JPS63287833A - Variable focus camera - Google Patents

Abstract

PURPOSE:To attain variable power and focusing by turning a cam barrel against a fixed barrel so as to move a moving lens frame holding a moving lens which is engaged with a cam groove in parallel along an optical axis direction. CONSTITUTION:The variable power part 3b of a first group of lens moving cam groove 3 and the variable power part 4b of a third group of lens moving cam groove 4 are inclined to the optical axis and the first group and the third group of lenses 5a and 5c are moved from a telephotograph to a wide-angle (or an opposite direction) by turning the cam barrel 2. And the wide focusing part 3a and the telefocusing part 3c of the first group of lens moving cam groove 3 are inclined to the optical axis direction so as to move them by quantity necessary for focusing with the inclination. Moreover, the wide focusing part 4a and the telefocusing part 4c of the third group of lens moving cam groove 4 are parallel with the turning direction of the cam barrel 2 and the third group of lens 5c is not moved even if the cam barrel 2 is turned. Thus, the wide focusing - variable power - telefocusing are continuously executed by turning the cam barrel 2.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a so-called variable focus camera that can be switched to a plurality of focal lengths by switching an optical system.

(Background of the Invention) Conventionally, various variable focus cameras in which the focal length of a photographic lens can be changed have been proposed. However, in those variable magnification systems, after the main optical system moves along the optical axis, the sub optical system
This method involves inserting a conversion lens).

(Problems to be Solved by the Invention) A variable-focus camera of a variable magnification type in which the above-mentioned sub-optical system (conversion lens) is inserted into the optical axis requires a mechanism for inserting the sub-optical system. In addition, the mechanism has the problem that the sub-optical system must be inserted precisely on the two optical axes, which makes the mechanism complicated and that it is difficult to adjust the alignment of the optical axes during the manufacturing process. Furthermore, when a sub-optical system is inserted, the value (value indicating brightness) of the lens becomes significantly larger, causing the problem that the lens becomes darker.

The present invention was made in view of the above problems, and its objectives are to eliminate the need for a sub-optical system, to have a simple mechanism, to facilitate adjustment during the manufacturing process, and to prevent the F-number of the lens from changing much at each focal point. Our goal is to provide a variable focus camera.

(Means for Solving the Problems) The present invention, which solves the above problems, is a variable focus camera that can switch to a plurality of focal lengths by moving a plurality of lenses along the optical axis. a lens barrel, a cam barrel rotatably supported by the fixed barrel, and a movable lens frame that holds the plurality of lenses, and one of the fixed barrel and the cam barrel has a corresponding focal length. a plurality of focusing sections and a variable power section J connected to the focusing sections;
a cam groove in which the movable lens frame engages;
On the other hand, a linear guide means for guiding the movable lens frame parallel to the optical axis is provided, and magnification change and focusing are performed by rotating the cam cylinder.

(Function) In the variable focus camera of the present invention, by rotating the cam cylinder relative to the fixed cylinder, the movable lens frame that engages with the cam groove and holds the movable lens is moved in the optical axis direction by the linear guide means. The lens is moved parallel to the lens, and magnification and focusing are performed.

(Example) Next, embodiments of the present invention will be described using the drawings.

FIG. 1 is a perspective view showing an embodiment of the present invention.

In the figure, 1 is a fixed body fixed to the camera body, 2 is a fixed J
111 is a cam cylinder rotatably supported.

A pair of cam grooves 3 for moving the first group lens and a pair of cam grooves 4 for moving the third group lens are formed on the cam cylinder 2. A prefectural lens 5 is disposed within the fixed barrel 1, and the arrangement of the lens is shown in FIGS. 2 and 3.

The lens 5 in this embodiment includes a first lens group 5a, a second lens group 5b, a third lens group 5C, and a mask lens 5d. FIG. 2 shows the lens arrangement on the telephoto side, and focusing is performed by moving only the first lens group 5a along the optical axis. Also, FIG. 3 shows the lens arrangement on the wide-angle side, and compared to the state shown in FIG. It is moving towards the main body. Even in this lens arrangement, focusing is performed by moving only the first lens group 5a along the optical axis.
, will be held. Further, an aperture mechanism 6 is disposed between the third lens group 5C and the mask lens 5d.

