JPH0434507A - Zoom lens device - Google Patents

Abstract

PURPOSE:To accurately switch focusing in a normal zoom area and focusing in super-wide-angle mode by performing focusing operation by rotating a zoom ring in a macrophotography area in response to the ON signal of a switch when a wide converter lens is inserted into an optical system. CONSTITUTION:When the insertion of the wide converter lens 35 into the optical system is detected by the signal from a microswitch 50, the focusing is performed by the rotation of the zoom ring, but the rotation range of the zoom ring is limited to only the macrophotography area. Therefore, when the microswitch 50 is turned on while the zoom ring is in the normal zoom area, a focus controller 47 puts a zoom motor driving circuit 48 to rotate the zoom ring forcibly to the macrophotography area. Consequently, zoom ring forcibly to the macrophotography area. Consequently, the focusing mechanism for the macrophotography area can be utilized for the focusing in super-wide-angle mode and the focusing is automated even at this time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a zoom lens device having a macro photography function.

[Conventional technology]

Modern video cameras often use zoom lenses with a macro function that allows focusing even on objects as close as 10 cm, for example.

For zoom lenses with a macro function, focusing in the normal zoom range from the telephoto end to the wide-angle end is generally done by extending the front lens, and focusing in the macro range is done by correcting the movement of the focusing plane when changing the magnification. In many cases, this is done by moving a compensator lens. Therefore, with such a zoom lens, in the normal zoom range, the focus is adjusted by rotating the focus ring for extending the front lens, and in the macro range, the focus is adjusted by moving only the compensator lens by rotating the zoom ring. will be held.

However, when using such a zoom lens in the macro range, the distance range to the subject that can be focused is narrow, about several IQ cm from the front of the lens, and the subjects to be photographed are quite limited. The reality is that photography in the macro range is not done very often.

Against this background, attempts have been made to utilize movement of the compensator lens in the macro range for focus adjustment during ultra-wide-angle shots. That is, by combining a zoom lens with a wide converter, a larger angle of view is obtained than at the wide-angle end in the normal zoom range, and the compensator lens is moved to adjust the focus in this ultra-wide-angle state. According to this, the conventional focusing mechanism in the macro range can be used as is for focusing in the ultra-wide angle, and there is an advantage that new functions can be added at a low cost.

[Problem to be solved by the invention]

On the other hand, most recent video cameras are equipped with an autofocus device, and the focusing operation is automated. Since the above-mentioned ultra-wide-angle photography is expected to be used much more frequently than conventional macro photography, it is necessary to automate the focusing during the ultra-wide-angle photography. In this case, in the normal zoom range, focusing is done by rotating the focus ring, but in ultra-wide-angle, focusing is done by rotating the zoom ring, so depending on the usage status of the zoom lens, You have to change the focusing method accordingly.

[Purpose of the invention]

The present invention was made in consideration of the above background.
An object of the present invention is to provide a zoom lens device capable of accurately switching between focusing in a normal zoom range and focusing in an ultra-wide angle.

[Means to solve the problem]

In order to achieve the above object, the present invention includes a wide converter lens that is inserted into an optical system for ultra-wide angle, a switch that detects when the wide converter lens is moved to a use position, and a zoom ring that has a macro a sensor that detects whether or not it is within the macro range, and a focus that, when the switch is on, rotates the zoom ring within the macro range while monitoring the signal from the sensor and focuses by moving the compensator lens. This uses a controller.

[Function] When the wide converter lens is inserted into the optical system, an on signal is obtained from the switch, and the focus is switched to super wide-angle mode. Focusing at ultra-wide angle is performed by the focus controller while monitoring the signal from the sensor that corresponds to the rotating position of the zoom ring. The compensator lens moves accordingly to perform focusing.

Hereinafter, the present invention will be explained according to the illustrated embodiments.

