JPS5862512A - Distance detector - Google Patents

Abstract

PURPOSE:To enable to perform a reliable and precise detection of a distance through a simple constitution, by a method wherein a part, which light transmits, is partially formed on a liht shielding member which runs on a surface of a light receiving element in correlation with a distance to an object to be photographed. CONSTITUTION:Light is projected from a light emitting element 1 through a projecting lens 2, and a light shielding member 7 is located between a light receiving element 6, which measures a distance to an object 8 to be photographed through collection of light reflected by the object 8 to be photographed, and a light receiving lens 5. The light shielding member 7 is caused to run on the surface of the element 6 and in correlation with a distance to the object 8 to be photographed, and a distance is found from a peak point lp where a peak value of an amount of a light spot 6a, whose image is formed on the element 6 through a light transmitting slit 7a formed in the light shielding member 7, is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a distance detection device that measures the distance to a subject by detecting changes in the photoelectric output of a single light-receiving element in a floodlight-type distance detection device that utilizes the principle of triangulation. It is related to the device.

The present invention is based on Japanese Patent Application No. 55-124268 filed by the applicant.
It is a famous product that is based on the technique of numbering.

That is, a light projecting device consisting of a light emitting element and a light projecting lens projects light toward a subject, and the reflected light is received by a single general light receiving element such as a silicon photodiode. A light blocking member is operable on the light incident surface of the subject, and the light blocking member operates in a certain correlation with the distance to the subject, so that when the light reflected from the subject is blocked by the light blocking member, the light blocking member Distance measurement is performed by utilizing changes in the photoelectric output of the light-receiving element. Therefore, since there is no need to use a plurality of light receiving elements, the circuit configuration is very simple, and since it is not a special light receiving element, it can be manufactured at low cost.

The present invention applies the above basic technology to equipment such as cameras,
The purpose of this invention is to more reliably and accurately perform one-off detection during implementation, and to provide a simpler method in terms of configuration.

To be more specific, in the basic invention described above, the light shielding member running over the light receiving element does not cover any part of the light receiving element surface that is effective for distance measurement before operation. Therefore, between the time the light emitting means, light receiving element, and detection circuit become operational and the time the light shielding member starts operating, the conditions of the subject may change significantly or a false output signal may be generated due to changes in natural light. That could happen. Although it is possible to completely take measures against these special conditions by electric circuit means, in the present invention, the light shielding member can be used at a distance even under the above conditions in exactly the same way as in other cases. It is configured to be detectable. Therefore, the detection circuit does not need to be complicated at all, and the purpose can be achieved with an extremely simple mechanical configuration.

The distance detection circuit of the present invention will be explained below according to embodiments.

FIG. 1 is a diagram showing a configuration in which the distance detection device of the present invention is applied to a still camera.

FIG. 2 is a diagram for explaining the operation of the distance detection device of the present invention.

FIG. 3 is an example of a detection circuit of the distance detection device of the present invention.

FIG. 4 is a diagram showing an example of a light shielding member in the distance detection device of the present invention.

In the figure, 1 is a light emitting element such as a crawler lamp or LID, 2 is a light projecting lens for converting the emitted light into a beam, 3 is a light projecting optical axis, 4 is a reflected light optical axis, 5 is a light receiving lens, 6 is a light receiving element, 6a is a light spot formed by reflected light (optical axis 4) on the light receiving element, 7 is a light shielding member, 8 is a subject, and 9 is an optical axis of a light receiving lens. 10.11 is an operational amplifier, 12
, s 13 is a feedback resistor, 14 is an AC coupling capacitor,
16 is a detection diode, 17 is an integrating capacitor, 15
゜18.19 is the resistance, and vo is the output voltage.

Next, the operation will be explained.

The distance detecting device of the present invention has a light shielding member 7 disposed between a light receiving lens 5 and a light receiving element 6, as shown in FIG. The light shielding member 7 moves on the surface of the light receiving element 6 in the direction shown by the arrow in FIG.

In FIG. 3, the output terminal of the light receiving element 6 is connected to the operational amplifier 10.
The short-circuit current of the light receiving element 6 is amplified, inputted to the next stage amplifier 11 via the AC coupling capacitor 14, further AC amplified, and detected by the diode 16. The output integrated by the capacitor 17 is obtained as the voltage v0. In this embodiment, the description will be made on the assumption that the light emitting element is driven by pulse modulation at a certain predetermined frequency. In practice, by using modulated light as the projection light, it is possible to almost eliminate shadows 1 caused by natural light, so-called extraneous light.

