JPH0435866Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a range finder for electro-optically detecting the distance of a subject, and the distance detection is based on whether the subject is within a certain range of the actual distance, that is, inside or outside the display. This is the display.

US Pat. No. 3,617,128 describes a rangefinder in which light is transmitted to an object whose distance is to be detected. The light reflected by the object is received by an optical system having an outer annular portion of the lens arranged around the light transmission device. The light transmission device includes a light source and its own lens. The light source is within a light-tight housing such that the light generated within itself does not directly reach the photosensitive material at the image plane of the optical system. Such range finders require shielding of the light source from photosensitive materials, the optics of the transmission and detection elements are separate so that the effective aperture of each is smaller than the sum of the parts, and manufacturing It has disadvantages such as being relatively complex.

The purpose of the present invention is to eliminate the above-mentioned disadvantages.

The present invention provides a microwave oven having a single lens, a radiant energy applicator that provides a beam of radiant energy proximate to one focal point of the lens, and a detector that detects the radiant energy reflected from an object. the object of the present invention is to position a detection device relative to the lens to form a field of view that overlaps the beam of radiant energy in a near-field detection region extending a predetermined distance from the lens; an effective aperture for a radiant energy applicator provided by a lens and a detection device configured to detect radiant energy reflected by an object in a close range detection region and generate an electrical signal representative of the detection; The effective apertures for the lens substantially coincide with each other, and the radiant energy irradiation device and the detection device are integrally provided on a common substrate substantially within the focal plane of the lens and substantially with respect to the optical axis of the lens. and a signal processing device for detecting whether or not there is an object reflective to the radiant energy within the short-range detection area in response to the electrical signal. This was achieved by generating a signal.

In FIG. 1, the preferred embodiment of the invention includes a single lens 10. In FIG. A light emitting device, such as a light emitting diode (LED) 12 or a diode laser, is shown as one example of a radiant energy emitting device, and a lens 1 is used to direct the beam from the light emitting device forward as a light beam 14.
It is placed near the zero focus. A light detection device 16, such as a photodiode, is placed near the light emitting device and receives light directed into the vicinity of the detection device by a lens in the opposite direction, which light is directed into the field of view 17.
The lens is directed from an object within the lens, that is, a subject. The effective apertures of the lenses for the detection device and the light emitting device are substantially the same size and matched so that both the detection device and the light emission device fully utilize the light collection power of a single lens. The light ray 14 and the field of view 17 are connected to the lens 1
They overlap within a short-distance detection area 18 that extends by a predetermined distance D from zero. When LED 12 is energized, objects within beam 14 will be illuminated by the light beam from the LED. If an object is present within the detection area 18, this object will be seen by the photodetector 16, thereby causing an increase in the output signal of the photodetector. The output of the photodetection device 16 is an electrical signal, which is detected in a detection circuit shown as an example of a signal processing device described below to determine whether the subject is within the detection area 18.

FIG. 2 shows a rangefinder embodying the invention utilized in a still camera 20 for exposing disc film. The camera includes a housing 22 having an opening for a viewfinder 24, an electronic flash 26, an objective lens 28, and an exposure control photosensitive element 30. The body of the camera is mounted so that it slides into the optical path of the objective lens 28 to change the focus of the objective lens 28 from normal photography to close-up photography (e.g., closer than approximately 91 cm (3 ft)). The auxiliary proximity lens 32 is partially cut away to show that it is provided on the objective lens 28.
An electromagnetic actuator 34, such as a solenoid, and more preferably a planar actuator such as that described in U.S. Pat. It is connected.

A range finder device embodying the invention controls the position of the proximity lens 32. This rangefinder device includes a lens 36, a light emitting device 38, which in this example is a light emitting diode, and a detection device 40, which in this example is a photodiode. The light emitting diode and photodiode are electrically connected to an electronic control circuit 42 that drives the electromagnetic actuator 34. This camera is provided with a shutter release button 44.

As shown in FIG. 3, the camera housing 2
The second extension 46 forms a side surface of the housing in which the light emitting device 38 and the detection device 40 are housed. A lens 36 covers the front of the housing. Behind the casing,
Light emitting device 38, detection device 40, and electronic control circuit 42
formed by a printed circuit board that supports the Printed circuit boards have been identified as part of a mechanical plate made of mild steel coated with a layer of electrically insulating material as described in US Pat. No. 4,333,722. printed circuit board 48
is an integral stud 50 extending into the through hole 52.
is attached to the rear of the housing extension 46 by.

In this embodiment, the light emitting device 38 and the detection device 40 are integrated on a common chip 54 (see FIG. 4). This light emitting device/detecting device chip 5
4 is formed on an n-type gallium arsenide substrate 56 by a method well known in the art. The light emitting and detecting diodes are formed by p-doped regions 58 and 60, respectively. Individual addressing electrodes 62 and 64 are formed on the top surfaces of the light emitting and detecting diodes to address each p
Make ohmic contact with the mold area. Common ground electrode 6
6 is formed on the back side of this chip. For example, a slot 68 is formed using a diamond saw to half the depth of the chip. A sheet of light-absorbing material, such as a carbon-filled polymeric film, is secured in the slot to shade the light-emitting and detecting devices.

Lens 36 (see FIG. 3) is covered with an anti-reflection coating that is tuned to the wavelength of the light emitted by the LEDs forming light emitting device 38. The solid line 72 in FIG. 5 indicates the transmission of an antireflective coating as optimized for LEDs emitting in the infrared region of the spectrum at approximately 940 nm. An infrared transmission filter 74 is placed over the photodiode detector 40 to adjust the detector response to the wavelength of light emitted by the LED, thereby enhancing the signal-to-noise ratio of the ranging device. A suitable filter for this purpose is
Wratten manufactured by Eastman Kodak
It is an 87C filter. The spectral transmission state of the infrared transmission filter is indicated by dotted line 76 in FIG.

Control electronics 42 will be described with respect to FIG. The control circuit 42 includes a camera control logic circuit 78 comprising a programmed microprocessor as is well known in the art of conventional camera control.
Contains. The camera control logic circuit 78 receives input from the shutter release button 44 and begins operating. The computer generates an oscillator 80.
When turned ON, an alternating current voltage is applied to the light emitting diode forming the light emitting device 38, causing the diode to produce a light beam having the same alternating brightness component. The frequency of the oscillator 80 is selected to be compatible with the frequency response of the LED and to be distinguished from flicker frequencies associated with artificial illumination.

The signal produced by the photodiode forming the detection device 40 is amplified and filtered in a bandpass filter 82 having a passband approximately centered at the oscillator frequency. The output of bandpass filter 82 is provided to a trigger circuit 84 which produces a logic level output signal when the output of bandpass filter 82 exceeds a predetermined threshold. The threshold of the trigger circuit 84 is set to substantially eliminate the possibility of triggering on noise such as crosstalk between the light emitting device and the detection device caused by light reflected inside the housing. The sides and back of the enclosure are painted black to further reduce this potential source of noise. Camera control logic circuit 78 receives logic signals from trigger circuit 84 and controls focus drive control circuit 86 in response to the signals. The circuit 86 powers the electromagnetic actuator 34 (see FIG. 2) to move the proximity lens 32 in and out of the optical path of the objective level 28.

The camera control logic may also receive signals from the photometer 88 to control camera exposure in controlling the shutter drive circuit 90 in a well known manner.

The embodiment has the following dimensions. Lens 36 has a focal length of 20mm and an aperture ratio of
2.0 convex lens. The width of the slot 68 in the chip 54 is approximately 150μ, so that
Space the LED and photodiode approximately 150μ from each other. The emitting device 38 and the detecting device 40 are disposed approximately in the focal plane of the lens 36 and are generally symmetrically disposed about the optical axis of the lens 36 . As a result of this configuration, the detection area 18 (see FIG. 1) extends approximately 1.3 m from the lens.

A single lens is provided to direct the light beam forward from the emitting device and to direct the reflected light in the opposite direction near the detecting device, such that the effective aperture provided by the lens to the emitting device and the detecting device is substantially By matching, for example, the area at the front of the camera occupied by the range finder is minimized, and the area occupied by the range finder is minimized because the lens aperture is used for both pointing and collecting purposes. It is used to the maximum extent possible. Also, manufacturing the range finder is relatively simple.

[Brief explanation of drawings]

Fig. 1 is a ray path diagram useful in explaining the working principle of a single rangefinder device according to the invention, and Fig. 2 is a ray path diagram useful in explaining the working principle of a single range finder device according to the invention, and Fig. 2 is a ray path diagram of a single range finder according to the invention partially cut away to show internal details of the camera. FIG. 3 is a perspective view showing a camera having a lens range finder device;
The figure is an enlarged partial view showing details of the range finder device of the camera shown in FIG. 2, and FIG. Perspective view shown, No. 5
The figure is a graph showing the transmission state of the anti-reflection coating and the spectrum of the infrared filter for the lens used in one embodiment of the present invention, and Figure 6 is a circuit diagram showing the electronic circuit for controlling the range finder shown in Figure 2. It is a diagram. 12,38,58...Radiant energy irradiation device, 16,40,60...Detection device, 10,36
...a single lens.

Claims (1)

[Claims for Utility Model Registration] A single lens, a radiant energy application device that provides a beam of radiant energy in close proximity to one focal point of the lens, and a detection device that detects the radiant energy reflected from an object. a rangefinder having: the detection device is positioned relative to the lens to form a field of view that overlaps the beam of radiant energy in a near-field detection region extending a predetermined distance from the lens; configured to detect radiant energy reflected by an object in the near-field detection area and generate an electrical signal representative of the detection; the aperture and the effective aperture for the detection device substantially coincide, the radiant energy application device and the detection device are integrally provided on a common substrate and are substantially in the focal plane of the lens; and is arranged substantially symmetrically with respect to the optical axis of the lens, and further includes a signal processing device, the processing device being responsive to the electrical signal to direct radiant energy into the near field detection region. A range finder characterized in that it generates a signal indicating whether or not a reflective object is present.