JPH04278906A - Variable focusing camera - Google Patents

Abstract

PURPOSE:To prevent a zoom lens from being out of focus by the application of an external force to a lens barrel at the time of zooming. CONSTITUTION:A mobile cylinder 27 moved in the direction of the optical axis at the time of variable magnification is provided with a pressure sensor 35. A main control circuit detects the position of the mobile cylinder 27 moved in accordance with the operation of a variable magnification operation member through an encoder 31 and stores this position data. When a correcting signal is outputted from a pressure sensor 35 after movement of the moving cylinder 27 is completed, the main control circuit moves the mobile cylinder 27 again based on stored position data after moving the mobile cylinder 27 in one direction of the optical axis by a prescribed distance.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable focus camera.

0002

[Prior Art] Recently, a two-group zoom system has been put into practical use.
Compact cameras are also increasingly incorporating zoom lenses. As is well known, in a zoom lens, the focal length is changed by simultaneously moving the variable magnification lens and the correction lens in the optical axis direction, but in order to properly compensate for the movement of the focal plane caused by the variable magnification lens, it is necessary to , it is necessary to accurately determine the position of these lenses. For this reason, it is possible to improve the processing accuracy of the movement mechanism of the variable power lens and correction lens, and furthermore, when stopping these lenses at a desired variable power position, it is possible to shift the lens to one side so that it always moves from a certain direction and then stops. Drive methods have also been proposed.

0003

[Problem to be Solved by the Invention] However, even if the accuracy of the lens moving mechanism is increased as described above, or even if the lens position is determined with high precision by adopting a biasing drive method, the problem occurs after zooming operation. If an external force is applied to the lens barrel holding the variable magnification lens or correction lens,
These lenses often deviate from their optimal magnification positions, resulting in poor focus.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a variable focus camera which solves the above-mentioned problems and prevents photographing in an out-of-focus state.

[0005]

[Means for Solving the Problems] The present invention has been made in view of the above-mentioned drawbacks.The first invention provides a variable focus camera provided with a variable magnification operation member, in which the lens that is moved when changing the magnification is A lens frame to be supported, a variable magnification movement mechanism for moving the lens frame in the optical axis direction based on a signal from the variable magnification operation member, a position detecting means for detecting the position of the lens frame, and a position detecting means for detecting the position of the lens frame, External force detection means detects and outputs a correction signal; and when the correction signal is output after the position of the lens frame is determined by the variable magnification movement mechanism, the lens frame is moved by a predetermined amount in one direction of the optical axis. and a movement control means for moving the lens frame again to the position determined by the zooming movement mechanism.

Further, in a second aspect of the invention, in a variable focus camera provided with a variable magnification operating member, there is provided a lens frame that supports a lens that is moved during zooming, and a signal from the variable magnification operating member that controls the lens frame to be illuminated. A variable magnification movement mechanism that moves in the axial direction, a position detection means that detects the position of the lens frame, an external force detection means that detects an external force applied to the lens frame and outputs a correction signal, and the variable magnification movement mechanism. The lens frame includes a movement control means for moving the lens frame to a predetermined specific position when a correction signal is output after determining the position of the lens frame.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a lens barrel of a variable focus camera according to an embodiment of the present invention. This lens barrel has a two-group zoom lens consisting of a front group lens 20 that serves as both a compensator lens and a focusing lens, and a rear group lens 21 that is a variator lens, and moves it forward and backward in the optical axis direction using a cam mechanism. Perform zooming.

The structure of the lens barrel is: a fixed barrel 23 formed on the camera body; a cam barrel 25 rotated by a zoom motor 24 inside the fixed barrel 23; It is composed of a movable barrel 27 that moves forward and backward in the optical axis direction, and a rear group lens frame 28 that moves forward and backward in the optical axis direction inside the movable barrel 27. The front group lens frame 29 is attached to the movable barrel 27 via a helicoid mechanism, and moves together with the movable barrel 27 during zooming, and moves along the movable barrel 27 by driving the focusing motor 30 during focusing.
7, move forward and backward in the optical axis direction.

