connects the fulcrum 27 and the fulcrum 28 and a straight line 39 that connects the fulcrum 31 and the fulcrum 32 have the same length L3 and are parallel. The straight line 40 connecting the fulcrum 27 and the fulcrum 31 and the straight line 41 connecting the fulcrum 28 and the fulcrum 32 are equal in length LB and parallel. Therefore, a parallelogram or a rectangle is formed by the four straight lines 33, 40, 39 and 41.

  Here, when comparing the diaphragm mechanism of FIG. 1A and the diaphragm mechanism of FIG. 2A, both the movable diaphragm 4 and the movable diaphragm 24 are substantially half-moon shaped. On the other hand, the configuration of FIG. 2A differs from the configuration of FIG. 1A in that the connecting members 25 and 26 are attached not only to the movable diaphragm 23 but also to the other movable diaphragm 23 at the positions of the fulcrums 29 and 30. It has been.

However, the connecting members 25 and 26 can rotate around the fulcrums 29 and 30, respectively. For this reason, the movement of the movable diaphragm 23 is the same as that of the movable diaphragm 4 shown in FIG. 1A, and is formed by four straight lines 33, 40, 39, and 41 when the gear 38 rotates. The parallelogram or rectangle maintains the shape of the parallelogram or rectangle while changing the angle formed between the sides. For this reason, the side 24a of the straight line moves in parallel with the movement of the movable diaphragm 24. Next, according to the above-described configuration, the fulcrum 29 moves on the arc of the radius LA with the fulcrum 27 as the center. 31 moves on an arc having a radius LB with the fulcrum 27 as the center. When the rotation angle is θ (radian), the movement amount D1 of the fulcrum 29 on the arc is expressed by the equation (1), and the movement amount D2 of the fulcrum 31 on the arc is expressed by the equation (2). In this case, the movement amount D1 can be considered as an approximate value of the parallel movement amount of the side 23a of the movable diaphragm 23, and the movement amount D2 can be considered as an approximate value of the parallel movement amount of the side 24a of the movable diaphragm 24.

Formula (1) D1 = LA × θ
Formula (2) D2 = LB × θ
Since LA> LB, the movement amount D1 of the fulcrum 29 is larger than the movement amount D2 of the fulcrum 31, and the difference ΔD is expressed by Expression (3).

Expression (3) ΔD = (LA−LB) × θ
If the movement amount of the fulcrum 29 integral with the movable diaphragm 23 and the movement amount of the fulcrum 31 integral with the movable diaphragm 24 are different, the movement amount of the side 23a of the movable diaphragm 23 and the movement amount of the side 24a of the movable diaphragm 24 are also Will be different.

  From equation (3), the difference in the amount of movement increases as the rotation angle increases. For this reason, the position of the side 23a of the movable diaphragm 23 facing the unshielded open portion of the opening 22 at the initial position where the shielding area is the maximum approaches the side 24a of the movable diaphragm 24 as the rotation proceeds. become. That is, the movable diaphragm 23 and the movable diaphragm 24 overlap each other. FIG. 2B shows this state.

  FIG. 2C shows a state in which the rotation further proceeds as compared with the state of FIG. 2B. In FIG. 2C, when the opening 22 is in an open state and it is not necessary to shield the opening 22, the movable diaphragms 23 and 24 are held in this state.

  Here, in addition to the relationship of LA> LB as described above, it is preferable to satisfy the relationship of the following formula (4).

Formula (4) LB <LA <2 × LB
When the length of L4 becomes 2 × LB or more, LA becomes too long compared to LB, and the moving amount of the movable diaphragm 23 becomes too large. In this case, in the state of FIG. 2C, the amount of protrusion of the movable diaphragm 23 from the diaphragm 24 becomes too large, which is disadvantageous for downsizing the diaphragm mechanism. 2C, when the movable diaphragm 23 and the movable diaphragm 24 are set so as to overlap each other, if the movable diaphragms 23 and 24 are moved in the direction of shielding the opening 22, the movement amount of the diaphragm 23 becomes too large. As a result, a gap is formed between the movable diaphragm 23 and the movable diaphragm 24.

  Although the number of movable apertures is increased and the number of fulcrums is increased in the present embodiment as compared with the first embodiment, it is not necessary to add a complicated mechanism such as increasing the number of gears. With this configuration, each side of the movable diaphragm can be moved in parallel.

