JPH08278441A - Distance measuring device for camera - Google Patents

Abstract

PURPOSE: To provide the distance measuring device for camera performing a highly accurate distance measurement and realizing miniaturization of a camera while reducing a distance measuring error in a wider photographing range. CONSTITUTION: This device is provided with a light projecting means projecting distance measuring lights toward an object, that is, light projecting elements 1 (1a, 1b) and light projecting lenses (2a, 2b) and a first light receiving means outputting a first signal corresponding to the incident position of the reflected signal light of the distance measuring light from the object, that is, a first light receiving lens 3a and a first PSD (position detecting element) 4a. Moreover, the device is provided with a second light receiving means arranged at a position different from the first light receiving means and outputting a second signal corresponding to the incident position of the reflected signal light of the distance measuring light from the object, that is, a second light receiving lens 3b and a second PSD 4b and an operation control means 10 controlling the light projecting means and the first and second light receiving means, calculating respectively a first value corresponding the incident position of the reflected signal light based on the first signal and a second value corresponding to the incident position of the reflected signal light based on the second signal and determining the distance of the object based on the first value or the first and second values.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring device for a camera,
More specifically, the present invention relates to a distance measuring device for a camera which is an active automatic focus adjusting device for measuring a distance to a subject when taking a picture.

[0002]

2. Description of the Related Art Conventionally, in a small camera for taking a picture, the distance to an object is measured by electrically measuring the distance, and the focus of a taking lens for taking the object is automatically adjusted. Various devices equipped with such an automatic focusing device (autofocus (AF) device, distance measuring device) have been proposed and put into practical use.

In the AF device (distance measuring device) of the camera, for example, a distance measuring light such as infrared light is projected onto the subject by a light projecting means, and the reflected signal light of the light from the subject is projected. Various so-called active distance measuring devices and the like have been proposed, which are detected by the light receiving means and, based on the detected reflected signal light, perform distance measurement using a triangulation method or the like to the object. It has been put to practical use.

Generally, the active distance measuring device is widely applied to small cameras because it can measure the distance even in darkness.
When the light spot from the light projecting lens of the light projecting means for projecting the distance measuring light is projected only on a part of the subject, it is projected on the light receiving surface of the light receiving means for receiving the reflected signal light. A missing part in the image of the light spot
There is a problem that a so-called "spot defect" may occur, which causes a measurement error.

For example, FIG. 21 is a diagram simply showing a screen frame in the viewfinder of the camera and a subject image in this screen frame. The main subject 105 in this screen frame is shown in FIG.
The light spot projected on a part (portion indicated by A in FIG. 21) of the light is reflected brightly on the part projected on the main subject 105, while it is reflected dark on the background part. When the light is received by the light receiving means, the above-mentioned “spot lack” state occurs.

Therefore, in order to reduce the measurement error due to the "spot defect", in addition to the above-mentioned light receiving means, a second light receiving means is additionally provided and two light receiving means are arranged, so-called three-lens. The active type distance measuring device is disclosed in, for example, Japanese Patent Laid-Open Nos. 55-119006 and 1-217425.

FIG. 18 is a block diagram showing the outline of the distance measuring device of the above-mentioned three-lens active type camera.

As shown in FIG. 18, this distance measuring apparatus includes a light projecting means, that is, a light projecting element 101 formed by an infrared light emitting diode (hereinafter referred to as IRED), and the like.
A light projecting lens 102 for condensing the light from the light projecting element 101 and projecting it on a subject 105, and first and second light receiving means, that is, the light projecting element 101 and the light projecting lens 102.
The first and second light receiving lenses 103a and 103b that collect the reflected signal light of the light projected onto the subject 105 by
And the first and second light receiving lenses 103a and 103b
First and second position detecting elements (hereinafter referred to as PSD) 1 which are respectively provided at the rear of the above and on which the reflected signal light is incident.
04a, 104b and the first and second PSD 104
It is composed of a PSD signal processing circuit 109 which receives and processes the current signals output from a and 104b, an arithmetic control unit 110 formed by a CPU which controls the entire camera, and the like.

Here, the light emitting / receiving lens 10 of the distance measuring device is used.
2, 103a, 103b to the subject 105, that is, subject distance = L, the light projecting means (1
01, 102) and reflected signal lights 106a, 106b reflected by the subject 105 are transmitted through the principal points of the first and second light receiving lenses 103a, 103b, respectively, and are respectively reflected by the first and second PSDs 104a, 104b. 1
It is projected at the positions indicated by X1 and X2 on 04b. Then, a signal corresponding to each incident position is input to the PSD signal processing circuit 109.

Here, the PSD signal processing circuit 109
Is a signal corresponding to each of the incident positions, that is, a first signal that is a signal corresponding to the incident position X1, and an incident position X2.
The distance L to the subject is obtained based on the second signal which is a signal corresponding to

That is, the distance between the light projecting lens 103 and the first light receiving lens 103a = S1, and the distance between the light projecting lens 103 and the second light receiving lens 103b = S.
2, and the first and second light receiving lenses 103a and 103
If the distance S between b is S = (S1 + S2) and the focal lengths of the first and second light receiving lenses 103a and 103b are fj,

[Equation 1] Becomes Further, from the above formula (1),

[Equation 2] Becomes Here, since S = S1 + S2,

(Equation 3) And the subject distance L is

[Equation 4] Becomes

That is, in the three-lens type active distance measuring device, when measuring the distance L to the object 105, the light projecting lens 102 and the first and second light receiving lenses 103a and 103b are used. It can be seen that it does not depend on the distances S1 and S2 between the two.

Therefore, for example, the light projecting means (101,
102) is a light spot projected from the subject 105.
When the reflected signal lights 107a and 107b are projected onto only a part of (X1-Δx), respectively on the first and second PSDs 104a and 104b.
The distance L to the subject 105 when incident on the position shown by (X2 + Δx) is X1, X2 in the above equation (4).
Can be obtained by substituting (X1−Δx) and (X2 + Δx) into In this case, focusing on the denominator of the above equation (4), Therefore, it is understood that the subject distance L can be calculated without being affected by the Δx in the equation (4).

Therefore, in the three-lens active type distance measuring device or the like, it is possible to reduce the measurement error even when the above "spot defect" occurs, and to provide a more accurate distance measuring device. Is something that can be done.

[0015]

SUMMARY OF THE INVENTION However, the means disclosed in JP-A-55-119006, JP-A-1-217425, and the like, that is, the three-lens type active distance measuring device, etc. According to this, there is a problem that the range-finding range fluctuates depending on the arrangement of the light-projecting means on the front side of the camera. There are problems that the internal arrangement is restricted and it is difficult to reduce the size of the device itself.

That is, FIG. 19 is a diagram simply showing the structure of the conventional three-lens type active distance measuring device. As shown in FIG. 19, the light projecting means (101a, 102) is used.
The reflected signal light of the distance measuring light projected from
The range of light that can be received by the second PSDs 104a and 104b is limited to the shaded portion in FIG. In other words, the photometric light projected by the light projecting element 101a through the light projecting lens 102a can measure the distance only when the object distance is equal to or more than LB. Placement
In FIG. 19, when it is moved by ΔX, that is, when projection is performed by the light projecting element 101b through the light projecting lens 102b, it is possible to measure the distance only when the object distance = LC and beyond. Become.

Therefore, the light projecting element (101a, 101b) and the light projecting lens (102) are provided on the front side of the camera.
a, 102b) and the first and second light receiving lenses (10
3a, 103b) and the first and second PSDs (104a, 10)
By changing the arrangement such as 4b), there may be a problem that the distance-measurable position on the short distance side, that is, the shortest shooting distance becomes long.

In FIG. 19, two light projecting means, that is, the light projecting elements 101a and 101b and the light projecting lenses 102a and 102b are shown at the same time. In order to explain the difference in the shortest shooting distance that occurs depending on the position of the means, it is shown for convenience, and only one light projecting means is required in the distance measuring device.

In the case where the shortest shooting distance becomes long by changing the arrangement of the light projecting means, the first and second PSD 104 are provided as a countermeasure.
If the a and 104b themselves are large, the shortest shooting distance can be set short. However, by making the first and second PSDs 104a and 104b themselves large, there is a problem in that, for example, unnecessary signal light is incident and problems such as deterioration of the S / N ratio occur.