The cam cylinder 25 has two cam grooves 25a.
, 25b are provided, and these cam grooves 25a, 2
A cam follower pin 27a provided on the movable barrel 27 and a cam follower pin 28a provided on the rear group lens frame 28 are respectively engaged with the cam follower pin 5b. As a result, when the cam barrel 25 rotates, the movable barrel 27 and the rear group lens frame 28 move forward and backward. In addition, the movable barrel 27 and the rear group lens frame 2
8 moves linearly in the optical axis direction by a well-known linear guide (not shown).

Movement of the movable cylinder 27 is detected by an encoder 31 provided on the fixed cylinder 23. This encoder 31 has a slider in contact with a resistor 32 provided on the outer peripheral surface of the cam barrel 25 through an opening 23a, and detects the amount of rotation of the cam barrel 25 corresponding to the movement of the movable barrel 27 back and forth. do. Further, a pressure sensor 35 for detecting external force applied to the cover tube 34 is sandwiched between the movable tube 27 and the cover tube 34 provided with the lens window 34a. When this pressure sensor 35 detects an external force, a main control circuit 41 (described later)
sends a correction signal to Note that the reference numeral 26 is a shutter block.

FIG. 3 shows a schematic diagram of the electrical configuration of the camera shown in FIG. 2. When the main switch 11 shown in FIG. 2 is operated to the ON side, the main switch 11 shown in FIG. 3 is connected to the contact C. As a result, the main control circuit 41 controls the driver I so that the movable barrel 27 is extended from the collapsed position where it has entered the camera body to the wide position.
The zoom motor 24 is controlled via C43.

Reference numeral 12 shown in FIG. 3 is a zoom operation member, and the camera user can use the zoom operation member 12 shown in FIG.
When the zoom operation member 12 shown in FIG. 3 is connected to the contact a, the main control circuit 41
A wide signal is output. Further, when the camera user operates the zoom operation member 12 to the T side, that is, to the telephoto side, the contact b is connected and a telephoto signal is output to the main control circuit 41.

The main control circuit 41 drives the zoom motor 24 via the driver IC 43 in response to the times when the wide and tele signals are captured. When the camera user finishes operating the zoom operation member 12, the main control circuit 41 stops driving the zoom motor 24, and the encoder 3
1, the amount of rotation of the cam cylinder 25 is detected. The amount of rotation of the cam cylinder 25 at this time is temporarily stored in the main control circuit 41. Note that when the camera user finishes operating the zoom operation member 12, the zoom operation member 12 automatically returns to the neutral position.

Furthermore, when the main control circuit 41 receives a correction signal from the pressure sensor 35 via the pressure detector 44 after the operation of the zoom operation member 12 is completed, it drives the zoom motor 24 again. This re-driving involves, for example, driving the movable barrel 27 to once move it toward the wide end,
Thereafter, when the amount of rotation of the cam barrel 25 reaches a predetermined amount of rotation via the encoder 31, the zoom motor 24 is driven in the opposite direction to the aforementioned driving direction. and,
The main control circuit 41 connects the cam cylinder 25 to the cam cylinder 25 via the encoder 31.
When the amount of rotation of the cam barrel 25 becomes the same as the stored amount of rotation of the cam cylinder 25, the drive of the zoom motor 24 is stopped.

Reference numeral 10a denotes a switch that is turned on when the shutter button is pressed halfway, and the main control circuit 41 operates the distance measuring circuit 14 and the photometer 13 in response to the turning on of the switch 10a to determine the subject distance and subject brightness. is detected, and the focusing motor 30 is driven via the driver IC 46 according to the detected object distance. Furthermore, code 10
b is a switch that is turned on when the shutter button is pressed from halfway to fully pressed, and in the main control circuit 41, in response to the turning on of the switch 10b, the shutter control circuit 26h is turned on.
The shutter is opened and closed with an exposure amount corresponding to the brightness of the subject.