〔Example〕

In FIG. 1 showing an embodiment of the present invention, this zoom lens device includes a focusing lens barrel 3 incorporating a focusing lens 2, a lens frame 5 incorporating a variator lens 4, and a lens frame 7 incorporating a compensator lens 6. and a guide bar 8 for guiding the movement of the lens frame 57.
9, a cam barrel 14 with a cam groove 12° 13 for controlling the extension of the lens frame Jl 7 according to the amount of rotation, a pin 14a and a notch 15a. It has a zoom ring 15 that rotates the cam barrel 14 when engaged, a lens frame 17 that holds a part of the master lens and is fixed to the master lens barrel 16, a focus morph 19, and a zoom motor 20.

A gear 3a is formed on the outer periphery of the focus lens barrel 3, and a gear 2 driven by a focus morph 19 is connected to the gear 3a.
1 meshes. A guide hole through which a guide bar 8 is pushed is formed in the lens frame 5, and a pin 5a and a key 5b are also provided. The pin 5a passes through the opening 10a of the intermediate lens barrel 10 and is engaged with the cam groove 12 of the cam barrel 14,
The key 5b engages with the key 10b of the intermediate lens barrel 10. Like the lens frame 5, the lens frame 7 has a guide hole into which the guide bar 9 is inserted, as well as a pin 7a.

A key 7b is formed, the pin 7a passes through the opening 10c and engages with the cam groove 13, and the key 7b engages with the keyway 10b.

The cam barrel 14 rotates around the intermediate lens barrel 10 in unison with the rotation of the zoom ring 15. A gear 15b is formed on the zoom ring 15, and a gear 22 driven by a zoom motor 20 meshes with the gear 15b. A brush 24 is fixed to the zoom ring 15 and comes into contact with a sliding resistor 25 attached to the master lens barrel 16. This brush 24 and sliding resistance 25 are connected to a zoom position sensor 28 (FIG. 3) for detecting the rotational position of the zoom ring 15.
It consists of

A master lens is built in the master lens barrel 16, and an iris 29 is provided. The iris 29 is driven by an iris motor 30 according to the brightness of the subject, and functions to maintain an appropriate amount of exposure to an image sensor, which will be described later.

The cam grooves 12, 13 conceptually have a shape as shown in FIG. In addition, in this figure, in order to clarify the correspondence with the rotational position of the cam cylinder 14, the cam grooves 12 and 13 are
This table shows the telephoto end (starting point) and ending point of . The cam groove 12 consists of a cam part 12a corresponding to the normal zoom range and a cam part 12b corresponding to the macro range, and the cam tube 14 is configured to move toward the wide-angle side (counterclockwise in FIG. 1) within the normal zoom range. When rotating, the lens frame 5 is moved forward via the pin 5a. When rotating in the macro range, the lens frame 5 is not moved in the optical axis direction.

On the other hand, the cam groove 13 consists of a cam part 13a for the normal zoom range and a cam part 13b for the macro range.
After moving forward, move it back again. Also, when rotating beyond the wide-angle end to the macro range,
Although the lens frame 7 comes to be extended forward, the amount of extension becomes smaller on the terminal end side relative to the rotation of the cam barrel 14.

According to the shapes of these cam grooves 12 and 13, the cam cylinder 14
When the lens is rotated from the telephoto end to the wide-angle end in the normal zoom range, the variator lens 4 moves to continuously change the magnification, and the compensator lens 6 moves to correct the shift in focus position due to the change in magnification. Compensation will be made. Also,
When the macro range is reached, the variator lens 4 remains at the wide-angle end position, and only the compensator lens 6 is extended.
It is now possible to focus on close objects from 5 cm to 5 cm.

As shown in FIG. 1, this zoom lens device is configured such that a lens frame 36 holding a wide converter lens 35 made of a concave lens can be inserted in front of the focusing lens 2. When the wide converter lens 35 is inserted, an ultra-wide angle of view larger than the angle of view obtained at the wide-angle end can be obtained only when the cam cylinder 14 is rotated to the macro range. and,
Focusing at this time can be performed by moving the compensator lens 6.

