JP2614446B2 - Distance measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a distance measuring device based on the principle of triangulation used as an autofocus mechanism for optical products or a position sensor of an automated assembly device.

(Prior art) As a distance measuring device of this kind used for an auto-focus camera or the like, a light emitting portion to an object and a light receiving portion of reflected light from the object are provided at a base line distance, and the principle of triangulation is used. Some devices measure the distance to an object. In such an apparatus, the infrared light emitted from the light emitting unit to the target is narrowed down so that the distance can be measured as far as possible. For this reason, the distance measurement range in the screen is narrow. For example, when two persons are lined up, if the center of the finder is set between the two persons, the infrared light is emitted between the two persons, and the distance to the background of the person is increased. There is a problem that it is difficult to measure an accurate distance because the distance is measured.

As means for solving such a problem, a proposal by the present applicant (Japanese Patent Application No. 61-67459) has been made.
This means uses a light emitting element array in which a plurality of light emitting elements are arranged along a horizontal direction orthogonal to the base line length as a light emitting unit, and generates an electric signal corresponding to a change in a light receiving position in a direction along the base line length as a light receiving unit. It uses a one-dimensional semiconductor position detecting element (hereinafter referred to as a one-dimensional PSD). The field is scanned horizontally by sequentially turning on the plurality of light emitting elements, and the reflected light from the object is received by the one-dimensional PSD.

This method makes good use of the fact that the one-dimensional PSD has a position detection capability only in the base line length direction and does not detect a position in a direction perpendicular to the base line length. That is, a triangulation can be performed on a subject (object) at the same distance without being influenced by the angle of view (center, right, or left of the screen) of the subject, and a correct distance can be measured. .

(Problems to be Solved by the Invention) However, in the above-described method, there is a problem that an angle (framing) for holding the camera is restricted. That is, in the case of vertically long framing, the object field cannot be scanned horizontally, and a distance measurement error may occur. If two systems of distance measuring devices of this type are provided, the above problem can be solved, but the size of the device is doubled and the whole device becomes large.

An object of the present invention is to provide a distance measurement position in which a distance measurement error is reliably prevented by performing distance measurement in two directions using one distance measurement optical system.

[Configuration of the invention]

(Means for Solving the Problem) The distance measuring device according to the present invention is a
And a light receiving unit 14 for reflected light from the object 15 are provided at a base line distance, and the distance to the object 15 is measured by the principle of triangulation, and the light emitting unit 13 connects a plurality of light emitting elements to each other. X-direction light-emitting element arrays respectively arranged in orthogonal linear directions
13X and a Y direction light emitting element array 13Y, and a light receiving unit 14
Uses a two-dimensional semiconductor position detecting element. This 2
The three-dimensional semiconductor position detecting element is the X direction light emitting element row 13X.
And the Y-direction light-emitting element row 13Y, the light-emitting element rows are arranged with a predetermined base line length in the Y-direction and the X-direction orthogonal to the light-emitting element rows, and correspond to light-receiving positions along the Y-direction and the X-direction. Each produces an electrical output.
Further, the respective light emitting element rows 13X, 13Y are sequentially controlled to be turned on, and when the X direction light emitting element row 13X is turned on, an electric output corresponding to the light receiving position in the Y direction is output.
At the time of lighting 13Y, there is provided an arithmetic and control unit which inputs an electric output corresponding to the light receiving position in the X direction from the two-dimensional semiconductor position detecting element and performs a distance calculation for each of these input values.

(Operation) In the present invention, the object is moved in the X direction and the Y direction orthogonal to each other.
Scanning is performed in each of the two directions, and a distance calculation is performed for each direction, so that the distance to the object is always correctly measured.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
This embodiment is an example used as a distance measuring device for a camera.

1, 2 and 3, reference numeral 11 denotes a light projecting lens,
Reference numeral 12 denotes light receiving lenses, which are arranged near the taking lens 27 with a base line length L therebetween, as shown in FIG. 13 is a light emitting portion, is provided at a position relative to the projection lens 11 held at that focal length f _1. The light emitting section 13 includes an X direction light emitting element array 13 provided along the X direction and the Y direction orthogonal to each other.
It comprises an X and Y direction light emitting element array 13Y. Each of the light emitting element rows 13X and 13Y has a plurality of light emitting elements, for example, infrared light emitting diodes IRx ₁ ... IR along the X direction and the Y direction.
xn or IRy ₁ ……. The light emitting element rows 13X and 13Y are installed such that their orthogonal rows coincide with the horizontal and vertical directions of a camera body (not shown).

