JPH07104176A - Range finder - Google Patents

Abstract

PURPOSE:To prevent the sacrifice of the degree of spatial freedom in constituting a device by arranging parts so that a direction linking between 1st projecting element and position photodetecting element may be almost orthogonally crossed with a direction linking between 2nd projecting element and position photodetectlng element, and also to obtain a range finder at a low cost by preventing the increase of the size of a light receiving element. CONSTITUTION:Range-finding light projected from a fixed IRED 1 is projected to a range finding point 7 through a projecting lens 2, and the reflected range- finding light is made incident on a PSD 5 through a light receiving lens 4. In addition to this, scannable range-finding light from an IRED 8 is projected to a range finding point 10 through a projecting lens 9. The IRED 8 and the projecting lens 9 are arranged in a direction orthogonally crossed with a direction linking between the light projecting and receiving lenses 2 and 4.

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 used for focusing a camera, and more particularly to a distance measuring device which projects a distance measuring light onto a subject and measures the distance to the subject by reflected signal light. Is.

[0002]

2. Description of the Related Art A distance measuring device is widely known in which a distance measuring light is projected onto a subject from a camera side, and a subject distance is obtained using reflected signal light from the subject. There is also known a technique in which distance measuring light is projected onto a plurality of points on a photographic screen so that focusing can be performed regardless of the position of the main subject on the screen. Such a technique is disclosed in, for example, Japanese Patent Laid-Open No. 59-107332 (multi-auto focus (AF)).

On the other hand, as a photographing lens of a camera, a zoom lens which can cope with a longer advance distance from a user's aim to photograph a farther subject in a large size is becoming mainstream.

FIG. 12 shows the principle of a so-called active triangle side distance method in which distance measuring light is projected from the camera side to obtain a subject distance L. In the figure, an infrared light emitting diode (IRED) 1 is a projection source of distance measuring light. The light projected from the IRED 1 is condensed by the light projecting lens 2 on the subject 3 as distance measuring light. The distance measuring light reflected from the subject is detected by a semiconductor position detecting element (PS) for detecting the incident position of the reflected signal light by the light receiving lens 4 arranged at a distance of the baseline length S from the light projecting lens 2.
D) Focused on 5.

When the focal length of the light receiving lens 4 is f _J , the signal light incident position x on the PSD 5 is a function of the object distance L and the baseline length S, and L = S · f _J / x (1) . Therefore, if S and f _J are fixed, the subject distance can be obtained from x.

The technique of the above-mentioned Japanese Patent Laid-Open No. 59-107332 is such that the light projecting / receiving lens and the light projecting / receiving element configured as shown in FIG.

[0007]

Attention must be paid to the relationship between the unit of the light emitting and receiving system and the distance measuring frame in a general camera finder. That is, as shown in FIG. 13, when a subject 3 is put into the general camera finder 6, a distance measuring point 7 is a point that can be surely measured.
Is provided in the center of the screen. This is 8 of the main subject
It is a device to be present in the central part of the screen and that the main subject in the central part of the screen is likely to be a failure photograph when it is out of focus (so-called out-of-focus). However, JP-A-59-1073
In the distance measuring device disclosed in Japanese Patent No. 32, it is not possible to reliably aim at the central portion of the screen depending on the stopping accuracy at the time of rotation.

If the stop position shifts due to rattling at the time of rotation, it may happen that the distance measuring point 14a instead of the distance measuring point 7 in the finder 6 is measured. In this case, the main subject 3 is out of focus. In particular, as described above, in a camera having a photographing lens with a long focal length, the subject distance L tends to be long, and this influence becomes larger.

As shown in FIG. 12, IRED1 is φ
_Although it has the light emitting area of only _{LED, when} the light is projected by the projection lens 2 with the focal length f _T , the size φ of the distance measuring light on the subject is φ = (L / f _T ) · φ _LED … (2) As is clear from the above formula (2), φ increases as L increases. Further, when φ becomes large, the size becomes larger than the size of the face of the subject 3, and the distance measuring light is deficient, resulting in erroneous distance measurement.

