JPS59133511A - Zoom lens - Google Patents

Abstract

PURPOSE:To prevent a focus variation due to various causes by moving other lens group than a variable power lens group in a zoom lens in accordance with a signal generated by three detecting means corresponding to each of a variation of temperature and humidity, a variation of a distance of an object to be photographed, and a variation of a focal distance caused by a variable power. CONSTITUTION:A zoom lens is provided with a focal distance detecting mechanism 6 for generating an electric signal showing a focal distance of the zoom lens from a moving extent of the second lens group 2 for a variable power, a temperature and humidity detecting mechanism 7 for generating an electric signal corresponding to temperature and humidity, and a photographed object distance detecting means 8 for generating an electric signal showing a distance of an object to be photographed. These three electric signals are inputted and the operation is executed by a focusing member moving extent calculating mechanism 9, by which an electric signal showing a necessary moving extent of the third lens group for not generating a focus variation as the zoom lens even if a variation of three catagories is generated is outputted. An output electric signal of this calculating mechanism 9 is applied to a focusing member driving mechanism 10, and the third lens group 3 being a focusing member is moved along the optical axis.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a zoom resis, in particular, to a zoom resistor which is made of a material whose refractive index and shape change depending on the temperature and humidity, and which does not change its refractive index depending on the temperature and humidity. Zoom error that was prevented from occurring: Regarding J's.

In recent years, it has become common to incorporate shields made of materials such as synthetic resins into systems to reduce costs, reduce weight, and improve optical performance due to aspherical surfaces. Ta. However, the refractive index and shape of such materials change significantly depending on temperature and humidity, and these changes in refractive index and shape affect the resis-based hydrocarbons.

Japanese Patent Application Laid-Open No. 55-143 as a method for correcting changes in refractive index due to changes in refractive index due to temperature and humidity such as side grains and υ.
A method disclosed in No. 518 is known, which relates to cicicle ratio and attempts to completely correct cicicle changes using optical means in response to temperature changes. Furthermore, Japanese Patent Application Laid-Open No. 19757/1983 discloses a device in which Hill 1 changes caused by expansion and contraction of a lens barrel are corrected by mechanical means using materials with different coefficients of thermal expansion. As a zoom ratio, one disclosed in Japanese Patent Application Laid-open No. 176015/1982 is known, but this is a zoom ratio system in which the amount of change in the residual bis(1) of the cis group is substantially canceled out by the zoom filter. It is a combination of glass and inorganic glass, and overcomes the drawback that the degree of freedom of the refractive index is reduced depending on the refractive power combination and material selection within each resis group.

In a zoom ratio that does not use the above-mentioned @rebetsu, by detecting the focal length and determining the amount of movement of the focusing ratio based on this, even if the amount of extension changes due to the zoom, the focus remains constant. A zoom resis with an automatic focusing device that maintains the
It is disclosed in Publication No. 6. However, even with this zoom resolution, if the temperature and humidity change! When a lens made of a material with a large change in refractive index is used in a system, a problem arises in that it naturally changes in temperature and humidity, and the amount of change in resistance varies depending on the focal length. It turns out.

The present invention eliminates the above-mentioned conventional absenteeism, and is effective against changes in temperature and humidity and changes in focal length in a zoom lens that uses materials such as synthetic resin whose refractive index and shape change greatly depending on temperature and humidity. The purpose is to provide a zoom lens that causes changes in height regardless of the situation.

A feature of the present invention is that in a zoom resis system that includes a resis system made of a material whose refractive index and shape change greatly depending on temperature and humidity, the system detects the temperature and humidity of the environment and generates a signal corresponding to the temperature and humidity of the environment. a second detection means that detects a subject distance and generates a signal corresponding to the subject distance; and a second detection means that detects movement of a zoom ratio group that changes the focal length of the zoom ratio and generates a signal corresponding to the focal length. The present invention is equipped with a third detection means and a means for moving a reduction group other than the variable magnification reduction group during one zoom so that the lenses are aligned properly based on the signals generated by these detection devices. be.

The present invention will be explained in detail below.

In Fig. 1, the fixed lens group 11 is fixed during zooming, the second lens group 2 is movable in the optical axis direction for zooming, and the second lens group 2 is movable in the optical axis direction to correct the shift in magnification. A zoom ratio is shown that includes a three-res group 3 and a fourth lens group 4 that has an imaging function to form an image of a subject on an imaging plane 5.