On the other hand, the above-mentioned first and second PSDs 104
Since the outputs of a and 104b are current signals, as shown in FIG.
If the signals are output to the SD signal processing circuit 109, the currents i1 and i2 of the output signals of the first and second PSDs 104a and 104b can be obtained. Here, the length of the first and second PSDs 104a and 104b =
If t and total current amount = iφ,

(Equation 5)

(Equation 6) And i1 = i1a + i1b i2 = i2a + i2b,

(Equation 7)

(Equation 8) The relationship is established. Therefore, the above-mentioned first and second PSDs
The PSD signal processing circuit 109 from 104a and 104b.
The current input to

[Equation 9] As described above, when the PSD signal processing circuit 109 performs arithmetic processing,

[Equation 10] In this form, (X1 + X2) shown in the above equation (3) is calculated and output.

Therefore, in the conventional trinocular active type distance measuring device, as shown in FIG.
The second PSDs 104a and 104b and the PSD signal processing circuit 109 are electrically connected to each other, and
The current signals output from the second PSDs 104a and 104b are output to the PSD signal processing circuit 109.

The expressions (1) to (10) applied in the above description are expressed by the two light receiving means, that is, the first light receiving means.
The second light receiving lenses 103a and 103b, and the first and second PSDs 104a and 104b are established only when exactly the same ones are applied, and for example, the first PSD 104a and the second PSD are used.
If the lengths t of the D104b are different from each other, the above equation (7) is not established.

The first light receiving lens 103a and the second light receiving lens 103a
When the light receiving lens 103b has different apertures, F numbers, etc., the first and second PSDs 10
Since the value of the total current amount iφ output by each of 4a and 104b changes, the above equations (7) and (8) do not hold.

Further, the first and second PSDs 104 described above.
Since the respective current signals of a and 104b are to be processed by different circuits, respectively, two PSD signal processing circuits 109 are required, which causes a problem of an increase in manufacturing cost. is there.

On the other hand, when designing the camera for miniaturization, the projection lens 102 and the first and second light receiving lenses 103a and 103b in FIG.
There is also a problem that a device for arranging them in the same line on the front side of the camera is required.

For example, FIG. 20 is a diagram showing the outline of the front side of the camera when the above-mentioned three-lens active type distance measuring device is applied to the camera.

As shown in FIG. 20, on the front side of the camera body 121, the finder system 122 and the taking lens 11 are provided.
When the light projecting lens 102 and the first and second light receiving lenses 103a and 103b are arranged in the vicinity of 2 on the same line, the dimension in the height direction of the camera is required to some extent for the arrangement of the distance measuring device. Therefore, the miniaturization design of the camera itself is regulated.

An object of the present invention is to solve the above-mentioned problems of the prior art and, in a three-lens type active distance measuring device, reduce a distance measuring error in a wider photographing range from a short distance to a long distance to a subject. It is an object of the present invention to provide a distance measuring device for a camera, which can reduce the number of distances with higher accuracy and can easily realize miniaturization.

[0029]

SUMMARY OF THE INVENTION A camera distance measuring device according to the present invention includes a light projecting means for projecting distance measuring light toward a subject and incidence of reflected signal light of the distance measuring light from the subject. A first light receiving unit that outputs a first signal according to the position, and a second light receiving unit that is arranged at a position different from the first light receiving unit and that corresponds to the incident position of the reflected signal light of the distance measuring light from the subject.
A second light receiving unit that outputs a signal, the light projecting unit, and the first and second light receiving units are controlled, and a first value corresponding to the incident position of the reflected signal light is obtained based on the first signal. , A second value corresponding to the incident position of the reflected signal light can be calculated based on the second signal, and the first value can be calculated.
And a calculation control means for determining the subject distance based on the first value or the first and second values, the calculation control means compares the first value with a predetermined value, According to this comparison result, the subject distance is determined based on the first value or the subject distance is determined based on the first and second values.

Further, a light projecting means for projecting the distance measuring light to the object, a pair of light receiving means for receiving the reflected signal light of the distance measuring light from the object, and output results of the pair of light receiving means. Changeover switch means for time-divisional switching, a detection circuit for time-divisionally detecting the incident position of each of the pair of light-receiving means of the distance measuring light, and projection control of the distance measuring light to control the switching. And a calculation control means for calculating the distance to the subject in accordance with the output result of the detection circuit.

[0031]

The light projecting means projects the distance measuring light toward the subject, and the first light receiving means outputs the first signal corresponding to the incident position of the reflected signal light of the distance measuring light from the subject. At the same time, the second light receiving means arranged at a position different from the first light receiving means outputs a second signal according to the incident position of the reflected signal light of the distance measuring light from the subject.

The arithmetic control means controls the light projecting means and the first and second light receiving means,
A first value corresponding to the incident position of the reflected signal light is calculated based on the first signal, and a second value corresponding to the incident position of the reflected signal light is calculated based on the second signal. The subject distance is determined based on the first value or the first and second values.

Further, the arithmetic control means compares the first value with a predetermined value and determines the object distance based on the first value according to the comparison result, or the first and the first distances are determined. Whether to determine the subject distance is selected based on the value of 2.

Further, the light projecting means projects the distance measuring light toward the subject, and the pair of light receiving means receives the reflected signal light of the distance measuring light from the subject. At this time,
The output results of the pair of light receiving means are switched in a time division manner by the changeover switch means, and the respective incident positions of the pair of light receiving means of the distance measuring light are detected in a time division manner by the detection circuit.

The calculation control means controls the projection of the distance measuring light, performs the switching control, and calculates the distance to the subject according to the output result of the detection circuit.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. FIG. 1 is a block diagram showing the basic arrangement of a distance measuring device for a camera according to the first embodiment of the present invention. As shown in FIG. 1, the distance measuring apparatus for a camera according to the first embodiment uses one light projecting unit for projecting distance measuring light toward a subject, that is, an infrared light emitting diode (IRED) or the like. A light projecting element 1b to be formed, and a light projecting lens 2b for condensing and projecting light from the light projecting element 1b on a subject,
The first and second light receiving elements are the first and second light receiving means, that is,
First and second light receiving lenses 3a and 3b for condensing reflected signal light of the distance measuring light projected on the subject by the light projecting element 1b and the light projecting lens 2b, and the first and second light receiving lenses. First and second position detecting elements (PS) formed respectively by semiconductor one-dimensional position detecting elements or the like, which are provided behind 3a and 3b, and on which the reflected signal light is incident, are formed.
D) PS which is an analog calculation means for inputting and processing the current signals of the first and second PSDs 4a and 4b.
It is composed of a D signal processing circuit 9, an arithmetic control unit (CPU) 10 formed by a CPU for controlling the entire camera, and the like.

The first and second position detecting elements (PS
D) 4a and 4b are not limited to the semiconductor one-dimensional position detecting element as long as they output a signal according to the position of incident light.

Further, in FIG. 1, the light projecting element 1a, which is the light projecting means, and the light projecting lens 2b are arranged so that the light projecting element 1b and the light projecting lens 2b are arranged at positions away from the light projecting lens 2a by ΔX. Although the light projecting means is also shown in the figure, this is the light projecting element 101 described in FIG.
Similar to the relationship between a and 101b, the light projecting elements 1a and 1b are shown at the same time for comparison. Therefore, in the configuration of the distance measuring device for the camera of the first embodiment, it is sufficient that each of the light projecting element and the light projecting lens, which are the light projecting means, be provided.

The first light receiving lens 3a and the first light receiving lens 3a
The first light receiving means formed by the PSD 4a outputs a first signal corresponding to the incident position of the reflected signal light of the distance measuring light from the subject, and the second light receiving lens 3b and the second light receiving lens 3P.
The second light receiving means formed by SD4b is the first light receiving means.
It is arranged at a position different from the light receiving means and outputs a second signal corresponding to the incident position of the reflected signal light of the distance measuring light from the subject.

The focal lengths f of the first and second light receiving lenses 3a and 3b constituting the first and second light receiving means, respectively.
About j, the substantially same thing shall be applied.

Further, in the PSD signal processing circuit 9,
Changeover switch means 18 is provided for switching the first and second signals output from the first and second PSDs 4a and 4b in a time division manner.

In the distance measuring device of the camera of the first embodiment having the above-described structure, the distance measuring light is projected from the light projecting element 1b through the light projecting lens 2b toward the subject. The reflected signal light of the distance measuring light from the subject is received by the first and second PSDs 4a and 4b through the first and second light receiving lenses 3a and 3b and converted into electric signals. And output to the PSD signal processing circuit 9.

Here, the first PSD 4a outputs a first signal corresponding to the incident position of the reflected signal light of the distance measuring light from the subject to the PSD signal processing circuit 9, and also the second PSD 4b. Outputs a second signal corresponding to the incident position of the reflected signal light of the distance measuring light from the subject to the PSD signal processing circuit 9.

Further, the changeover switch means 18 in the PSD signal processing circuit 9 has the first and second PSDs 4a and 4b.
Respective outputs from the first signal and the second signal
The signal is processed by time division.

That is, the arithmetic control means 10 controls the light projecting element 1b to emit light in a time-division manner so as to project the distance measuring light toward the object, and the first and second PSDs.
4a and 4b are controlled, and a first value corresponding to the incident position of the reflected signal light based on the first signal and a first value corresponding to the incident position of the reflected signal light based on the second signal. The value of 2 is calculated independently of each other. As a result, the subject distance is determined based on the first value or the first and second values.

On the other hand, the arithmetic control means 10 outputs the reflected signal light of the distance measuring light projected from the light projecting means (1a, 1b and 2a, 2b) to the object on the short distance side. The light is received only by the first PSD 4a, and the second PSD 4b is not used, and the subject distance is measured by using the triangulation method described in the above formula (1).

That is, in the case of measuring the distance to a subject on the short distance side, the distance measuring light projected from the light projecting means (1b, 2b) can be received only by the first PSD 4a. Subject position at, that is,
The shortest shooting distance, which is the position where the distance can be measured on the short-distance side, is
As shown in, the distance is indicated by the subject distance La.

That is, the distance can be measured at the object distance La which is closer to the distance than the object distance LB where the distance can be measured on the light emitting element 1a.

Therefore, in the distance measuring apparatus for the camera of the first embodiment, the object distance La which is the shortest photographing distance that can be measured only by the light projecting element 1b and the first PSD 4a.
From the light emitting element 1b and the first and second PSDs 4a and 4b.
In the range up to the object distance Lc which is the object position on the shortest distance side where the distance can be measured by
b, the distance measurement is performed only by the first PSD 4a, and the distance measurement is not performed by the so-called three-lens active system in which the first and second PSDs 4a, 4b are used together. Will not be corrected. However, since the spread of the light spot of the distance measuring light projected by the light projecting means (1b, 2b) is small with respect to the object on the short distance side, there is a possibility that "spot defect" will occur. Considered to be few.

That is, as shown in FIG.
The distance measuring light projected from b is emitted through the light projecting lens 2b. At this time, the light projecting element 1
Assuming that the emission diameter of b is φLED, the light spot diameter φSPOT can be obtained from the following equation (11) from the relationship between the focal length ft of the light projecting lens 2b and the distance L to the illuminated subject. .

[0051]

[Equation 11] Therefore, as the distance L to the subject increases, that is,
The farther the subject is, the larger the light spot diameter φSPOT of the distance measuring light projected from the light projecting element 1b becomes, and the “spot defect” is likely to occur, while the short distance side causes the above light spot. Since the diameter φSPOT is small, it is considered that there is little possibility of “spot defect”.

For example, the light emission diameter φLE of the light projecting element 1b.
D = 0.4 mm, focal length ft of the projection lens 2b =
In the case of 10 mm, φSPOT = 4 cm when the distance L = 1 m, and φSPOT = 20 cm when the distance L = 5 m.

That is, in the three-lens active type distance measuring device, the "spot defect" becomes important when the subject is at a long distance, so that the subject is at a short distance. In some cases, as described above, even if the distance measurement is performed only by the light projecting element 1b and the first PSD 4a, the practical problem is small.

As described above, according to the first embodiment, by providing the changeover switch means 18 for switching the output results of the first and second PSDs 4a and 4b by time division, the first and second PSDs 4a are provided. , 4b, the first signal and the second signal, which are the respective outputs, are processed by time division, and the first and second values are independently calculated based on the first and second signals, respectively. Therefore, the first and second light receiving lenses 3
It is possible to apply a and 3b having different sizes and shapes. As a result, it is possible to obtain the degree of freedom in arranging the distance measuring device in the camera.

Further, for a subject at a short distance,
The reflected signal light of the distance measuring light projected from the light projecting element 1b is not used by the second PSD 4b, but the first PSD is not used.
Since the light is received only by 4a and the distance measuring operation is performed, it is possible to improve the degree of freedom in the arrangement of the light projecting means.

When the object is at a long distance, the reflected signal light of the distance measuring light projected from the light projecting means (1b, 2b) is used as the first and second PSDs 4a, 4b.
Since the so-called three-lens active method is adopted in which the light is received by, it is possible to perform distance measurement with higher accuracy.

FIG. 3 is a block diagram showing the schematic arrangement of a distance measuring device for a camera according to the second embodiment of the present invention. In addition,
Since the second embodiment basically has the same configuration as that of the first embodiment described above, the same components are designated by the same reference numerals and detailed description thereof will be omitted.

As shown in FIG. 3, the distance measuring device of this camera includes a light projecting element 1 and a light projecting lens 2 which are light projecting means for projecting distance measuring light toward the object 5, and the object 5 described above. The first and second light receiving lenses 3a and 3b and the first and second PSDs 4a and 4b, which are a pair of light receiving means for receiving the reflected signal light of the distance measuring light, are provided. The 2PSDs 4a and 4b are supplied with two output signals, that is, the currents i1 and i2 of the first and second signals, respectively.

(Equation 12) A PSD signal processing circuit 9 for processing in the form of is electrically connected.

In the first embodiment described above, the light projecting element 1b includes the first PSD 4a and the second PSD.
It was placed so as to be located between 4b and
In the embodiment, the light projecting element 1 includes the first and second light emitting elements.
The PSDs 4a and 4b are arranged at different positions.

On the other hand, in the PSD signal processing circuit 9,
Preamplifier 1 for amplifying the output signal currents i1 and i2 of the first and second PSDs 4a and 4b, respectively.
4, 15, 16, and 17 are provided, and the outputs from the preamplifiers 14, 15, 16, and 17 are switched by the changeover switch means 18 and 19 in a time division manner and output to the arithmetic circuit 20. ing. This arithmetic circuit 2
Reference numeral 0 denotes a detection circuit that detects the respective incident positions of the first and second PSDs 4a and 4b of the distance measuring light in a time division manner by performing the calculation shown in the equation (12).

In the PSD signal processing circuit 9,
A signal other than the reflected signal light, which is a desired signal for distance measurement, such as a filter circuit for removing a background light component, etc., is provided from the signals output from the first and second PSDs 4a, 4b. However, since it is a member not directly related to the present invention, its illustration is omitted.

The operation control means 10 formed by a CPU such as a one-chip microcomputer for controlling the entire camera is connected to the driver 8 for causing the light projecting element 1 to emit light, and the changeover switch means 18 is provided. , 19
And the arithmetic circuit 20 is electrically connected. As a result, the arithmetic control means 10 controls the driver 8 to cause the light projecting element 1 to emit light, control the switching of the changeover switch means 18 and 19, and the arithmetic circuit 20.
The distance to the subject 5 is calculated according to the output result of.

Further, the calculation control means 10 determines the focusing means 11 based on the calculated distance to the subject 5.
The photographic optical system 12 is controlled by.
Here, when the photographing optical system 12 has, for example, a zoom optical system in which the photographing magnification can be changed, the information such as the focal length at the time of photographing can be obtained by the zoom information input unit 13 which is the focal length detecting unit. The arithmetic control means 10, which is also a determining means, determines whether the changeover switch means 18 or 19 is switched in accordance with the value of the focal length information or the like input to the arithmetic control means 10. , Determining the subject distance using the output of either or both of the pair of light receiving means,
With this, each control of the focusing operation and the exposure operation is performed.

By the way, the distance measuring light emitted by the light projecting element 1 is projected toward the subject by the light projecting lens 2, but the reflected signal light of the distance measuring light is converted into The range in which both the first and second PSDs 4a and 4b can receive light is the range indicated by the diagonal lines in FIG.

Therefore, for a subject within this range, the distance measurement using the triangulation method by the pair of light receiving means of the first and second PSDs 4a and 4b is performed. In this case, the distance measurement is performed. First and second light receiving lens 3
The distance S between a and 3b will be the baseline length.

On the other hand, for a subject on the short distance side other than the hatched portion in FIG. 3, distance measurement using the triangulation method by the light projecting element 1 and the first PSD 4a is performed. That is, the distance measurement is performed without using the second PSD 4b. In this case, the distance ST between the light projecting lens 2 and the first light receiving lens 4a is the baseline length.

FIG. 4 is a flow chart showing the distance measuring operation of the distance measuring device of the camera of the second embodiment. Also, FIG.
In order to explain the distance measuring operation in the above distance measuring device,
FIG. 3 is an enlarged view of a main part showing the members related to distance measurement such as the light projecting unit and the pair of light receiving units.

First, in FIG. 5, when the object 5a on the short distance side is measured, step S1 in FIG.
In the above, the arithmetic control means 10 causes the light projecting element (I
The RED) 1 is caused to emit light, and the light projecting lens 2 projects the distance measuring light toward the subject. At the same time, the arithmetic control means 10 switches the changeover switch means 18 and 19, and the reflected signal light of the distance measuring light is received by the first PSD 4a.

