JP3199969B2 - Multi-point distance measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-purpose apparatus mounted on an optical device such as a camera for projecting light to a distance measuring object and calculating the distance to the distance measuring object by receiving the reflected light. The present invention relates to an improvement in a point ranging device.

[0002]

2. Description of the Related Art Conventionally, infrared light is projected toward a subject,
A so-called active type distance measuring device that receives reflected light from the subject and calculates the distance to the subject based on the principle of triangulation is widely known.

[0003] A method of determining the close distance of this type of multipoint distance measuring apparatus is based on an output by a combination of light emitting and receiving elements for measuring a photographable distance of a camera, for example, a distance measuring apparatus having a configuration as shown in FIG. , Which is determined from the output when the light is emitted by the light emitting element 1002 and received by the light receiving element 1005;
In order to be able to measure the distance to a closer distance compared to the former, the output of the light emitting and receiving element by a combination different from the combination of the light emitting and receiving element for measuring the photographable distance of the camera, for example,
In the distance measuring apparatus of such structure of FIG. 8, the light emitting element 1002
In some cases, the light is detected by the light receiving element 1006 and the output is determined based on the output.

[0004]

However, recently, in order to secure as many distance measuring points as possible and to reduce the size of the light projecting element, a divided light projecting lens having a plurality of focal points of the light projecting lens exists. A multi-point distance measuring device employing divided light projection (see the divided light projection lens indicated by 204 in FIG. 2) has appeared.

In the multi-point distance measuring method of projecting light by using the divided light projecting lens, according to the conventional method of determining the closest distance, a combination of light emitting and receiving elements for measuring a photographable distance of a camera is used. In the method of discriminating from the output, the light receiving element is downsized along with the downsizing of the product, and the element length (the length of the light receiving surface in the base line length direction) is becoming shorter. The light receiving spot image 80 as shown in FIG.
4 protrudes from the light receiving element 802 corresponding to the combination of the light emitting and receiving elements for measuring the distance that the camera can photograph, and the distance measuring ability is reduced.

Further, in the current active type distance measuring device, the photographing working distance of the camera is 3 m or more, and the light projecting means and the light receiving means of the distance measuring device are required to sufficiently secure the distance measuring ability at the distance. The focus is set at 3 m or more than 3 m. For this reason, the light receiving spot image 804 is out of focus and larger as the subject distance is shorter, and the center of gravity of the image moves to the far side. As a result, assuming that the integrated output of the light receiving element 802 [for example, when both ends of the output are A and B, A / (A +
B)] is, is made smaller extent the original object distance is close, reaching the a close distance position, the output is increased as in FIG. 9 (b), the light receiving element 8 at a certain close distance point P
Since the output of 02 is equal to the output at a certain distance point Q, erroneous distance measurement has been performed.

Further, in the method of discriminating using a combination of light emitting and receiving elements different from the combination of light emitting and receiving elements for measuring a distance at which a camera can photograph, in FIG. The output of the light receiving element 903 with respect to the light receiving spot image 905 is the same as that in FIG. 9B described above. However, in the case of multi-point distance measurement in which divided light projection is performed, if one infrared light emitting element is turned on. A plurality of infrared signals are simultaneously incident on the light receiving means. As a result, when the subject distance reaches a position at a short distance, the light receiving element 903 receives the light receiving spot images 904 and 905 at the same time, so that the output of the light receiving element 903 becomes as shown in FIG. Since the output of the light receiving element 903 at the close distance point P becomes equal to the output at the close distance point Q, erroneous distance measurement is performed.

In FIGS. 8 to 10, reference numerals 1001,
1003 is a light emitting element, 1007 is a light emitting lens, 1008
Denotes light receiving lenses, 1004, 801, 803, 901, 9
02 is a light receiving element.

(Object of the Invention) It is an object of the present invention to provide a multipoint distance measuring apparatus capable of preventing erroneous distance measurement on a close distance side.

[0010]

Means for Solving the Problems In order to achieve the above object, the present invention according to claims 1 to 5, according to the present invention, comprises a light projecting means for projecting light toward an object to be measured, and a light projecting means. A divided light projecting lens that divides the projected light into a plurality of light beams, and a reflected light of the projection light divided by the divided light projecting lens and separated by the divided light projecting lens, the light being reflected by the distance measuring object. Respectively , and a plurality of first light receiving means on which light receiving spot images are respectively formed, and a plurality of first light receiving means on a side surface of the first light receiving means.
It is arranged at the upper part or the lower part, and only when the distance measurement target is located at a close distance, it is one of the light receiving spot images of the light receiving spot images , and the image is blurred and large, and the
The present invention is a multi-point distance measuring device provided with a second light receiving means for receiving an image protruding from the first light receiving means .

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

FIG. 2 is a block diagram schematically showing a distance measuring apparatus according to one embodiment of the present invention. In the figure, reference numeral 201 denotes a timing pulse which is output to a driving circuit to be described later, and A control circuit that performs distance measurement by output,
202 is a driving circuit that receives a timing pulse output from the control circuit 201 and drives a light emitting unit described below;
203 is a light projecting means such as an infrared light emitting diode, 204 is a divided light projecting lens for dividing the infrared light from the light projecting means 203 into two, 205 is a subject, and 206 is reflected light of the infrared signal from the subject 205 Light-receiving lens for condensing light, 10
Reference numerals 1 and 104 denote light receiving elements for receiving the infrared signals, respectively, and reference numeral 208 denotes a distance measuring circuit that amplifies and integrates a signal based on an output of the light receiving element.

The light receiving elements 101 and 104 include a semiconductor position detecting element (PSD: Position Sensitive Device),
Silicon Photo Diode (SPD)
ode) (in the present embodiment, the case of PSD will be described), and based on the output, information on the distance to the subject is calculated by an arithmetic circuit (not shown).

Next, the arrangement of the respective light receiving elements and the positional relationship between the light receiving elements and the light receiving spot image at a short distance will be described.

In FIG. 1, reference numerals 101 and 104 denote light receiving elements for receiving two infrared signals reflected by a subject located at a distance which can be photographed by a camera, respectively.
Reference numeral denotes a light receiving element which can receive only an infrared signal reflected by an object near a close distance where a camera cannot capture an image. Reference numerals 110 and 111 denote light-receiving spot images which are focused on the light-receiving elements 101 and 104 by light-receiving lenses, respectively. 102, 103, 105, 10
6, 108 and 109 are light receiving elements 101, 104,
Reference numeral 107 denotes output terminals. Each output from these terminals changes depending on the position where the light-receiving spot image hits, and distance information to the subject can be obtained based on each output.

According to FIG. 1, the light receiving spot image 110 (1
The more the light receiving element 11) is received at the position closer to the left of the light receiving element 101 (104), the farther the object distance is, and the more the light receiving element 11 (104) is received at the position closer to the right, the closer it is.

In the current active type distance measuring device, the photographing working distance of the camera is 3 m or more, and the light projecting means and the light receiving means of the distance measuring device are required to secure sufficient distance measuring ability at the distance. Is set to around 3 m or more. In addition, in order to avoid a decrease in the distance measuring ability due to the protrusion of the light receiving spot image at a long distance, the matching distance between the light projecting means and the light receiving means of the distance measuring device (up to the subject when the light receiving spot image is at the center of the light receiving element) 3m)
It is set near. At this time, the light receiving spot image 110,
Reference numeral 111 denotes a size that can be accommodated in each of the light receiving elements 101 and 104 as shown in FIG. 3, but the focus of the received light spot image becomes larger as the distance to the subject becomes shorter. FIG. 4 shows this state.

FIG. 4 shows a light receiving spot image at each distance, where 501 is a light receiving element, 502 is a long distance object, 503 is a medium distance, 504 is a short distance, and 505 is a light receiving spot when the object is located at a close distance. It is a spot image, and from FIG.
It can be seen that the light-receiving spot image becomes larger as the distance to the subject becomes shorter, and the light-receiving spot image protrudes from the light-receiving element 501 at a close distance.

Therefore, the second light-receiving spot provided at a position where the light-receiving spot image 110 can be received only when the light-receiving spot image 110 which has become blurred and large in FIG. In this embodiment, the closest distance is determined by receiving light with the element 107.

Referring to the flow chart of FIG. 5, first, when the distance measured by the light receiving element 107 (step 301) exceeds a predetermined position, the positional relationship between the spot image 110 and the light receiving element 107 in FIG. Therefore, the distance measurement result becomes close, and the user is warned that photographing is impossible (steps 302 → 307 → 308).

On the other hand, when the distance measurement result is equal to or less than the predetermined position, the light receiving element 107 performs the normal distance measurement because the spot image 110 does not exist on the light receiving element 107 (performs a well-known double integration of the output at both ends of each light receiving element). The distance measurement result D is obtained (steps 302 → 303 → 304 → 305 → 306).

As described above, the light receiving element 107 is arranged at a position where the light receiving spot image 111 is not always received and at a position where the light receiving spot image 110 can receive light only when the subject is in the vicinity of a close distance. It is determined whether or not the distance to the subject is a close distance based on the output level of the light receiving element 107 when receiving the light 110.

