JPH05333256A - Manual focusing device for lens - Google Patents

Abstract

PURPOSE:To accomplish the more miniaturization of a device. and to improve the detection and resolution of the rotational amount of a manual focusing ring by providing a means for detecting the magnetic rotational amount of the manual focusing ring. CONSTITUTION:When the manual focusing (MF) ring 2 is rotated, a ring-like magnet 3 fixed on the MF ring 2 is rotated, and a signal corresponding to the positional relation between a HALL element 4 and the ring-like magnet 3 is outputted. The signal is converted to the encoded output by an IF (interface) circuit 7 where the signal is inputted. Thereafter, it is converted to a signal of one pulse in synchronism with the rise and fall of the signal by an MF control circuit 8 so as to be outputted to a microcomputer 9. A driving command is outputted to a motor driving circuit 10 by the microcomputer 9 based on information on the number of driving pulses of a focusing motor 6 and the rotating direction of the focusing motor 6 so as to drive the focusing motor 6 and a focusing lens group 5 which is interlocked with the focusing motor 6, and then, the focusing operation is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention detects the amount of rotation of a manual focus ring when it is rotated,
The present invention relates to an improvement of a lens manual focusing device that drives a focus motor to move a focus lens.

[0002]

2. Description of the Related Art Conventionally, a lens for a video camera, in particular, an inner focus type lens cannot directly mechanically focus, unlike a front lens type lens.
A manual focus ring and an electric encoder linked to the manual focus ring detect the amount of movement of the focus lens to operate the focus lens,
It is designed to focus.

The above-mentioned conventional details will be described with reference to FIGS.

FIG. 10 is a block diagram showing an outline of a conventional manual focus. In FIG. 10, 14 is a manual focus ring having a comb-teeth-shaped pulse plate, and 15 is a manual focus ring.
Is a photo interrupter (two are arranged as described later), 16 is an interface circuit capable of transmitting the output of the photo interrupter 15 to a microcomputer (hereinafter referred to as a microcomputer) described later, and 17 controls the entire lens. A microcomputer, 18 is a motor drive circuit for controlling the focus motor 19 by a focus motor drive signal generated from the microcomputer 17, and 20 is a focus motor 19
The focus lens group 21 is connected to the lens barrel 21.

FIG. 11 is a view showing the positional relationship between the comb teeth of the manual focus ring 14 and the photo interrupter 15 shown in FIG. 10, and in FIG. 11, 14a is the comb teeth (protruding portion) of the manual focus ring 14. , 15
Reference numerals a and 15b are photo interrupters.

FIG. 12 is an output waveform diagram showing the transition of the manual focus output signal by the interface circuit 16 shown in FIG.

The manual focus ring 14 shown in FIG.
The comb teeth 14a shown in FIG. 11 which are integrated with the manual focus ring 14 rotate by turning the photo-interrupter 15a, 15a depending on the position of the comb teeth 14a.
From b, signals having waveforms such as signals F and G shown in FIG. 12 are output. The relationship between the signals F and G is 90 in advance based on the relationship between the comb teeth 14a and the photo interrupters 15a and 15b.
It is designed to maintain the phase relationship of °.

The signals F and G output from the photo interrupters 15a and 15b are the interface circuit 1
As shown by the signal H in FIG. 12, the signal is converted into a signal capable of outputting one pulse at each of the rising and falling timings of the signals F and G, which is the focus motor 19
Is output to the motor drive circuit 18 from the microcomputer 17 as the drive pulse output of Further, the microcomputer 17 determines the rotation direction of the focus motor 19 based on the phase relationship between the photo interrupters 15a and 15b (the phase of the photo interrupter 15b leads or lags by 90 degrees with respect to the photo interrupter 15a), and determines this as a logic level. (“H” level or “L” level). As a result, the focus lens group 20 connected to the output shaft of the focus motor 19 is interlocked, and the focus operation is performed.

[0009]

However, in the above-mentioned conventional example, in the recent miniaturization of the lens, the minimum number of teeth of the comb teeth 14a is caused by the electrical characteristics of the comb teeth 14a of the manual focus ring 14 and the photo interrupter 15. Since the width is determined and the size of the lens is further reduced, the outer diameter of the manual focus ring 14 is reduced and the number of teeth per one round of the ring is reduced, so that the resolution per one round of the manual focus ring is naturally lowered. There was a problem such as.

In view of the above points, an object of the present invention is to provide a manual focusing device for a lens which can achieve further downsizing of the device and can improve the resolution of detecting the rotation amount of the manual focus ring. It is to be.

[0011]

According to the present invention, a rotation amount detecting means for magnetically detecting the rotation amount of a manual focus ring is provided, and a focus motor is driven based on the magnetically detected rotation amount. I have to.

