JPH01200313A - auto focus camera - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an autofocus camera that measures the distance to a subject and automatically focuses the camera when photographing.

[Prior Art] Conventionally, in this type of autofocus camera, when shooting, a near-infrared beam, for example, is emitted from a light-emitting element installed at the front of the camera body toward a subject located at the center of the photographic angle of view. The light receiving element placed at different positions on the front of the camera body receives the reflected light beam from the subject, and the distance to the subject is measured using the triangulation method, and the distance measurement lens is used to measure the distance. The focus is automatically achieved by driving the camera based on the results.

That is, the light receiving element installed at the front of the camera body is
It uses an array element known as D, in which multiple light receiving sections are arranged in a straight line, and since the position of the light receiving section hit by the reflected light beam differs depending on the distance to the subject, the position of the light receiving section hit by the reflected light beam is The distance to the subject is measured using a triangular distance measurement method.

Furthermore, in recent years, automatic focusing has been developed that divides the shooting angle of view into multiple areas and assigns a light-emitting element and a light-receiving element to each shooting angle range, making it possible to obtain distance measurement information for different subject positions. Cameras have been put into practical use.

The reason for having multiple distance measuring means in an autofocus camera is mainly when the main subject is not in the center of the shooting angle of view.
This is to prevent the lens from being controlled to infinity by obtaining distance measurement information of surrounding objects.

[Problems to be Solved by the Invention] However, with such conventional autofocus cameras, when taking pictures through a show window or through a window on a train, etc., the glass surface of the window and the camera are parallel to each other. If it is, there is no problem because the emitted beam and the reflected light beam from the subject will pass through the window glass as is, but if it is at a certain angle to the window glass, the projected beam will be reflected by the window glass. In some cases, the light does not return to the light-receiving element, and since distance detection is not possible, the camera determines that the light is at infinity and focuses on it.

As a result, when photographing through glass, it is necessary to pay sufficient attention to whether or not a distance measurement error will occur. For example, when shooting through glass, check the distance information in the viewfinder to determine whether the distance measurement is abnormal or not. If the distance measurement is abnormal, you may have to focus on another subject, lock it, then change the composition, etc. operation is required.

However, even if a distance measurement error occurs when shooting through glass, the camera often takes pictures without noticing the distance measurement error, and even though it is an autofocus camera, there is a problem that the photos are often out of focus.

The present invention has been made in view of such conventional problems, and is designed to notify the photographer of distance measurement abnormalities that occur depending on the situation of the subject, such as when shooting through glass, to prevent shooting failures. The purpose is to provide an autofocus camera with

[Means for Solving the Problem] In order to achieve this object, the present invention includes a plurality of light emitting elements that project a light beam for distance measurement toward a subject existing in a predetermined photographing angle range. a plurality of light-receiving elements provided corresponding to each of the light-emitting elements that receive a light beam reflected by a subject of a light beam emitted from the light-emitting element; A focus detection control means for detecting the focal lengths of a plurality of subjects and focusing on an arbitrary subject; a light emission drive means for sequentially driving the plurality of light emitting elements to emit light; and a light emission drive means for sequentially driving the plurality of light emitting elements to emit light; Abnormal distance measurement determination means is provided for determining and displaying abnormal distance measurement when a light reception output is obtained from another light reception element different from the light reception element corresponding to a specific light emitting element driven to emit light by the means. It is something.

[Function] In the autofocus camera of the present invention having such a configuration, when photographing through glass, the projected light beam is reflected on the glass surface and the light receiving element corresponding to the specific light emitting element driven to emit light is activated. If the light receiving output is obtained from a light receiving element other than
It is determined that there is a distance measurement error, and the abnormal distance measurement display is displayed in the viewfinder, etc., and the photographer can immediately see the abnormal distance measurement when shooting through glass, etc., so he or she can change the camera angle or focus on another subject. By taking appropriate measures, such as taking photos through glass, you can take flawless photos.

[Embodiment] FIG. 1 is an explanatory diagram showing an embodiment of an autofocus camera of the present invention.

In FIG. 1, 1 is a camera body;
A light projecting section 2 is provided at the upper front surface of the camera, and the projecting section 2 is provided with a plurality of light emitting elements that emit near-infrared beams for distance measurement, etc., as will be explained later. A light receiving section 3 is provided below the light projecting section 2 provided on the front surface of the camera body 1, and a number of PSDs or the like corresponding to the number of light emitting elements provided in the light projecting section 2 are used in the light receiving section 3. A plurality of light receiving elements are provided.

Note that 4 is a release button, 8 is a finder, and 9 is a photographic lens driven to a focusing position by automatic focus control.

FIG. 2 is a block diagram showing an embodiment of the autofocus camera of the present invention.

In FIG. 2, 2a, 2b, and 2C are the light projecting parts 2 of FIG.
In this embodiment, a case where three light projecting elements 2a to 2C are provided is taken as an example. 3
a, 3b, and 3c are light-receiving elements provided in the light-receiving section 3 of FIG. Further, a light receiving element 3C is provided corresponding to the light emitting element 2C.

That is, three light emitting elements 2a to 2C and three light receiving elements 3a to 3C.
As is clear from the explanatory diagram of the viewfinder display shown in FIG.
The shooting angle range is A.

The light emitting element 2a and the light receiving element 3a are used for distance measurement in the view angle range A, and the light emitting element 2b and the light receiving element 3b are used for distance measurement in the view angle range B. Further, a distance measurement range is assigned in advance so that the light projecting element 2C and the light receiving element 3C are used for distance measurement in the field angle range C.

Referring again to FIG. 2, the light emitting elements 2a to 2C are activated by the light emitting drive circuit (
(not shown), the light emitting element 2a.

2b and 2C are sequentially driven to emit light. At this time, as shown in the figure, subjects 3a and 8b are located in the viewing angle ranges assigned to the light emitting elements 2a to 2C, respectively.

8C exist at different distances from each other, the light beam from the light projecting element 2a reflected by the subject 8a is reflected within the light receiving area of the light receiving element 3a using the PSD, and the light beam reflected from the subject 8a is A light receiving output is generated according to the light receiving position in the light receiving element 3a. Further, the reflected light beam from the subject 8b enters the light receiving element 3b, and a light receiving output corresponding to the light receiving position is similarly obtained.
The reflected light beam C is incident on the light receiving element 3C, and a light receiving output corresponding to the light receiving position is similarly obtained.

The light receiving output of the light receiving elements 3a to 3C is determined by the automatic focus detection circuit ga.
, gb, and gc, and the focal lengths of the subjects 8a to 8C are detected by a triangulation method. The focal lengths detected by the automatic focus detection circuits 9a to 9C are sent to the control circuit 10, and the lens drive section 1
1 drives the photographing lens 9 in FIG. 1 to the in-focus position. Here, as an algorithm for automatic focus control set in the control circuit 10, for example, three automatic focus detection circuits 9
Control is performed to adjust the focal length of the photographic lens to the object at the closest distance from among the distance measurement information obtained from a to 9C. As another example of the algorithm for automatic focus control in this control circuit 10, for example, the light receiving element 3
As shown in Fig. 4, the automatic focus detection circuit 9b corresponding to the focus detection circuit 9b obtains distance measurement information for the enemy shadow angle of view range B in the center, so the photographic lens is adjusted to obtain the distance measurement in the center. If the distance measurement information of the central photographing angle of view range B is infinite, the surrounding angle of view range A or C is
It is also possible to control the focus of the traverse lens based on the distance measurement information, and an appropriate algorithm can be determined as necessary.

Further, the control circuit 10 is provided with a function as an abnormal distance measurement determining means for detecting and displaying a distance measurement abnormality due to reflection of the projected beam on the glass surface when a Vji shadow is cast through the glass.

The abnormal distance measurement determination function in the control circuit 10 is such that when the light emitting elements 2a to 2C are sequentially driven to emit light, if normal subject distance measurement is performed, specific light receiving elements 3a to 3a corresponding to each of the light emitting elements 2a to 2C are detected. A light receiving output is obtained from 3C, but when the projected light beam is reflected through the glass 11, a specific light receiving element 3a having a correspondence relationship with the light projecting elements 2a to 2C is detected.
~ When the light receiving output is no longer obtained from 3C and the light receiving output is obtained from another light receiving element that does not have this correspondence, it is determined that there is a distance measurement error and the distance measurement error is displayed in the finder using LED 7 etc. become.

Next, referring to FIG. 3, an explanation will be given of the operation when the autofocus camera of the present invention shown in FIG. 1.2 is used to cast an i-shadow through the glass.

