JPS6015613A - Zoom lens equipped with ttl-active auto-focus mechanism - Google Patents

Abstract

PURPOSE:To prevent the impossibility of distance measurement due to compentition between close and far distances on the wide-angle side while securing the use range in the telephoto side, by varying the use range of a light receiving sensor with a sensor mask which is interlocked with a zoom operating member. CONSTITUTION:If a variator moving ring 5 of a zoom lens equipped with an active auto-focus mechanism approaches the front element side and the zoom position is in the wide-angle side, a bending-up part 14a of a sensor mask 14 is brought into contact with the variator moving rint 5 to move the sensor mask 14 forward in the direction of the optical axis, and a part of a light receiving sensor 15 is masked to cut a luminous flux which causes the competition between close and far distances. Thus, the impossibility of distance measurement due to the competition between close and far distances in the wide-angle side is prevented with a simple constitution.

Description

[Detailed Description of the Invention] The present invention projects infrared light or the like onto a subject at an equivalent position on the image forming plane, and when the reflected light is focused, it forms an image at a predetermined position equivalent to the image forming plane. This invention relates to a zoom lens equipped with an autofocus mechanism that uses this to perform focusing.

Conventionally, in zoom lenses that utilize the above-mentioned TTL-active autofocus mechanism, when the focal length on the wide-angle side is relatively short, when the zoom position is on the wide-angle side, The problem is that the projected infrared light, etc. is reflected on the lens surface of the front lens or variator, and the reflected light is captured by the light receiving optical system, competing with the light reflected from the original subject, causing distance measurement to become impossible. There was a point.

In view of the problems of the prior art described above, the present invention provides a TTL-active auto that makes it possible to prevent conflict between near and far on the wide-angle side while ensuring a usable range on the telephoto side by making the usage range of the light receiving sensor variable. An object of the present invention is to provide a zoom lens equipped with a focusing mechanism.

Embodiments of the present invention will be described below based on the drawings.

1 to 3 show an embodiment of a zoom lens according to the present invention.

In the figure, a focus ring 2 holding a front lens 1 of the zoom lens is screwed onto the front outer periphery of a fixed barrel 3 that is the structure of the zoom lens. The cam ring 4 is fitted into the inner diameter of the fixed cylinder 3, and the variator moving ring 5 that holds the variator 6 and the compensator moving ring 7 that holds the compensator 8 are fitted into the inner diameter of the cam ring 4. Further, the zoom ring 9 is rotatably fitted on the outer periphery of the fixed cylinder 3 and is coupled to the cam ring 4, and the variator movable ring 5 and the compensator movable ring 7 fit into the cam groove of the cam ring 4. It moves forward and backward in the direction of the optical axis. An aperture lens 1o and a relay lens 11 are mounted inside the rear end of the fixed barrel 3.

Furthermore, a half prism 12 is disposed in the space between the compensator moving ring 7 and the aperture 1o to reflect and guide only the infrared light passing through the zoom optical system to the autofocus light receiving optical system. The infrared light reflected by the light receiving lens 1 of the autofocus light receiving optical system
3 to form an image on a light-receiving sensor 15 provided outside the lens barrel, and a sensor mask 14 for adjusting the usage range of the light-receiving sensor 15 is provided in front of the light-receiving sensor 15. Further, a light emitting lens 16 and an infrared light emitting element 11 of the autofocus light emitting optical system are provided on the side of the autofocus light receiving optical system, and the infrared light is reflected by the half prism 12 and projected through the zoom optical system. It is supposed to be done.

The sensor mask 14 has an arm extending in the optical axis direction as shown in FIGS. 3 and 4, and comes into contact with the variator moving ring 5 by an upright bent portion 14a at one end or a spring 18. The sensor mask 14 moves in accordance with the movement of the light receiving sensor 15 to adjust the usage range of the light receiving sensor 15.

Next, the operation of this embodiment having the above configuration will be explained.

Figure 3 shows the position of the sensor mask 14 when the variator moving ring 5 is away from the front lens 1 side and there is no autofocus distance conflict at the telephoto side, and the light receiving sensor 15 is used for full range autofocus distance measurement. Even if it is, no near-far conflict will occur.

