JPH03188313A - Range finder - Google Patents

Abstract

PURPOSE:To prevent the generation of out-of-focus at a central part by measuring the distance of an adjacent part corresponding to the range finding result of the central part of a visual field only at a necessary time. CONSTITUTION:At first, when the light emitting element IR2 provided in the center of a range finding zone is allowed to emit light, the emitted light is projected on an objected on an object 2 through a projection lens 11 and the reflected light is incident on a unidimensional semiconductor position detection element 14 through a light detection lens 12. The distance up to the object 2 is cleared from the incident position. If this distance is infinite, the adjacent light emitting element IR1 is allowed to emit light and the range finding of the adjacent zone is performed. If this measured distance is not infinite, said distance is set as a measured value and, when the measured distance is infinite, the range finding of the adjacent zone is further performed. This operation is repeated and, when the measured distance is infinite until the last, infinity is set to a measured value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a triangulation type distance measuring device used in an autofocus camera.

(Prior art) A distance measuring device used in an autofocus camera emits infrared light toward a subject, receives reflected light from the subject with a photoelectric conversion element, and measures the distance to the subject using a triangulation method. A distance is used. In this method, infrared light is generally focused to enable distance measurement to be carried out as far as possible. However, since the infrared light is condensed, the distance measurement range within the screen is narrow.For example, if two people are lined up and the center of the viewfinder is placed between them, the infrared light will be The background of the person will be in focus, resulting in incorrect distance measurement. In order to solve this problem, various methods have been proposed for expanding the distance measurement range within the screen.

For example, in US Pat. No. 4,470,681, imaging lenses for an infrared light emitting diode and a light receiving element are connected to each other so as to be horizontally movable. That is, the two lenses for projecting and receiving light form an image at the same point, and these lenses are moved simultaneously, and the object surface is scanned using infrared light. Furthermore, a technique is also disclosed in which each of the imaging lenses for the extra-field light emitting diode and the light receiving element is made into a compound eye (lens array), and the distances are measured at the same number of points as there are lens arrays.

Furthermore, in the device disclosed in Japanese Patent Application Laid-open No. 59-193406, scanning is performed by rotating the light emitting source, but a diffraction grating is placed in front of the light emitting source and the main beam (0th order) is First-order diffraction beams are generated on both sides, and the object plane is scanned by these three beams.

(Problems to be Solved by the Invention) The above-mentioned systems that horizontally move both imaging lenses and systems that rotate the light emitting source enable multi-point distance measurement by scanning the object plane. There is. However, providing such a movable part poses a problem of durability and a decrease in accuracy.

Further, in the method using a lens array, there is a troublesome problem in that the optical axes of the lens arrays of the light emitting section and the light receiving section must be aligned. Furthermore, if a lens array is used, the distance measuring section becomes large, which imposes significant restrictions on the design of the camera.

SUMMARY OF THE INVENTION An object of the present invention is to provide a multi-point distance measuring device that can measure distances over a wide range without using movable parts, lens arrays, or the like.

[Structure of the invention]

(Means for Solving the Problems) The present invention includes a light emitting source that irradiates a subject with infrared light, and a light emitting source that is arranged to maintain a baseline length with respect to the light source to receive reflected light from the subject. A distance measuring device comprising a one-dimensional semiconductor device detection element whose electrical output changes according to a change in the light receiving position along the baseline length direction, and measures the distance to a subject based on the output of the one-dimensional semiconductor device detection element. In this method, triangulation means consisting of the light emitting source and the one-dimensional semiconductor device detection element are arranged above and below the front surface of the camera body, and the light emitting source includes a light emitting element that illuminates the center of the screen, and a triangulation means that includes the light emitting element that illuminates the center of the screen. The light emitting element that illuminates at least two areas adjacent to the screen is equipped with a light emitting element that illuminates at least two areas adjacent to the screen, and the light emitting element that illuminates the center area is first irradiated, and the area adjacent to the center area of the screen is measured in accordance with the distance measurement value obtained from this result. The apparatus is equipped with a control means for determining whether or not to run the distance.

