JPS58166328A - Automatic focus adjusting device of camera - Google Patents

Abstract

PURPOSE:To make a device small-sized and to realize its power saving and high accuracy, by driving a lens for adjusting a focus by a measuring worm moving device consisting of the first piezoelectric member which expands and contracts in the moving direction, and the second and the third piezoelectric members which are provided on both ends of said member, expand and contract in the radial direction. CONSTITUTION:A measuring worm moving device 101 consists of a piezoelectric member 101b which expands and contracts in the moving direction, and piezoelectric members 101a, 101c which expand and contract in the radial direction of both its ends and are made to selectively press-contact with a moving shaft 102. Information from a distance measuring device 110 is compared with lens position information from a potentiometer 106 by an operating circuit 111, and the moving direction and extent of a lens are transmitted to a driving circuit 112 of the measuring worm moving device 101. When the moving shaft moves in the direction being parallel to an optical axis C through the moving device 101, a lens 104 is controlled as to its movement in accordance with distance information. The measuring worm moving device providing a lens barrel on a hollow part is also shown.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic focus adjustment device for a camera, and more particularly to an automatic focus adjustment device that uses a linear movement device made of a piezoelectric material as a drive source for a focus adjustment mechanism of a photographic lens.

Various types of electronic distance measurement methods are known that measure the distance from the camera to the subject and extract the distance information as an electrical signal.Based on this distance information, the photographing lens is moved, and the imaging surface of the film, etc. Various methods have also been proposed for focusing an image on a subject. In such a conventional automatic focus adjustment method, in order to drive and control the photographic lens, for example, a spring is stored, and when the lens moves to a lens position according to the 31i1L information, an electromagnet is used to move the lens. A method was used to stop the According to this method, a power storage means such as a motor is required to store energy in the spring, and two electromagnetic driving means are required together with an electromagnet to stop the movement of the lens.

Another method is to adjust the focus by directly moving the photographing lens using a motor according to the distance information mentioned above. Some do I.

All of the conventional methods described above require an electromagnetic drive source such as a motor.From the viewpoint of power consumption, it is suitable for cameras that use a small lid power source, as well as for corporate use. In this case, there are restrictions on the town structure. Furthermore, the mechanical structure of the deceleration mechanism, stop mechanism, etc. from the drive source becomes complicated, and problems arise in the accuracy of lens movement and position setting. Particularly in the case of small cameras, the amount of lens extension is generally extremely small, and it is necessary to improve the precision of each part of the lens moving mechanism.

The object of the present invention is to obtain a new automatic focus adjustment device that eliminates the various drawbacks of the conventional methods as described above, and can be made into a focus adjustment device that has many advantages as shown below. .

(b) Power consumption is extremely low.

(b) Highly accurate focus adjustment is possible with a very simple configuration.

(c) It has few mechanical components and is highly durable.

2) It is not easily affected by temperature changes due to its material and composition.

It has an advantage.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments with reference to the drawings, but first a description will be given of a one-inch insect moving device used as a drive control source for the device according to the present invention.

``One inch*b insect locomotion device using piezoelectric materials'' has already been described in r USP3, 902, 084 Burlei (h
Although it is described as In5-ut firwen (s Inc, JK), it will be explained based on FIG. It is formed from three piezoelectric material (for example, PZT) parts, and the part 41m and 1c is formed as a hollow cylinder that comes into pressure contact with the moving shaft 2 when no voltage is applied to electrodes (not shown). When a voltage is applied to the poles, distortion occurs in the tangential direction, and the pressure contact is released.

On the other hand, the 1bO part is formed as a hollow cylinder that does not touch the horizontal movement axis 2, and when a voltage is applied to an electrode (not shown) during Thj, it extends in a direction parallel to the linear axis 2. Reference numeral 1d designates a rounded identification member that defines the portion 1b as a main body portion (not shown).

