JPS62232610A - Lens barrel driving device - Google Patents

Abstract

PURPOSE:To instantaneously reproduce focused position without executing a distance measuring operation, by storing in advance an automatic focus or a manually focused position in a storage means a storage command member, and operating a storage regenerative command member in an optional moment. CONSTITUTION:A defocus of an object which has passed through a photographic lens by a focusing start button is calculated by a defocus quantity detecting circuit 4 through a distance measuring optical system 3, and by this defocus quantity, a lens barrel driving controlling circuit 2 operates and drives a lens to focusing position. When a storage command means 7 is operated, lens barrel position information is stored in a storing circuit 6. When a selecting command means 10 is operated, by this stored position information, and thereafter, after a lens barrel 1 has been moved automatically or manually to various framing points, the driving controlling circuit 2 of the lens is driven immediately so that an error become '0' in accordance with a difference of the stored lens position and the present lens position, namely, to a position where a storage switch has been depressed previously, and stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic focusing system, particularly to a lens barrel driving device for a camera equipped with an automatic focusing system using Tanabata. .

[Conventional technology]

Conventionally, lens barrel drive devices for cameras of this type are configured to drive and control the lens barrel by lens barrel drive control means that is energized by an output signal from a focus detection circuit.

[Problem that the invention seeks to solve]

As described above, in the lens barrel drive device in which the drive control means drives and controls the lens barrel based on the output signal of the focus detection circuit, the focus detection circuit cannot detect the focus of the subject or 7t. There is a drawback that if the detection takes a long time, a photographing opportunity may be missed.

In particular, in automatic focusing devices for eye reflex cameras, passive light receiving elements such as COD line sensors are used due to lens exchange, operation, distance, etc. -T
A TL type focus detection circuit is often used, and when measuring a horizontal main turn, a subject with low contrast, a low brightness subject, etc., the above-mentioned drawbacks are likely to occur.

For example, if you are filming a baseball game.

During the game, you are photographing various subjects such as the first baseman, the pitcher, and the fielders, and at the moment when the runner goes around third base and heads toward home plate. Since there is no subject present, the focus detection circuit can perform focusing operations.

The present invention attempts to solve the above-mentioned drawbacks or inconveniences in the conventional camera lens barrel drive device.

[Means for solving problems]

The present invention, as a means to solve the above-mentioned problems, stores the automatic focusing or manual focusing position in advance in a memory command member, and operates the memory regeneration command member at an arbitrary moment. By doing so, the lens barrel is driven to the position stored in the storage means without performing a distance measuring operation.

To provide a lens barrel drive device that is capable of instantly reproducing the above-mentioned in-focus position. As mentioned above, this lens barrel drive device is not only effective for photographing subjects that require time to measure the distance, but also for shooting while standing at home base, such as recording a friend's baseball game, as exemplified above. The camera focuses on the batter in advance, operates the memory operation member to memorize the focus position, and then scans around third base at a certain moment in the game while photographing other targets. At the end, operate the memory regeneration command member to focus on the home base, keep scanning in a state of mind, and release the camera at the decisive moment.

[R) f@ overview]

To summarize, 1. The lens barrel drive device according to the present invention includes an automatic focusing system that automatically performs focus alignment by energizing the lens barrel drive control means based on the output signals of the distance measuring optical system and the defocus amount detection means. A lens barrel position storage system comprising means for detecting the position of the lens barrel, means for storing the output of the position detection means, and storage operation means for instructing the storage to be stored in the storage means. and selecting between the difference detection means for detecting the difference between the outputs of the position detection means and the storage means in the lens barrel position storage system and the output of the defocus amount detection means in the automatic focusing system. The present invention is characterized in that it includes a selection means that can transmit information to the lens barrel drive control means and a selection command means that commands the above selection.

〔Example〕

The invention will now be described with reference to illustrative embodiments.

FIG. 1 is a diagram showing a basic embodiment of the present invention, in which 1 is an imaging optical system and a lens barrel that supports it, 2 is a driving member for advancing or retracting the lens barrel and performing focusing. A drive control circuit including a control circuit, and 3 a distance measuring optical system that converts an optical system necessary for distance measurement and an input of the optical system into an electrical signal.

Reference numeral 4 denotes a defocus amount detection circuit for detecting the difference between the electric output of the distance measuring optical system, the current lens barrel position, and the true in-focus position, and these constitute an automatic focusing system. This can be constructed using various types of circuits that are conventionally known. 5F
a position detection circuit for detecting the position of the i mirror; 6 a storage circuit for detecting the output of the position detection circuit; 7 a storage command means for storing the output of the position detection circuit in the storage circuit; The lens barrel position storage system is constituted by the circuit 8. Reference numeral 8 denotes a difference detection circuit for detecting the difference between the position detection circuit 5 and the storage circuit 6.

A difference detection circuit 8 that detects the difference between the outputs of the position detection circuit 5 and the storage circuit 6 in the above lens barrel position storage system, and a defocus amount detection circuit 4 in the above automatic focusing system.
A selection circuit 9 which selects the output of the lens barrel drive control circuit 2 and transmits the selected output to the lens barrel drive control circuit 2, and a selection command means 1o which instructs the selection circuit 9 to make a selection are provided.

Is the storage command means 7 pressed? The selection command means 10, a memory switch in the form of a button switch, is preferably toss a home switch in the form of a push button switch which selects the output of the difference detection means 8 when pressed.

The operation of the above device is as follows.