[0012]

1 to 3 show a first embodiment of the present invention, and FIG. 1 shows a mechanical and electrical configuration of a lens manual focusing apparatus according to the first embodiment. It is a figure.

In the figure, 1 is a lens barrel, 2 is a manual focal ring (hereinafter referred to as MF ring),
3 is an annular multi-pole magnet fixed to the MF ring 2
Is a hall element, 5 is a focus lens group, 6 is a focus motor for driving the focus lens group 5, 7 is an interface (hereinafter referred to as IF) circuit for encoding (digitally) outputting the signal from the hall element 4, and 8 is A manual focus control circuit (hereinafter referred to as an MF control circuit) that generates a determination output in the rotation direction of the focus motor 6 and a drive pulse output from a signal of the IF circuit 7, 9 is a microcomputer that controls the position of the focus lens group 5, and 10 is a microcomputer. Is a motor drive circuit that drives the focus motor 6 based on a signal from the microcomputer 9.

FIG. 2 is a side view of the MF ring 2 and the ring magnet 3 of FIG. 1, and in FIG.
Reference numeral b represents the Hall element of FIG.

The outputs of the Hall elements 4a and 4b are such that a phase difference of 90 ° is produced between the outputs of the Hall elements 4a and 4b when the MF ring 2 is operated.

FIG. 3 shows the Hall element 4 to the IF circuit 7 and MF.
It shows the transition of the output signal until it goes to the microcomputer 9 via the control circuit 8.

When the MF ring 2 is rotated, the annular magnet 3 fixed to the MF ring 2 is rotated and the Hall element 4 is rotated.
Signals A and B correlated with the positional relationship between each Hall element and the annular magnet 3 are output by a and 4b. The signals A and B are set to have a phase difference of 90 ° when the MF ring 2 is rotated in the positive direction. Due to the characteristics of the outputs of the Hall elements 4a and 4b, the signals A and B are outputs that are approximated to the sine wave of the S pole and the N pole, respectively.

IF circuit 7 to which the above signals A and B are input
Converts the N pole output to a plus (“H” level) and the S pole output to a minus (“L” level) encoded output. As a result, the signal C becomes a signal obtained by converting the output of the hall element 4a, and the signal D becomes a signal obtained by converting the output of the hall element 4b. After that, in the MF control circuit 8, the signal 1 synchronized with the rising and falling of the signals C and D
It is converted into a pulse signal (signal E), and this signal E is output to the microcomputer 9. At this time, the focus motor 6
In order to clearly send the rotation direction of the signal from the MF control circuit 8 to the microcomputer 9, for example, if the phase of the signal C leads the signal D by 90 °, the positive output (“H” level) and the signal C become the signal D. If the phase is delayed by 90 °, a negative output (“L” level) is set.

Microcomputer 9 to which the above signals are input
Outputs a drive command to the motor drive circuit 10 based on the drive pulse number (operation step number) and rotation direction information of the focus motor 6 sent from the MF control circuit 8 to drive the focus motor 6 to move. The focus lens group 5 interlocked with is moved to perform the focus operation.

(Second Embodiment) FIG. 4 is a sectional view showing the structure of the essential parts of the second embodiment of the present invention.

In the figure, reference numeral 24 is a manual focus ring, and 25 is a ring-shaped multi-pole magnet that also serves as a knurl of the manual focus ring 24 (the first magnetized is a magnetized one).
(Similar to the above embodiment), 26 is a photo interrupter, and 27 is a lens barrel.

The operation is the same as that of the first embodiment, but this second embodiment considers the case where the ring-shaped multipole magnet as in the first embodiment cannot be arranged. Since the magnet is disposed integrally with the knurls on the outer diameter, the resolution is increased by the same pitch and the number of parts is reduced.

(Third Embodiment) FIG. 5 is a view showing the arrangement of the essential parts of the third embodiment of the present invention.

In the figure, 28 is a lens barrel, 29 is a flexible substrate, 30a and 30b are Hall elements, and 31 is a magnet connected to the manual focus ring 13 shown in FIG. 1, for example.

The Hall elements 30a and 30b are mounted on a flexible substrate 29 in advance by a positioning jig so that the phase relationship between the outputs is kept at 90 °.

In the third embodiment, the Hall element 30a, the ring-shaped magnet (radially magnetized) 31,
30b also uses the flexible substrate 29 to set the center of the lens on the radiation, thereby improving the precision of the output pulse of the manual focus.

(Fourth Embodiment) FIG. 6 is a view showing the arrangement of the essential parts of a fourth embodiment of the present invention. The same parts as those of the third embodiment shown in FIG. 5 are designated by the same reference numerals. is there.

This drawing is similar to FIG. 5 described above, except that a ring-shaped back yoke 32 is provided below the flexible substrate 29.
The difference is that they are arranged.