In other words, when the cam cylinder 14 is rotated toward the end in the macro range, at any position between the wide-angle end and the bent part 13c of the cam part 13b, the depth of focus is set to a subject ranging from 1.3 m to infinity. It is possible to obtain a pan-focus state that covers the inside of the camera. When the compensator lens 6 is moved from the bending portion 13c toward the end, it becomes possible to focus on an even closer object from 1.3 m to 7 cm.

In FIG. 3, which schematically shows the configuration of a video camera using the zoom lens device, an image sensor 40 such as a CCD is provided on the imaging plane of the zoom lens device, and converts an optical image into a photoelectric signal. . A photoelectric signal from the image sensor 40 is input to a video signal processing circuit 42 via a preamplifier 41. The video signal processing circuit 42 performs processing such as gamma correction and one-color correction on the input photoelectric signal, and also performs processing for converting the input photoelectric signal into a video signal compliant with the NTSC system. A subject image is displayed on the finder CRT 43 in response to a video signal from the signal processing circuit 42, and is recorded on a videotape by the recording circuit 45 when the record button is operated.

A luminance signal is taken out from the video signal processing circuit 42 and input to the focus detection circuit 46. The focus detection circuit 46 monitors the spatial frequency of the image in the central area based on the luminance signal corresponding to the central area of the subject screen. The focus detection device 46 searches for the focus position of the optical system so that the spatial frequency of the image in the central area reaches its peak. For this purpose, a focus controller 47 is connected to the focus detection device 46, and this focus controller 47 operates the zoom motor drive circuit 48 or the focus morph drive circuit 49 according to the control signal from the focus detection device 46, and performs focusing. The lens 2 or the compensator lens 6 is moved forward and backward in the optical axis direction.

The focus controller 47 is further supplied with a position signal of the zoom ring 15 obtained from the zoom position sensor 28 and a signal from a microswitch 50 that detects that the wide converter lens 35 is inserted into the optical system. It has become. When the zoom ring 15 is in the normal zoom range, the focus controller 47 operates the focus morph drive circuit 49 and focuses by moving the focusing lens 2 via the focus morph 19. Also, zoom ring 1
5 is in the macro range, the focus controller 47 operates the zoom motor drive circuit 48, rotates the zoom ring 15 by driving the zoom motor 20, and focuses by moving the compensator lens 6.

Further, when it is detected that the wide converter lens 35 is inserted into the optical system based on a signal from the microswitch 50, focusing is performed by rotating the zoom ring 15.
The rotation range is limited only within the macro range. Therefore, when the microswitch 50 is turned on while the zoom ring 15 is in the normal zoom range, the focus controller 47 operates the zoom motor drive circuit 48 to forcibly rotate the zoom ring 15 to the macro range. In addition,
The zoom motor drive circuit 4B is provided with a seesaw switch 51 for performing normal zooming operations.
When the microswitch 50 is on, normal zooming operations are disabled.

Hereinafter, the operation of the zoom lens device of the present invention will be explained based on the video camera shown in FIG.

When photographing in the normal zoom range, the zoom motor drive circuit 48 is activated in response to the operation of the seesaw switch 51, and the zoom ring 15 can be rotated arbitrarily between the telephoto end and the wide-angle end. .

As the zoom ring 15 rotates, the cam cylinder 14 rotates,
The lens frame 5.7 moves forward and backward in the optical axis direction by the cam grooves 12.13, thereby compensating for magnification change and a shift in the focus position that accompanies the magnification change. Furthermore, when the zoom ring 15 is in the normal zoom range, as shown in the flowchart of FIG.
The focus controller 47 moves the focusing lens 2 via a focus morph drive circuit 49.

By moving the focusing 2, the image sensor 40
The above image formation state changes, but this change is caused by the focus detection device 4.
6 as a change in spatial frequency, and when the spatial frequency reaches its peak, focusing is completed.