In this embodiment, as shown in FIG. 1, the second light receiving element 107 for determining the closest distance is replaced with the first light receiving elements 101 and 10 for measuring the distance that can be photographed by the camera.
4, the position of the second light receiving element is not limited to this. One of the pair of light receiving spot images is not always received, and the other light receiving spot image is If it is a position where light can be received only when there is a close distance, it is arranged on the upper side of the first light receiving elements 101 and 104 or on the side surface on the near side as shown in 601 in FIG. 6 and 701 in FIG. May be.

According to the present embodiment, when determining the close distance of a multi-point distance measuring apparatus using a divided light projecting lens, the first signal for receiving an infrared signal reflected by a subject located at a distance that can be photographed by a camera is used. The light receiving elements 101 and 104 are not used, and only one infrared signal out of a plurality of infrared signals is received in the base line length direction with respect to the light projecting means only when the subject is located near a distance at which a subject cannot be photographed. Second light receiving element 10 capable of
7 (601, 701), it is possible to prevent erroneous distance measurement due to close distance determination.

(Modification) The present invention is also applicable to a distance measuring device mounted on a camera such as a single-lens reflex camera, a lens shutter camera, a video camera, and other optical devices.

[0026]

As described above, according to the present invention,
At a position provided separately from the first light receiving means used at the time of measuring the working distance, that is, at a position capable of receiving one of a plurality of light receiving spot images reflected and formed by the distance measuring object located at the closest distance. The closeness determination is performed based on the output of the second light receiving means arranged.

Therefore, it is possible to prevent erroneous distance measurement on the close distance side.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining an arrangement of each light receiving element shown in FIG. 2 and a positional relationship between these light receiving elements and a light receiving spot image at a short distance.

FIG. 2 is a configuration diagram schematically showing a distance measuring apparatus according to an embodiment of the present invention.

FIG. 3 is a diagram showing a positional relationship between a size of a light receiving spot image and a light receiving element when the light projecting means and the light receiving means shown in FIG. 2 are in focus.

FIG. 4 is a diagram showing a positional relationship between the size of a light receiving spot image at each subject distance and the light receiving element of FIG. 2;

FIG. 5 is a flowchart showing an operation of the distance measuring apparatus in one embodiment of the present invention.

FIG. 6 shows a second light-receiving element of FIG.
FIG. 3 is a diagram for explaining a light receiving unit disposed above a first light receiving element.

FIG. 7 shows a second light receiving element of FIG.
FIG. 3 is a diagram for explaining a light receiving unit arranged on a short distance side of a first light receiving element.

FIG. 8 is a diagram showing a schematic configuration of a conventional distance measuring device.

FIG. 9 is a diagram for explaining a conventional example of close distance determination and an output of the light receiving element 802 at each subject distance.

FIG. 10 is a diagram for describing a conventional example of close distance determination and an output of the light receiving element 903 at each subject distance.

[Explanation of symbols]

101, 104 A light receiving element for measuring a subject at a photographable distance 107 A light receiving element for determining a close distance 203 Light emitting means 204 A divided light projecting lens 601 and 701 A light receiving element for determining a close distance

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01C 3/06 G02B 7/32

Claims (5)

(57) [Claims] 1. A light projecting means for projecting light toward an object to be measured, a divided light projecting lens for dividing light projected from the light projecting means into a plurality of light, and a light emitting means which is arranged in a base line length direction. are spaced apart, the split by split light projecting lens was the light reflected by the measuring object of the projected light respectively received, a plurality of first light receiving means for respectively receiving spot image is formed, said Placed on the upper or lower side of the light receiving means
Is, only when the distance measuring object is located in close proximity, I met one of the light receiving spot image of the light spot image
The image becomes blurred and large, and the image is blurred from the first light receiving means.
And a second light receiving means for receiving the output image . 2. A multi-point distance measuring apparatus according to claim 1, wherein said first and second light receiving means are one of a semiconductor position detecting element and a silicon photodiode. 3. The multi-point distance measuring apparatus according to claim 1, wherein said second light receiving means is disposed near said first light receiving means. 4. The split light projection lens according to claim 1, wherein the split light splits at least the projection light into two.
The multipoint distance measuring device as described. 5. The first light receiving means receives reflected light from a subject located at a photographable distance,
5. The multi-point distance measuring device according to claim 1, wherein said second light receiving means receives the reflected light only when the subject is located near a distance where photographing is not possible. apparatus.