JPS61264308A - Automatic focus adjusting device - Google Patents

Abstract

PURPOSE:To allow a photographer to evade keeping on photographing an unsharp object image within the close distance of a photographic lens by providing an alarm which judges whether or not an object in within a focusable range from the close distance to infinite distance and warns the photographer of that unless the object is within the focusable range. CONSTITUTION:When the object is within the focusable range, the high-order digit bit b0 of a digital B is 0 and it is found by the alarm 30 that the object is within the focusable range. Further, the low-order digit bits (b1,b2nu,bn) of the signal B are compared with a signal A by a comparator 27 and a focus signal indicating the degree of their coincidence is outputted; and a lens driving part 28 moves a focus adjusting mechanism 29 on the basis of the focus signal to adjust the photographic lens 25 to an optimum focusing position. When the object is within the close distance, the high-order digit bit b0 becomes 1 and the alarm 30 decides that the object within the close distance and also warns the photographer of that.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an automatic focus adjustment device that accurately focuses an image of a subject at a predetermined position when adjusting the focus of a camera.

BACKGROUND OF THE INVENTION Various automatic focusing devices for cameras have been proposed and implemented to date, and are now becoming popular in the field of video cameras as well as in the field of still cameras.

An example of a conventional automatic focus adjustment device will be described below with reference to the drawings.

FIG. 3 is a system configuration diagram showing the basic principle of a conventional automatic focus adjustment device. In the figure, infrared light for distance measurement projected from a light projector 1 passes through a converging lens 2 and reaches a distance measuring object 3, and is then reflected and enters a light receiving element 5 through a converging lens 4. At this time, if the distance between the light projector 1 and the light receiving element 5 and the distance measuring object 3 changes, the angle of incidence of the reflected light on the light receiving element 6 or the angle of incidence of the reflected light on the light receiving element 6 changes.
The position on the surface changes. The calculator 6 performs a predetermined calculation based on the incident angle or position of this reflected light. The lens encoder 7 mechanically detects the rotation angle of the helicoid of the focusing lens group that adjusts the focus of the photographic lens 8 (schematically shown as a single convex lens), converts it into an electrical signal, and outputs it.

A comparator 9 compares the output value of the arithmetic unit 6 and the output value of the lens encoder 7, and outputs a focus signal indicating the degree of coincidence. Based on the focus signal, the lens drive unit 1o moves the focus adjustment mechanism 11 of the photographic lens 8 forward or backward until the output value of the arithmetic unit 6 and the output value of the lens encoder 7 match, and the lens drive unit 1o moves the photographic lens 8 forward or backward. The focus adjustment is completed by driving to the optimal focusing position.

Problems to be Solved by the Invention In an automatic focusing device, there is a focus adjustable range, and the focus adjustable range is a rotatable range corresponding to the shooting distance from close range to infinity of the helicoid of the focusing lens group. corresponds to

Therefore, if the subject to be distance-measured is within the close range, the photographic lens cannot be adjusted to the optimal focusing position. However, with the above-mentioned conventional technology, even though it is not possible to obtain a clear photographed image of the subject when the subject to be distance-measured is within the close distance, it is not possible to obtain a clear photographed image of the subject when the subject is within the close distance. There was a problem in that the photographer continued to take unclear images of the subject because there was no means for notifying the person.

SUMMARY OF THE INVENTION The present invention provides an automatic focus adjustment device that warns the photographer when the subject is within the close range, thereby avoiding the need to continue photographing an unclear subject image. It is.

Means for Solving the Problems In order to solve the above-mentioned problems, the automatic focus adjustment device of the present invention enables the subject to adjust the focus using a warning device based on a distance signal corresponding to the distance to the subject to be measured. It has the function of determining whether the subject is within the range and warning the photographer if the subject is within close range.

action The effect of the above means is as follows.

In other words, if the subject is within the focus adjustable range, the photographic lens can be adjusted to the optimal focusing position, so the warning device only determines that the subject is within the focus adjustable range, and the camera returns to normal as before. You can take great pictures. Furthermore, if the subject is within close range of the photographic lens, this can be determined by a warning device, and the photographer can be warned that the subject is within close range.

As a result, even if the subject is within close range of the photographing lens,
A warning device informs the photographer of this fact, and it is possible to avoid continuing to photograph an unclear subject image.

EXAMPLES Hereinafter, examples of the present invention will be described with reference to the drawings.

FIG. 1 is a system configuration diagram of an embodiment of the present invention. In the figure, a light projector 12 projects infrared light for measurement, which passes through a convergent lens 13 and reaches a distance measuring object (subject) 14, is reflected once, and enters a light receiving element 16 through a convergent lens 15.