A focus start button (not shown) (often used on the first stroke of the shutter release in normal single-lens reflex cameras) defocuses the subject passing through the photographic lens, causing the distance measuring optical system 3 to defocus. It is calculated by the optical defocus amount detection circuit 4. Based on this amount of defocus, the lens barrel drive control circuit 2 operates to drive the lens to the in-focus position.

The lens barrel may be provided with a position detection circuit, and the output of this detection circuit may be fed back to the drive control circuit 2 to control the lens barrel position, but in the illustrated example, the signal from the ranging optical system is simplified. Focusing is performed using open-loop control. When the storage command means 7 (storage switch) is operated, the lens barrel position information is stored in the storage circuit 6. As can be easily seen, this memory mechanism has nothing to do with autofocus operation, so even if the focus is manually adjusted, it may be possible to set the focus at a position unrelated to focus (e.g. infinity, hyperfocal distance, etc.). )
It doesn't matter if it is stopped.

Using this stored position information and after automatically or manually moving the lens barrel to various framing points, when the selection command means 10 (home position switch) is operated, the lens drive control circuit 2 In other words, the lens is immediately driven to the position where the memory switch was pressed before and then stopped so that this error becomes 0 according to the difference between the memorized lens position and the current lens position. becomes.

In the automatic focusing system of a general TTL-eye reflex camera, the distance measurement result is calculated as the amount of defocus, and the control of the lens barrel is also ratio controlled according to the amount of defocus, that is, focusing is performed from the current lens barrel position. Control is performed based on the difference in lens barrel position to the focal position. To be sure, the lens barrel position signal does not have a complicated absolute position signal, but a simple 14
It is often determined by generating and counting AP sequences. Therefore, in the case of such a system, an absolute position signal can be constructed by providing a quantator in the position detection circuit and holding the power supply, but generally the system power supply is configured as a HimbanK0N10FF. This will cause problems. The second example shows an example in which such measures were taken.
The diagram shows.

This is a UP711 bias counter that retains memory regardless of whether the overall power is 0N10FF or when the power is OFF.
A non-volatile memory that saves the data of the UP/1) OWN counter when the power is turned on, and an UP/DOWN counter that reloads the value of the non-volatile memory when the power is turned on are set up as follows.

In the one shown in Figure 81!2, the automatic focusing system is
Similar to the one shown in FIG. 1, a lens barrel 1, a lens barrel drive control circuit 2, a distance measuring optical system 3. The defocus amount detection circuit 4 includes a defocus amount detection circuit 4, and in this example, the defocus amount detection circuit 4 indicates in which direction the in-focus point is located. It is configured to output two types of out-of-focus data, and controls the forward movement, backward movement, and stop of the lens barrel according to the output signals.

The lens barrel position detection means is constituted by a relative position pulse generator 5', and the memory means is constituted by an UP/DOWN counter 61, which is configured by a memory command means (memory switch) 7.
It operates according to the command. This UP/D (WN counter 6
' is reset when memory switch 7 is pressed, and then
Each time the automatic focusing system operates, an UP count is made when moving forward, and a FiDOWN count is made when moving backward. 10
is a selection command means (home position switch), and when this home position switch is pressed, a positive value is given if the lens barrel is moving forward while the memory switch is pressed, and a negative value is given if it is backward. Remaining. Therefore UP/I)OW
By inverting the sign pit of the N counter and driving the counter in that direction until it reaches φ, it is possible to return to the position where the memory switch was pressed.

The above embodiment shows an example in which control is not performed using the defocus amount, and even if the friend memorizes the defocus amount before driving the full amount and performs t drive according to the amount, the memory in the storage means described above may be used. It is obvious that control can be performed by comparing the amount of defocus and the amount of defocus, and the present invention can also be implemented in such an embodiment.

〔Effect of the invention〕

As explained above, the present invention can achieve all the following effects by adding all the above-mentioned memory functions.

(1) A so-called focus lock function used when there is no subject to focus on in the distance measuring section.

(2) A function that performs proxy distance measurement by placing an object that can be focused on when the distance measurement unit is unable to focus.

(3) A function that increases the chance of taking pictures from the second time onwards when it is necessary to take pictures of a subject that requires a long distance measurement time after focus detection.

(4) When using lenses with extremely large amounts of defocus, such as telephoto lenses and macro lenses, a function that instantly moves the lens to a focus position that is useful for one drawing.

As mentioned above, one aspect of the present invention achieves a truly remarkable effect.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a basic embodiment of the present invention;
FIG. 2 is a block diagram showing another embodiment of the invention. 1... Lens barrel, 2... Lens barrel drive control circuit, 3... Distance measuring optical system. 4... Defocus amount detection circuit. 5... Position detection circuit, 6... Memory circuit. 7... Memory command means, 8... Difference detection circuit, 9...
- Selection circuit, 10... selection command means. Figure 1

Claims (1)

[Claims] In a lens barrel drive device for a camera equipped with an automatic focusing system that automatically performs focus alignment by energizing the lens barrel drive control means based on output signals from the distance measuring optical system and the defocus amount detection means, A lens barrel position storage system is provided, which includes a means for detecting the position of the lens barrel, a means for storing the output of the position detection means, and a storage command means for instructing storage in the storage means, and a position in the lens barrel position storage system is provided. a selection means for selecting between a difference detection means for detecting a difference between the outputs of the detection means and the storage means and an output of the defocus amount detection means in the automatic focusing system and transmitting the selected result to the lens barrel drive control means; A lens barrel drive device characterized in that it is provided with selection command means for commanding the above selection.