JPH0552808U - Projector projection lens - Google Patents

Abstract

(57) [Abstract] [Purpose] To reduce the number of parts significantly and to provide an inexpensive projection lens for a projector. [Structure] Lens barrel body 30 and lens barrel body 3
The first group lens 32 and the second group lens 34, which are arranged so as to be independently movable in the optical axis direction within 0, and the first group lens 32 and the second group lens 34 are independently arranged on the optical axis. A focus ring 36 and a pin 38 that move in the direction are used to linearly move only one group that mainly contributes to zooming at the start of projection, and then the other one group performs focus adjustment. As a result, the mechanism for moving the lenses of the second group while maintaining a constant relationship is omitted.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to a projection lens for a projector, and more particularly to a projection lens for a projector that can change the magnification of a projected image.

[0002]

[Prior Art]

 As a conventional projection lens for this type of projector, there is one as shown in FIG. This projection lens is composed of two groups, a front lens group 12 and a rear lens group 14, and mainly comprises a lens barrel body 10, a front lens group 12, a rear lens group 14, a focus ring 16, a zoom ring 18, and a zoom cam ring 20. Etc.

The front lens group 12 is supported by a lens support frame 13 fixedly arranged in a focus ring 16, and a male screw 13 A is formed on the outer circumference of the lens support frame 13. The male screw 13A of the lens support frame 13 can be screwed with the female screw 22A formed on the inner peripheral surface of the sliding ring 22 slidably arranged in the lens barrel body 10. There is. A pin 24 is screwed onto the sliding ring 22, and the pin 24 is engaged with a guide groove 10A formed on the lens barrel body 10 to move the sliding ring 22 only in the optical axis direction. I will guide you to.

Therefore, since the sliding ring 22 does not rotate, when the focus ring 16 is rotated, the front lens group 12 can be moved in the optical axis direction by the action of the screws 13A and 22A, thereby adjusting the focus. Is done. The rear group lens 14 is supported by a lens support frame 15 slidably arranged in the lens barrel body 10. A pin 26 is screwed into the lens supporting frame 15, and the pin 26 engages with a guide groove 10B formed in the lens barrel body 10 to guide the lens supporting frame 15 so as to be movable only in the optical axis direction. To do.

On the other hand, the zoom cam ring 20 is rotatably arranged on the outer periphery of the lens barrel body 10 and can rotate together with the zoom ring 18. The zoom cam ring 20 has two cam grooves (not shown) formed therein, and these cam grooves each have a pin 24 planted in the sliding ring 22 and a pin planted in the lens support frame 15. 26 is slidably engaged.

Therefore, when the zoom cam ring 20 is rotated by the zoom ring 18, the sliding ring 22 having the pins 24 and 26 respectively engaged with the respective cam grooves of the zoom cam ring 20 and the lens support frame 15 (that is, the front The group lens 12 and the rear group lens 14) move while maintaining a constant relationship in the optical axis direction. This prevents the focus from moving during zooming.

Reference numeral 28 is a fixing screw for fixing the focus ring 16 to the lens barrel body 10 so as not to rotate.

[0008]

[Problems to be solved by the device]

 However, the conventional projection lens described above requires the zoom cam ring 20 and the like for moving the front lens group 12 and the rear lens group 14 while maintaining a constant relationship in the optical axis direction, and for focus adjustment. A mechanism for moving the front lens group 12 independently of the rear lens group 14 is also required, which requires a large number of parts, resulting in an increase in weight and a cost increase. In particular, the zoom cam ring 20 is expensive because it requires complicated machining and high precision.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a projection lens for a projector that can reduce the number of parts significantly and is inexpensive.

[0010]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention comprises a lens barrel body, a first lens group and a second lens group which are arranged in the lens barrel body so as to be independently movable in the optical axis direction. And an operation unit for independently moving the first group lens and the second group lens in the optical axis direction.