Then, in the arithmetic circuit 20, the light receiving position of the reflected signal light, that is, the position X1a of the incident light on the first PSD 4a (the shift amount from the optical axis of the first light receiving lens 3a in FIG. 5). The value of 1) is detected and output to the arithmetic control means 10, and the process proceeds to the next step S2.

In step S2, the focal length fL of the photographing optical system 12 is compared with a predetermined value f0. Here, in the case where the photographing optical system 12 is a wide-angle system, the first PSD is taken into consideration in consideration of the fact that the depth of focus is deep and there are many opportunities to photograph a subject at a short distance side.
Distance measurement is performed based on the first value X1a on 4a.

That is, when it is determined in step S2 that the taking optical system 12 is not the wide-angle system (fL>
In the case of f0), when it is determined that the photographing optical system 12 is a wide-angle system while the process proceeds to the next step S3 (fL).
For ≦ f0), the process proceeds to step S7, and as described above, the distance measurement (calculation of the distance La to the subject) is performed based on the first value X1a on the first PSD 4a.

Next, in step S3, the first value X1a is the distance L to the closest object which can be received by both the first and second PSDs 4a and 4b.
b, that is, a predetermined value X0 of the position of the incident light on the first PSD 4a of the reflected signal light from the subject at the shortest shooting distance
(See FIG. 1) When (X1a ≦ X0) or less, the first and second light receiving lenses 3a and 3b, which are the pair of light receiving means, are provided.
Then, assuming that the distance measurement is performed by the first and second PSDs 4a and 4b, the process proceeds to the next step S4.

On the other hand, in step S3, when the first value X1a is larger than the predetermined value X0 (X
1a> X0), the reflected signal light from the subject 5a does not enter the second PSD 4b (arrow A (X2a) indicated by a dotted line in FIG. 5), and the first and second PSD4.
Assuming that the subject 5a is closer to the short distance side than the shortest shooting distance Lb at which both a and 4b can receive light, step S
In step S7, the first
Distance measurement is performed based on the value X1a of
Will be decided.

That is, in step S7, distance measurement is performed with the distance ST between the light projecting lens 2 and the first light receiving lens 3a as the base line length. At this time, as shown in FIG. 5, the focal length ft of the light projecting lens 2, the deviation amount Xt of the light projecting element 1 from the optical axis of the light projecting lens 2 and the first light receiving lens 3a. The focal length fj and the position of the incident light on the first PSD 4a of the reflected signal light, that is, the first value X1a, can be obtained by the following equation (13).

[0075]

(Equation 13) In this equation (13), since the only variable is the amount of deviation X1a from the optical axis of the first light receiving lens 3a,
By detecting the position on the first PSD 4a, the distance La to the subject 5a can be obtained.

Next, referring to FIG. 5, the object 5 on the far side is shown.
In the case of measuring the distance b, the above-mentioned steps S1 to S3 are similarly performed, but here, the reflected signal light of the distance measuring light projected from the light projecting element 1 in the above step S1. Is received by the first PSD 4a and the position X of the incident light on the first PSD 4a.
The point 1b (the amount of deviation from the optical axis of the first light receiving lens 3a in FIG. 5; the first value) is detected by the arithmetic circuit 20 and output to the arithmetic control means 10. The other points are the same as in the case of measuring the distance to the short-distance side subject 5a described above.

Then, in step S3, the relation between the first value and the predetermined value X0 is X1a≤X0. Therefore, as described above, the process proceeds to the next step S4, and in this step S4. , The arithmetic control means 10
Causes the light projecting element (IRED) 1 to emit light again, and projects the distance measuring light toward the subject by the light projecting lens 2. At the same time, the arithmetic control means 10 switches the changeover switch means 18 and 19 to change the second changeover means.
The PSD 4b receives the reflected signal light of the distance measuring light.

Then, in the arithmetic circuit 20, the light receiving position of the reflected signal light, that is, the position X2b of the incident light on the second PSD 4b (deviation amount from the optical axis of the second light receiving lens 3b. Second value). .) Is detected and output to the arithmetic control means 10 to proceed to the next step S5.

In step S5, the above-mentioned step S
Based on the first value X1b calculated in step 1 and the second value X2b calculated in step S4, the distance Lb to the subject 5b can be calculated by the equation (3). it can.

As shown in FIG. 5, the arrangement of each member on the front side of the camera of the light projecting element 1 and the first and second PSDs 4a and 4b is the same as the arrangement of the same members in the first embodiment. That is, the light projecting element 1 is the first PS
The first value X1b becomes smaller as the subject distance becomes longer than in the case of being arranged between the D4a and the second PSD 4b. Therefore, when performing the calculation by the equation (3), The sign of the value X1b is inverted and substituted to perform the operation.

Then, based on the distance La to the subject 5a (near side) calculated in step S7, or the distance Lb to the subject 5b calculated in step S5 (far side), the above calculation is performed. Control means 10
Controls the focusing means 11 to control the photographing optical system 1 of the camera.
2 is driven, the focusing operation is performed, and the series of processing is ended.

As described above, according to the second embodiment, the positional relationship is such that the light projecting means is arranged between the pair of light receiving means (see the first embodiment described above. However, the degree of freedom in the arrangement of each member on the front side of the camera can be ensured.

Further, the arithmetic control means 10 compares the first value X1 (a, b) with a predetermined value X0, and according to the comparison result, the object distance is calculated based on the first value. Whether to determine or to determine the subject distance based on the first value and the second value is selected, and for the subject 5a at the short distance, based on the first value X1a. Then, the subject distance La is determined and the first value X1b is set for the subject 5b at the long distance.
And the subject distance Lb is determined based on the second value X2b, the subject 5 at a long distance is detected.
The "spot defect" that occurs during distance measurement of b can be corrected to perform more accurate distance measurement, and the first and second PSDs 4a and 4b can be made closer without increasing the size. It is possible to perform highly accurate distance measurement for a certain subject 5a.

Next, a distance measuring device for a camera according to the third embodiment of the present invention will be described below.

FIG. 6 is a front view of a camera to which the distance measuring apparatus according to the third embodiment is applied, and simply shows the arrangement of members and the like relating to the distance measuring apparatus on the front side thereof.

As shown in FIG. 6, a photographic optical system 12 is provided at a substantially central portion on the front side of the camera body 21, and a finder section is provided above the photographic optical system 12. A finder objective lens 22 is arranged on the front side of the camera body 21.

Further, the light projecting lens 2 and the first and second light receiving lenses 3a and 3b are arranged around the photographing optical system 12 so as to surround it. The light projecting lens 2 is arranged near the finder section.

FIG. 7 is a diagram simply showing the positional relationship between the light projecting lens 2 and the first and second light receiving lenses 3a and 3b on the front side of the camera of the third embodiment shown in FIG. 8 is a view showing a state in which the first and second light receiving lenses 3a and 3b shown in FIG. 7 are removed,
The light projecting lens 2 and the first and second light receiving lenses 3
The first and second PSDs 4 arranged behind a and 3b
The positional relationship with a and 4b is simply shown.

As shown in FIGS. 7 and 8, the distance between the first and second light receiving lenses 3a and 3b = S, the distance between the light projecting lens 2 and the first light receiving lens 3a = STa.
(First Baseline Length), the distance between the light projecting lens 2 and the second light receiving lens 3b = STb (second baseline length), and FIG.
As shown in, the angle between the line connecting the first and second PSDs 4a and 4b and the line connecting the light projecting lens 2 and the second PSD 4b is θ, and the first and second PSDs 4a and 4b.
Width dimension of wa, wb, respectively, the first, second
The dimensions of the PSDs 4a and 4b in the longitudinal direction are ta and t, respectively.
b.

Further, in the distance measuring device for the camera of the third embodiment, the first PSD 4a is "spot missing".
The first PSD 4a is used only for a subject at a long distance.

By the way, the light projecting means (light projecting element 1 and light projecting lens 2) and the pair of light receiving means (first and second light receiving lenses 3a and 3b and first and second PSDs 4a and 4b) are provided on the front side of the camera. In order to obtain a more accurate distance measurement result by correcting the measurement error due to "spot defect" or the like that occurs when the distance measurement is performed, it is necessary to use both the first and second light receiving lenses 3a and 3b. It is necessary to arrange the first and second PSDs 4a and 4b in the line direction connecting the lenses (hereinafter, referred to as the first condition).

In order to perform distance measurement using the triangulation method using the light projecting means and one of the pair of light receiving means, the light projecting means and the distance measuring method are used. It is necessary that the first and second PSDs 4a and 4b are arranged so that the detection directions of the first and second PSDs 4a and 4b coincide with each other in the line direction connecting either one of the light receiving means (hereinafter referred to as the second condition).