In FIG. 1, light from a light emitting element 1 is condensed into a beam by a projection lens 2 'C' (optical axis 3) and impinges on a subject 8. The light (optical axis 4) reflected from the surface of the subject 8 is condensed by the light receiving lens 5, and a light spot 6 m is generated on the light receiving element 6. Other imaging means may be used in place of the light-receiving lens 5. The position of this light spot 6a on the light-receiving element 6 differs depending on the distance to the subject 8. If the object is at infinity, the reflected light will enter from an angle that coincides with the optical axis 9 of the light receiving lens 5, and a light spot will be created at the point on the light receiving element 6 where it intersects with the optical axis 9. Similarly, as the subject approaches, the position of the light spot will shift little by little to the right on the light receiving element 6 in FIG. Therefore, the position of the light spot is detected by the method described later using the moving light shielding member 7 and the output of a circuit connected to the light receiving element 6 to perform distance detection.

When the light shielding member 7 is in the position shown in FIG. 2, the light spot 6 passes through the light transmission slit 7α provided in the light shielding member 7.
α is imaged onto the light receiving element 6. As a result, the current generated in the light receiving element 6 is amplified and detected by the detection circuit shown in FIG. 3, and appears as an output voltage. This position is the peak point 1 of the output waveform shown in FIG. 2 (6). This is the position shown in . With this 1 degree as the peak, the output voltage v0 shows attenuation characteristics on both sides. This is because the light that passes through the light shielding member 7a is only natural light, and the detection circuit has an AC amplification characteristic that hardly detects current output due to natural light, so no output voltage can be obtained.

Therefore, the output voltage v0 is obtained from the subject 8 subjected to AC modulation through the slit 7α on the light shielding member.
This occurs only when reflected light from the In this way,
Position 1 of the light shielding member when the peak of the output voltage v0 is obtained. In principle, the distance to the subject can be determined by reading, for example, the pointer 7b in FIG. 2 (α).

FIG. 4 shows some examples of light shielding members having the above-mentioned light transmitting portions. (α) has a slit formed on the light shielding member, and (b) has nine chambers.

In addition, (6) leaves a narrow transparent part (slit) in the center on the surface of a transparent thin plate made of glass or plastic,
Other parts may be processed to block light, such as by vapor deposition, pasting, coating, etc.

Further, the light receiving element is normally completely covered by the light shielding member and is in a dark state, and when the light receiving element suddenly enters the light receiving state due to the movement of the light shielding member, a delay in response may occur. In this case, the part corresponding to the light-shielding part in Figure 4 (1) above is constructed with an infrared cut filter, and by using an infrared light emitting diode as the light emitting element, the reflected light from the subject is transmitted through the transmission slit part. In the normal state, it receives natural light such as visible light.By doing so, at least the dark state does not occur and response delay can be prevented.

As explained above, the distance detection device of the present invention uses a method of detecting distance by receiving the reflected light of the projected light, and is configured with one light receiving element, and the light receiving element also does not require special performance. First, it is possible to use an element such as a general photodiode. Therefore, the circuit configuration becomes extremely simple and the cost can be reduced. Furthermore, since there is no movable mirror for scanning, there is no need for difficult adjustments, and the device can be applied not only to still cameras but also as a distance detection device in many fields.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an example in which the distance detecting device of the present invention is applied to a still camera, Fig. 2 is a diagram for explaining the operation of the distance detecting device of the present invention, and Fig. 3 is a diagram showing the distance detecting device of the present invention. An example of a detection circuit of the detection device, and FIG. 4 is a diagram showing an example of a light shielding member in the distance detection device of the present invention. 1... Light emitting element 2... Light emitting lens 3.4.9... Optical axis 5... Light receiving lens 6... Light receiving element 7... Light shielding member 8... Subject 10.11... Operational amplifier 12.13, 15, 18.19... Resistor 14.
17... Capacitor 16... Diode and above Applicant Seiko Koki Co., Ltd. Kinsha representative Patent attorney Muto Mogami 1 Figure! r 1-2 Figure /J/2, /J spear 30 +41?

Claims (1)

[Claims] 1. A light projecting means comprising a light emitting element and a light projecting lens;
A distance detection device that measures the distance to the object by receiving light projected from the light projecting means and reflected from the object, comprising: an imaging means for receiving the reflected light from the object; and an imaging means for receiving the reflected light from the object; a light-receiving element disposed on the imaging side of the imaging means; a light-shielding member that walks on the surface of the light-receiving element in correlation with the distance to the object and partially transmits light; and (3) the light-shielding member. A distance detecting device comprising: a detection path for detecting a change in photoelectric output caused by receiving reflected light from the object by the light receiving element when the member is activated. 2. In the device described in claim 1, the light emitting element is an infrared light emitting diode, and the light shielding member is made of an infrared cut filter and has a portion that transmits infrared light. distance detection device. (v) A distance detection device according to claim 1 or 2, characterized in that the light emitted from the light emitting element is pulse modulated light.