JPH0514244B2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an automatic focusing device for a camera.

(Prior Art) Autofocus devices that automatically measure the distance to a subject have been known. This type of automatic focusing device is configured such that a distance measuring section measures a distance to a main subject located in the center of a photographic screen, and focuses a lens on this main subject.

(Problems to be Solved by the Invention) However, in a camera equipped with this conventional autofocus device, it is difficult to focus on the main subject unless the main subject is located in a limited area such as the center of the shooting screen. Therefore, when trying to obtain a photograph that is in focus, the composition becomes uniform, making it unsuitable for taking photographs with different tastes.

In order to eliminate such drawbacks, for example, a distance measuring section that measures the distance to the main subject by positioning it in the center of the screen in advance is provided, and the distance information obtained from this distance measuring section is stored. A device has been proposed that is provided with a storage means to determine the composition and then operate the shutter.

However, since such devices require troublesome operations to determine the composition before taking a picture, they have the disadvantage that they are difficult for beginners, let alone camera enthusiasts, to fully master.

The present invention has been made in view of these conventional problems, and provides a camera that can determine the composition of the subject to be photographed as desired and that can take photographs with accurate focus through simple operations. The purpose is to provide an automatic focusing device.

(Means for Solving the Problems) In order to achieve the above-mentioned problems, an automatic focusing device for a camera according to the present invention includes a light emitting unit that emits a light beam toward a subject and spreads in a direction orthogonal to the baseline length direction. , a plurality of sets of light-receiving elements are provided along the baseline length direction, and are arranged in a direction perpendicular to the baseline length direction, and are provided at a position separated by a long baseline distance from the light emission section, and emit light from the light emission section. A light receiving section that receives the light flux reflected by the subject at a distance from the subject with different light receiving elements depending on the distance of the subject, and a light receiving section that receives the output signal from each light receiving element of the light receiving section and receives the reflected light from the subject located closer to the subject. A logic circuit that outputs distance information corresponding to the light-receiving element by prioritizing the output signal of the element, and a lens drive that extends the photographic lens to focus on the subject located at the shortest distance based on the distance information from the logic circuit. It is characterized by comprising a section.

(Example) Hereinafter, an example of an automatic focusing device for a camera according to the present invention will be described with reference to the drawings.

In FIG. 1, 1 is a distance measuring section. Distance measurement section 1
has a light emitting section 2 and a light receiving section 3. The light emitting section 2 is composed of an oblong light source 4 extending in the horizontal direction and a semi-cylindrical condensing lens (toric lens) 5. The light receiving section 3 is composed of a horizontally elongated light receiving element array 6 extending in the horizontal direction and a semi-cylindrical imaging lens (toric lens) 7. Each horizontally elongated light-receiving element row 6 is composed of light-receiving elements 6a to 6d, and the light-receiving elements 6a to 6d are arranged in the vertical direction. The semi-cylindrical condensing lens 5 and the semi-cylindrical imaging lens 7 are separated by a baseline long distance D in the vertical direction. A plane including the optical axis of each lens 5, 7 is perpendicular to the longitudinal direction of the horizontally long light source 4, and a longitudinal direction of the horizontally long light receiving elements 6a to 6d is perpendicular to a plane including the optical axis of each lens 5, 7. A photographing lens 10 is located between the semi-cylindrical condenser lens 5 and the semi-cylindrical imaging lens 7. The photographing lens 10 is driven in five stages by a lens drive circuit which will be described later. When the distance measuring section 1 is configured in this way, the horizontally long light source 4 extends in the width direction of the finder surface F, and each light receiving element 6
The longitudinal direction also coincides with the zone E of the finder surface F. Therefore, the light emitting unit 2 plays the role of projecting light toward a plurality of objects X, Y, Z, etc. that are spaced apart in the horizontal direction, and as shown in FIG. Visible subject X,
Light is projected to cover all of Y and Z.

For the horizontally elongated light source 4 of the light emitting section 2, a light source with a large amount of light, such as an infrared flash, is used. The horizontally elongated light receiving element array 6 serves to receive reflected light from each subject X, Y, Z, . . . . Each light receiving element 6a~
6d are associated in order from farthest to closest, and the distance measuring unit 1 defines the distance to each subject based on this association.

The output of each of the light receiving elements 6a to 6d is supplied to a photoelectric conversion circuit 8, and the photocurrent obtained from each of the light receiving elements 6a to 6d is converted into a predetermined voltage. Further, each output of the photoelectric conversion circuit 8 is applied to one input terminal of the voltage comparators 8a to 8d, and a reference power supply 9' is applied to the other input terminal.
is compared with the reference voltage of Voltage comparators 8a to 8d
becomes an H lens when the output voltage of the photoelectric conversion circuit 8 exceeds the reference voltage.

Each output of the voltage comparators 8a to 8d is input to one input terminal of the register 9. The output of the one-shot circuit 10' is input to the other input terminal of the register 9. While the output pulse of the one-shot circuit 10' is being input to the register 9,
Each output of the voltage comparators 8a to 8d is taken in, and thereby the register 9 stores each output of the voltage comparators 8a to 8d.

The output of register 9 is input to logic circuit 11. The logic circuit 11, together with the register 9 and the register 12, constitutes a storage section that detects and stores only the signal corresponding to the object located at the shortest distance among the distance signals defined by the distance measuring section 1. logic circuit 1
1 has four input terminals 1 as shown in FIG.
4, 15, 16, and 17. The input terminal 14 is directly connected to an output terminal 18 and also connected to a first input terminal of an AND circuit 20 via an inverter 19. Further, the input terminal 15 is connected to a second input terminal of an AND circuit 20 and is also connected to a first input terminal of an AND circuit 22 via an inverter 21 . The output terminal of the inverter 19 is connected to the second input terminal of the AND circuit 22, and the input terminal 16 is connected to the third input terminal of the AND circuit 22. The input terminal 16 is connected to the first input terminal of the AND circuit 24 via the inverter 23, the output terminal of the inverter 21 is connected to the second input terminal of the AND circuit 24, and the third input terminal of the AND circuit 24 is connected to the output terminal of the inverter 21. The output terminal of the inverter 19 is connected, and the fourth input terminal 17 is connected to the fourth input terminal of the AND circuit 24. The output side of each AND circuit 20, 22, 24 is connected to output terminals 25, 26, 27. Each output terminal 18 , 25 , 26 , 27 is connected to a register 12 , and the output side of the register 12 is connected to a lens drive circuit 13 .

Since the logic circuit 11 is configured in this way, for example, when a high level signal is input to the input terminal 14, a high level signal is output from the output terminal 18, and the first input terminal of the AND circuit 20, A low level output is input to a second input terminal of the AND circuit 22 and a third input terminal of the AND circuit 24. Therefore, in this case, input terminals 15, 16, 17
Regardless of whether a high level or a low level is input to the output terminal 18, a high level is output only from the output terminal 18. The high level output of the output terminal 18 is made to correspond to the first extension amount of the photographic lens 10. Furthermore, when a low level signal is input to the input terminal 14 and a high level signal is input to the input terminal 15, the output of the AND circuit 20 becomes high level, and therefore the output of the output terminal 25 becomes high level. .
Further, the outputs of the remaining output terminals 18, 26, and 27 become low level. The high level output of the output terminal 25 is made to correspond to the second extension amount of the photographic lens 10. Similarly, when a low level is input to the input terminals 14 and 15 and a high level is input to the input terminal 16, a high level output is obtained only from the output terminal 26. The high level output of the output terminal 26 is made to correspond to the third extension amount of the photographic lens 10. Similarly, the high level output of the output terminal 27 is made to correspond to the fourth extension amount of the photographic lens 10.
Further, the time when the outputs of the output terminals 18, 25, 26, and 27 are all at low level corresponds to the infinitely distant position of the subject.

By configuring the logic circuit 11 in this way, it is possible to associate the amount of extension of the photographing lens 10 with each of the light receiving elements 6a to 6d, and the lens driving section 13 moves the photographing lens 1 toward the object located at the shortest distance.
You will end up rolling out 0.

That is, in FIG. 1, subject X is closest to the camera, subject Z is farther from the camera than subject X, and subject Y is at an intermediate position between subjects X and Z. Assuming that objects X, Y, and Z are appropriately spaced apart in the horizontal direction, reflected light from object X is received by light receiving element 6c, reflected light from object Y is received by light receiving element 6b, and object Z is received by light receiving element 6c. If the reflected light from
The photographic lens 10 is extended by the second extension amount corresponding to the light receiving element 6c.

If the subject Y is closer to the camera than the subject X and its reflected light is received by the light receiving element 31d, the photographing lens will be extended by the first extension amount corresponding to the light receiving element 31d. When objects X and Y are not present, there is no reflected light from them, so only the output terminal 27 corresponding to the light receiving element 6a becomes high level, and the photographing lens 1 is moved by the fourth extension amount corresponding to the light receiving element 6a.
0 will be rolled out.

In the above embodiment, the number of each element in the light-receiving element array 6 is four, but the number is not limited to four.

(Effects of the Invention) As explained above, the present invention measures the distance from the camera to the object located at the shortest distance,
Since the configuration allows the amount of extension of the photographic lens to be determined based on this measurement result, it is possible to always take a photograph in focus regardless of the relative positional relationship of the main subject with respect to the remaining subjects, and the desired composition can be arbitrarily taken. There are effects that can be selected. In addition, there is no need for any troublesome operations when taking pictures.
Easy to handle even for beginners. Furthermore, since you can select the shortest distance without scanning the subject,
Structural complexity can also be eliminated.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram showing the main parts of the autofocus device of a camera according to the present invention, FIG. 2 is a diagram showing the relative positional relationship of the subject as seen from the viewfinder window, and FIG. 3 is shown in FIG. 1. FIG. 2 is a detailed diagram of a logic circuit. DESCRIPTION OF SYMBOLS 1... Distance measuring part, 2... Light emitting part, 6... Light receiving element row, 11... Logic circuit, 12... Register, 13
...Lens drive unit, X, Y, Z...Subject, D...
...Baseline long distance.

Claims (1)

[Scope of Claims] 1. A light emitting unit that emits a beam of light that spreads toward the subject in a direction perpendicular to the baseline length direction; A light-receiving section is configured with a plurality of sets of light-receiving elements arranged along the base line length direction, and receives the light beam emitted from the light-emitting section and reflected by the object by different light-receiving elements depending on the distance of the object. and receiving output signals from each light receiving element of the light receiving section, and giving priority to the output signal of the light receiving element that receives reflected light from a subject located closer to the object, thereby obtaining distance information corresponding to the light receiving element. An automatic focusing device for a camera, comprising: a logic circuit that outputs an output; and a lens drive unit that extends a photographing lens so as to focus on a subject located at the shortest distance based on distance information from the logic circuit.