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Zoom lens, and its manufacturing method

A zoom lens, focal length technology, applied in the direction of lenses, optics, instruments, etc., can solve the problems of expensive glass aspheric lenses, changes in refractive index, lens deformation, etc.

Inactive Publication Date: 2005-10-12
PANASONIC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The problem is that, as in the case of conventional example 2, the lens is prone to deformation due to temperature changes
[0006] As mentioned above, the current problem is that glass aspheric lenses used for miniaturization of video camera zoom lenses are expensive
In addition, there is another problem: if a low-priced plastic lens is used instead of a high-priced glass aspheric lens, since the linear expansion coefficient of plastic is about 10 times that of glass, the refractive index will change and the lens will be deformed due to temperature changes.

Method used

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  • Zoom lens, and its manufacturing method
  • Zoom lens, and its manufacturing method
  • Zoom lens, and its manufacturing method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0061] Below, refer to Figure 1 ~ Figure 4 The first embodiment of the present invention will be described.

[0062] figure 1 It is a structural diagram of a zoom lens according to Embodiment 1 of the present invention. Such as figure 1 As shown, starting from the object side (the left side of the figure), the zoom lens of this embodiment includes a first lens group 1, a second lens group 2, a diaphragm S, a third lens group 3, a fourth lens group 4, and the like. Equivalent glass parts EG such as the glass cover and low-pass filter of the camera unit. The first lens group 1 is formed by cementing the lens L1 and the lens L2. The overall refractive index of the two lenses is positive, and they are fixed on a lens barrel (not shown). Both lenses L1 and L2 are glass spherical lenses with positive refractive index. The second lens group 2 is composed of a lens L3 and two cemented lenses L4, and the overall refractive index is negative. They can move on the optical axis 10 and hav...

Embodiment 2

[0134] Figure 5 This is a structural diagram of a zoom lens according to Embodiment 2 of the present invention. The zoom lens of this embodiment is different from the zoom lens of Embodiment 1 in that the plastic aspheric lens L7 of the fourth lens group 4 is provided on the image surface side of the glass spherical cemented lens L8. The other structure is the same as that of embodiment 1, because figure 1 The same symbols are used for the components with the same function, and the description is omitted.

[0135] Below, specific numerical values ​​of the zoom lens of Example 2 are given in Table 2. The meanings of various symbols used in Table 2 are the same as those in Table 1.

[0136] Table 2

[0137] f=3.76~73.4 F / 1.66~F / 3.24

[0138] r1 45.883 d1 1.000 n1 1.84666 v1 23.8

[0139] r2 23.833 d2 5.450 n2 1.60311 v2 60.6

[0140] r3 -135.640 d3 0.150

[0141] r4 20.326 d4 3.000 n3 1.62041 v3 60.3

[0142] r5 53.370 d5 variable

[0143] r6 31.633 d6 ...

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PUM

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Abstract

A zoom lens comprising, in the order from the object side, a first lens group (1) fixed and having a positive refracting power; a second lens group (2) movable along the optical axis and having a negative refracting power and a power varying function; a third lens group (3) fixed and having a positive refracting power; and a fourth lens group (4) movable along the optical axis and having a positive refracting power and a function of correcting the image plane variation accompanying the power variation or the change in the object distance. Both the third lens group (3) and the fourth lens group (4) are provided with positive glass spherical lenses (L5 and L8) and plastic aspherical lenses (L6 and L7) having weak refractive powers. As a result, a compact zoom lens can be obtained at a low cost although it has a power varying ratio as high as 20 times.

Description

Technical field [0001] The invention relates to a high-power, small-sized and low-cost high-performance zoom lens suitable for a video camera and a manufacturing method thereof. Background technique [0002] The well-known conventional zoom lens for video cameras, as disclosed in JP 2-55308, has the following components in order from the object side: a fixed first lens group with positive refractive index, and negative refractive index The variable magnification ratio uses an adjustable second lens group, a fixed third lens group with a positive refractive index, and an adjustable fourth lens group with a positive refractive index that is used for focusing and correcting image plane changes by zooming. [0003] Furthermore, in the zoom lens disclosed in JP 4-104114 (hereinafter referred to as Conventional Example 1), mainly for miniaturization, the third and fourth lens groups in the above four-group structure zoom lens are respectively used A glass aspheric lens. However, the gl...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G02B13/18G02B15/173
CPCG02B13/18G02B15/173G02B15/144113G02B15/143105G02B13/009G02B1/041G02B3/04G02B3/0087G02B2003/0093
Inventor 北冈泰久村松昭宏
Owner PANASONIC CORP