For example, L = 6 m, f _T = 15 mm, φ
_{If LED} = 0.4mm, φ will be 12cm, which is almost the same as the size of a human face. If rattling when the whole unit is stopped is added to this, accurate distance measurement is possible. Guaranteeing the projection of light becomes difficult. That is, JP-A-59-1
It can be said that the technique of Japanese Patent No. 07332 is not suitable for distance measurement up to a long distance.

Therefore, the applicant of the present patent application has proposed a device in which the distance measuring light for measuring the central portion of the screen is fixed, and the distance measuring light for the other portions is scannable.
Filed as an issue. As shown in FIG. 14, the fixed IRED 1 and the scannable IRED 8 are arranged behind the light projecting lens 2, and the distance measuring light is received by the PSD 5 via the light receiving lens 4. .

However, in this device, the fixed distance measuring light by the IRED 1 and the IR by the common projection lens 2 are used.
Since the movable distance measuring light is projected by the ED 8, the degree of space freedom of the configuration is sacrificed.

In addition, these rays are made into a common one-dimensional PSD.
Since I was trying to receive light at 5, the light receiving element became large,
In addition to being disadvantageous in terms of S / N, it was expensive.
The present invention has been made in view of the above problems, and does not sacrifice the spatial freedom of the device configuration, does not increase the size of the light-receiving element, is not disadvantageous in terms of S / N, and is inexpensive. An object is to provide a distance measuring device.

[0014]

That is, according to the present invention, first and second light projecting means for projecting a plurality of distance measuring lights onto a subject and the first and second light projecting means are sequentially projected. And a light position capable of receiving the signal light of the distance measuring light reflected by the first and second light projecting means from the subject and detecting the incident position two-dimensionally. In a distance measuring device including a detecting means, a direction connecting the first light projecting means and the light position detecting means and a direction connecting the second light projecting means and the light position detecting means are substantially orthogonal to each other. It is characterized by being arranged.

[0015]

In the distance measuring apparatus of the present invention, the direction connecting the first light projecting means and the light position detecting means and the direction connecting the second light projecting means and the light position detecting means are substantially orthogonal to each other. Is arranged as. Then, the control means causes the plurality of distance measuring lights to be sequentially projected onto the subject from the first and second light projecting means. The reflected signal light of the distance measuring light from the first and second light projecting means from the subject is received by the light position detecting means, and the incident position thereof is two-dimensionally detected.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the concept of a distance measuring device according to a first embodiment of the present invention. The distance measuring light projected from the fixed IRED 1 is projected through the light projecting lens 2 to the object distance measuring point 7 (not shown). Then, the distance measuring light reflected by the subject enters the PSD 5 via the light receiving lens 4. In addition, the distance measuring light from the IRED 8 provided so as to be scannable is projected to the distance measuring point 10 of the subject (not shown) via the light projecting lens 9.

This range finder has an IRED1, a light projecting lens 2, a light receiving lens 4 and a PSD 5 as in the active triangulation system of FIG. 12 described above. A two-dimensional PSD that can be detected is used. Further, the light position in the direction (x direction) connecting the light emitting / receiving lenses 2 and 4 is determined by the output current I _{1 of the} PSD ₅ ,
A direction that can be detected by I _{2 and} is orthogonal to it (y direction)
Can be detected by the output currents I ₃ and I ₄ . Then, another light projecting element (IRED) 8 and a light projecting lens 9 are arranged in the y direction orthogonal to the direction connecting the light projecting and receiving lenses 2 and 4.

As shown in FIG. 1, the IREDs 8 are arranged side by side in the direction (x direction) connecting the light projecting and receiving lenses 2 and 4, and as shown in FIG.
Distance measuring light can be projected to the distance measuring points 10 arranged in the horizontal direction (x direction). Of course, the IRED8 is not one in which a plurality of elements are arranged side by side.
It may be configured so that one element can be mechanically scanned within the range of θ shown in FIG.

On the other hand, the projection direction of the distance measuring light by the IRED 1 and the light projecting lens 2 is fixed so that light can be projected onto the distance measuring point 7 at the center of the finder 6. Considering the parallax of the finder and the projection lens, these optical axes shall be designed to intersect at 5 to 6 m.