Therefore, the first P which is one of the above-mentioned light receiving means.
The SD4a can satisfy both the first and second conditions by being a position detection element (PSD) having a two-dimensional detection direction, and the second PSD 4b can be
A position detecting element (PS having a general one-dimensional detection direction)
By setting D), it becomes possible to satisfy both the first and second conditions.

Therefore, as shown in FIG. 8, the light spot of the reflected signal light emitted from the light projecting lens 2 and reflected by the subject changes when the distance to the subject changes from the short distance side to the long distance side. In the above, the first PSD 4a
In the direction of the arrow Yt shown in FIG.
On D4b, it moves in the arrow Xt direction shown in FIG.

That is, the light spot of the reflected signal light incident on the second PSD 4b is the second PS shown in FIG.
In the enlarged view of the main part of D4b, the first and second PSD4
It moves in the direction of the angle θ (Xt direction) with respect to the line connecting the lines a and 4b. Therefore, the second PSD4
On b, as described above, the movement of the light spot in the Xt direction is detected and distance measurement is performed, but here,
As shown in FIG. 9, it is assumed that the subject distance is measured (ranging) by detecting the incident position X1 of the light spot.

For example, the above-mentioned first and second PSDs 4a, 4b
The angle between the line connecting the light projecting lens 2 and the line connecting the light projecting lens 2 and the second PSD 4b is 22 ° (degrees), and the distance STa between the light projecting lens 2 and the first light receiving lens 3a is 20 m.
m, the distance STb between the light projecting lens 2 and the second light receiving lens 3b is 50 mm, and the focal length fj of the second light receiving lens 3b is fj = 15 mm, the distance Lmin to the subject is Lmin = 50 cm (near side). To Lmax = ∞
Considering the case of measuring the distance to the (far distance side),

[Equation 14] The first value X1 corresponding to the incident position of the light spot on the second PSD 4b is given by the amount Xt = 1.5 mm that the light spot moves on the second PSD 4b.

(Equation 15) X1 = 1.39 mm. As a result, the dimension tb in the longitudinal direction of the second PSD 4b may be set to about tb = about 2 mm even if a margin is taken into consideration.

Further, the movement amount Yt of the light spot in the direction orthogonal to the longitudinal direction of the second PSD 4b, that is, in the width direction on the second PSD 4b, is the same as in the above equation (14).

[Equation 16] Can be obtained by the following, and the movement amount of the light spot Yt =
Since it is about 0.6 mm, the dimension wb in the width direction of the second PSD 4b is wb = about 1.2 even if a margin is taken into consideration.
It should be about mm.

The smaller the light receiving area of the first and second PSDs 4a and 4b, the less likely it is to be affected by light other than the reflected signal light. The smaller the first and second PSDs 4a and 4b, the more accurate the distance measurement accuracy. The shape of the second PSD 4b and the like will be described with reference to FIG.
It is also possible to change the shape to the second PSD 4ab shown in FIG. However, in this case, the second
It is necessary to detect the light spot movement amount Xt on the PSD 4b.

In addition, on the first PSD 4a,
Since the light spot of the reflected signal light moves in the width direction (the arrow Yt direction in FIG. 8) and does not change in the longitudinal direction, the dimension ta in the longitudinal direction may be about 0.5 mm.

Regarding the dimension wa of the first PSD 4a in the width direction, the first PSD 4a is used only when measuring an object at a long distance, and the moving amount of the light spot of the reflected signal light is used. However, it is not necessary to make it as large as the width dimension wb of the second PSD 4b.
Therefore, it is sufficient to set the width dimension wa = 1 mm or less.

The operation of the distance measuring device for a camera of the third embodiment thus constructed will be described below. FIG.
FIG. 1 is a flow chart showing a distance measuring operation of the distance measuring device of the camera of the third embodiment.

First, as shown in FIG. 11, step S1
At 0, the distance measuring light is projected by the light projecting means. That is, the light projecting element (IRED) 1 emits light,
The distance measuring light projected from the light projecting lens 2 is reflected on the subject, and the reflected signal light is incident on the second PSD 4b. Then, the incident position X1 (first value) of the light spot on the second PSD 4b at this time is detected.

In step S11, the arithmetic control means 10 compares the first value X1 corresponding to the incident position of the light spot with the predetermined value X0, and the next processing is performed according to the comparison result. different.

That is, if the first value X1 <the predetermined value X0, it is determined that the subject is at a relatively long distance,
While proceeding to the processing of the next step S12, the first value X
If 1 <predetermined value X0 is not satisfied, it is determined that the subject is closer than the predetermined position, and based on the first value X1, the light spot movement on the second PSD 4b is performed by the above equation (15). The quantity Xt is calculated, and the next step S1
Proceed to the process of 6.

Then, in step S16, the calculation control means 10 calculates the light spot movement amount Xt calculated in step S15 and the distance STb (predetermined) between the light projecting lens 2 and the second light receiving lens 3b. Value) and the focal length fj (default value) of the second light receiving lens 3b, the distance Lmin to the subject is calculated from the above equation (14), and the process proceeds to the next step S14.

On the other hand, in step S11, it is determined that the light spot position X1 <the predetermined value X0,
When the process proceeds to step S12, in step S12, the light projecting element (IRED) 1 emits light again,
The reflected signal light is incident on the first PSD 4a. Then, the incident position X2 (second value) of the light spot on the first PSD 4a at this time is detected, and the process proceeds to the next step S13.

In step S13, based on the first and second values X1 and X2 corresponding to the incident position of the light spot detected in steps S10 and S12 described above,
The distance Lmin to the subject is calculated by the above equation (14), and the process proceeds to the next step S14.

In step S14, the subject distance Lmin calculated in steps S13 and S16 described above.
Based on the above, the arithmetic control means 10 controls the focusing means to drive the photographing optical system to perform the focusing operation, and the series of operations is ended.

As described above, according to the third embodiment, with respect to the member related to the distance measuring device arranged on the front side of the camera, the light projecting lens 2 and the first and the first lenses are provided around the photographing optical system 12. By arranging the two light-receiving lenses 3a and 3b, the camera can be downsized.

By disposing the light projecting lens 2 in the vicinity of the finder section, the photographing optical system 1
It is possible to correct parallax, that is, parallax, generated between the lens 2 and the viewfinder optical system. Therefore, a more accurate screen configuration (framing) can be performed when a subject at a short distance is photographed.

Further, when detecting the movement of the light spot of the reflected signal light incident on the second PSD 4b, the incident position X1 of the light spot on the second PSD 4b is detected.
Since the distance measurement is performed by detecting the distance, it is possible to further reduce the light receiving area of the first and second PSDs 4a and 4b. Therefore, the influence of light other than the reflected signal light is less likely to occur, and more accurate distance measurement can be performed.

FIG. 12 is a block diagram showing the schematic arrangement of a distance measuring device for a camera according to the fourth embodiment of the present invention. The arrangement of the light emitting / receiving means and the like in the fourth embodiment is basically the same as that in the third embodiment.

That is, as shown in FIG. 12, the distance measuring device of the camera of the fourth embodiment is a light projecting means for projecting the distance measuring light toward the object, that is, the light projecting element 1 and the light projecting lens. Two
And a pair of light receiving means for receiving the reflected signal light of the distance measuring light from the subject, that is, the first and second position detecting elements (PS
D) 4a, 4b and first and second light receiving lenses 3a, 3b
And the above-mentioned first and second PSDs 4a, 4b.
Is electrically connected to the PSD signal processing circuit 9 to which the first and second signals, which are the two output signals output thereby, are input.

Further, the PSD signal processing circuit 9 is connected to an arithmetic control means 10 formed by a CPU such as a one-chip microcomputer for controlling the entire camera, and the arithmetic control means 10 is connected to the light projecting element. A driver 8 for making 1 emit light is connected.

The first baseline length direction connecting the light projecting lens 2 and the first light receiving lens 3a and the second baseline length direction connecting the light projecting lens 2 and the second light receiving lens 3b are It is arranged so as to be substantially orthogonal.

Further, the first and second PSDs 4a, 4b
Has a detection direction in the same direction as the second baseline length direction connecting the light projecting lens 2 and the second light receiving lens 3b,
The lengths of the first and second PSDs 4a and 4b in the detection direction are set to be substantially equal to each other.

Further, on the first PSD 4a, for example, aluminum or the like is attached at a shaded portion in FIG. 12 so that unnecessary constant light is prevented from entering.

In the distance measuring device for a camera according to the fourth embodiment having the above-described structure, the distance measurement using the triangulation method is performed. Here, in order to measure the object distance, The distance-measuring light projected by the light-projecting means including the light-projecting element 1 and the light-projecting lens 2 is reflected on the subject, and the reflected signal light is incident on the second PSD 4b, and the position of the light spot is detected. The output signal (the second signal; the output signal of the light spot moving on the second PSD 4b depending on the subject distance) is the PS signal.
It is input to the D signal processing circuit 9.

At this time, the reflected signal light from the subject is also incident on the first PSD 4a.
On D4a, the moving direction in which the light spot from the light projecting element 1 moves according to the subject distance and the first PS
Since the detection directions of D4a do not match and are arranged so as to be substantially orthogonal to each other, the distance measurement by the first PSD 4a is not performed, but the first PSD 4a outputs the first signal which is a constant amount of signal. It will be.

That is, as shown in FIG. 12, for example, when a "spot defect" occurs in the distance measuring light projected from the light projecting element 1, the first PSD 4a
The first signal output by the signal fluctuates depending on the degree of "spot defect". At this time, the fluctuation of the first signal output from the first PSD 4a is caused by the fluctuation of the first and second PSDs 4a,
Since the lengths of 4b are substantially the same and the detection directions of the first and second PSDs 4a and 4b are the same, fluctuations in the output signal caused by "spot deficiency" on the second PSD 4b. It is almost equal to.

Therefore, as described above, the PSD signal processing circuit 9 receives the second signal (distance measurement result) obtained by detecting the position of the light spot on the second PSD 4b and the first PSD.
The first signal that fluctuates due to the "spot defect" on 4a is input, and the calculation control means 10 calculates based on the first and second signals to calculate the subject distance. Therefore, the correction for "spot defect" is performed.

As described above, according to the fourth embodiment, the pair of light receiving means, that is, the first and second PSDs 4a,
4b and the first and second light receiving lenses 3a and 3b are substantially the same, and the second signal output from the second PSD 4b and the first signal output from the first PSD 4a are sent to the PSD signal processing circuit 9. The calculation control means 10 calculates the object distance based on the first and second signals respectively inputted, so that the "spot defect" is corrected and the accuracy is higher. It can be a distance measuring device.

Further, the distance measuring light projected by one emission of the light projecting element 1 is converted into the first and second PSD 4a,
Since the light is simultaneously received by 4b to measure the distance, it is possible to contribute to the power saving of the power consumption by the light emission of the light projecting element 1.

Then, the PSD signal processing circuit 9 switches the two output signals of the first and second signals in a time division manner, inputs them to the changeover switch means 10, and outputs them to the arithmetic control means 10. Since it is sufficient, a simple circuit can be provided, which can contribute to a reduction in manufacturing cost of component members.

It should be noted that the amount of fluctuation of the reflected signal light on the first PSD 4a is reduced by bringing them closer to each other on the first base line length connecting the light projecting lens 2 and the first light receiving lens 3a. Therefore, the projection lens 2 and the first lens
If the arrangement is made such that the distance between the light receiving lens 3a and the light receiving lens 3a is reduced, the width wa of the first PSD 4a can be reduced.

In the above-mentioned first to fourth embodiments, the focal lengths of the first and second light-receiving lenses constituting the pair of light-receiving means are substantially the same, but, for example, a camera is used. In the case of disposing the distance measuring devices and the like of each of the above-described examples in the above, it may be difficult to make the specifications of the pair of light-receiving lenses substantially the same.

Therefore, the case where different specifications of the focal lengths of the first and second light receiving lenses constituting the above pair of light receiving means are applied will be described below with reference to the following fifth embodiment.

FIG. 13 is a block diagram showing the schematic arrangement of a distance measuring device for a camera according to the fifth embodiment of the present invention. In the fifth embodiment, basically, the above-mentioned second
Since it has the same configuration as that of the embodiment, the same components are designated by the same reference numerals and detailed description thereof will be omitted.

As shown in FIG. 13, in the distance measuring device 31 of the camera of the fifth embodiment, light projecting means for projecting the distance measuring light toward the object 5, that is, the light projecting element 1 and the light projecting device. The lens 2 and a pair of light receiving means for receiving the reflected signal light of the distance measuring light from the subject 5, that is, the first and second PSDs 4.
a, 4b and the first and second light receiving lenses 3a, 3b are arranged, and the focal lengths fja, fjb of the first and second light receiving lenses 3a, 3b are set to be different from each other. I shall.

The first PSD 4a has preamplifiers 14 and 15 for amplifying the first signal output thereby.
Is electrically connected to the second PSD 4b.
Are electrically connected to preamplifiers 16 and 17 for amplifying the second signal output thereby.

The output signals (first and second signals) from the preamplifiers 15 and 16 are changed by the changeover switch means 18, and the output signals (first and second signals) from the preamplifiers 14 and 17 are changed. The changeover switch means 19 can be used to change over. The change-over switches 18 and 19 are electrically connected to the arithmetic circuit 20 so that the first and second signals are inputted.

The arithmetic control means 1 formed by a CPU such as a one-chip microcomputer for controlling the entire camera
A driver 8 for causing the light projecting element 1 to emit light is connected to 0, and the changeover switch means 18, 19 and the arithmetic circuit 20 are electrically connected. As a result, the arithmetic control means 10 controls the driver 8 to cause the light projecting element 1 to emit light, control the changeover of the changeover switch means 18 and 19, and the arithmetic circuit 20.
The distance to the subject 5 is calculated according to the output result of.

Further, the arithmetic control means 10 includes an EEPROM 25 which is an electrically writable memory, an information processing device such as a personal computer and the like, and a checker 26 which controls the arithmetic control means 10 and the like. It is designed to be electrically connected.

In the distance measuring device 31 of the camera having the above-mentioned fifth embodiment, the operation when the distance is measured will be described below.

FIGS. 14 and 15 show the first and second PSDs.
FIG. 14 is a simplified view showing a state in which the light spots of the reflected signal light on 4a and 4b are projected.
Is an example when the first and second light receiving lenses 3a and 3b have the same focal length, and FIG. 15 shows the first and second light receiving lenses 3a and 3b in which the focal lengths are different from each other. It is an example in the case of 5 examples.

As shown in FIG. 14, when the focal lengths of the first and second light receiving lenses 3a and 3b are equal,
The light spots 26a of the reflected signal light projected on the first and second PSDs 4a and 4b have the same size.
Therefore, the “spot lack” amount (the upper part of the light spot shown by the dotted line in FIG. 14) is also the above-mentioned first and second PSDs.
Although the amounts are the same in 4a and 4b, as shown in FIG. 15, when the focal lengths of the first and second light receiving lenses 3a and 3b are set to be different from each other,
The light spots 26b and 26c of the reflected signal light projected on the first and second PSDs 4a and 4b have different sizes, and the "spot missing" amount (the upper part of the light spot indicated by the dotted line in FIG. 15). .) Are also different.

Therefore, the first and second light receiving lenses 3a,
When the focal lengths of 3b are different, it is necessary to perform correction in order to measure the distance to the subject by the two reflected signal lights. So in this case,
The calculation of the subject distance by the above equation (3) does not hold.

That is, in this case, the first,
The incident positions of the light spots 26b and 26c of the reflected signal light on the second PSDs 4a and 4b are respectively Xa and Xb, the distance L to the subject 5, the first and second light receiving lenses 3
Letting a distance S between a and 3b, a focal length fja of the first light receiving lens 3a, and a focal length fjb of the second light receiving lens 3b,

[Equation 17] The formula will be satisfied.

By the way, the first and second light receiving lenses 3 are
It is conceivable that the focal lengths fja and fjb of a and 3b may have an error due to factors such as a deviation and a mounting error that occur at the time of manufacturing the component. Therefore, it is necessary to make adjustments for each device in consideration of errors and the like that occur in each member. That is, when the correction value (adjustment amount) α is added, the above equation (17) becomes

(Equation 18) And the first and second light receiving lenses 3a having different focal lengths,
In the case of the range finder to which 3b is applied, the above (1
The subject distance L is determined based on the equation (8).

Regarding the correction value (adjustment amount) α,
This will be described in more detail with reference to FIGS. 16 and 17. FIG.
FIG. 6 is a block configuration diagram showing a schematic configuration when an adjusting device for adjusting is attached to the distance measuring device of the camera of the fifth embodiment. The distance measuring device 3 shown in FIG.
1 is the same as that described in the above-mentioned fifth embodiment, but in order to avoid complication of the drawing, some members are simplified and shown.

As shown in FIG. 16, the distance measuring device 31 includes the first and second light receiving lenses 3 having different focal lengths.
a and 3b are applied, and an adjusting device 29 for adjusting the distance measuring device 31 is provided.

That is, the adjusting device 29 is connected to the arithmetic control means 10 (CPU) in the distance measuring device 31. The adjusting device 29 includes a checker 26 including an information processing device such as a personal computer and a selection driver 27. The checker 26 includes:
While being electrically connected to the arithmetic and control means 10 of the distance measuring device 31, it is electrically connected to the selection driver 27 in the adjusting device 29.

Further, the selection driver 27 has the first and second light projecting elements (IRED) 2 which are the first and second light sources.
8a and 28b are arranged side by side at a predetermined interval in the same direction as the arrangement direction of the first and second light receiving lenses 3a and 3b of the distance measuring device 31, and the first and second light projections are provided. The elements (IREDs) 28a and 28b and the first and second light receiving lenses 3a and 3b of the distance measuring device 31 are set to be separated by a predetermined distance L.

The checker 26 controls the selection driver 27 to control the first and second light projecting elements 28.
a and 28b are selectively made to emit light, and the light projected by the light emission of the first and second light projecting elements 28a and 28b is the first and second light receiving lenses 3a of the distance measuring device 31. , 3b through the first and second PSDs 4a, 4
b, and the distance measuring device 3
When attached to No. 1, it also controls the arithmetic control means 10.

FIG. 17 shows the operation of the distance measuring device 31 adjusted by the adjusting device 29 thus constructed.
The flowchart will be described below. The adjusting operation is performed on the manufacturing line of the distance measuring device 31, for example.

As shown in FIG. 17, first, in step S2
At 0, the checker 26 of the adjusting device 29 controls the arithmetic control unit 10 to cause the driver 8 to operate.
The emission of the light projecting element 1 of the distance measuring device 31 is stopped (OFF) via the, and the process proceeds to the next step S21.
As a result, in the processing from the next step S21, the light emitting operation of the light projecting element 1 of the distance measuring device 31 is prohibited.

Next, in steps S21 to S24,
The checker 26 of the adjusting device 29 controls the selection driver 27 and the arithmetic control means 10 to cause the first and second light projecting elements (IREDs) 28a and 28b and the switch 18 of the distance measuring device 31 to operate. , 19 are switched and controlled so that the first and second light projecting elements (IRED) 28a, 28
The light projected by the light emission of b is emitted from the first and second PSDs.
It is made incident on 4a and 4b sequentially.

That is, in step S21, the checker 26 controls the selection driver 27 to cause the first light projecting element (IRED) 28a to emit light, and
The change-over switch 18, through the arithmetic control means 10,
19 is controlled so that the first PSD 4a receives the light projected from the first light projecting element (IRED) 28a, the signal light position Xa1 is detected, and the process proceeds to the next step S22.

Subsequently, in step S22, the checker 26 controls the selection driver 27 to cause the second light projecting element (IRED) 28b to emit light, and the changeover switch via the arithmetic control means 10. 1
8 and 19 to control the second PSD to the first PSD 4a.
The light projected from the light projecting element (IRED) 28b is received to detect the signal light position Xa2, and the next step S23.
Go to processing.

Then, in step S23, the checker 26 controls the selection driver 27 to cause the first light projecting element (IRED) 28a to emit light, and the changeover switch 1 via the arithmetic control means 10.
8 and 19 to control the first PSD 4b to the second PSD 4b.
The light projected from the light projecting element (IRED) 28a is received to detect the signal light position Xb1, and the next step S24.
Go to processing.

Further, in step S24, the checker 26 controls the selection driver 27 to cause the second light projecting element (IRED) 28b to emit light, and the changeover switch 1 via the arithmetic control means 10.
8 and 19 to control the second PSD 4b to the second
The light projected from the light projecting element (IRED) 28b is received to detect the signal light position Xb2, and the next step S25.
Go to processing.

Then, in step S25, the checker 26 detects the detected signal light positions Xa1 and Xa.
2, the correction value (adjustment amount) α based on Xb1 and Xb2
Is performed and the process proceeds to the next step S26.

Subsequently, in step S26, the checker 26 causes the correction value (adjustment amount) α and the first and second light receiving lenses 3a and 3b of the distance measuring device 31 and the first and second projections. Based on the predetermined distance L between the optical elements IRED 28a and 28b, the value of the coefficient A is calculated by the equation (18).

Then, in step S27, the correction value (adjustment amount) α and the coefficient A calculated in steps S25 and S26 are stored in the EEPROM 25 by a writing means (not shown) or the like. A series of processing ends.

In order to correct the "spot deficiency" in the distance measuring device 31, even when either of the first and second light projecting elements 28a and 28b emits light,
The predetermined distance L must be accurately calculated by the signal light positions Xa1, Xa2, Xb1, Xb2 of the light projected on the first and second PSDs 4a, 4b. Therefore, the focal lengths fja of the first and second light receiving lenses 3a and 3b,
α (Xa1−Xa2) = (Xb1−Xb2) always regardless of the difference in fjb and the error that occurs during mounting.
The relationship must be established.

In this way, the distance measuring device 31 adjusted by the adjusting device 29 has a distance measuring operation performed during photographing, that is, the light emitting operation of the light projecting element 1 and its reflection. First and second PSDs 4a and 4b of signal light
The incident position Xa of the reflected signal light is
Xb is detected and the EEPROM 25
The correction value (adjustment amount) α and the coefficient A stored in
Is read.

Then, the detected incident positions X1, X
b, the correction value (adjustment amount) α, the coefficient A, etc. read from the EEPROM 25, the arithmetic control means 10 performs the arithmetic operation of the equation (18),
The subject distance L is calculated.

Then, by the arithmetic control means 10,
Based on the calculated subject distance L, the focusing means and the like are controlled to drive the photographing optical system, and the focusing operation is performed.

As described above, according to the fifth embodiment, an error or the like that occurs when the components of the distance measuring device 31 are attached or assembled is adjusted by the adjusting device 29 at the manufacturing stage or the like. Therefore, the first and second light receiving lenses 3a, 3 of the distance measuring device 31 are used.
Even if b have different focal lengths, more accurate distance measurement can be performed and the production cost of the apparatus itself can be reduced.

Further, when the distance measuring device 31 is arranged in the camera, the degree of freedom in arrangement can be improved and the miniaturization can be easily realized.

In the above embodiment, the incident position X calculated as the first and second values according to the incident position is calculated.
1 and X2 are used, the value according to the incident position is not limited to these incident positions X1 and X2, but the subject distance L calculated directly or indirectly from these values and the subject distance L It is also possible to use a value such as an inverse number. In this case, the judgments in the flowcharts of FIGS. 4 and 11 are different, but may be appropriately changed according to the purpose.

[Additional Notes] (1) A light projecting means for projecting distance measuring light onto the subject,
A pair of light receiving means for receiving the reflected signal light of the distance measuring light from the subject, a changeover switch means for switching the output results of the pair of light receiving means in a time division manner, and the pair of light receiving light for the distance measuring light. A detection circuit for detecting each incident position of the means in a time division manner, controlling the projection of the distance measuring light, performing the switching control, according to the output result of the detection circuit,
A distance measuring device comprising: a calculation control unit that calculates a distance to the subject.

(2) The arithmetic control means detects the incident position of the reflected signal light on one light receiving means of the pair of light receiving means when the distance measuring light is projected by the light projecting means. 6. The distance measuring device according to supplementary note 1, wherein the distance is detected by a circuit, and it is determined whether to use the detection result based on the other light receiving means according to the detection result.

(3) The distance measuring device is incorporated in a camera with a zoom lens, has focal length detecting means for detecting focal length information of the zoom lens, and the arithmetic control means is detected by the focal length detecting means. The distance measuring method according to the first aspect, wherein it is determined whether the subject distance is obtained by using the output of either or both of the pair of light receiving means according to the value of the focal length information. apparatus.

(4) Light projecting means for projecting distance measuring light to the object, and first light receiving means for receiving reflected signal light of the distance measuring light from the object and detecting the incident position thereof.
According to the incident position of the reflected signal light on the first light receiving means, the light projecting means is restarted to receive the reflected signal light, and the second light receiving means is arranged at a position separated from the first light receiving means. 2 light receiving means, the light projecting means, switching control of the first and second light receiving means, and arithmetic control means for determining the distance to the subject according to the output results of the first and second light receiving means. Distance measuring equipment equipped.

(5) The fourth aspect, further comprising a photographing lens for photographing the subject and having a judging means for judging switching of the second light receiving means according to an output result of means for obtaining focal length information of the photographing lens. Distance measuring device described in.

(6) When the distance measuring light is projected, when the distance is longer than a predetermined distance based on the output of the first light receiving means, the arithmetic control means outputs the distance measuring light by the light projecting means. 6. The distance measuring device according to appendix 4, wherein the distance to the object is determined based on the outputs of the first and second light receiving means.

(7) The distance measuring device is incorporated in a camera with a zoom lens, has a focal length detecting means for detecting the focal length of the zoom lens, and the arithmetic control means has a focal length greater than a predetermined focal length. In the case of the wide angle side, the subject distance is determined based on the outputs of the first and second light receiving means, and in the case where the focal length is on the telephoto side of a predetermined focal length, the object distance is determined based on the output of the first light receiving means. The distance measuring device according to attachment 4, which is adapted to determine a subject distance.

(8) The first base line length direction formed by the light projecting means and the first light receiving means and the second base line length direction formed by the light projecting means and the second light receiving means are predetermined. The distance measuring device according to attachment 4, wherein the distance measuring device intersects at an angle.

(9) The length of the first baseline formed by the light projecting means and the first light receiving means and the length of the second baseline length formed by the light projecting means and the second light receiving means are The distance measuring device according to Appendix 4, which is different.

(10) The focal length of the light receiving system of the first light receiving means is different from the focal length of the light receiving system of the second light receiving means.
Distance measuring device described in.

(11) A measuring unit having a light receiving system of the first and second light receiving units, a calculating unit for calculating the object distance from the incident position of light on the two light receiving systems, and an electrically writable memory. In a distance adjusting device, first and second light sources arranged at a predetermined distance from the distance measuring device and arranged at a predetermined interval in the same direction as the arrangement direction of the two light receiving systems; The two light sources are sequentially driven while switching one light receiving system, and the first light receiving system is connected to the first light receiving system.
And the outputs of the first light receiving system when light from the second light source is incident, and the outputs of the second light receiving system when the first and second light sources are incident on the second light receiving system. An adjusting device for a distance measuring device, comprising: a calculating device that calculates a value; and a writing device that writes the correction value in the memory of the distance measuring device.

(12) Projecting means for projecting the distance measuring light to the object and the reflected signal light of the distance measuring light from the object are received, and a pair of signals corresponding to the light receiving position are output. The first and second light receiving means having the first and second light receiving elements, which are semiconductor one-dimensional position detecting elements, and the outputs of the first and second light receiving elements are connected one by one, and two signals are input. A distance measuring device having analog calculating means and performing distance measurement based on the principle of triangulation, wherein the position detecting capability of the first and second light receiving elements in the base line length direction composed of the light projecting means and the first light receiving means. Of the light emitting means and the first and second light receiving means so that the position detection ability is oriented in a direction orthogonal to the base length direction of the light emitting means and the second light receiving means. Distance measuring device with elements.

(13) The distance measuring device according to the twelfth aspect, wherein the distance measuring device further has the same length in the direction of the position detection capability of the first and second light receiving elements.

(14) The distance measuring light is projected toward the object by the light projecting means, the reflected signal light from the object is received by the light receiving means, and the incident position of the reflected signal light output from the light receiving means. In the range finder of the camera for obtaining the subject distance based on the signal according to the above, the light receiving means has a pair of light receiving elements, and when the subject is at a short distance, one of the pair of light receiving elements The object distance is obtained based on the signal output from the light receiving element of, and when the object distance is a long distance, the object is output based on the signals output from both the light receiving elements of the pair of light receiving elements. A distance measuring device for a camera that seeks the distance.

(15) The distance measuring light is projected toward the subject by the light projecting means, the reflected signal light from the subject is received by the light receiving means, and the incident position of the reflected signal light output from the light receiving means. In the range finder of the camera for obtaining the subject distance based on the signal according to the above, the light receiving means has a pair of light receiving elements, and each of the signals output from each of the pair of light receiving elements corresponds to the incident position. A distance measuring device for a camera which obtains a value and determines the subject distance based on this value.

[0177]

As described above, according to the present invention, in the three-lens type active distance measuring device, the distance measuring error is reduced in a wider photographing range from a short distance to a long distance to the object. Thus, it is possible to provide a distance measuring device for a camera capable of performing distance measurement with higher accuracy and easily realizing miniaturization.

[Brief description of drawings]

FIG. 1 is a block configuration diagram showing a basic configuration of a distance measuring device for a camera according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining the relationship between the light spot diameter of the distance measuring light projected by the light projecting unit and the subject distance in the distance measuring device of FIG. 1;

FIG. 3 is a block configuration diagram showing a schematic configuration of a distance measuring device for a camera according to a second embodiment of the present invention.

4 is a flowchart showing a distance measuring operation of the distance measuring device of the camera shown in FIG.

FIG. 5 is an enlarged view of a main part of the distance measuring device shown in FIG. 3 for explaining a distance measuring operation, in which members related to distance measuring such as the light projecting means and the pair of light receiving means are taken out.

FIG. 6 is a front view of a camera to which the distance measuring device for a camera according to the third embodiment of the present invention is applied, and is a diagram simply showing the arrangement of members and the like related to the distance measuring device on the front side thereof.

7 is a diagram simply showing the positional relationship between the light projecting lens and the first and second light receiving lenses on the front side of the camera shown in FIG.

FIG. 8 is a diagram showing a state in which the first and second light receiving lenses shown in FIG. 7 are removed, and is a diagram simply showing a positional relationship between the light projecting lens and the first and second PSDs.

9 is an enlarged view of a main part of the second PSD shown in FIG.

FIG. 10 is an enlarged view of another exemplary main part of the second PSD shown in FIG. 9;

11 is a flowchart showing a distance measuring operation of the distance measuring device of the camera shown in FIG.

FIG. 12 is a block configuration diagram showing a schematic configuration of a distance measuring device for a camera according to a fourth embodiment of the present invention.

FIG. 13 is a block configuration diagram showing a schematic configuration of a distance measuring device for a camera according to a fifth embodiment of the present invention.

14 is a diagram showing the first and second P in the range finder of FIG.
FIG. 6 is a diagram showing a simplified state in which a light spot of reflected signal light on an SD is projected, and is an example when the focal lengths of the first and second light receiving lenses are the same.

15 is a diagram showing the first and second P in the range finder of FIG.
FIG. 6 is a diagram showing a simplified state in which a light spot of reflected signal light is projected on the SD, and is an example of a case where the focal lengths of the first and second light receiving lenses are different from each other.

16 is a block configuration diagram showing a schematic configuration when an adjusting device for adjusting is attached to the distance measuring device of FIG.

FIG. 17 is a flowchart of an operation at the time of adjustment by the adjustment device of the distance measuring device for the camera of FIG.

FIG. 18 is a block diagram schematically showing a conventional distance measuring device for a three-lens active camera.

19 is a block diagram showing the operation of the distance measuring device shown in FIG.

20 is a diagram showing an outline when the distance measuring device of FIG. 18 is applied to a camera.

FIG. 21 is a diagram simply showing a screen frame in the viewfinder of the camera and a subject image in this screen frame, and a diagram for explaining “spot lack”.

[Explanation of symbols]

1 ... Projecting element (projecting means) 2 ... Projecting lens (projecting means) 3a ... First light receiving lens (first light receiving means) 3b ... Second light receiving lens (second light receiving means) 4a ... ... 1st position detecting element (1st PSD; 1st light receiving means) 4b ... 2nd position detecting element (2nd PSD; 2nd light receiving means) 5 ... subject 9 ... PSD signal processing circuit 10 ... arithmetic control means ( CPU) 18 ... Changeover switch means

Claims (3)

[Claims] 1. A light projecting means for projecting distance measuring light toward an object, and a first light receiving means for outputting a first signal according to an incident position of reflected signal light of the distance measuring light from the object. And a second light receiving means which is arranged at a position different from that of the first light receiving means and which outputs a second signal corresponding to the incident position of the reflected signal light of the distance measuring light from the subject, and the light projecting means. And controlling the first and second light receiving means, and the first value corresponding to the incident position of the reflected signal light based on the first signal, and the incident of the reflected signal light based on the second signal. A second value according to the position, each of which can be calculated, and calculation control means for determining the subject distance based on the first value or the first and second values. Distance measuring device for cameras. 2. The calculation control means compares the first value with a predetermined value and determines the subject distance based on the first value according to the comparison result, or the first and the second distances are determined. 2. The distance measuring apparatus for a camera according to claim 1, wherein whether to determine the subject distance is selected based on a value of 2. 3. A light projecting means for projecting distance measuring light to a subject, a pair of light receiving means for receiving reflected signal light of the distance measuring light from the subject, and output results of the pair of light receiving means. Changeover switch means for time-divisional switching, a detection circuit for time-divisionally detecting the incident position of each of the pair of light receiving means of the distance measuring light, and projection control of the distance measuring light to control the switching. And a calculation control means for calculating the distance to the subject according to the output result of the detection circuit.