Returning to FIG. 1, the explanation will continue. The fixed cylinder 1 includes a main body part 1a that rotatably supports a cam cylinder 2, a second group lens fixed body part 1b that holds a second group lens 5b, and a mask system lens 5.
d.

As linear guide means, there are linear guide grooves 1d for moving the first group lens extending parallel to the optical axis on the left and right sides of the main body 1a in the drawing, and on the upper and lower parts of the drawing (A), A straight guide groove 1e for moving the third snoring lens that extends parallel to the optical axis.
and is drilled. The first group lens 5a is held by a first group lens frame 7 which is a movable lens frame, and the first group lens frame 7 is fitted into the main body portion 1a of the fixed barrel 1. A square frame 7I for the first group lens is provided, and the cam pin 7a engages with the linear guide groove 1d for moving the first group lens and the cam groove 3 for the first group lens. ing.

The third group lens 5C is held by a third group lens frame 8 which is a movable lens frame, and the third group lens frame 8 is disposed within the second lens group fixed body portion 1b. 2nd lens group fixed cap 1
A through groove 1f for the third group lens is bored in the upper and lower parts of the drawing of b, and the supporting portion 8 of the frame 8 for the third group lens described above is formed.
a passes through the third group lens through groove 1e, and furthermore, the cam bin 8b with a small friction coefficient provided on the support part 8a is inserted into the third group lens through groove 1e.
It engages with the linear guide groove 10 for moving the group lens and the cam groove 4 for moving the third group lens. Further, the base of the cam barrel 2 is provided with a cam barrel gear portion 2a in which a rack is carved in the circumferential direction. Reference numeral 9 denotes a DC motor for driving the cam cylinder, and the motor 9 is driven through a reduction gear train 10 that meshes with the binion 9b of the output shaft 9a of the motor 9 for driving the cam cylinder and the cam cylinder gear A7 portion 2a. The rotation output is transmitted to the cam cylinder 2, and the cam cylinder 2 is configured to rotate. Cam barrel gear part 2 of cam barrel 2
An encoder board 11 provided with a predetermined printed pattern is fixed to the fixed cylinder 1 near a. A protrusion 2b is provided on the cam barrel 2, and a brush 12 that slides on the encoder board 11 is attached to the protrusion 2b.

Next, the cam grooves 3 for moving the first group lens and the cam grooves 4 for moving the third group lens will be explained using FIG. 4 showing a developed configuration diagram of the cam cylinder 2. The first group lens moving cam groove 3 has three parts: a wide focusing part 3a, a variable power part 3b connected to the wide focusing part 3a, and a pre-focusing part 3C connected to the variable power part 3b. Consists of parts. Similarly, the cam groove 4 for moving the third group lens also includes a wide focusing portion 4a and a wide focusing portion 4a.
It consists of three parts: a variable power section 4b connected to the variable power section and a telefocusing section 4C connected to the variable power section. When the cam cylinder 2 rotates, the first group lens square frame 7 is guided by the first group lens moving cam groove 3 and has a cam pin 7a that engages with the first group lens moving cam groove 3. (The first lens group 5a) moves in the optical axis direction (indicated by an arrow).

Further, the third group lens square frame 8 (third group lens 5c) having a cam pin 8b that is guided by the third group lens moving cam groove 4 and engaged with the third group lens moving cam groove 4 is also aligned with the optical axis. move in the direction. Here, the variable power portion 3b of the cam groove 3 for moving the first group lens and the variable power portion 4b of the cam groove 4 for moving the third group lens are inclined with respect to the optical axis, and the inclination is 2 rotates, the first group lens 5a and the third group lens 5
C is selected to move a predetermined amount in the optical axis direction from a telephoto lens arrangement to a wide-angle lens arrangement (or vice versa). Furthermore, the wide focusing section 3a and the telefocusing section 3C of the cam groove 3 for moving the first group lens are inclined with respect to the optical axis direction, and the inclination is different from that of the first group lens 5.
a is each lens i[! (at the location) A-Cashing is chosen to move through the states necessary to do so. Furthermore, the wide focusing section 4a and the telefocusing section 4C of the cam groove 4 for moving the third group lens are parallel to the rotating direction of the cam cylinder 2 (see FIG. 2 rotates, the third group lens 5C does not move.By doing this, the cam cylinder 2 can be rotated to perform wide focusing, magnification changing, and telephoto focusing. can be performed continuously.

Next, the means (encoder) 13 for detecting rotation of the cam cylinder 2 will be explained using FIGS. 5 to 7. Fixed 111
As shown in FIG. 5, the encoder board 11 provided in the
11C and 11d are installed. These line-shaped patterns 11a, 11b, 11c and 11
d, four conductive sliding branches 12a, 12b, 12c
and 12d, the brush 12 slides in contact with the rotation of the cam cylinder 2 and moves from the wide focusing area to the telefocusing area via the variable power area.

Furthermore, the proximal ends of the sliding branches 12a, 12b, 12C, and 12d of the brush 12 are connected.

Each pattern 11a, 11b, 11 of encoder board 11
Terminals 1, 2, 2 and IV are provided at one end of G and 11d, and these terminals I, II, 2 and TV are connected to the circuit shown in FIG. Terminal ■ is terminal a, resistor R
It is connected to the anode of the DC power supply B of V(v) via the V(v). Terminal (2) is connected to terminal (b) and the anode of DC power supply B via resistor R1.

Terminal ■ is grounded. Terminal ■ is terminal C1 resistance RJ[
is connected to the anode of DC power supply B via. The cathode of the DC power supply B is grounded similarly to the terminal (2). When such a circuit is connected, the outputs at terminals a, b and C will be as shown in FIG.

The output at terminal C in the wide focusing area and telefocusing area is a pulse, but this is because the pattern 11d of the encoder board 11 has comb-shaped parts 11e and 11[ in the wide focusing area and telefocusing area. This is because. In this embodiment, the pitch and the number of steps of the comb teeth in the wide ) A-focusing area and the comb teeth 11f in the telefocusing area are different, and the pitch is narrower in the telefocusing area. Also, the number of stages of comb teeth has increased.

By detecting the outputs of terminals a, b, and C of the encoder 13, it is possible to detect in which range the cam cylinder 2 is located.

Next, the drive circuit of this embodiment will be explained with reference to FIG.

In the figure, 13 is an encoder that detects in which range the cam cylinder 2 is located, 14 is a distance measuring element that uses, for example, a phase difference detection method to detect the direction of defocus and the amount of defocus, and 15 is a tele/wide magnification. A changeover switch 16 is a motor power supply, and 17 is a control circuit that takes in information from the encoder 13, distance measuring element 14, and magnification changeover switch 15 and controls the motor 9 based on these information.

This control circuit 17 controls the motor 9 shown in FIG. 9 at Meijo. (a) is a method of controlling the motor 9 in the variable magnification range. At this time, the motor 9 is driven at high speed by constant voltage. (b) is a method of controlling the motor 9 in a wide focusing range.

At this time, the motor 9 is driven at a low speed by the pulse voltage, but the positioning accuracy is improved compared to the constant voltage drive described above. (c) is a method of controlling the motor 9 in the telefocusing range. At this time, the motor 9 is driven at low speed by the pulse voltage as in the wide focusing range, but
Since the depth of focus in a telephoto lens is shallower than that in a wide-angle lens, the due diligence is made even smaller than in (b), and driven at a slower speed than in the wide focusing range, further improving positioning accuracy.

Next, the operation of the above configuration will be explained. First, operate the magnification changeover switch 15 to switch to telephoto or wide-angle. Then,
The control circuit 17 drives the motor 9 at a constant voltage to rotate the cam barrel 2 until the lens system is in the telefocusing range or wide focusing range. Next, information on the defocus direction and defocus amount of the subject is taken into the control circuit from the distance measuring element 14. The control circuit 17 includes the encoder 1
Based on the position information of the cam cylinder 2 from 3 and the defocus direction and defocus amount information from the distance measuring element 14 mentioned above, it is possible to determine in which direction and by how much the cam cylinder 2 should be rotated to bring the lens system into focus. Based on the calculation result, the motor 9 is driven by the above-mentioned pulse voltage, and the cam cylinder 2 is rotated to the in-focus position.

According to the above configuration, since the lens system of the multifocal camera of this embodiment has no sub-optical system, the mechanism is simple, adjustment in the manufacturing process is easy, and the F value of the lens at each focal point does not change much. In addition, information from the encoder 13, distance measuring element 14, and magnification changeover switch 15 is input into the control circuit 17, and the motor 9 is controlled based on this information.
Autonomous 4-cass can be realized. Furthermore, in the focusing region and the variable magnification region, the driving speed of the motor 9 can be freely set by driving the motor 9 with a pulse voltage, and the pattern 11d in the focusing region
By changing the pitch and the number of stages of the comb teeth of the comb teeth portions 11e and 11f, the control method and precision of the motor 9 can be changed as desired depending on the focal length of the lens system.

Note that the present invention is not limited to the above embodiments.

For example, in the above embodiment, the fixed barrel 1 has a linear guide groove 1e for moving the first group lens and a linear guide groove 1f for moving the third group lens.
The cam cylinder 2 is provided with a cam groove 3 for moving the first group lens. Although the cam groove 4 for moving the third group lens was carved, on the contrary, the fixed 1
Even if a cam groove for moving the first group lens and the third group lens is carved in the cam cylinder 2, and a linear guide groove for moving the first group lens and the third group lens is carved in the cam cylinder 2, the present invention still works. realizable. Cam bins 7a and 8 engage with the linear guide groove and the cam groove.
b may be a roller. Furthermore, a cam cylinder is used as a linear guide means, using a rondo installed parallel to the optical axis.

The present invention can also be realized by providing the rod on one of the fixed barrels, providing a cam groove on the other, and engaging the movable lens frame with the rod. Further, in the above embodiment, the explanation has been given using the photographing lens 5 in which the first lens group 5a and the third M lens 5C move for variable magnification, and only the first lens group 5a moves for focusing. For example, zooming is performed by moving the second group lens 5b and third group lens 5C, and focusing is performed by a dynamic lens in which only the first group lens 5a is moved (in this case, the first group lens is moved). The cam groove for the magnification variable part is carved with a groove in the direction around the optical axis.
The present invention can be applied even if the first group lens does not move in the optical axis direction during zooming.

Then, as shown in FIG. 10, the pattern 11d of the encoder board 11 is all comb-shaped, pulses are counted in the variable power range, and when the cam cylinder 2 is rotated within the variable power range, when the cam cylinder 2 approaches the focusing range, the motor 9 may be decelerated. In this way, it is possible to smoothly switch from a high-speed variable magnification range to a focusing range that requires precision.

Although the motor 9 is a DC motor, the present invention is not limited to this, and for example, a stepping motor may be used, or focusing may be performed manually without being driven by a motor. Further, in the above embodiment, the photographic lens 5 has been described as having two focal points, a telephoto lens and a wide-angle lens, but the photographing lens 5 may have three focal points: a telephoto lens, a standard lens, and a wide-angle lens. If the cam barrel 2 is provided with a cam groove 23 for moving the first group lens and a cam groove 24 for moving the third group lens, which are shaped as shown in FIG. It is possible to continuously perform focusing from variable magnification to wide-angle focusing. Furthermore, in this case, as shown in FIG.
If 1o, 11h, and 111 are provided, outputs as shown in FIG. 13 can be obtained at terminals a, b, and C of the circuit shown in FIG. can be detected.

Further, as shown in FIGS. 14 and 15, m is carved on the circumferential surface of a disc-shaped encoder board 21, and the encoder board 21 is meshed with the cam barrel gear portion 2a. Then, the pattern shown in FIG. 13 is provided on the encoder board 21, and the cam cylinder 2 is rotated from wide-angle U-CO to telephoto position 10O (or from wide-angle LJ-min to telephoto jJ=-min). The encoder board 21 is made to rotate once. By doing this, the pattern of the focusing area can be used for both wide-angle and telephoto lenses. Although the distance measuring element 14 uses a phase difference detection method, it may also use a contrast detection method.

(Effects of the Invention) As explained above, according to the present invention, there is no need for a sub-optical system, the mechanism is simple, the adjustment in the manufacturing process is easy, and the F value of the lens at each focal point can be adjusted without changing much. A focus camera can be realized.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the main parts showing one embodiment of the present invention, and FIG.
3 and 3 are views showing the lens arrangement in FIG. 1, FIG. 4 is a developed configuration diagram of the cam cylinder in FIG. 1, FIG. 5 is a plan view of the encoder board in FIG. 1, and FIG. 1 is a circuit diagram connected to the encoder board, FIG. 7 is a diagram showing outputs in six areas of terminals a, b, and c in FIG. 6, FIG. 8 is a drive circuit diagram in FIG. 1, and FIG. The figure shows the motor drive control in 6 areas in Figure 1.
The figure is a plan view of an encoder board showing another embodiment of the present invention, FIG. 11 is a developed configuration diagram of a cam cylinder showing another embodiment of the present invention, and FIG. 12 is a plan view of an encoder board showing another embodiment of the present invention. A plan view of the second encoder board, FIG. 13 shows the 6 terminals a, b, c in FIG. 6 when using the encoder board of FIG. 12.
14 is a perspective view of the main part showing another embodiment of the present invention, and FIG. 15 is a plan view of the encoder board similar to that shown in FIG. 14.1.・Fixed body 1a ・Body portion 1b ・・
・Second group lens fixed body part 1C... Master lens system fixed body part 1d... Linear guide groove for moving the first group lens 1e... Linear guide groove for moving the third group lens 2... Cam Il&i
2a...Cam barrel gear part 2b...Protrusion 3.23...Cam groove for moving the first group lens 4.24...
-Cam groove 5 for moving the third group lens...Photographing lens 5a...First group lens 5b...Second group lens 6
... Aperture mechanism 7 ... First group lens peripheral frame 7
a, 8b...Cam pin 8...Frame for third group lens 8a...Support part 9...
Motor 9a... Output shaft 10... Reduction gear train 11.21... Encoder board 12... Brush 13... Encoder 14
- Distance measuring element 15... Magnification changeover switch 16... Motor power supply 17... Control circuit patent applicant Roku Konishi Photo Industry Co., Ltd. Agent
Patent attorney Fuji Ijima Jigai 1 person - 19 =

Claims (4)

[Claims] (1) A variable focus camera that can switch to multiple focal lengths by moving multiple lenses along the optical axis, which includes a fixed barrel and a cam barrel rotatably supported by the fixed barrel. , a movable lens frame that holds the plurality of lenses, a plurality of focusing sections corresponding to each focal length on either the fixed cylinder or the cam cylinder, and a variable power section connected to the focusing section. A cam groove with which the movable lens frame engages is carved, and a linear guide means is provided on the other side to guide the movable lens frame parallel to the optical axis, and the magnification can be changed by rotating the cam cylinder. A variable focus camera characterized by performing both focusing and focusing. (2) The variable focus camera according to claim 1, wherein the cam cylinder is rotated by a motor. (3) The second aspect of the present invention is characterized in that the speed of the motor changes in the variable magnification range and the focusing range.
Variable focus camera as described in section. (4) The variable focus according to claim 1, 2 or 3, further comprising means for detecting the variable magnification area and the focusing area by rotation of the cam cylinder. camera.