FIG. 3 shows photographing through the glass when the glass plate 13 is not parallel to the camera body. When the positive mode is started by pressing the shutter button 4 halfway, etc., the light emitting elements 2a to 2C are sequentially driven to emit light. This shows a state in which a light beam is emitted by driving the second light emitting element 2b to emit light. If the glass plate 13 were not present, the light beam emitted from the light projecting element 2b would be reflected by the object 8b existing within the angle of view corresponding to the light projecting element 2b, as shown in FIG. 2, and would be reflected by the corresponding light receiving element 3b. However, since the glass plate 13 is positioned diagonally between the light projecting element 2b and the subject, the light beam from the light projecting element 2b is reflected by the glass plate 13 and enters another light receiving element 3a which has no corresponding relationship. For this reason, in the control circuit 10, although the distance measurement output can be obtained from the automatic focus detection circuit 9b originally corresponding to the light receiving element 3b by driving the light emitting element 2b to emit light, the light received by the different light receiving element 3a due to reflection by the glass plate 13. Since a distance measurement output is obtained from the automatic focus detection circuit 9a based on the output, a distance measurement abnormality is determined from the distance measurement output of the automatic focus detection circuit 9a, and the distance measurement abnormality is displayed in the finder by driving the LED 7 to emit light.

FIG. 4 is an explanatory diagram showing an example of a finder display equipped with a distance measurement abnormality display, and the finder includes a field of view frame 5, three light emitting elements 2a to 2C, and light receiving elements 38 to 3.
Range measurement range marks 6a, 6b, and 6c corresponding to C are displayed, and IED7 is also used to display distance measurement abnormalities outside the field of view.
a, 7b, and 7C are provided corresponding to the ranging range marks 6a to 6C. Therefore, as shown in FIG. 3, when the control circuit 12 determines that there is a distance measurement error due to abnormal reception of the reflected light beam by the glass plate 13 at the distance measurement range mark 6b corresponding to the light emitting element 2b and the light receiving element 3b. , LED7b
lights up to indicate a distance measurement error, and the operator can see the distance measurement error display in the viewfinder and the moving image through the glass (
Immediately recognize the distance measurement error and take appropriate measures, such as changing the camera angle so that it is parallel to the glass plate 13, or taking pictures through the glass after focusing and locking on another subject. You can take it.

[Effects of the Invention] As explained above, according to the present invention, even if erroneous distance measurement is performed due to an abnormality of the light beam for distance measurement when photographing through glass, etc., the distance measurement can be performed within the viewfinder etc. The abnormal distance measurement display allows the photographer to immediately know that abnormal distance measurement has been performed, and prevents the photographer from taking a picture without noticing the abnormal distance measurement. In addition, when abnormal distance measurement is displayed, change the camera angle so that normal distance measurement can be performed, or focus on the abnormal focal position or infinity to take a picture that is satisfactory. can be taken.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing an embodiment of the present invention; Fig. 2 is a block diagram showing an embodiment of the circuit configuration of the present invention; Fig. 3 is a block diagram showing the operation when shadowing through glass. Figure: Figure 4 is an explanatory diagram of the display in the file radar, which is equipped with a distance measurement error display. 1: Camera body 2: Light emitter 2a to 2C: Light emitter 3: Light receiver 3a to 3C: Light receiver (PSD) 4 Release button 5: Viewing frame 6a to 6C: Ranging range mark 7.7a to 7c : LED (abnormal distance measurement display section) 8
: Finder 9: Photographic lens 10: Control circuit 11: Lens drive section 13 Glass plate Patent applicant Nippon Kogaku Kogyo Co., Ltd.

Claims (1)

[Claims] (1) A plurality of light-emitting elements that project distance-measuring light beams toward subjects existing in different predetermined shooting angle ranges, and a light beam that is reflected from the subject by the light beam emitted from the light-emitting elements. A plurality of light receiving elements are provided corresponding to each of the light emitting elements that receive light, and the focal lengths of a plurality of subjects existing within different photographing angles of view are detected based on the light receiving output of the light receiving element, and an arbitrary subject is detected. and a focus detection control means for focusing on the light emitting element; and a light emitting drive means for sequentially driving the plurality of light emitting elements to emit light; An autofocus camera comprising: an abnormal distance measurement determination means for determining abnormal distance measurement and displaying the result when a light reception output is obtained from another light reception element different from the light reception element.