The lens encoder 18 adjusts the focusing distance of the helicoid of the focusing lens group that adjusts the focus of the photographic lens 19 from close range to infinity (i.e., focal adjustment possible distance).
The rotation angle corresponding to is equally divided into a plurality of preset numbers of divisions, and the current position of the focusing lens group is expressed as a digital signal having a number of bits (= n bits) determined according to the number of divisions. Output.

The calculator 17 performs a predetermined calculation based on the angle of incidence or position of the incident light incident on the light receiving element 16, and
The photographing distance of the photographing lens 19 from close range to infinity is divided into the same number of divisions (same number of bits=n) as the lens encoder 18.

A distance signal to the subject is converted into an n-bit digital signal. Furthermore, a high-order bit for determining whether or not the subject is within the focus adjustable range is added to the obtained n-bit signal and output.

A comparator 17 compares the n-bit focusing lens group position signal output from the lens encoder 18 with the n-bit distance signal to the object output from the arithmetic unit 17, and generates a focus signal indicating the degree of coincidence. Output.

The lens driving section 21 moves the focus adjustment mechanism 22 based on the focus signal, and drives the photographing lens 19 to an optimal focusing position.

The warning device 23 determines whether or not the subject is within the focus adjustment range based on the upper bits of the digital signal output from the arithmetic unit, and if the subject is within the close range of the photographic lens, it notifies the photographer of this fact. Warning.

Next, signal processing in the configuration of this embodiment will be explained with reference to FIG. FIG. 2 shows a conceptual diagram of signal processing in the configuration of this embodiment.

Lens encoder 24 Photography lens 26 (7) 7
The position signal of the excusing lens group is converted into an n-bit digital signal ('1 r lL2 +..., IL
Output as n). At that time, if the subject is at infinity, the person - (0, 0, ..., 0), and if the subject is at a very close distance, the person = (1, 1, ...
..., output as 1).

The arithmetic unit 26 adds upper bits to the distance signal to the subject to determine whether the subject is within the focus adjustable range, and generates an n+1 bit digital signal B: (bo, b,
, ..., bn).

At that time, if the subject is at infinity, B=(0°0,・
. . . , 0), and if the subject is at a very close distance, B=(0, 1, 1, . . . 1) is output. Furthermore, when the subject is within close range, all outputs are made as B=(1, 1, 1, . . . , 1).

Therefore, when the subject is within the focus adjustment range, the upper bits of digital signal B are present. -0, alarm 30
This shows that the subject is within the focus adjustment range.

Furthermore, the lower n bits of signal B) (bl, b21...
. can be adjusted to the optimal focusing position.

Furthermore, when the subject is within close range of the photographing lens, the upper bit of signal B is present. = 1, alarm 3
0, it is possible to determine that the subject is within close range and to warn the photographer of this fact.

In this embodiment, the distance signal to the subject and the position signal of the focusing lens group are converted into digital signals,
Adjustment and determining whether or not the subject is within the focus adjustment range are possible. By setting a threshold value corresponding to the close distance of the photographing lens in the distance signal, the distance signal can be adjusted depending on whether or not it exceeds the threshold value. Forward φ: Fortune-telling” journey
A interval 1 is 5+5! III. Similar effects can be obtained even if the distance signal to the object and the position signal of the focusing lens group are compared and adjusted as analog signals.

Effects of the Invention The present invention determines whether or not the subject is within the focus adjustable range of the photographing lens from close range to infinity based on a distance signal to the subject, and By installing a warning device that notifies the photographer when the subject is outside the possible range (i.e., within the close range), the photographer may continue to take images of unclear objects within the close range. You will be able to avoid it.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an automatic focus adjustment device according to an embodiment of the present invention, FIG. 2 is a block diagram of the main parts thereof, and FIG. 3 is a block diagram of a conventional automatic focus adjustment device. 12... Emitter, 16... Light receiving element,
17... Arithmetic unit, 18... Lens encoder, 20... Comparator, 21... Lens drive section, 23... Warning device .

Claims (1)

[Claims] a projector that emits infrared light for distance measurement; a converging lens that collects the reflected light of the infrared light for distance measurement from the object to be measured; An optical position detector that outputs a current, a calculator that calculates and outputs a distance signal corresponding to the distance to the object to be measured from the photocurrent, and a focusing lens group that adjusts the focus of the photographic lens. A lens encoder that mechanically detects and converts it into an electrical signal and outputs it; a comparator that compares the output value of the arithmetic unit with the output value of the lens encoder and outputs a focus signal indicating the degree of coincidence; and a comparison thereof. a lens drive unit that drives the focusing lens group until the output value of the arithmetic unit and the output value of the lens encoder match based on the output of the arithmetic unit; a warning device for determining whether or not the subject is within the focus adjustable range, and notifying the photographer if the subject is outside the focus adjustable range (i.e., within the close range); An automatic focus adjustment device characterized by comprising: