JPS58211720A - Interlocking mechanism of slave lens in focusing device - Google Patents

Abstract

PURPOSE:To make a slave lens interlocked with a focusing lens with high precision by allowing the reverse surface of a slave lens frame to abut on a circumferential cam and an end surface cam which vary in height successively in a circumferential direction on the rotating barrel of a main lens barrel. CONSTITUTION:A slave lens barrel 10 having the slave lens frame 16 engaged slidably with a fixed barrel 14 is pivotally supported freely rockingly at the rear end of the fixed barrel on the main lens barrel 12 which has the rotating barrel for moving a focusing lens group out to a focusing position, and the slave lens frame 16 is displaced from the fixed barrel 14 in a projecting direction by a spring 34 to contact the end surface cam 45 formed so that a lock shaft projecting from the slave lens frame 16 toward the main lens barrel 12 is displaced axially. The reverse surface of the slave lens frame 16 is supported in contact with the circumferential cam 44 which varies in height in the circumferential direction on the rotating barrel 36, and the frame 16 moves back so that a shaft body 30 is guided in a slit 26.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mechanism for interlocking a slave lens in a focusing device, and more particularly, the present invention relates to a mechanism for interlocking a slave lens in a focusing device, and more particularly, the interlocking mechanism of a slave lens that follows a focus lens can be easily achieved by using a circumferential cam and an end cam. The present invention relates to an interlocking mechanism of a slave lens in a focusing device that can be configured and interlocked with accuracy.

2. Description of the Related Art In some cameras, video cameras, and the like, a slave lens barrel equipped with a solid-state imaging device such as a COD is provided separately from an imaging lens system to perform distance measurement or photometry.

In order to perform automatic distance measurement, this slave lens barrel needs to move the optical axis and focus position in conjunction with the movement of the focus lens in the imaging lens system. This was done using a gear device such as.

However, depending on the positional relationship of the focal planes of the slave lens system and the imaging lens system, a certain functional relationship arises in the amount of extension of the slave lens and the focus lens, and when the slave lens and the focus lens are linked in accordance with this function, the gear device described above can be used. However, not only is the drive device extremely complicated, but it also has the disadvantage that accurate control cannot be performed.

The present invention has been made to solve the above-mentioned difficulties, and its purpose is to provide an interlocking mechanism for a slave lens in a focusing device that allows the device to be easily configured and interlocked with high precision. is fixed tube 1
A slave lens barrel 10 formed by sliding a slave lens frame 16 onto the fixed barrel 14 is mounted on the main lens barrel 12 having a rotary barrel 36 for moving the focus lens group to the focusing position.
The slave lens frame 16 is pivotably supported at the rear end.
is biased in the protruding direction against the fixed barrel 14 by the spring 34, and a locking shaft protruding from the slave lens frame 16 in the direction of the main lens barrel 12 is displaced toward the end surface of the rotating barrel 36 in the axial direction of the rotating barrel 36. End face cam 4 formed as follows.
5, and the lower surface of the slave lens frame 16 is brought into contact with the rotating barrel 3.
6 so that the height thereof is sequentially displaced in the circumferential direction.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below based on the accompanying drawings.

10 is a slave lens barrel, and 12 is a main lens barrel which is an imaging lens system, and both optical axes thereof are set to be on substantially the same plane. The slave lens barrel 10 is fixed 1i1
4, and a slave lens frame 16 that slides onto the fixed barrel 14 at one end thereof.A shaft 18 is supported on the main lens barrel 12 at the rear end of the fixed barrel 14, and is formed to be swingable about the shaft 18. has been done.

20 is a slave lens built into the slave lens frame 16.

Reference numeral 22 denotes a distance measuring element such as a CCD placed on the optical axis of the slave lens barrel 10, so that the pattern of the object enters through the slave lens 20.

Note that the pattern of the subject that enters the CCD is an image that is more magnified than the pattern of the subject that is imaged by the focus lens of the imaging lens system, for example, if a zoom lens is incorporated in the imaging lens system, the pattern of the subject that enters the CCD is The slave lens system is set so that an image of the same size as the image at the position enters the light.

That is, the center of the screen imaged by the focus lens of the imaging lens system is selectively illuminated.

The information from this ranging element 22 is then input to a microcomputer (not shown) that is installed separately. Only in the range where the output signal of each of the connected light-receiving elements arranged in series with the element is comparable to the output signal of the reference light-receiving element, the output signals of the reference light-receiving element and the connected light-receiving element included within that range are extracted and used. This output signal is then programmed into a microcomputer in advance, and compared with a certain pattern to perform calculations and distance measurements, and determine how far the focus position of the imaging lens system should be moved, as described later. It issues commands.

Next, 24 is a guide frame that covers the lower surface of the slave lens frame 16 and guides the slave lens frame 16 in its axial direction;
It has a U-shaped cross section and is fixed at one end to the loose end of the fixed tube 14. A slit 26 is formed in the lower surface of the guide frame 24 in the axial direction of the slave lens frame 16, and a shaft body 30 that protrudes from the lower surface of the slave lens frame 16 and has a feeding roller 28 at its lower end passes through the slit 26. Ori,
By guiding this shaft body 30 within the slit 26, the slave lens frame 16 moves back and forth within the guide frame 24 in a non-rotating state.

Reference numeral 32 denotes a rotating roller provided on the lower surface of the guide frame 24, which supports the slave lens barrel 10 by coming into contact with a peripheral surface groove provided on a rotating barrel, which will be described later.

34 is a coil spring, which is interposed between the fixed cylinder 14 and the slave lens frame 16, and is inserted between the fixed cylinder 14 and the slave lens frame 16.
is urged against the fixed cylinder 14 in the z-separation direction, that is, in the protruding direction.

Reference numeral 36 denotes the above-mentioned rotating barrel, which is fitted into the main lens barrel 12-H and rotates over the main lens 1212 by meshing the sprocket 42 provided on the output shaft of the drive motor 40 with the focus gear 38 provided on the peripheral surface. It is designed to rotate in a fixed position.

Reference numeral 44 denotes the above-described circumferential cam, which is provided in an arc shape eccentric to the circumferential surface of the rotating tube 36 in the circumferential direction of the rotating tube 36.
When the rotating roller 32 comes into contact with the surface of the peripheral cam 44 and rolls due to the rotation of 6, the slave lens 910 moves toward and away from the main lens barrel 12 about the axis 18, that is, when the slave lens 910 moves toward and away from the main lens barrel 12. It swings so that the angle of intersection of the optical axis with the lens barrel 112 is displaced.

Further, the feeding roller 28 is pressed against the end face of the rotary cylinder 36 by the urging force of the coil spring 34.
As shown in FIG. 3, an end surface cam 45 is formed on the end surface of the rotating barrel 36, and when the rotating barrel 36 rotates, the slave lens frame 16 can move back and forth under the control of this cam surface.

Reference numeral 50 designates a focus ring, in which a free rotating roller 5 protruding from the outer circumferential surface of the rotary tube 36 is placed in a groove 52 provided in the axial direction of the inner circumferential surface of the focus ring.
4 rotate together with the rotating cylinder 36,
Further, it is movable in the axial direction of the rotary cylinder 36. The focus link 50 has a helicoidal engagement with the inner wall of the main lens barrel 12 and rotates as the group lens frame 5 moves forward and backward.
It is screwed to 6.

However, due to the rotation of the rotary cylinder 36, the focus ring 5
0, the first group lens frame 56 rotates, and therefore moves forward and backward.

Note that 58 is a focus lens which is a group of lenses. 6
0 is an encoder (see Figs. 3 and 4), which is formed into a disk shape by using a conductive material such as carbon, and an encoder gear 62 provided on its axis meshes with the focus gear 38. This allows it to rotate around its axis. A large number of non-conducting parts are formed on this disc according to a predetermined pattern in the circumferential direction, and
A brush 64a that alternately contacts the non-conducting portion and the conductive portion as the disk rotates, and a brush 641) that is constantly in contact with the conductive portion of the disk are slid. A predetermined pulse signal is emitted by turning on and off.

The present invention is configured as described above.

Next, its functions and effects will be explained.

As mentioned above, first, when the pattern of the center of the subject enters the distance measuring element 22 from the slave lens 2o, this signal is input to the microcomputer (not shown), and the microcomputer records the above! The optimum focus position is selected so that the center of the subject, for example, the face of a person, is in focus.

Next, in order to move from the current focus position to the optimum focus position selected above, move the lens 58 closer and closer.
It is calculated how far and by how far it should be moved, and this is converted into the number of pulses of the encoder 60.

A drive signal from the drive motor 40 is sent to the corresponding trench, and the drive motor 40 is driven to rotate the rotary barrel 36, and as described above, the focus link 50 is moved back and forth to focus, and the slave lens barrel 10 also moves in this direction. The camera moves forward and backward and oscillates to focus.

The rotation of the rotary cylinder 36 is detected as a pulse signal by the encoder 60, and this pulse signal is input to the microcomputer, and a stop signal is issued to the drive motor 40 slightly before reaching the set number of pulses. Although the drive motor 40 is stopped, the drive motor 40 is accurately controlled for every pulse until the set value is reached, and the drive motor 40 is accurately controlled for each pulse until the set value is reached.

Note that the cam surface of the end cam 45 is connected to the focus lens 58.
From the relationship such as the focal length of the slave lens 20 and the positional relationship between the imaging plane of the main lens system and the detection image plane of the ranging element 22,
Extension amount of focus lens 58 and slave lens 2
The relationship with the amount of delivery of 0 is determined and set according to this fixed function. Furthermore, in the above embodiment,
Of course, the focus ring 50 and the rotary tube 36 may be integrated, and the first group lens frame 56 incorporating the half focus lens 58 may be engaged with the focus ring 50 so as to be movable forward and backward.

As described above, according to the present invention, since the slave lens is formed to swing and move back and forth using the circumferential cam and the end cam, the slave lens operates smoothly and continuously following the movement of the focus lens. It is particularly suitable for use in video cameras that track moving subjects, and accuracy can be improved by forming the end cam in advance according to the correlation between the extension amounts of both lenses, which is determined by the positional relationship of the focal planes of the focus lens and slave lens. It works well together,
In addition, it has various advantages such as a simple structure, fewer failures, and can be provided at low cost.

Although the present invention has been variously explained above using preferred embodiments, the present invention is not limited to these embodiments.
Of course, many modifications can be made without departing from the spirit of the invention.

[Brief explanation of drawings]

Figure 1 is a sectional view showing the interlocking mechanism of the slave lens, Figure 2
The figure is an explanatory diagram as seen from the front, FIG. 3 is an explanatory diagram showing the end cam and the encoder, and FIG. 4 is an explanatory diagram showing the encoder. 10...Slave lens barrel, 12...Main lens barrel, 14...Fixed barrel, 16...Slave lens frame, 18...Shaft, 20...Slave lens, 22... Distance measuring element, 24...
Information frame. 26...slit, 28...rolling roller. 30...Shaft body, 32...Rotating roller, 3
4... Coil spring, 36... Rotating tube, 38... Focus gear, 40...
・Drive motor, -42... Sprocket, 44
...peripheral cam. 45... End cam, 50... Focus ring. 52...groove, 54...idling roller, 56...
...First group lens frame, 58...Focus lens. 60...Encoder, 62...Encoder gear, 648.641]...Brush. Patent applicant Cosina Co., Ltd. Figure 1 Figure 2 Figure 3 Figure 9

Claims (1)

[Claims] 1. The slave lens barrel 10, which is formed by sliding the slave lens frame 16 onto the fixed barrel 14, is swung at the rear end of the fixed barrel 14 onto the main lens barrel 12, which has a rotating barrel 36 that moves the focus lens group to the focusing position. The slave lens frame 16 is freely pivoted, and the slave lens frame 16 is biased in the projecting direction with respect to the fixed cylinder 14 by a spring 34.
A locking shaft protruding in the direction of the main lens barrel 12 is brought into contact with an end face cam 45 formed on the end surface of the rotating barrel 36 so as to be displaced in the axial direction of the rotating barrel 36, and the lower surface of the slave lens frame 16 is attached to the rotating barrel. The slave lens frame 16 is supported in contact with a circumferential cam 44 provided on the cam 36 so that its height is sequentially displaced in the circumferential direction, and the slave lens frame 16 follows the movement of the focus lens group due to the rotation of the rotary cylinder 36. An interlocking mechanism for a slave lens in a focusing device that swings and moves forward and backward.