Next, the operation of the above configuration will be briefly explained. When the camera user operates the main switch 11 shown in FIG. 2 to the ON side, the aforementioned movable barrel 27 moves out from the collapsed position to the wide position, and the camera enters the standby state. after that,
When the zoom operation member 12 is operated to the T side, that is, to the telephoto side, the main control circuit 41 drives the zoom motor 24 via the driver IC 43 in response to the time of this operation. Thereby, the zoom motor 24 rotates the cam barrel 25 and moves the movable barrel 27 toward the telephoto end. When the camera user finishes operating the zoom operation member 12, the main control circuit 41 stops driving the zoom motor 24 and stores the amount of rotation of the cam barrel 25 via the encoder 31.

After the camera user finishes operating the zoom operation member 12, for example, the camera user etc.
When an external force is applied to the pressure sensor 35, this external force
This pressure sensor 35 is detected by the pressure detector 4.
A correction signal is sent to the main control circuit 41 via 4. The main control circuit 41 receives this correction signal, and the driver I
The zoom motor 24 is re-driven via C43.

This re-driving is performed by moving the moving cylinder 27 as described above.
The zoom motor 24 is controlled to move in the wide end direction, and when the amount of rotation of the cam cylinder 25 that is read via the encoder 31 reaches a predetermined amount of rotation, the zoom motor 24 is moved in the driving direction. Drive in the opposite direction. This drive causes the zoom motor 24 to rotate the cam barrel 25 so as to move the movable barrel 27 toward the telephoto end. Thereafter, the main control circuit 41 controls the cam barrel 25 in which the amount of rotation of the cam barrel 25 read via the encoder 31 is stored.
The drive of the zoom motor 24 is stopped when the amount of rotation becomes the same as the amount of rotation.

Note that in the above-mentioned embodiment, the main control circuit 4
1 receives a correction signal from the pressure sensor 35 via the pressure detector 44, the movable barrel 27 is once moved toward the wide end, and then the zoom motor 24 is driven again to move it toward the telephoto end. However, the present invention is not limited to this. For example, the zoom motor 24 may be driven again to move the movable barrel 27 toward the telephoto end and then toward the wide end.

Furthermore, in the embodiment described above, when re-driving the zoom motor 24, the timing for moving the movable barrel 27 from its wide end direction to its telephoto end direction is determined by a predetermined amount of rotation of the cam barrel 25. However, the rotation time of the cam cylinder 25 may be determined in advance.

Furthermore, in the embodiment described above, the main control circuit 4
1 re-drives the zoom motor 24 to move the moving cylinder 27 determined by the previous operation of the zoom operation member 12.
In this example, the movable cylinder 27 is controlled to be returned to the position shown in FIG. For example, the specific position may be a position corresponding to the focal length of the zoom lens which has become 50 mm, or the specific position may be a position where the movable barrel 27 has moved to the collapsed position.

Further, in the above-mentioned embodiment, the external force detection means was used as the pressure sensor 35, but this embodiment is not limited to this, and may be one using a strain gauge attached to an elastic body, a piezoelectric element, etc. But that's fine. Furthermore, in another embodiment shown in FIG. 4, a spring member 50 is interposed so that the cover cylinder 34 and the movable cylinder 27 repel each other, and an external force larger than the biasing force of the spring member 50 is applied to the cover cylinder 34. This is an example in which the main control circuit 41 controls the zoom motor 24 to be driven again when the zoom motor 24 is turned on. In this example, when an external force larger than the biasing force of the spring member 50 is applied to the cover tube 34, the contact point 51 provided at the rear end of the cover tube 34
When the contact point 52 provided at the front end of the movable cylinder 27 comes into contact with the contact point 52, a correction signal is sent to the main control circuit 41.

