JPH06347690A - Lighting device for detecting focal point - Google Patents

Abstract

PURPOSE:To deal with even the combination of a focal point detecting device having many ranging views with a high magnification zoom lens and to light a broad range by setting an overlapping part of a light source image on the ranging view ranging on an optical axis of a photographing lens. CONSTITUTION:A light beam emitted from a light emitting diode 37 is projected on an object side through a dome 32 and a floodlight lens 31, and the image of the light emitting diode 37 is formed. The emitting surface of the floodlight lens 31 is divided into four parts, and four optical axes A-D are arranged in a line. A luminous flux is divided into four directions, and the images of four light emitting diodes are projected in a line. The overlapping part of the images of the light emitting diodes is formed by the luminous flux transmitting through the surfaces 31b and 31c of the floodlight lens 31, and the overlapping width is decided by a gap between the optical axes B, C. The overlapping part is projected on the optical axis of the photographing lens. Thus, even when the photographing lens is zoomed, the object whose overlapping part is projected is caught by the ranging view on the optical axis used maximally always.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination device for focus detection, which is most suitable for single-lens reflex cameras, still video cameras, video cameras and the like.

[0002]

2. Description of the Related Art Conventionally, as disclosed in Japanese Patent Laid-Open No. 3-20705, in a lighting device for focus detection, a light projecting lens is divided into a plurality of regions, and these optical axes are arranged on the same plane. There is known a technique of irradiating illumination light to a wide range while irradiating the center strongly by arranging them.

On the other hand, the range-finding field of a focus detection device for a camera is widened, and a standard zoom lens which covers a fairly short focal length is also generalized. Therefore, even in the focus detection illumination device, a wider angle of view is desired.

[0004]

In view of the demands, the present invention supports a combination of a focus detection device having a large number of distance measuring fields and a high-power zoom lens, and illuminates a wide range while having a high illuminance range. The purpose is to realize a focus detection illuminating device.

Further, it is an object of the present invention to realize a focus detection illuminating device in which the area where the number of bright and dark patterns is reduced by the bonding wire connecting portion, which is a problem when a light emitting diode is used as a light source, is reduced, and distance measurement is less likely to occur. It is what

[0006]

According to the present invention, in order to detect a focus state of a photographing lens based on reflected light from a subject, a plurality of light sources are provided by a light source and an optical system having a plurality of optical axes different from each other. In a focus detection illumination device that projects an image onto a subject, two of the plurality of light source images are:
A focus detection device having a large number of distance measuring fields by having an overlapping portion formed by overlapping a part thereof and setting the overlapping portion on a distance measuring visual field for distance measuring on the optical axis of the photographing lens. This is a focus detection illuminating device that can illuminate a wide range and that is compatible with a high-power zoom lens.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, FIGS. 4 and 5 show a single-lens reflex camera incorporating a focus detection illuminating device according to the present invention.
FIG. 4 is a perspective view and FIG. 5 is a sectional view. In the figure, 10 is a single-lens reflex camera body, and 11 is a lens barrel for moving and holding the taking lens 1 in the direction of the optical axis 12 based on a command from the single-lens reflex camera body 10.

Reference numeral 13 is a half mirror, 15 is a focusing screen, 16 is a pentaprism, and 17 is an eyepiece lens, which constitute a finder system.

Reference numeral 9 is a known focus detecting device which constitutes an automatic focus adjusting device together with a lens driving device (not shown).
The object light transmitted through the half mirror 13 is guided through a sub mirror 14 arranged behind it. The distance measuring fields of the focus detection device are arranged in the horizontal direction at two locations on the optical axis of the taking lens and on both sides thereof.

Reference numeral 2 is a red panel for emitting a light beam from the focus detection illumination device, 5 is a dial for setting photographing conditions, and 7 is a release button.

1 and 2 are views showing an embodiment of a focus detection illuminating device according to the present invention. FIG. 1 is an exploded perspective view,
FIG. 2 is a sectional view. In the figure, 33 is a transparent package accommodating a light emitting diode 37 serving as a light source, 32 is a dome to which the package 33 is fixed with a transparent adhesive, 3
Reference numeral 1 is a light projecting lens. When the light emission wavelength of the light emitting diode 37 is set to about 700 nm, the sensor sensitivity of the focus detection device is high at this wavelength, and conversely the visual sensitivity is low, which is convenient.

A lens holder 30 is provided with a light projecting lens 31 attached from the front and a dome 32 attached from the rear. Further, 34 and 35 are lead wires for electrically connecting the light emitting diode 37 and a drive circuit (not shown), and 36 is a light shielding adhesive sheet for preventing light leakage to the internal mechanism side of the camera.

6 and 7 are views showing the details of the light emitting diode 37 and the package 33, FIG. 6 is a plan view of the package, and FIG. 7 is a detailed plan view of the light emitting diode 37 housed in the package 33. Reference numerals 38 and 39 shown in FIG. 6 are leads for electrically connecting the light emitting diode 37, and have a shape shown by a broken line inside the package. FIG. 7 is an enlarged view of the portion indicated by the broken line. The portion excluding the electrode 37a on the light emitting diode emits light, and as will be described later, the light emission pattern by this electrode is projected on the subject. In addition, the back surface of the light emitting diode 37 is connected to the lead 38, and the electrode 37a is connected to the bonding wire 4
It is connected to the other lead 39 by 0.

Now, the operation of the focus detection illuminating device having the above configuration will be described.

First, the light emitted from the light emitting diode 37 passes through the transparent adhesive layer and enters the dome 32. After that, the light is projected onto the subject side through the light projecting lens 31 and the red panel 2 to form an image of the light emitting diode. At this time, the incident surfaces of the dome 32 and the light projecting lens 31 are single optical surfaces, but the exit surface of the light projecting lens 31 is divided into four as shown in FIG. 3, and the light flux is divided into four directions. To be done.

In FIG. 3, A is the optical axis of the surface 31a, B is the optical axis of the surface 31b, C is the optical axis of the surface 31c, and D is the optical axis of the surface 31d. Since the four optical axes are arranged side by side in this manner, the images of the four light emitting diodes are projected side by side.

8 and 9 are views showing this state.
(A)-(d) is an image of the light emitting diode by the light flux which passed each surface 31a-31d. Brightness and darkness due to the light emission pattern described with reference to FIG. 7 are formed inside each image. In reality, since these images are projected at once, an overlapping portion is formed and the image becomes as shown in FIG.

In FIG. 9, the hatched area with diagonal lines is the dark area, the white area is the bright area, and the dotted area is the high-illuminance area where the bright areas overlap to give double the illuminance. That is, this high illuminance portion is a bright portion in the overlapping portion of the light emitting diode images, and is formed by the light flux transmitted through the surfaces 31b and 31c of the light projecting lens. Therefore, the overlapping width is determined by the distance between the optical axes B and C shown in FIG.

By projecting this overlapping portion on the optical axis of the taking lens, even when the taking lens is zoomed,
The most frequently used distance measuring visual field on the optical axis can always catch the object on which the overlapping portion is projected. Moreover, by limiting the overlapping of images to the central portion, the illumination range can be expanded to the left and right, and it becomes possible to deal with a focus detection device having a wider field of view. Further, it is possible to support a photographing lens having a shorter focal length and a wider angle of view.

Further, as shown in FIG. 7, since the electrode connecting the bonding wire of the light emitting diode 37 is thicker than the other electrodes and the number of bright and dark patterns is reduced, the ability when distance measuring this portion is different. Will be reduced compared to. In the present embodiment, since the images of four light emitting diodes are projected, four such regions can exist. However, in the present embodiment, since the images of the bonding wire connection portions are overlapped, conversely, a part of the electrode corresponding to the overlapped portion of the images is used as a region for electrical connection with the lead. As a result, the number of areas where this bright and dark pattern is reduced is reduced to three as a whole. As a result, the focal length of the taking lens, which covers the five distance measuring fields of the focus detection device in this area, is reduced, and it becomes difficult for distance measurement to be impossible.

[0021]

As described above, according to the present invention,
In order to detect the focus state of the photographing lens based on the reflected light from the subject, a focus detection illumination device that projects a plurality of light source images onto the subject by a light source and an optical system having a plurality of different optical axes, Two of the plurality of light source images have an overlapping portion formed by overlapping a part thereof, and the overlapping portion is set on the distance measuring field for measuring the distance on the optical axis of the photographing lens. It has the following effects.

(1) Since the overlapping portion is projected onto the optical axis of the photographing lens, even when the photographing lens is zoomed, the distance measuring field on the optical axis most frequently used is always projected with the overlapping portion. I was able to capture the subject. Therefore, the distance measuring visual field on the optical axis can always catch a far object as compared with other distance measuring visual fields.

(2) By limiting the overlapping of images to the central portion, the illumination range can be expanded to the left and right, and it becomes possible to deal with a focus detection device having a wider field of view.

As compared with (3), it is possible to support a photographing lens having a short focal length and a wide angle of view.

Further, a light emitting diode having a light emitting pattern by electrodes is used as the light source, and a part of the light emitting pattern corresponding to the overlapping portion of the light source image is set as a region for electrical connection with the lead, so that light and dark It has become possible to reduce the number of patterns that appear to have decreased. As a result, for example, the focal length of the photographing lens that covers the five distance measuring fields of the focus detection device in this area is reduced, and it is possible to obtain the effect that distance measurement is unlikely to be impossible.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a focus detection illumination device according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of the focus detection illumination device shown in FIG.

FIG. 3 is a plan view of the light projecting lens of FIG.

FIG. 4 is a perspective view of a single-lens reflex camera equipped with a focus detection illumination device.

5 is a cross-sectional view of the single-lens reflex camera in FIG.

FIG. 6 is a plan view of a light emitting diode of the focus detection illumination device of FIG.

FIG. 7 is an enlarged view showing details of the light emitting diode of FIG.

8A and 8B are views showing respective light source images by the light flux divided into four by the light projecting lens of the focus detection illuminating device of FIG.

9 is a diagram showing an actual projected image of the focus detection illumination device of FIG. 1. FIG.

[Explanation of symbols]

30 ... Lens holder 31 ... Projection lens 32 ... Dome 33 ... Transparent package 34, 35 ... Lead wire 36 ... Shading adhesive sheet 37 ... Light emitting diode 38, 39 ... Lead 40 ... Bonding wire

Claims (2)

[Claims] 1. A focus detection for projecting a plurality of light source images on a subject by a light source and an optical system having a plurality of optical axes different from each other in order to detect the focus state of a photographing lens based on the reflected light from the subject. In the lighting device for a vehicle, the optical system forms a duplication portion in which two of the plurality of light source images overlap, and the duplication portion is distance-measured on the optical axis of the photographing lens. An illumination device for focus detection, which is set in the field of view. 2. The light source according to claim 1, wherein the light source is a light emitting diode having a light emitting pattern by electrodes, and light and dark due to the pattern are formed in the plurality of light source images,
Furthermore, a part of the light emission pattern corresponding to the overlapping portion of the light source image is used as a region for electrical connection with a lead, and a focus detection illumination device.