(Function) The present invention emits light using a plurality of light emitting elements and measures the distance to the subject based on the output of the one-dimensional semiconductor device detection element. At this time, first of all, distance measurement is performed at the center of the screen, and when the control means determines that distance measurement is to be performed not only at the center but also at the adjacent area, the distance measurement at the center of the screen is performed. Also measure the distance of the part. Further, when the control means determines that distance measurement is to be performed not only for this adjacent portion but also for an even more adjacent portion, distance measurement for the further adjacent portion is performed.

This also prevents blurring at least near the center of the screen.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows the configuration of the triangulation means. In the figure, 11 is a light projecting lens, 12 is a light receiving lens, and the distance between the light projecting lens 11 and the light receiving lens 12 is arranged with the base line length l maintained. Reference numeral 13 denotes a light emitting source, and this light emitting source 13 faces the projection lens 11 at a distance f1, and includes a plurality of light emitting sources (n ) light emitting elements, such as infrared light emitting diodes IR,,! R2...has IRn. 14 is a one-dimensional semiconductor device detection element (hereinafter referred to as one-dimensional PSD);
This one-dimensional PSDI 4 has a distance f to the light receiving lens 12.
2, and the length direction thereof is arranged along the y-axis direction along the base line length l. 15 represents the subject at position M. In addition, each optical axis line in the figure represents the irradiation light to the subject 15 and the reflected light from the subject 15 at each position N, M, F, and each reflected light passes through the light receiving lens 12 to the one-dimensional PSDI 4. The light is received at each position on the y-axis. In this case, when the light irradiated from the plurality of infrared light emitting diodes IRI, lR2...IRn is reflected by the subject 15 at the same position, for example M, the light emitted from the plurality of infrared light emitting diodes IRI, lR2...IRn will appear on the one-dimensional PSD 14 at the same position on the y-axis. The images are formed in a row in the width direction (X-axis) at the position.

The one-dimensional PSDI4 has an electrical output (Δ■7.Δ
tz) changes. Note that the electrical output does not change with respect to a change in the light receiving point in the width direction (X-axis).

FIG. 2 is a plan view of the triangulation means shown in FIG. 1, seen from above, FIG. 3(a) is a plan view of the triangulation means shown from the side, and FIG. indicates reflected light for each position N, M, and F imaged on the one-dimensional PSDI 4.

FIG. 4 shows a control circuit for the above-mentioned triangulation means, and in this FIG. has been done. Reference numeral 21 denotes a lighting circuit, and this lighting circuit 21 controls the plurality of infrared light emitting diodes IR, according to instructions from the microcomputer 20.

lR2...The corresponding one among lR11 is made to emit light.

23 is a distance calculation circuit, and this distance calculation circuit 23 receives the outputs Δ■1. Enter Δ■2,
The distance to the subject is calculated using a predetermined calculation method. Then, the calculated result is output to the microcomputer 20 as an m-bit digital signal. 24 is a light emission selection means, and this light emission selection means 24 includes switches sw, ,
sw2...SWn, switch s
w, , sw, ......corresponding to the number of SWn,
How many infrared light emitting diodes IR,,lR2 from the center
. . . A selection signal is given to the microcomputer 20 to select whether to cause IRn to emit light. microcomputer 2
0 causes the corresponding infrared light emitting diodes to emit light one by one based on this selection signal. In addition, all switches SW1
．． SW2... When SWn is off, the microcomputer 20 is set so that only the infrared light emitting diode located at the center emits light. Reference numeral 25 denotes a distance calculation instruction switch, which gives a precise calculation instruction to the microcomputer 20 in its on state, and gives a quick calculation instruction to the microcomputer 20 in its off state. That is, the distance calculation circuit 23
, IR2...lRn calculates the distance to the object each time it emits light and outputs it as an m-bit digital signal, but the microcomputer 20 stores these and If a precise calculation command is given by turning on the switch 25, each infrared light emitting diode IR8゜R2...IRn is made to emit light many times and distance measurement is performed multiple times, and the average value is calculated for each. The measured distance value is On the other hand, if the quick calculation command is given due to the off state of the switch 25, each infrared light emitting diode I
R.

lR2...IRn both calculate the distance value with one light emission.