The light receiving unit 14 is using a two-dimensional semiconductor position detecting element (hereinafter referred to as two-dimensional PSD), with respect to the light receiving surface thereof is the light-receiving lens 12, provided at a position which is at a focal length f _2. The two-dimensional PSD 14 has a light receiving position detecting function in each of the X direction and the Y direction orthogonal to each other.
As shown in the figure, both ends in each direction have corresponding electrode terminals
X ₁ , X ₂ and Y ₁ , Y ₂ are provided. As shown in FIG. 2, the center thereof has a predetermined base line length Ly in the Y direction perpendicular to the X direction light emitting element row 13X and the X direction perpendicular to the Y direction light emitting element 13Y. It is located while maintaining a predetermined base line length Lx in the direction. Accordingly, the length and angle of the base length L are determined by the lengths of the base lengths Lx and Ly. Here, the lengths of both the base lines Lx and Ly are set to be equal.

Reference numeral 15 denotes an object at the position M (subject). In addition, each ray axis in the drawing represents irradiation light to the subject 15 by the X-direction light emitting element array 13X and reflected light from the subject 15 at each of the positions N, M, and F. Each reflected light is received at each position along the Y direction of the two-dimensional PSD 14 via the light receiving lens 12. In this case, when the light emitted from the infrared light emitting diodes IRx ₁ ... IRxn constituting the X direction light emitting element array 13X is reflected by the planar object 15 at the same position, for example, the position M, FIG. As shown by a solid line, on the two-dimensional PSD 14, an image is formed in a line in the X direction at the same position in the Y direction.
The Y direction electrode terminals Y ₁ and Y ₂ of the two-dimensional PSD 14 have electric outputs (ΔIy in FIGS. 3 and 5) corresponding to changes in the light receiving position in the Y direction.
₁ , ΔIy ₂ ). Note that a change in the light receiving position in the X direction does not occur as a change in the electrical output at the electrode terminals Y ₁ and Y ₂ .

The same applies to the case where the subject 15 is irradiated by the Y-direction light emitting element array 13Y. That is, the Y-direction light emitting element row
The reflected light from the subject 15 due to the 13Y irradiation forms an image in a line in the Y direction at the same position in the X direction on the two-dimensional PSD 14 as shown by the broken line in FIG. 2D PSD14
The X direction electrode terminals X ₁ and X ₂ generate electric outputs (ΔIx ₁ and ΔIx _{2 in} FIG. 5) according to the change in the light receiving position in the X direction.

FIG. 5 shows a control circuit of the above-described triangulation means. In the figure, reference numeral 20 denotes an arithmetic control unit, which includes a CPU 20A, a lighting control circuit 20B, an input switch circuit 20C, and a distance arithmetic circuit 20.
Consists of D. The CPU 20A performs overall control based on a command from the command circuit 24. The lighting control circuit 20B is
According to the selection code from A, either the X direction light emitting element row 13X or the Y direction light emitting element row 13Y is selected. Further, the CPU 20A sequentially controls lighting of the light emitting element array selected by the timing signal given in synchronization with the distance calculation circuit 20D, for example, each of the 13X infrared light emitting diodes IRx ₁ ... IRxn.

The input switch circuit 20C converts the electric signals ΔIRx ₁ , ΔIRx ₂ and ΔIRy ₁ , ΔIRy ₂ generated at the electrode terminals X ₁ , X ₂ and Y ₁ , Y ₂ of the two-dimensional PSD 14 according to the mode selection signal from the CPU 20A. And input them to the distance calculation circuit 20D as inputs ΔI ₁ and ΔI ₂ . For this purpose, it has four analog switches a, b, c, d and an inverter e for ON / OFF control. That is, the input end (shown left) electrode terminals X ₁ analog switches a, after the input terminal of the analog switch d is connected to the electrode terminals Y _2, these output terminals (right side in the figure) is in common connection, the distance Connected to one input terminal of arithmetic circuit 20D. Further, the input terminal electrode terminal X ₂ of the analog switch c, the input terminal of the analog switch b is connected to the electrode terminals Y _1, after the common connection of these output ends, the other input terminal of the distance calculating circuit 20D Connect to The inverter e inputs a mode selection signal of "H" and "L" levels that are mutually inverted from the CPU 24A to the right side in the figure, and outputs an inverted output, that is, "L" for an "H" level input at the left end in the figure. An "L" level output is produced, and an "H" level output is produced for an "L" level input. The gates of the analog switches a and c are connected to the output terminal (the left end in the figure) of the inverter e.
The gates of b and d are connected to the input terminal (right end in the figure) of the inverter e. The analog switches a, b, c, and d are turned on when the corresponding gates are at the “H” level. Therefore, when the CPU 20A outputs a mode selection signal of “H” level, the analog switches b and d are turned on, and ΔI
y ₁ and ΔIy ₂ are input to the distance calculation circuit 20D as ΔI ₂ and ΔI ₁ . Conversely, when an "L" level mode selection signal is output from the CPU 20A, the analog switches a and c are turned on, and ΔIx ₁ and ΔIx ₂ are input to the distance calculation circuit 20D as ΔI ₁ and ΔI ₂ .

Distance calculation circuit 20D above two input values [Delta] I _1, [Delta] I ₂ from 2
The light receiving position of the dimension PSD 14 is detected, the distance to the subject 15 is obtained from the light receiving position and a predetermined base line length Lx or Ly, and the value is given to the CPU 20A as an m-bit digital signal.

The CPU 20A generates the above-described selection code, mode selection signal, timing signal, and the like, and temporarily stores the distance values sequentially given from the distance calculation circuit 20D, and obtains the minimum value, the most frequent value, and the average value by calculation. One of these is given to the lens drive circuit 26. Lens drive circuit 26 is CPU 20A
The lens 27 is operated in accordance with the output value from.

The command circuit 24 instructs the CPU 20A not only to start, but also a distance measurement width corresponding to the angle of view of the lens 27, that is, a light emitting element array.
The instruction information of the emission width of 13X and 13Y and the instruction to output any of the minimum value, the most frequent value, and the average value to the lens drive circuit 26 are issued.

In the above configuration, the start signal from the command circuit 24
When the CPU 20A is started, first, a distance is measured based on the base line length Ly in the vertical direction (Y direction) of the camera. That is, the X-direction light-emitting element array 13X is selected by the selection code, and the analog switches b and d are turned on by the mode selection signal. In this state, each infrared light emitting diode IRx of the X direction light emitting element row 13X
₁ ... Turn on the IRXn sequentially, and scan the field horizontally. At this time, the distance calculation circuit 20D performs the distance calculation each time one of the infrared light emitting diodes IRx ₁ ... IRXn is turned on, and outputs the CPU 20A each time.

Next, distance measurement is performed based on the base line length Lx of the camera in the horizontal direction (X direction). That is, the Y-direction light-emitting element array 13Y is selected by the selection code, and the analog switches a and c are turned on by the mode selection signal. In this state, the infrared light emitting diodes IRy ₁ ... IRYn of the Y direction light emitting element row 13Y are sequentially turned on, and each time the lights are turned on, the distance calculation circuit 20D performs a distance calculation. Then, the obtained distance value is assigned to CPU2 each time.
Output to 0A.

After performing each distance measurement in the Y direction and the X direction in this manner, the CPU 20A obtains a minimum value, a most frequent value, an average value, and the like from each distance value input by the above-described distance measurement operation. Either of these can be used as a lens drive circuit
Output to 26. Therefore, the lens driving circuit 26 drives the lens 27 according to the given distance value.

In the above embodiment, the base lengths Lx and Ly in each direction are equal, but they may be different. That is, two-dimensional PSD1
This is because the position of the incident light of No. 4 is proportional to the base line length. Also,
In the above embodiment, the X direction and the Y direction are aligned with the horizontal direction and the vertical direction of the camera body, and the screen is scanned in a cross shape as shown in FIG. 6, but as shown in FIG. And Y direction with respect to the horizontal and vertical directions of the camera body
May be 45 ° inclined. In this case, scanning is performed in an X-shape on the screen. Either way, camera framing is not subject to any restrictions.

〔The invention's effect〕

As described above, according to the present invention, distance measurement in substantially two directions can be performed by one set of distance detection systems without enlarging the apparatus, and correct distance measurement without a distance measurement error can be performed. it can.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a distance measuring device according to the present invention, FIG. 2 is a front view showing the relationship between a light emitting section and a light receiving section in FIG. 1, and FIG. FIG. 4 is a side view showing a distance measurement state in the Y direction. FIG. 4 is a two-dimensional PS shown in FIG.
FIG. 5 is a control circuit diagram of the apparatus shown in FIG. 1, and FIGS. 6 and 7 are X and Y directions in the present invention. It is a figure showing the example of setting of. 13 ... Light-emitting unit, 13X ... X-direction light-emitting element row, 13Y ... Y-direction light-emitting element row, 14 ... 2-dimensional semiconductor position detecting element, 15 ...
… Target object, 20 …… Operation control device.

Claims (1)

(57) [Claims] An apparatus for measuring a distance to an object based on the principle of triangulation by providing a light-emitting section to the object and a light-receiving section for reflected light from the object at a base length, wherein the light-emitting section is An X-direction light-emitting element row and a Y-direction light-emitting element row in which a plurality of light-emitting elements are respectively arranged in linear directions orthogonal to each other; A two-dimensional semiconductor position detecting element that generates an electric output corresponding to a light receiving position in the orthogonal Y direction and X direction is used.
When the X-direction light-emitting element array is turned on, an electric output corresponding to the light receiving position in the Y direction is output.
A distance measuring device, comprising: an arithmetic control unit for inputting an electrical output corresponding to a light receiving position in each direction from a two-dimensional semiconductor position detecting element and performing a distance calculation for each of these input values.