  As in the first embodiment, the amount of movement of the movable diaphragms 23 and 24 can be controlled by controlling the amount of rotation of the motor that drives the gear 38 included in the gear mechanism, and the shielding area of the opening 22 is adjusted. be able to. Further, as in the first embodiment, the connecting members 25 and 26 are provided with bent portions or curved portions to prevent the connecting members 25 and 26 from being exposed to the opening 22.

  In this embodiment, space can be used more effectively than in the first embodiment. Specifically, when the state of FIG. 2C is compared with the state of FIG. 1C, in FIG. 1C, the substantially half-moon shaped movable diaphragm 4 of FIG. 1A moves out of the opening 3 as it is. On the other hand, in the state shown in FIG. 2A where the shielding area is maximized, the movable stops 23 and 24 forming a substantially half-moon shape are overlapped with each other in the state shown in FIG. 2C. Yes.

  1A and FIG. 2A, even if the substantially half-moon-shaped area of the movable diaphragm is the same, the configuration of FIG. The area occupied by can be reduced. For this reason, this Embodiment can achieve size reduction of an aperture mechanism, and becomes advantageous when the external dimension of the fixed aperture 21 has restrictions.

  In addition, although the description has been given with the example of two movable diaphragms, the movable diaphragm may be three or more and the connecting members 25 and 26 may be attached to each movable diaphragm.

(Embodiment 3)
FIG. 3A shows a schematic configuration diagram of a main part of the aperture mechanism of the projection lens according to Embodiment 3 of the present invention. The diaphragm mechanism 50 shown in FIG. 3A has the same configuration as the diaphragm mechanism 20 shown in FIG. 2A except that the shapes of the movable diaphragms 51 and 52 are different.

  FIG. 3A shows a state where the shielding area by the movable diaphragms 51 and 52 is maximum. In this state, a chamfered portion 53 is formed on both sides of the movable diaphragm 52 on the movable diaphragm 51 facing the open portion of the opening 22 that is not shielded. The movable diaphragm 52 is formed with an extending portion 54 so as to correspond to the chamfered portion 53.

  The operation when the gear 38 is rotated is the same as that of the diaphragm mechanism 20 shown in FIGS. 2A to 2C, and the shielding area of the opening 22 changes when the two movable diaphragms 51 and 52 move while overlapping. It will be. FIG. 3B shows a state in which the shielding area of the opening 22 is reduced in the diaphragm mechanism 50 shown in FIG. 3A, and FIG. 3C shows an open state of the opening 22.

  The aperture mechanism according to the present embodiment is advantageous for downsizing compared to the aperture mechanism according to the second embodiment. Specifically, since the chamfered portion 53 is formed, the movable diaphragms 51 and 52 are in a circle 55 centered on the center 2a of the opening 22 in the open state of the opening 22 in FIG. 3C. In contrast, the shape indicated by the broken line 56 in which the chamfered portion 53 is not formed protrudes from the circle 56.

  That is, by forming the chamfered portion 53, the extension amount of the movable diaphragm in the opened state of the opening 22 can be suppressed, the diaphragm mechanism can be reduced in size, and it is effective for the arrangement of the diaphragm mechanism in a limited space.

(Embodiment 4)
FIG. 4A shows a schematic configuration diagram of a main part of a diaphragm mechanism of a projection lens according to Embodiment 4 of the present invention. The diaphragm mechanism 60 shown in FIG. 4A is obtained by adding a movable diaphragm to the diaphragm mechanism 1 shown in FIG. 1A. In FIG. 4A, the movable diaphragm 4 and its connecting parts arranged on the upper side of the opening 3 have the same configuration as in FIG. 1A, and are assigned the same reference numerals, and detailed description thereof is omitted.

  A gear mechanism is attached to the connecting member 5, and a gear 70 whose center of rotation is the position of the fulcrum 7 is attached. A gear 71 is engaged with the gear 70. The gear 71 is attached to a motor (not shown) that is a power source. A gear 72 is further attached to the motor, and the gear 71 and the gear 72 rotate around the same rotation axis by the rotation of the motor.

  The gear 72 meshes with the gear 73. The gear 73 has a gear formed on the inner periphery of the ring-shaped member, and the gear 72 meshes with the gear on the inner periphery. The gears 72 and 73 are shown only for the main parts.

  By driving the gear mechanism by the rotation of the motor, the connecting member 5 rotates about the fulcrum 7 via the gears 71 and 70. The movement of the movable diaphragm 4 by the rotation of the connecting member 5 is as described in the first embodiment. Further, the gear 72 is rotated by the rotation of the motor, and the gear 73 engaged therewith is also rotated. This operation will be described later.

  A movable diaphragm 61 is disposed so as to face the movable diaphragm 4 across the opening of the opening 3. With this arrangement, the straight side 61 a of the movable diaphragm 61 faces the straight side 4 a of the movable diaphragm 4. One ends of the connecting members 62 and 63 are attached to the fixed diaphragm 2 at the positions of the fulcrums 64 and 65, respectively, and the other ends are attached to the movable diaphragm 61. The coupling mechanism on the movable diaphragm 61 side has the same configuration as that on the movable diaphragm 4 side, and the movement operation of the movable diaphragm 61 is the same as that of the movable diaphragm 4.

  A gear mechanism is attached to the connecting member 62 similarly to the connecting member 5, and a gear 74 whose center of rotation is the position of the fulcrum 64 is attached. A gear 75 is engaged with the gear 74. Further, a gear 76 is provided, and the gear 76 has the same rotating shaft as the gear 75.

  Here, as described above, the rotation of the gear 71 causes the connecting member 5 to rotate around the fulcrum 7, but at the same time, the ring-shaped gear 73 meshed with the gear 72 also rotates. When the gear 73 rotates, the gear 76 rotates, and accordingly, the gear 75 and the gear 74 also rotate, and the connecting member 62 rotates around the fulcrum 64.

  More specifically, when the gear 71 is moved in the direction of arrow A by the rotational drive of the motor, the movable diaphragm 4 is moved in the direction in which the opening 3 is opened by the rotation of the connecting member 5 by the rotation of the gear 70 interlocked therewith. In this case, the ring-shaped gear 73 rotates in the arrow B direction. Along with this, the gear 76 and the gear 75 rotate in the direction of the arrow C, and the movable diaphragm 61 moves in the direction in which the opening 3 is opened by the rotation of the connecting member 62 due to the rotation of the gear 74 interlocked therewith.

  FIG. 4A shows a state in which the shielding area of the opening 3 by the movable diaphragms 4 and 61 is maximum, and FIG. 4B shows that the shielding area is reduced by the movement of the movable diaphragms 4 and 61 and the opening 3 is opened. The state where the area of the part has increased is shown. FIG. 4C shows a state in which the movement of the movable diaphragms 4 and 61 has further progressed, and the opening 3 is completely open. From the state of FIG. 4C, when the rotation of the motor for rotating the gears 71 and 72 is reversed, the movable diaphragms 4 and 61 are moved in the direction of closing the opening 3.

  According to the present embodiment, the opening 3 can be shielded from both sides. For this reason, the cross-sectional shape of the light beam passing through the opening of the opening 3 can be made symmetric with respect to the optical axis, and the optical performance can be improved. Further, since the amount of light to be shielded is shared by each movable diaphragm, the amount of light to be shielded by each movable diaphragm can be reduced. Thus, if the amount of light that the movable aperture should block light can be reduced, the movable aperture can be brought into a surface state with low reflectivity. For example, black processing can be performed and contrast can be improved.

  In addition, although the example in which the movement of the gear mechanism on the movable diaphragm 4 side and the movement of the gear mechanism on the movable diaphragm 61 side are linked using the ring-shaped gear 73 has been described, a power source is provided to both the gear 71 and the gear 75. The rotation control of the gear 71 and the gear 75 may be provided separately and independently.

  Each movable aperture is not limited to the movable aperture 4 as shown in FIG. 1A, and may be a movable aperture as shown in FIGS. 2A and 3A.

(Embodiment 5)
FIG. 5A shows a schematic configuration diagram of the main part of the aperture mechanism of the projection lens according to Embodiment 5 of the present invention. The diaphragm mechanism shown in each of the above embodiments uses a gear mechanism to rotationally drive the connecting member, whereas the diaphragm mechanism 80 shown in FIG. 5A uses a pin and a hole that are protrusions for rotationally driving the connecting member. The engagement is used.

  The diaphragm mechanism 80 shown in FIG. 5A has the same coupling mechanism between the diaphragm mechanism 1 and the movable diaphragm shown in FIG. 1A. Accordingly, the movement of the movable diaphragm is the same for both. For this reason. Components having the same configuration as in FIG. 1A will be assigned the same reference numerals and detailed description thereof will be omitted, and description will be made focusing on the rotation drive mechanism of the connecting member.

  The movable diaphragm 4 is supported by a pair of connecting members 6 and 81. An extension part 81a is formed in the connecting member 81, and a hole 82 is formed in the extension part 81a. A pin 83 which is a protrusion is engaged with the hole 82. The pin 83 is provided at one end of the lever 84, and the other end of the lever 84 is attached to the rotating shaft of the motor 85 that is a power source. For easy understanding, the vicinity of the rotary drive mechanism is shown in a state where the fixed aperture 2 is broken.

  When the rotation shaft of the motor 85 rotates in the direction of arrow D, the lever 84 rotates in the direction of arrow E, and the extension portion 81a is also displaced in the direction of arrow E while the pin 83 engages with the hole 82. In this case, since the connecting member 81 is attached to the fixed aperture 2 at the position of the fulcrum 7, the extending portion 81 a rotates in the direction of arrow E around the fulcrum 7. By this rotation, the movable diaphragm 4 integrated with the fulcrums 9 and 10 moves in a direction to open the opening 3. Thereafter, as the motor 85 rotates, the area of the opening of the opening 3 increases. Since the hole 82 is a long hole and is longer than the diameter of the pin 83, the rotational movement of the lever 84 is not hindered by the hole 82.

  5A shows a state in which the shielding area of the opening 3 by the movable diaphragm 4 is the maximum, and FIG. 5B shows a state in which the open area is increased by the movement of the movable diaphragm 4. FIG. 5C shows a state in which the movement of the movable diaphragm 4 has further progressed, and the opening 3 is completely open.

  According to the present embodiment, the driving force is increased as compared with the case where a gear mechanism is used, but the component parts can be reduced in size as compared with the gear mechanism, which is advantageous for securing a space when the diaphragm mechanism is mounted.

  Although the example in which the pin 83 engages with the hole 82 has been described, a groove may be used instead of the hole 82.

  Further, the movable diaphragm is not limited to the movable diaphragm as shown in FIG. 1A, and may be a movable diaphragm as shown in FIGS. 2A, 3A, and 4A.

(Embodiment 6)
In each of the above-described embodiments, the shape of the movable diaphragm has been described as an example in which the shape of the portion facing the opening of the opening is a straight line. The movable diaphragm 90 in the diaphragm mechanism shown in FIG. 6A is an example in which the straight side 4a in the movable diaphragm 4 shown in FIG. 1A is a curved side 90a. The movable diaphragms 90 and 91 in the diaphragm mechanism shown in FIG. 6B are examples in which the straight side 4a is the curved side 90a and the straight side 61a is the curved side 91a in the configuration shown in FIG. 4A. is there.

  In this way, by changing the shape of the movable diaphragm, the light shielding state is also changed, and the cross-sectional shape of the light beam that is transmitted through the opening portion of the opening 3 is also changed. In the present embodiment, for example, when unnecessary light cannot be sufficiently shielded by a linear shape, unnecessary light can be shielded more completely by using a curved shape to prevent a decrease in contrast.

  In addition, although this Embodiment was demonstrated based on the structure of FIG. 1A and FIG. 4A, you may comprise based on the aperture mechanism which concerns on other embodiment.

(Embodiment 7)
FIG. 7 is a sectional view of a projection lens according to the seventh embodiment. In the projection lens 100 shown in this figure, a lens group 102 and a diaphragm mechanism 103 are arranged in a lens barrel 101. The diaphragm mechanism 103 is the diaphragm mechanism according to any one of the first to sixth embodiments. The projection lens 100 can be used, for example, in a projection display device that enlarges and projects an optical image formed on a light valve on a screen.

  Since the projection lens 100 includes the diaphragm mechanism 103, the position of the movable diaphragm 104 can be changed to change the shielding area of the opening 105. As described in the first to sixth embodiments, when the movable diaphragm 64 moves, the linear part or the curved part facing the open part of the meniscus member moves in parallel, so compared with the diaphragm that narrows the opening concentrically, The necessary light can be prevented from being blocked. For this reason, it is possible to improve the contrast performance of the projected image while blocking unnecessary light entering the projection lens 100 and minimizing the decrease in brightness.

  When the projection lens 100 is used in a projection display device, a signal corresponding to the intensity of the luminance signal of the video signal is sent to the motor that drives the movable aperture 104, and the shielding area of the opening 105 is set to the luminance signal of the video signal. You may make it change according to strength. In this case, if the luminance signal is strong, the shielding area is reduced and the white level is emphasized. If the luminance signal is weak, the contrast and the black level are emphasized. Display performance can be obtained.

  In each of the above-described embodiments, the movable diaphragm is described as an example of a substantially half-moon shape formed by a straight line, a curved line, and an arc. However, the present invention is not limited to this and may be a quadrangle. Further, the opening to be shielded is not limited to a circular opening, but may be a rectangular opening or the like.

  As described above, according to the present invention, it is possible to adjust the shielding area of the opening by moving the light shielding plate substantially linearly with a simple structure, and minimize the decrease in brightness while shielding unnecessary light. Therefore, the projection lens of the present invention is useful for a projection lens of a projection display device.

The top view in the state with the largest shielding area of the aperture mechanism of the projection lens which concerns on Embodiment 1 of this invention. FIG. 1B is a plan view of the projection lens stop mechanism shown in FIG. FIG. 1B is a plan view of the projection lens aperture mechanism shown in FIG. 1A when the aperture is open. The top view in the state with the largest shielding area of the aperture mechanism of the projection lens which concerns on Embodiment 2 of this invention. The top view in the middle of the movement of a movable aperture stop in the aperture mechanism of the projection lens shown in FIG. 2A. FIG. 2B is a plan view of the aperture mechanism of the projection lens shown in FIG. 2A when the aperture is open. The top view in the state with the largest shielding area of the aperture mechanism of the projection lens which concerns on Embodiment 3 of this invention. FIG. 3B is a plan view of the projection lens stop mechanism shown in FIG. FIG. 3B is a plan view of the aperture mechanism of the projection lens shown in FIG. 3A when the aperture is open. The top view in the state with the largest shielding area of the aperture mechanism of the projection lens which concerns on Embodiment 4 of this invention. 4B is a plan view of the projection lens stop mechanism shown in FIG. 4A during the movement of the movable stop. FIG. FIG. 4B is a plan view of the aperture mechanism of the projection lens shown in FIG. 4A when the aperture is open. The top view in the state with the largest shielding area of the aperture mechanism of the projection lens which concerns on Embodiment 5 of this invention. FIG. 5B is a plan view of the projection lens stop mechanism shown in FIG. 5A during the movement of the movable stop. FIG. 5B is a plan view of the aperture mechanism of the projection lens shown in FIG. 5A when the aperture is open. The top view of the aperture mechanism of the projection lens which concerns on Embodiment 6 of this invention. Sectional drawing of the projection lens which concerns on Embodiment 7 of this invention.

Explanation of symbols

1, 20, 50, 60 Diaphragm mechanism 2, 21 Fixed iris 3, 22 Opening 4, 23, 24, 51, 52, 61, 90, 91 Movable iris 5, 6, 25, 26, 62, 63, 81 Connecting member 7, 8, 9, 10, 27, 28, 29, 30, 31, 32, 64, 65, 66, 67 fulcrum 15, 16, 37, 38, 70, 71, 72, 73, 74, 75, 76 gears 100 Projection lens

Claims (15)