The value thus determined is output to the lens drive circuit 26 as an m-bit digital signal.

The lens drive circuit 26 moves the photographing lens 27 to the in-focus position based on this input data. Reference numeral 28 denotes a start instruction switch, and when turned on, the start instruction switch 28 gives instructions to the microcomputer 20 to execute each of the functions described above.

FIG. 5 shows an autofocus camera in which the above-described triangulation means is incorporated into the camera body 30. In the figure, the light projecting lens 11 is provided at the lower part of the front surface of the camera body 30, and the light receiving lens 12 is provided at the upper part of the front surface of the camera body 30.

That is, although not shown, triangulation means consisting of a light emitting source 13 and a one-dimensional PSD 14 facing the light projecting lens 11 and the light receiving lens 12 are arranged above and below the front surface of the camera body 30.

For this reason, the plurality of infrared light emitting diodes IR, 1R2, .

In the above configuration, the operation will be explained by taking as an example a case where a subject is photographed in which two persons located at a relatively close distance are combined with a distant background, as shown in FIG. 6, for example.

As shown in FIG. 7, first, when the infrared light emitting diode provided at the center of the ranging zone is emitted, the infrared light is irradiated onto the subject 11 through the projection lens 11 shown in FIG. 1, and its reflected light is emitted. passes through the light-receiving lens 12 of FIG. 1, and is imaged at a predetermined position on the one-dimensional PSDIJ corresponding to the distance to this person. And the electrical output ΔII+ corresponding to the imaging position
It produces Δ■2. The distance calculation circuit 23 uses this output ΔII+
Calculate the distance to the subject based on Δ■2, output it to the microcomputer 20 as m-bit data, and measure the distance (step 1). If the measured distance value is infinite, the distance measurement range will gradually increase in the same way. (Steps 28 to 3N)
.

4) Complete distance measurement (step 5). If the measured distance value is infinite until the end, the lens 27 is driven to the infinite position. Of course, if the measured distance value is no longer infinite on the way, it is determined that the distance to the subject has been measured, and the lens is driven based on the measured distance value (step 6).

Even with this configuration, in the case of the subject shown in FIG. 6, the person can be brought into focus, and the background will not be in focus.

〔Effect of the invention〕

As described above, according to the present invention, multi-point distance measurement can be performed without using movable parts or compound lenses, and there is no distance measurement error and excellent durability can be achieved. can. Furthermore, it is possible to quickly measure distances from multiple points, and to avoid blurring the screen at least near the center of the screen.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of a distance measuring device according to the present invention, FIG. 2 is a plan view of FIG. 1, and FIG. 3 is a side view of FIG. 1.
FIG. 4 is a block diagram showing a ranging control circuit used in the present invention, FIG. 5 is an external view of a camera to which the device of the present invention is applied, and FIG.
This figure shows the inside of the finder during distance measurement in the present invention, and FIG. 7 is a flowchart illustrating the operation of another embodiment of the present invention. 13... Light emitting source, 14... One-dimensional semiconductor device detection element,
15...Subject, l, Baseline length, IR,, IR2...
・・・IRn・Light emitting element, 30・・Camera body.

Claims (1)

[Claims] (1) A light emitting source that irradiates the subject with infrared light, and a light emitting source that is arranged to maintain a baseline length with respect to the light source to receive reflected light from the subject, and responds to changes in the light receiving position along the baseline length direction. a one-dimensional semiconductor device detecting element whose electrical output changes depending on the light emitting source and the one-dimensional semiconductor device, the distance measuring device measuring a distance to a subject based on the output of the one-dimensional semiconductor device detecting element; Triangulation means consisting of detection elements are arranged above and below the front surface of the camera body, and the light source includes a light emitting element that illuminates the center of the screen, and a light emitting element that illuminates at least two locations adjacent to the center of the screen. A control means for first irradiating the light emitting element that illuminates the central part, and determining whether or not to perform distance measurement for a part adjacent to the central part of the screen according to a distance measurement value obtained from this result. A distance measuring device characterized by comprising: