JPS6217719A - Light emitting element for automatic focusing device - Google Patents

Abstract

PURPOSE:To decrease an unnecessary flare light generated by a reflection the inner wall of a covering can or the surface of a base part, etc., and to decrease a malfunction caused by ununiformity of a reflection factor distribution, by attaching a horn-shaped space filter to an output part of the covering can of a light emitting element. CONSTITUTION:An automatic focusing device use light emitting element is provided with a projector of a distance measuring infrared ray, and a photodetector for photodetecting a reflected light from an object, to be brought to distance measurement of the infrared ray, and a distance to the object is detected by an output corresponding to an image forming spot position of a focal plane of a photodetecting lens of the detector. A light emitting chip 6 is installed to a base 17 of this light emitting element, and a covering can 4 is placed between the base 17 and a cover glass 3. A horn-shaped space filter 2 is placed on an output surface opposed to a projection lens 1 of this covering can 4. In this way, an unnecessary flare light generated by a reflection from the surface of the inner wall of the covering can 4 or the surface of the base 17 is decreased, and a malfunction caused by ununiformity of a reflection factor distribution is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a light emitting element for an automatic focus adjustment device for a video camera and still camera. One such device is an active automatic focus adjustment device that projects infrared light onto a subject, detects the reflected light, calculates the distance to the subject, and adjusts the focus. The distance to the subject is calculated by applying the principle of triangulation, in which the output light from the light emitting element is projected onto the subject using a projecting lens, and the light reflected from the subject is placed on the focal plane using a receiving lens. The focus was adjusted by focusing the light on the light receiving element, detecting the center of gravity of the spot image formed on the light receiving element, and calculating the distance to the subject. (Patent Application No. 59-195011) In the above-mentioned infrared active type automatic focus adjustment device, the distance signal to the subject is obtained from the center of gravity of the spot of infrared reflected light from the subject connected to the light receiving element. Second, the light projection pattern of the light emitting elements affects distance measurement performance. Generally, an infrared active type automatic focus adjustment device uses an infrared light emitting diode (hereinafter abbreviated as LED) as a light emitting element.

The shape of a conventionally used LED is shown in Figure 3.
I, ED are light emitting chips 9. Pace 11. Electrode 12. It is composed of an exterior can 81 and a cover glass 1o. Infrared light emitted from the light emitting chip passes through the cover glass 1o and is projected onto the subject by the projection lens 7.

Problems to be Solved by the Invention In the conventional LED exterior can 8, the light output from the light emitting chip 9 and reflected by the end face of the cover glass 1o illuminates the base surface around the light emitting chip and the inner wall of the exterior can. Reflected light and scattered light are generated.

Therefore, when the light is projected onto the subject through the projection lens, flare or blurring occurs in the peripheral portion of the spot image of the output light from the light emitting chip 9. If the subject has a uniform reflectance, even if the reflected light is imaged onto the light receiving element, the center of gravity corresponding to the center of the spot of the LED light emitting part will be detected, so it will be difficult to measure the distance. There is no impact. However, if the subject has some kind of reflectance distribution, for example, if there is an area with particularly high reflectance around the area where the spot image of the light emitting unit is projected, the light generated by stray light or flare will be strongly reflected. , because the intensity distribution on the light receiving element becomes uneven, the center position of the light emitting spot image that contains distance information and the center of gravity detected by the light receiving element deviate, causing the imaging lens to be out of focus and blurred. The problem arises that the

In view of the above-mentioned problems, the present invention provides a method for projecting images onto a subject.
To provide a light emitting element for automatic focus adjustment that can reduce images caused by flare light caused by unnecessary reflection and scattering among KD light emission images and project only a light emitting body.

Means for Solving the Problems In order to solve the above problems, the light emitting device for an automatic focus adjustment device of the present invention has a horn-shaped spatial filter attached to the external can output portion of the light emitting device.

The present invention aims to solve the above-described problems by reducing unnecessary flare light generated by reflection on the inner wall of the exterior can of the light-emitting element or the surface of the base portion, etc., using the above-described configuration.

EXAMPLE Hereinafter, a light emitting element for an automatic focus adjustment device according to an example of the present invention will be described with reference to the drawings.

FIG. 1(a), Φ) shows a first embodiment of a light emitting element for automatic focusing of the present invention. Output light from the light emitting chip 6 passes through the cover glass 3, passes through the spatial filter 2 attached to the opening of the exterior can 4, and is projected onto the subject by the projection lens 1. The spatial filter 2 has a conical shape with the light-emitting chip 6 as the apex and the effective diameter of the light-emitting lens 1 as the base, and has a central axis within the conical shape with the light-emitting chip 6 as the apex and a generatrix in the direction of the light-emitting lens 1. The projection lens 10 has a light shielding wall having a thin conical shape with the optical axis being the optical axis. Therefore, if you look at the light emitting element from the direction of the projector lens 1 on the optical axis, only the light emitting chip 6 located in the center can be seen, and the base surface around the light emitting chip 6 and the inner wall of the external force /4 are light shielding walls. cannot be seen because it is blocked by Therefore, the light emitted from the light emitting chip 6 in the direction of the projection lens 1 passes through the spatial filter 2 and is projected onto the subject, while the light output from the light emitting chip 6 is reflected by the cover glass 3 and hits the inner wall of the exterior can 4 and the like. Stray light and flare light generated by illuminating the base surface hits the light-shielding wall of the spatial filter 2, so if the side of the light-shielding wall is painted black to make it a low-reflectance, high-light-absorbing surface, it will be projected onto the subject through the projection lens. The amount produced is significantly reduced. Therefore, even if there is an uneven reflectance distribution around the subject, as long as it is around the light emitting spot image, it will have little effect on the center of gravity of the light emitting spot detected on the light receiving element, and the focus will be adjusted. FIGS. 2(2L) and 2(b) are cross-sectional views of a light emitting element for an automatic focusing device showing a second embodiment of the present invention.

The configuration of the spatial filter 22 is different from the configuration shown in FIG. 1. In FIG. 1, the spatial filter is composed of a plurality of coaxial conical light-shielding walls, but in the second embodiment, the light-shielding walls are formed into one spiral shape. By constructing the horn, the same effects as those of the first embodiment can be obtained, and the present invention has the advantage that the construction is simple, the number of parts is small, and the cost is low.

Effects of the Invention As described above, according to the present invention, unnecessary flare light from a light emitting element can be reduced with an extremely simple configuration, and malfunctions due to uneven reflectance distribution of a subject during autofocus adjustment can be reduced. It is possible.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a light-emitting device according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view of a light-emitting device according to a second embodiment of the present invention, and FIG. 3 is a cross-sectional view of a conventional light-emitting device. FIG. 1.21.7... Light projection lens, 2.22...
...Spatial filter, 3,26.10...Cover glass, 4.23,8...Exterior can, 5
+ 27y 12... Electrode, 6, 24.9
......Light-emitting chip, 17,25°11...
·pace. Name of agent: Patent attorney Toshio Nakao and 1 other person
- Seven light lens 17 - Head \ l I l \ l (l \ ' Eight l \ l , I(b) \ ' 21 - M - Light projection lens? 5 ---- Base \ l \ l l ゝ l \ l Enter 1 7---Emission lens rt ---A-nu/2--Electric! \ l \ l \ . \ l l

Claims (1)

[Claims] a distance-measuring infrared light projector; a photodetector that outputs a signal according to the imaging spot position of the focal plane of the light-receiving lens of the reflected light of the distance-measuring infrared light from the object to be measured; Equipped with
An automatic focus adjustment device that detects a distance to a subject from the output signal and performs automatic focus adjustment, characterized in that a horn-shaped spatial filter is provided at the exterior can output section of the light emitting element of the projector. Light emitting element for devices.