A projection lens with a built-in aperture mechanism,
The diaphragm mechanism is
A fixed aperture formed with an opening;
A movable diaphragm for changing the shielding area of the opening;
The movable diaphragm, and a pair of connecting members attached to a position outside the movable diaphragm and supporting the movable diaphragm,
The pair of connecting members are rotatable about fulcrums at the respective attachment positions, and the positions of the fulcrums are arranged so that four straight lines connecting the fulcrums form a parallelogram or a rectangle. And
A projection lens, characterized in that a shielding area of the opening can be adjusted by changing a position of the movable diaphragm. A projection lens with a built-in aperture mechanism,
The diaphragm mechanism is
A fixed aperture formed with an opening;
A plurality of movable diaphragms for changing the shielding area of the opening;
Each of the movable diaphragms, and a pair of connecting members that are attached to positions outside the movable diaphragms and support the movable diaphragms,
The pair of connecting members can rotate around a fulcrum at each attachment position, and four straight lines connecting the fulcrum of each movable aperture and the fulcrum outside each movable aperture are parallelograms or The position of each fulcrum is arranged so as to form a rectangle,
A projection lens, wherein the shielding area of the opening can be adjusted by changing the position of each movable diaphragm while the movable diaphragms overlap each other.   The movable diaphragms are provided separately so as to face each other across the opening of the opening, and the pair of connecting members are provided separately to support the individually provided movable diaphragms. The projection lens according to claim 1.   The movable diaphragms are provided separately so as to face each other across the opening of the opening, and each of the separately provided movable diaphragms is provided, and the pair of connecting members are provided separately. The projection lens according to claim 2, wherein the projection lens is provided separately to support each movable diaphragm. The movable diaphragms supported by the pair of connecting members are the first movable diaphragm and the second movable diaphragm, and the first and second movable diaphragms in the state where the shielding area is maximized. The opening is shielded, and the movable diaphragm on the side facing the unshielded opening of the opening is the first movable diaphragm,
In any one of the pair of connecting members, the length of a straight line connecting the fulcrum outside the movable diaphragm and the fulcrum of the first movable diaphragm is LA, the fulcrum outside the movable diaphragm, and the second If the length of the straight line connecting the fulcrum of the movable diaphragm is LB,
LB <LA <2 × LB
The projection lens according to claim 2, wherein the projection lens satisfies the following relationship. The movable diaphragms supported by the pair of connecting members are the first movable diaphragm and the second movable diaphragm, and the first and second movable diaphragms in the state where the shielding area is maximized. The opening is shielded, and when the movable diaphragm on the side facing the open portion that is not shielded among the openings is the first movable diaphragm,
The chamfered portion of the first movable aperture is formed on the second movable aperture side, and the extended portion of the second movable aperture is formed so as to correspond to the chamfered portion. The projection lens according to 2, 4 or 5.   4. The projection lens according to claim 1, wherein the opening is circular, and the shape of the movable diaphragm is a substantially meniscus shape formed by an arc and a straight line. 5.   7. The opening according to claim 2, 4, 5, or 6, wherein the opening is circular, and the shape formed by each of the movable diaphragms in a state where the shielding area is maximized is a substantially half-moon shape formed by an arc and a straight line. The projection lens described.   The position of the movable diaphragm can be set within a range from an open position where the movable diaphragm does not shield the opening to a position where the shielding area of the opening is maximized. The projection lens described in 1.   10. The projection lens according to claim 1, wherein a shape of a portion of the movable diaphragm facing the opening portion of the opening includes a curve in a state where the movable diaphragm blocks the opening. 11.   The projection lens according to claim 1, further comprising a power source that rotates any one of the pair of connecting members around a fulcrum at a position outside the movable diaphragm.   The projection lens according to claim 11, further comprising a gear mechanism in which gears are engaged with each other, wherein the power source is a motor, and the rotation of the connecting member is driven by the gear mechanism by the rotation of the motor. .   A hole or groove is formed in one of the pair of connecting members, the power source is a motor, and a lever that is rotatably attached to the motor is provided with a protrusion that engages with the hole or groove. The projection lens according to claim 11, further comprising: rotating the connecting member by rotating the lever while the protrusion is engaged with the hole or groove by rotation of the motor.   The projection lens is used in a projection display device, the power source is a motor, a signal corresponding to the intensity of a luminance signal of a video signal is sent to the motor, and the shielding area is set as a luminance signal of the video signal. The projection lens according to claim 11, wherein the projection lens is changed corresponding to the intensity of the projection.   The pair of connecting members has a bent portion or a curved portion so that when the position of the movable diaphragm changes, a part of the pair of connecting members protrudes from the movable diaphragm and is not exposed to the opening. The projection lens according to claim 1.

Images