JPH0338608A - Variable power optical system - Google Patents

Abstract

PURPOSE:To vary the power only by the movement of the whole lens system without relative movement among individual lenses by using an image formation optical system which has a flexible lens varying in surface curvature by deformation. CONSTITUTION:The image formation optical system is put in one lens barrel on the whole and moved on the whole by a driving means in the direction of the optical axis, and its 1st and 3rd lens groups 10 and 30 are deformed to vary the power. When the power is varied, the internal diameters of frame bodies 41 and 42 are varied by displacing the frame bodies 41 and 42 relatively to the lens barrel 40 according to the movement of the lens barrel 40 to generate pressing forces to the 1st and 3rd lenses 10 and 30, thereby deforming the lens.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a variable magnification optical system that can change the magnification of an image relative to an object.

[Prior Art and Problems to be Solved by the Invention] Conventionally, variable magnification optical systems used in copying machines, etc., have the ability to relatively change the overall optical path length and the position of objects, images, and lens systems when changing magnification. There are two types: one type that changes the distance between the object and image without changing the power of the lens system itself, and the other type that moves the entire lens system while keeping the distance between the object and image constant.

However, the first type requires a mechanism for making the entire optical path length variable, making the variable magnification mechanism complicated.

In addition, in the second type, if the relative distance between the lens and the lens in the lens system is constant, the distance between the object and image can only be constant at two points of magnification that are sandwiched between equal magnification. It is necessary to change the power of the lens system itself by changing the relative distance between the lens and the lens. Therefore, a cam mechanism or the like is required for relative movement of the lenses, which increases the space occupied by the optical system.

[Purpose of the Invention] This invention has been made in view of the above problems, and aims to simplify the mechanism by keeping the object-image distance constant, while also eliminating the need for relative displacement between lenses, which is advantageous in terms of space. The purpose is to provide a variable magnification optical system.

[Means for Solving the Problems] In order to achieve the above object, a variable magnification optical system according to the present invention includes an imaging optical system that partially includes a flexible lens whose surface curvature changes by deformation; a driving means for moving the imaging optical system as a whole along its optical axis during zooming; and a driving means for deforming the flexible lens by applying force from the outer periphery of the flexible lens along with this moving operation. It is characterized by comprising a deforming means for changing the focal length.

In addition, when considering the ease of magnification control due to deformation and the influence of various aberrations, the change in power of the entire system is Δφ8, the change in power of the flexible lens is Δφi, and the maximum magnification of the entire system is rn.
a a X, the minimum magnification is m m + n, rn
It is preferable to satisfy each condition of s l n. If the upper limit of the equation is exceeded, the sensitivity of the power change to deformation becomes high and control becomes difficult; if it is below the lower limit, the sensitivity becomes low and the degree of deformation becomes becomes large, making it difficult to correct various aberrations. (2) If the upper limit of the formula is exceeded, the range of change in magnification becomes too large, making both power control and aberration correction difficult.

[Example] The present invention will be described below based on the drawings. FIG. 1 shows an embodiment of a variable magnification optical system according to the present invention.

The variable power lens shown in this example has negative power l!
1 lens group 10 and 12 lens group 2 having positive power
It is a completely symmetrical system consisting of a third lens group 30 having a negative power and a third lens group 30 having a negative power.
has a meniscus shape with weak power.

Which lens to deform among the lenses in the optical system is determined by considering the effects of aberrations due to deformation, etc., but it is preferable to select lenses that are not easily affected by these effects. Therefore, in this example, tJ41 at both ends with weak power. The third lens group 10.30 is targeted for deformation.

The imaging optical system shown in FIG. 1 is housed as a whole in one lens barrel, and is moved as a whole in the optical axis direction by a driving means (not shown). W43 lens group 10.
By deforming 30, the magnification is changed.

The specific design values for this lens are as shown in Table 1 on page 7. The symbol 0 in the table indicates the magnification of the entire system, r is the radius of curvature of each lens surface, and d is the distance between the surfaces (lens thickness and air spacing), na and no are respectively d-Line (58
8 nm), the refractive index at e-line (546 nm), vd represents the Abbe number of each lens, and Fe represents the focal length at e-line.