In this zoom resis, if you perform 7 orca silks by moving the first group like a normal zoom resis, the first
If at least one resis group other than 1-shiz includes a resis made of a material whose refractive index or shape changes greatly depending on temperature and humidity, the resis will change due to zooming, and the resis made of such material will Even if it is included only in the 1st LI group, the amount of contribution of the 1st LI group to the final surface changes with the zoom, so an external ranging mechanism that does not have a means of compensating for temperature and humidity. When setting the tv-th cis group, a change in hysito occurs due to the yake sis sumishita. In addition, especially when a subject distance detection means and a zoom ratio are combined, it is preferable to use the second lens group (5)-C or later lens groups instead of the heavy 1st lens group such as the 1st L/shiz group. When focusing with a reduction group other than the 11th lens, it is necessary to change the feed amount according to the zoom ratio, and in addition, it is necessary to change the amount of movement depending on the zoom ratio.
If a material whose refractive index or shape changes significantly due to humidity is used, and if the material is accompanied by changes in its refractive index or shape due to changes in temperature or humidity, correction for this is also required.

In view of the above, according to an embodiment of the present invention, as shown in FIG. 1, the third lens group 3 having a stiff besshi sweater function is provided with a function as a focusing member, and the following configuration is provided. Adopt.

That is, in FIG. 1, 6 is a focal length detection mechanism that zooms from the movement amount of the second lens group 2 for variable magnification and generates an electric signal representing the undisturbed distance of the system, and 7 is an electric signal corresponding to temperature and humidity. 8 is a temperature/humidity detection mechanism that generates an object distance, and 8 is an object distance detection means that generates an electric signal representing an object distance. 9
takes these three electrical signals as input and performs calculations based on them to calculate the three h:i: changes in focal point distance due to zooming, changes in temperature and humidity, and changes in subject distance. -Zoom 1 even if there is a change of 5 Lee
Focusing member movement that outputs electrical and electrical signals representing the required movement axis of the third lens group 3 in order to avoid causing a built-in change as a result of )! 11f+amount calculation mechanism. This calculation mechanism 9
The output electrical signal was applied to the focusing member drive mechanism IO to move the third lens group, which is the focusing member, along the optical axis, and its position was converted into an electrical signal by the focusing member position detection means 11. By feeding back the object to the m:t1i mechanism 9, the third realz group is moved by the above-mentioned movement period. This makes it possible to prevent fluctuations even when there are changes in any of the three categories.

Note that in calculating the output of the focusing member movement M'(1), the calculation is performed based on a functional formula determined in the design of the zoom lens (for example, 52-15226), and since there is an almost linear relationship between the amount of change in temperature and humidity and the amount of change that occurs with it, by giving the proportional coefficient in advance, it can be calculated based on the electric signal of temperature and humidity. You can perform calculations using

In the above embodiment, a normal fourth lens group zoom ratio in which the first lens group is fixed is described. The same objective can be achieved by employing a similar configuration as described above for a type of zoom V-system that moves on the optical axis for zooming.

In addition, in the embodiment described above, the third lens group is moved as a focusing member for preventing the above-mentioned focus fluctuation, but the other lens group is moved as a focusing member for the same purpose. Alternatively, an embodiment in which a plurality of groups of thrusters are moved in combination is also possible.

As explained above, according to the present invention, in a zoom resis system that includes a resis made of a material with a large temperature/humidity coefficient of refractive index, not only built-in changes that occur due to changes in magnification or subject distance, but also temperature・It is possible to prevent build changes based on changes in humidity all at once. Especially at this temperature
Since the nt of the same height change due to humidity differs depending on the focal length based on the zoom, it is difficult to correct it, but according to the present invention, the built-in change can be prevented all at once by taking into account the focal point FLE, 141. Therefore, it can provide an effective solution to such problems.

[Brief explanation of drawings]

The drawings show an embodiment of the invention 41! ′ is the factor. 2...Movable 21st/ for variable magnification: J's group 5...Imaging surface 6...Focal length detection mechanism 7...Temperature/
Humidity detection mechanism 8...Object distance detection means 9...Focusing member movement amount and output device

Claims (1)

[Claims] In a zoom resis system that includes a resis system made of a material whose refractive index changes greatly depending on temperature and humidity,
a first detection means for detecting the temperature and humidity of the environment and generating a signal corresponding thereto; a second detection means for detecting the object distance and generating a signal corresponding thereto; and a magnification changer for changing the focal length of the zoom ratio. A third detection means detects the movement of the resis group and generates a signal corresponding to the focal length, and a resis group other than the above-mentioned resis group for zooming is adjusted based on the signals generated by these detection means. A zoom resis characterized by comprising: a means for moving the zoom lens so that it aligns properly.