[0011]

[Action]

 The present invention focuses on the fact that once the projection lens of the projector is scaled to a desired magnification at the start of projection, it is rarely rescaled during use. That is, the first group lens and the second group lens are arranged so as to be independently movable in the optical axis direction, and are configured so that they can be independently moved and adjusted in the optical axis direction by the operation unit, and when the projection is started. Only one group, which mainly contributes to zooming, is moved linearly, and then the other group is used to adjust the focus. As a result, the mechanism for moving the lenses of the second group while maintaining a fixed relationship is omitted.

[0012]

【Example】

 Hereinafter, preferred embodiments of a projection lens of a projector according to the present invention will be described in detail with reference to the accompanying drawings. 1 is a sectional view showing an embodiment of a projection lens of a projector according to the present invention. As shown in the figure, this projection lens mainly comprises a lens barrel body 30, a front lens group 32, a rear lens group 34, a focus ring 36, a pin 38 and the like.

The front lens group 32 is supported by a lens support frame 33 slidably arranged in the lens barrel body 30. A pin 39 is screwed into the lens support frame 33, and the pin 39 engages with a guide groove 30A formed in the lens barrel body 30 to guide the lens support frame 32 movably only in the optical axis direction. To do. The focus ring 36 has a circumferential groove 36A and a female screw 36B formed on its inner peripheral surface. The circumferential groove 36A engages with a pin 39 implanted in the lens support frame 33, and the female screw 36B is a lens. It can be screwed with a male screw 30B formed on the outer periphery of the front part of the lens barrel body 30.

Therefore, when the focus ring 36 is rotated, the focus ring 36 moves in the optical axis direction by the action of the screws 30B and 36B, and the front lens group 32 moves the circumferential groove 36A of the focus ring 36, the pin 39 and the lens. It moves together with the focus ring 36 via the support frame 33. The rear group lens 34 is supported by a lens support frame 35 slidably arranged in the lens barrel body 30. A pin 38 is screwed into the lens support frame 35, and the pin 38 engages with a guide groove 30C formed in the lens barrel body 30 to guide the lens support frame 35 movably only in the optical axis direction. To do.

Fixing screws 40 and 42 are respectively screwed into the lens supporting frame 33 of the front lens group 32 and the lens supporting frame 35 of the rear lens group 34 via the guide grooves 30A and 30C of the lens barrel body 30. The front lens group 32 and the rear lens group 34 can be fixed to the lens barrel main body 30 immovably by tightening the fixing screws 40 and 42.

Next, the operation of the projection lens having the above configuration will be described. First, the fixing screws 40 and 42 are loosened so that the front lens group 32 and the rear lens group 38 can be moved within the lens barrel body 30 respectively. Next, the rear group lens 34, which mainly contributes to the magnification change of the projection image, is linearly moved in the optical axis direction by using the pin 38. This defocuses the projection image, but the projection image is almost desired. The magnification of

Subsequently, the focus ring 36 is rotated to move the front lens group 32 in the optical axis direction to adjust the focus of the projected image. Finally, the front group lens 32 and the rear group lens 34 are immovably fixed to the lens barrel main body 30 by tightening the fixing screws 40 and 42.

[0018]

[Effect of the device]

 As described above, according to the liquid crystal projector of the present invention, a highly accurate and expensive cam mechanism for moving the two lens groups while maintaining a constant relationship is omitted, so that the mechanism is simplified and the number of parts is reduced. It has the advantage of being able to reduce costs and prices.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a projection lens of a projector according to the present invention.

FIG. 2 is a sectional view showing an example of a projection lens of a conventional projector.

[Explanation of symbols]

 30 ... Lens barrel main body 32 ... Front group lens 33, 35 ... Lens support frame 34 ... Rear group lens 36 ... Focus ring 38, 39 ... Pin 40, 42 ... Fixing screw

Claims (2)

[Scope of utility model registration request] 1. A lens barrel main body, a first group lens and a second group lens which are arranged in the lens barrel main body so as to be independently movable in the optical axis direction, and the first group lens and A projection lens for a projector, comprising: an operation unit that independently moves the second group lens in the optical axis direction. 2. A projection lens for a projector according to claim 1, further comprising fixing means for immovably fixing the first lens group and the second lens group to the lens barrel body.