In this configuration, when a voltage of 1aK is first applied, the result shown in Fig. 1 (
II) As shown in K (1aK strain occurs and the pressure contact between 1m and axis 2 is broken.Next, when 1bK voltage is applied while applying voltage to 11, lb extends along axis 2 as shown in (lii)) The shaft 2, which is in pressure contact with the IC, moves to the right as shown by the arrow in the figure.Furthermore, as shown at 4ψ (remove the voltage of 1 m and add it this time), apply voltage to lc as shown in the figure. 0 In this case, the voltage remains applied to Fi, t, and lb. Then, as shown in (vl) (me), when the voltage on lb is released, 1b contracts, and the shaft 2, which is pressed against 1a and K, becomes horizontal as shown by the arrow in the figure. Move to the right as shown.

As shown in the next ec (vii) recommendation (release the lc voltage and then
If a voltage is applied to 1 m, the state will be (+)% again, and the same cycle will be repeated.) In turn, the shaft 2 will move to the right.

The above is an explanation of how to move the line axis to the right.Conversely, to move the line axis to the left, K can be done by changing the order of the voltages applied to 1a and 1eK (Fig. 2 is a diagram showing the above-mentioned timing) A voltage is applied to the pulse TK as shown in the diagrams 1a to 1elC. The movement of axis 2 is δ” as shown in L, but 1bV
By adding c, it is possible to change 1δ'' depending on the magnitude of the voltage.

Figure 3 is the above-mentioned 1-inch insect moving device? FIG. 2 is a diagram showing an automatic focus adjustment device for a photographing lens of a camera using an "IF" camera.

In the figure, reference numeral 101 designates the above-mentioned 1-saku vehicle moving device, which is formed from three parts, 101m, 101b, and 101e, each of which has the same length as explained in FIG.
, lb, lc K priest 0 or 101d is 10
1bllt - This is a part that is fixed to the main body (not shown). 10
Reference numeral 4 denotes a photographing lens, and by moving the lens along the optical axis C, the Il tube of the subject is connected to the connecting part 109 of a film sensor, etc. 0103 is the aforementioned lens 104
The moving shaft 102 has both ends 102m and 102b attached to the main body (not shown). It is supported by the optical axis CK and is movable in a direction parallel to the optical axis CK. And these supporting parts 102m, 102
The above-mentioned 01 scale removal wheel moving device "101" is provided between b. Reference numerals 107 and 108 are aperture wheels, which are located in the direction of arrow B in the figure, and one end 103b of the lens barrel section 103 mentioned above. K is a contact piece 10.
A signal indicating the position of the lens 104 is transmitted from the contact piece 105 to a podensimeter 106, for example.

A distance measuring device 110 generates information on the distance from the camera to the subject. 111 is a distance calculation circuit which compares the distance information from the distance measuring device 110 and the lens position information from 106 and informs the driving circuit 112 of the 1-shaku pick-up wheel moving device 101 in the direction and amount of movement of the lens. tell.

A moving shaft 102 is driven through 101 and is driven and controlled by 112.
The lens 104 moves in a direction parallel to the optical axis C.
is the zero point whose movement is controlled according to the distance information,
When the voltage application to the moving device 101 is stopped, the lens 104
is stopped and held at that position.

FIG. 4 shows another embodiment of the invention. Fourth
In the figure, 204 is a ti lens, and 203 is a lens barrel portion that holds the lens. and 201ae201b
, 201e is formed such that the lens barrel portion 203 is fitted into its hollow portion.

FIG. 5 is a cross-sectional view of FIG. 4.
3 K is the lens 2 as shown in 204a to 204d.
04 is fixed to the sand, further 203m at both ends,
203b is fitted into the main body portion 211. The lens barrel portion 203 is movable along the optical axis CK. Again 1
The center part 201b of the length center moving device #201 is the fixed part 2
Since it is fixed to the main body part 211 through the diaphragm 01d, it is possible to perform more precise control and also to make the device more structurally configurable.