1st. 3rd lens group 10.30 -1,415@, -1
,00M, the curvature at -0,707 times is as shown in Table 2.

As you can understand from this table, -1, 4 with equal magnification in between
The curvature is equal between 15 times and -0,707 times.

The power of the whole system φ8 at each magnification, 1st. The power φhφ3 of the third group is as shown in No. 311.

Note that the ■expression and ■expression take the following values.

m s I n Lens aberrations at each magnification are shown in FIGS. 2 to IJ4. Fig. 2 shows the data when magnified by -1,415 times, W43 shows the data when multiplied by -1,000 times, and Fig. 4 shows data when multiplied by -0,707 times.

Regarding the spherical aberration in each figure, the spherical aberration SA is the solid line, and the sine condition SC
is indicated by a broken line, and for axial chromatic aberration and lateral chromatic aberration, e-Line (546 nm), d-Line (546 nm)
88nm) + F-Line (488na+). Astigmatism is shown in the sagittal direction S by a solid line and in the meridional direction by a broken line.

Table 1 r Variable variable 81.685 -180.000 -82.400 217, 200 -217.200 82, 400 160,000 -81.685 Variable variable d n・ 3.000 1.54345 3.000 7. 750 1.89661 7.650 2.020 1.58482 7.780 2.020 1.58482 7.650 7.750 1.69661 3.000 3.000 1.54345 nd νd 1.54072 47.2 1. 69350 53.2 1.58144 40.7 1.58144 40.7 1.69350 53.2 1.54072 47.2 1.415 14.45 -128.000 -213.831 213.831 128.000 Second Table -1,000 12,40 137,272 -248,000 248,000 137,272 0,70? 10.29 128.000 213.831 213.831 128.000 Table 3 1.415 -1.000 -0.707 φe 4.368x to-3 4,239X 10-' 4.368X 10-3 φ1 1 .683X 10-3 1.751X 10-3 1.683X 10-3 φ3 -1.683X 10-3 1.751X 10-3 1.683X 10-' See other examples of the above lens design on page 9. This example is shown in Table 4: 11. The only difference is the refractive index and curvature of the third lens group 10.30 from the above example, and the other shapes are the same as the above example.

1st. The curvature of the third lens group at each magnification is shown in the fJiS table, the power φB of the entire system at each magnification, the first . Third group power φ1. φ3 is as shown in Table 6.

Note that the ■expression and ■expression take the following values.

The aberrations of the lens at each magnification are shown in FIGS. 15 to 7. Figure 15 is -1,000 times, Figure 6 is 1,
Figure 7 shows the data at -0,707 times.

(Left below) Table 4 Variable 81.685 -180.000 82, 400 217, 200 -217.200 82, 400 160, 0071 81.685 Variable d n11nd v d3.00
0 1.49399 1.49186 57.43.0
00 7.750 1.69661 1.69350 5
3.27.650 2.020 1.584g2 1.58144 40.
77.780 2.020 1.584g2 1.58144 40
．． 77.650 7.750 1.69661 1.69350 5
3.23.000 3.000 1.49399 1.49186 5
7.41.415 14.45 124.875 213.691 213.691 124.875 Table 5 -1,000 12,40 133,500 248,000 248,000 133,500 0,707 10,29 -124 ,875 213,891 213,691 124,875 Table 6 -1,415 -1,000 -0,707 φe 4.354X 10-3 4.235X 10-' 4.354X 10-3 φ1 1.626X 10 -3 1.694X 10-" 1.626X 10-3 φ3 1.626X 10-3 1.694X 10-' -1,628X 10-3 Next, the configuration for deforming the first and third lens groups An example is shown in FIG.

11 inside the lens barrel 40 that holds the entire lens system. Frames 41 and 42 are provided for holding the third lens groups 10 and 30, respectively. This frame body 41, 42 is shaped like a truncated cone and has a plurality of slots formed on the smaller diameter side.
, holds a third lens group 10.30. Further, at the ends of the large diameter side of the frames 41 and 42, there is an operation piece 41a having a 1-shape base.
.