However, as shown in FIG. 4, when the variator moving ring 5 approaches the front lens 1 side and the zoom position shifts to the wide-angle side, the vertically bent portion 14a of the sensor mask 14 comes into contact with the variator moving ring 5, and the sensor mask 14 forward in the optical axis direction, masking a portion of the light receiving sensor 15, and cutting off the light flux that causes near and far conflicts, it is possible to prevent near and far conflicts.

In this way, when the zoom lens system is on the telephoto side, the reflected light from the lens, etc. that causes the conflict will not enter the light receiving sensor, but when the zoom lens system is on the wide-angle side, the light reflected by the light emitting element will not enter the light receiving sensor. The M-reflected light, which causes distance and near conflict, enters the light-receiving sensor part on the opposite side.On the other hand, the distance measuring light enters only the central part of the light-receiving sensor. By masking, the reflected light can be removed without interfering with distance measurement.

Figures 5 and 6 show the adjustment movement of the sensor mask Φj)
This is another embodiment in which the zoom ring 9 is used.

In FIG. 1 ζ, the sensor mask 24 is rotatably supported on a fixed cylinder (not shown) by a shaft 25, and one end 24a of its arm can come into contact with a protrusion 9a provided on the rear end surface of the zoom ring 9. As shown, it is urged counterclockwise by a spring (not shown).

In such a configuration, FIG. 5 shows the position of the sensor mask 24 when the zoom lens system is on the telephoto side and there is no conflict between distance and distance in autofocus, that is, the position of the sensor mask 24.
The end 24a of the arm 4 is in a position where it touches the rear end flat surface of the zoom ring 9 and does not mask the light receiving sensor 15, and FIG. 6 shows the rotation of the zoom ring 9 toward the wide-angle side. The arm end 24a of the sensor mask 24 comes into contact with the sensor mask 24, rotates the sensor mask 24 clockwise, and masks a part of the light receiving sensor 15, causing near-far conflict as in the previous embodiment. It cuts the light flux and prevents conflict between distance and distance.

In this embodiment, instead of the shaft zoom ring 90, a projecting portion is provided on the rear end surface of the cam ring 4 connected to the shaft zoom ring 90.
It goes without saying that the arm ends 24a of the two may be brought into contact with each other.

As explained above, in a zoom lens equipped with a TTL-active autofocus mechanism, the present invention provides a sensor mask that moves in conjunction with the zoom operation on the light receiving sensor, thereby achieving distance measurement based on near and far competition on the wide-angle side. It has the effect of easily preventing disability.

[Brief explanation of the drawing]

The figures show an embodiment of the present invention. Fig. 1 is a schematic longitudinal cross-sectional view of an embodiment of a zoom lens equipped with a TTL-active autofocus mechanism, and Fig. 2 is a cross-sectional view of the A-A refining section in Fig. 1. 3 and 4 are side views of the main parts of the movable structure of the sensor mask by the variator moving ring, FIG. 3 shows the telephoto side position, FIG. 4 shows the wide-angle side position, and FIGS. FIG. 6 is a side view of a main part of a sensor mask movable structure according to another embodiment of the zoom section, with FIG. 5 showing the telephoto side position and FIG. 6 showing the wide-angle side position. 1... Front element, 2... Focus ring, 3... Fixed cylinder, 4... Cam ring, 5... Variator moving ring, 6...
Variator, 7...Convencator transfer am, s...
Consensator, 9...Zoom ring, 10...Aperture,
11... Relay lens, 12... Half prism,
13... Light receiving lens, 14.24... Sensor mask, 15... Light receiving sensor, 16... Light emitting lens,
17... Infrared light emitting element, 18... Spring Figure 3 and Figure 4' Figure 5 Figure 6

Claims (1)

[Claims] 1. In a zoom lens equipped with an autofocus mechanism that has a light emitting optical system and a light receiving optical system in the optical path passing through a zoom optical system or a part of the zoom optical system, light is received by a sensor mask that is linked to the movement of a zoom operating member. A zoom lens equipped with a TTL-active autofocus mechanism that allows the range of use of the sensor to be varied.