FIG. 6 is a block circuit diagram showing an embodiment of the circuit configuration of an automatic focusing camera according to the present invention. In the figure, 3
01 is a distance measuring section that uses various known electronic distance measuring devices. 30
2 The Fi photographing lens section moves in the optical axis direction using the "scale wheel moving device" of the present invention in accordance with the distance information from the distance measuring section to focus on the subject. The digital ranging signal A obtained from the ranging section 301 and the position signal B obtained from the photographing lens section are input to a digital comparator 303 and compared. The output of the comparator 303 is input to an up/down counter 304, which counters clock pulses from a clock generator 305 accordingly. In other words, the output of the comparator 303 is A
> When H, the counter 304 counts up; conversely, when A (H), it counts down. Also, when A and B match, it is inhibited and the count stops. This output from the up/down counter 304 is input to the switch circuit 307 via the decoder 306.

D from the high voltage DC generation circuit 308 to the switch circuit 307
A high voltage (approximately 100 to 200 V) is applied, and this is switched by a control signal to the switch circuit and supplied to each piezoelectric member of the "measure wheel moving device".
Reference numeral 0 denotes a lens drive unit by the "scale wheel moving device" of the present invention, and a signal applied there causes the photographing lens 302 to move linearly in the optical axis direction to bring it into focus. When the lens position approaches the distance measurement position, the digital comparator 303
The voltage switching circuit 309 is activated by the detection signals of A and B from the camera, and the voltage of the high-voltage DC generator 308 is switched by the output of the voltage switching circuit 309, and the voltage of the high-voltage DC generator 308 is switched.

The circuit indicated by the dotted line in Fig. 6 performs the above fine adjustment by controlling the frequency of the clock pulse generator 3050, and when A or B is reached, the clock frequency is lowered to slow down the movement of the lens. By using both the control of the high voltage DC generator 308 and the frequency control of this clock generator, even smoother automatic focus adjustment control can be performed.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram for explaining the operating principle of the inchworm moving device used in the focus adjustment device of the present invention, and FIG. 2 is a curve diagram showing the relationship between drive timing and movement amount of the device shown in FIG. FIG. 3 is a perspective view showing one embodiment of an automatic focus adjustment device for a camera according to the present invention, FIG. 4 is a perspective view showing another embodiment of the device of the invention, and FIG. 5 is a perspective view of the device shown in FIG. cross section,
FIG. 6 is a block circuit diagram showing an embodiment of the circuit configuration of an automatic focus adjustment device for a camera according to the present invention. 101...Screening 9 insect moving device, 102...
Movement axis, 103... Lens barrel section, 104...
... Lens, 105 ... Contact piece, 106 ...
Potentiometer, 107, 108-...Aperture blade, 109...Imaging section, 110...Distance measuring device, 111...Distance information calculation circuit, 112...
...Mobile device drive circuit. Osonomi No. 6M

Claims (1)

[Scope of Claims] (1) A shaku-tome constructed by second and third piezoelectric members that can be press-contacted or scaled against a first piezoelectric member that expands and contracts in the direction of movement of a moving axis. 9. An automatic focus adjustment device for a camera, characterized in that an in-focus state is obtained by driving a distance adjustment mechanism of a photographic lens by moving a central moving device along a sidewalk. (2. An automatic focus adjustment device for a camera according to claim (1), characterized in that it is configured to move the movement axis of the inchworm moving device straight in the optical axis direction of the photographing lens. (3. ) In what is stated in claim (1),
An automatic focus adjustment device for a camera, characterized in that the movement axis of the inchworm moving device includes an optical path of a photographing lens therein, and its movement directly moves a lens barrel. (4) The apparatus according to claim (1), further comprising means for automatically focusing on a subject by moving the inchworm moving device according to distance measurement information of a camera, and moving the lens. An automatic focus adjustment device for a camera, comprising control switching means for switching from coarse adjustment to fine adjustment near the in-focus point.