This embodiment is intended to further improve the outputs of the Hall elements 30a and 30b as compared with the third embodiment. That is, the magnetic flux path of the ring-shaped magnet 31 is formed from the back yoke 32, and the magnetic flux density passing through the Hall elements 30a and 30b is increased to improve the output of the Hall elements 30a and 30b. ..

(Fifth Embodiment) FIG. 7 shows the construction of the essential parts of a fifth embodiment of the present invention. The same parts as those in FIGS. 5 and 6 are designated by the same reference numerals.

5 and 6, the yoke 33 is sandwiched between the Hall elements 30a and 30b, and FIGS. 8 and 9 show the positional relationship between the Hall elements 30a and 30b and the yoke 33. This is an example.

The feature of this embodiment is that, in miniaturization of the lens, the Hall elements 30a and 30b are in a mounted state in which the mutual positions are close to each other and the magnetized polarization width of the magnet 31 becomes fine. This is for output failure due to magnetic disturbance of the outputs of 30a and 30b. As for the arrangement of the yoke 33, as shown in FIGS.
By arranging it between a and 30b, the yoke 3
By forming a magnetic pole 3 corresponding to the position of the magnet 31 interlocking with the manual focus ring, magnetic interference between the Hall elements 30a and 30b is eliminated.

According to each of the above embodiments, the Hall element is used for electrically detecting the amount of manual focus, so that the size is further reduced as compared with the conventional configuration using the comb-shaped encoder and the photo interrupter. It has become possible to make the resolution of the output pulse per rotation speed of the manual focus ring equal to or higher than that of the conventional lens.

Further, since the Hall element, which is a sensor, is arranged inside the ring-shaped magnet, it becomes difficult to make an erroneous reading due to the external magnetic change, and the processing becomes easy in terms of electrical mounting.

(Modification) In this embodiment, the Hall element is used for detecting the manual focus amount, but the present invention is not limited to this, and may be, for example, an SPD (silicon photodiode) or the like.

[0036]

As described above, according to the present invention,
A rotation amount detecting means for magnetically detecting the rotation amount of the manual focus ring is provided, and the focus motor is driven based on the magnetically detected rotation amount.

Therefore, it is possible to achieve further downsizing of the apparatus and to improve the resolution for detecting the number of rotations of the manual focus ring.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a main part of a first embodiment of the present invention.

FIG. 2 is a diagram showing a rotation amount detection unit of the manual focus ring of FIG.

FIG. 3 is a diagram showing a signal waveform in the first embodiment of the present invention.

FIG. 4 is a cross-sectional view showing the configuration of the main part of the second embodiment of the present invention.

FIG. 5 is a cross-sectional view showing the structure of a main part of a third embodiment of the present invention.

FIG. 6 is a cross-sectional view showing the structure of a main part of a fourth embodiment of the present invention.

FIG. 7 is a cross-sectional view showing the structure of a main part of a fifth embodiment of the present invention.

FIG. 8 is a diagram showing a positional relationship between a Hall element and a yoke in a fifth embodiment of the present invention.

FIG. 9 is a diagram showing another positional relationship between the Hall element and the yoke according to the fifth embodiment of the present invention.

FIG. 10 is a diagram showing a configuration of a conventional portion of the present invention.

11 is a diagram showing a rotation amount detection unit of the manual focus ring of FIG.

12 is a diagram showing a signal waveform in the conventional example of FIG.

[Explanation of symbols]

 1, 27 Lens barrel 2, 24, 28 Manual focus ring 3, 25, 31 Magnet 4, 26, 30 Hall element 5 Focus lens group 6 Focus motor 9 Microcomputer 29 Flexible substrate 32 Back yoke 33 Yoke

Claims (4)

[Claims] 1. A manual focus ring, a rotation amount detection means for detecting the rotation amount of the manual focus ring, a conversion means for converting the rotation amount from the rotation amount detection means into a drive signal for a focus motor, and the drive. In a lens manual focusing device including a focus control unit that drives a focus motor by a signal to move a focus lens, the rotation amount detection unit is a unit that magnetically detects the number of rotations of the manual focus ring. A manual focusing device for a lens, which is characterized in that 2. The rotation amount detecting means comprises an annular magnet which is alternately magnetized to have different polarities, and a plurality of magnetic detecting means arranged inside the annular magnet. 1. A manual focusing device for a lens according to 1. 3. Manual focusing of a lens according to claim 2, characterized in that the splits of the annular magnet are radially polarized with respect to the lens center and the magnetic detection means are mounted radially with respect to the lens center. apparatus. 4. The manual focusing device for a lens according to claim 2, wherein the knurling of the manual focus ring and the annular magnet are integrated.