42a is integrally provided.

On the other hand, tapered surfaces 40a and 40b whose diameter gradually decreases toward the outside are formed at both ends of the lens barrel 40, and the slotted portions of the frame 41 and 42 abut against these tapered surfaces. There is. An opening 40c is provided on the outer wall of the lens barrel on the upper side in the figure.
40d is bored, and the operating piece 4 of the frame body 41.42
1a and 42a protrude into the outside space from these openings.

At the time of zooming, by slightly displacing the frames 41 and 42 relative to the lens barrel 40 according to the movement of the lens barrel 40,
The inner diameters of the frames 41 and 42 are changed, and the inner diameters of the frames 41 and 42 are changed. The pressing force on the third lens 10.30 causes the lens to deform.

An example of a configuration for utilizing movement of the entire lens system for minute displacement of the frame bodies 41, 42 is schematically shown in FIG. 9.

A guide rail 50 is provided on the main body side along the moving path of the lens barrel 40.
to be fixed. The guide rail 50 has a symmetrical valley-like shape with the center portion being the most concave when viewed from the lens barrel side.

The lens barrel 40 is provided with a piston rod 43 that is biased to protrude toward the rail and slides into contact with the guide rail 50 as the lens barrel 40 moves. 44 is a cylinder that supports this piston rod 43 so that it can move forward and backward. A bottle 43a is installed at the end of the lens barrel side, and this bottle 43a has two symmetrical shapes.
The two L-shaped link arms 45 and 48 are loosely fitted into the long holes. Rotation shaft 45a of the link arm.

48a is fixed to the lens barrel 40.

Furthermore, a bushing rod 4 is attached to the other end of the link arm.
7.48 is connected, and the aforementioned operating pieces 41a and 42a of the frame body are connected to the tips thereof.

With this configuration, the piston rod 43, which protrudes at the same magnification, gradually retracts as the lens barrel 40 moves with the variable magnification operation, and the link mechanism moves the frames 41 and 42 into the lens barrel 40. Press toward both ends. As a result, the first. The third lens group 10.30 is deformed and its focal length changes.

[Effects] As explained above, according to the variable magnification optical system of the present invention, the distance between the object images can be kept constant, and relative movement between the individual lenses can be achieved by only moving the entire lens system. It is possible to change the magnification without having to do so.

Therefore, there is no need for a mechanism for changing the optical path length as in the past, and there is no need to use a complicated lens barrel using a cam or the like, and space can be saved.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a lens system showing an embodiment of a variable power optical system according to the present invention. Figures 92 to 1314 are aberration diagrams at each magnification of the optical system shown in Figure 1, and Figure 2 is -1,415x and Figure 3 is
The figure shows the time at -1,000 times, and FIG. 4 shows the time at -0,707 times. FIGS. 5 to 7 are aberration diagrams at each magnification of other embodiments of the variable magnification optical system according to the present invention, and FIG.
At 0 times, Figure 16 is -1,415 @ time, Figure 7 is -0,7
It shows the time of 0' times. #! 8 and 9 are explanatory diagrams showing an example of the deforming means, FIG. 8 is a sectional view of the lens barrel, and FIG. 8 is an explanatory diagram of the link mechanism. 10.3Q...1st. 3rd lens group (flexible lens)
40... Lens barrel 41.42... Frame (deformation means)

Claims (1)

[Scope of Claims] (1) An imaging optical system having a flexible lens whose surface curvature changes by deformation, and a drive that moves the imaging optical system as a whole along its optical axis when changing magnification. and a deforming means that deforms the flexible lens by applying force from the outer periphery of the flexible lens to change the focal length as the flexible lens moves. (2) The change in power of the entire system is Δφ_0, the power change of the flexible lens is Δφ_i, and the maximum magnification of the entire system is m_m_
a_x, the minimum magnification is m_m_i_n, 0.8<|ΣΔφ_i/Δφ_0|<1.2m_m_a
2. The variable magnification optical system according to claim 1, wherein the variable magnification optical system satisfies _x/m_m_i_n<2.5.