Next, another embodiment will be described with reference to FIG. The zoom lens of the above-mentioned embodiment has a two-group zoom lens structure consisting of a front group lens 20 that serves as a compensator lens and a focusing lens, and a rear group lens 21 that is a variator lens, and is moved in the optical axis direction by a cam mechanism. Although this is an example in which zooming is performed by moving forward and backward, in another embodiment, a front group lens 60 that is a variator lens and a rear group lens 61 that is a compensator lens and a focusing lens are each moved by a motor 63. , 64 is a rear focus type zoom lens that moves forward and backward in the optical axis direction.

In this embodiment, the position detecting means for detecting the movement of the movable tube 27 also serves as an external force detecting means. The position is detected by a voltage obtained by bringing a slider 66 provided at the tip of a cam follower pin 26a that moves together with the movable cylinder 27 into contact with a sliding resistance 65 provided along the direction. . Note that the position detection means may use an absolute value encoder pattern, a relative value encoder pattern, or the like.

According to this, an external force is directly applied to the movable cylinder 27, and the movement of the movable cylinder 27 due to this external force is directly read by the main control circuit 41 via the position detecting means, so that the movable cylinder 27 can be accurately redriven. It becomes possible.

Note that in another embodiment, when an external force is applied to the movable barrel 27, the main control circuit 41 drives the motor 63 to move the rear group lens 61 in response to the movement of the movable barrel 27 due to the external force. It may also be controlled.

As described above, in the embodiments according to the present invention, a camera incorporating a lens barrel which is a zoom lens has been described. It is possible and also
Needless to say, the present invention can also be used in a camera equipped with a lens barrel that performs the biasing control described in the prior art.

[0028]

As explained above, in the variable focus camera of the present invention, after the position of the lens frame is determined by the variable magnification movement mechanism, when the external force detection means detects the external force applied to the lens frame and outputs a correction signal. The camera is equipped with a movement control means that moves the lens frame a predetermined amount in one direction along the optical axis and then moves the lens frame again to the position determined by the variable magnification movement mechanism. Even if an image is added to the camera, the image will be photographed in a state where it is reliably in focus. Also,
The same effect can be obtained in another invention that includes a movement control means that moves the lens frame to a predetermined specific position when a correction signal is output after the position of the lens frame is determined by the variable magnification movement mechanism. .

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part showing a lens barrel used in a variable focus camera according to the present invention.

FIG. 2 is a perspective view showing the appearance of a variable focus camera.

FIG. 3 is a schematic diagram showing the electrical configuration of a variable focus camera.

FIG. 4 is a sectional view of a main part showing another example of a lens barrel used in a variable focus camera.

FIG. 5 is a sectional view of a main part showing another embodiment of a lens barrel used in a variable focus camera.

[Explanation of symbols]

20, 60 front group lens 21, 61 Rear group lens 23 Fixed tube 24 Zoom motor 25 Cam tube 27　Moving cylinder 31 Encoder 32 Resistor 35 Pressure sensor 50 Spring member 65 Sliding resistance 66 Slider

Claims (2)

[Claims] 1. A variable focus camera provided with a variable magnification operating member, comprising: a lens frame that supports a lens that is moved during zooming; and a variable focus camera that moves the lens frame in the optical axis direction in response to a signal from the variable magnification operating member. The position of the lens frame is determined by a magnification movement mechanism, a position detection means for detecting the position of the lens frame, an external force detection means for detecting an external force applied to the lens frame and outputting a correction signal, and the variable magnification movement mechanism. movement control means for moving the lens frame by a predetermined amount in one direction in the optical axis direction and then moving the lens frame again to the position determined by the variable magnification movement mechanism when a correction signal is output after A variable focus camera characterized by: 2. A variable focus camera provided with a variable magnification operating member, comprising: a lens frame that supports a lens that is moved during zooming; and a variable focus camera that moves the lens frame in the optical axis direction in response to a signal from the variable magnification operating member. The position of the lens frame is determined by a magnification movement mechanism, a position detection means for detecting the position of the lens frame, an external force detection means for detecting an external force applied to the lens frame and outputting a correction signal, and the variable magnification movement mechanism. and a movement control means for moving the lens frame to a predetermined specific position when a correction signal is output after the adjustment.