If focus cannot be obtained even when the focusing lens 2 is fully extended, the focus controller 47 activates the zoom motor drive circuit 49 and the zoom ring 1
Rotate 5 to macro area.

Thereafter, focusing is performed by moving the compensator lens 6 by rotating the zoom ring 15. In this way, when focus cannot be obtained by focusing with the focusing lens 2, the compensator lens 6
By performing focusing using , it becomes possible to continuously and automatically perform focusing from the normal zoom range to the macro range. Note that if the seesaw switch 51 is operated during this focusing process, the operation of the seesaw switch 51 takes priority;
Zooming operations are performed while focusing is interrupted.

Wide converter lens 35 for ultra-wide-angle shooting
is inserted into the optical system. As a result, when the microswitch 50 is turned on, the zoom position sensor 28 detects the set position of the zoom ring 15 at that time, and if it is in the normal zoom range, the focus controller 47 detects the set position of the zoom ring 15 at that time.
The zoom ring 15 is forcibly moved to the macro area by a command from . After the zoom ring 15 moves to the macro area, focusing is performed. This focusing is performed by operating the zoom motor drive circuit 48 in response to a control signal from the focus detection device 46, and by moving the compensator lens 6 in the same way as focusing during macro photography.

When the wide converter lens 35 is inserted into the optical system and becomes a super wide-angle state, not only the angle of view becomes wide, but also the depth of focus becomes considerably wide. When the compensator lens 6 is positioned at the bent portion 13c of the cam groove 13, a pan-focus state can be obtained in which the lens is substantially in focus in the range from 1.3 m to infinity. of course,
When the subject distance is shorter than that, it is possible to further rotate the zoom ring 15 counterclockwise to focus up to a close distance of 7 cm.

Note that when the wide converter lens 35 is inserted, the rotation range of the zoom ring 15 is limited only to the macro range, and zooming operations using the seesaw switch 51 are no longer possible. Therefore, even if the zoom ring 15 is manually rotated to the normal zoom range without using the zoom motor 20, the zoom ring 15 will not be rotated by the drive of the zoom motor 20 unless the wide converter lens 35 is retracted from the optical system. The image is returned to the macro area and focus is automatically adjusted.

4゜[Effects of the Invention] As described above, the zoom lens device of the present invention has the following effects:
The conventional focusing mechanism in the macro range can be used for focusing at ultra-wide angles with the addition of a wide converter lens, and even at ultra-wide angles, the autofocus device can be used to automatically focus. This makes it possible to add an ultra-wide-angle shooting function with excellent operability without significantly increasing the cost burden.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view schematically showing a zoom lens device using the present invention. FIG. 2 is a conceptual diagram of a cam groove used in the zoom lens device shown in FIG. 1. FIG. 3 is a schematic diagram showing the configuration of a video camera using the zoom lens device of the present invention. FIG. 4 is a flowchart showing the procedure of focusing processing. 2. 5. Focusing lens variator lens compensator lens cam tube zoom ring zoom position sensor wide converter lens focus controller micro switch. Procedural amendment August 27, 1990 2゜3゜4゜1990 Patent Application No. 142067 Name of the invention Person who corrects zoom lens device Relationship to the case Patent applicant

Claims (1)

[Claims] (1) A macro range is provided outside the normal zoom range from the telephoto end to the wide-angle end, and by rotating the zoom ring in this macro range, the compensator lens is moved to focus on a nearby subject. In a zoom lens device, a wide converter lens that widens the angle of view by being inserted into an optical system with a zoom ring rotated to the macro range, and a wide converter lens that is inserted into the optical system. a switch that turns on when the zoom ring is in the macro range, a sensor that detects that the zoom ring is within the macro range, and a sensor that responds to the on signal from the switch and rotates the zoom ring within the macro range while monitoring the signal from the sensor. A zoom lens device comprising a focus controller that performs focusing.