With the distance measuring device having such a structure, one PSD 5 can be effectively used, and therefore, the device can be simplified and the cost of the PSD 5 can be reduced, and the area can be reduced to prevent the incidence of light other than the signal light. It is possible to provide more accurate multi-AF. In other words, if the distance measurement range θ by the multi-AF IRED 8 increases, the PSD 5 needs to be lengthened in the x direction. However, if the PSD 5 lengthens in the x direction, the distance measurement area in the central portion of the screen becomes wider, and the distance from the near distance increases. It is possible to improve the range in which distance measurement up to a distance is possible.

On the other hand, most of the scenes requiring multi-AF are snapshots as shown in FIG. 4, for example.
In other words, it is not necessary to have a wide range-finding range in order to photograph (macro photographing) a subject existing at a distance of 1 m or less with multi-AF or photograph a long-distance subject such as a landscape.

Therefore, the length of the PSD 5 in the y direction is
Unlike the x direction, it can be designed small. FIG. 3 shows the arrangement of such a light emitting / receiving system on the camera. A photographic lens 12 is provided substantially in the center of the front surface of the camera body 11. A light projecting lens 2, a finder objective lens 13, a light receiving lens 4, and a light projecting lens 9 are provided around the photographing lens 12. The projection lens 2 for the central distance measurement is made as close to the finder 13 as possible to prevent parallax.

Next, a second embodiment of the present invention will be described. FIG. 5 shows the structure of a distance measuring apparatus according to the second embodiment of the present invention. In the figure, IRED
The arrangement of 1, 8, PSD 5, and each lens 2, 4, 9 is
Although the same ones as shown in FIG. 1 are assumed, the arrangements of these optical systems are not shown here for the sake of easy understanding of the operation of each configuration.

The IREDs 1 and 8 are arithmetic control circuits (CPU) 1 composed of a one-chip microcomputer or the like.
By the timing signal of 4, the drivers 15 and 1 are respectively
The light emission is controlled via 6.

As described above, the IRED 1 and the projection lens 2 are fixed, and the light is projected at a distance of 5 m to 6 m in a direction crossing the central portion of the finder (not shown). Has been done.

On the other hand, the IRED 8 behind the light projecting lens 9 is mounted on the movable member 17. Then, the movable member 17 is moved along the rail 20 by the motor 18 and the feed screw 19, so that the IRED 8 can be scanned. The motor 18 is a CPU
Rotational movement is controlled by 14 via a motor driver 21. The switch 22 is for detecting the initial position of the movable member 17.

The taking lens 12 is controlled in focus by the lens control circuit 24. The setting of the zooming position of the taking lens 12 is input to the CPU 14 by the focal length detection circuit 25.

On the other hand, the signal light collected by the light receiving lens 4 is imaged on the two-dimensional PSD 5. PSD5 4
The two output currents are the preamplifiers 26, 27, 28 and 2 respectively.
9 is sucked with a low input impedance, is current-amplified, and is flown into the compression diodes 30, 31, 32, and 33. The signal current is flowed into the compression diodes 30, 31, 32, and 33, and is generated at the reference voltage V _ref reference. The compressed voltage is applied to the buffer circuits 34, 35, 36, 3
7 is selectively supplied to the differential expansion circuit 38.
This differential expansion circuit 38 includes two NPN transistors 3
9 and 40 and a constant current source 41.

The preamplifiers 26, 27, 28, 29 and the buffer circuits 34, 35, 36, 37 are connected to the CPU 14
Is switched between an operating state and a non-operating state. However, as shown in FIG. 1, each IRED and PSD
, The preamplifiers 26 and 29 and the buffer circuits 34 and 37 are activated when the IRED 1 is caused to emit light. When the IRED 5 is made to emit light, the preamplifiers 27 and 28 and the buffer circuits 35 and 36 are activated to switch the output current of the two-dimensional PSD 5.

The output current of the differential expansion circuit 38 flows through the integration capacitor 42 connected to the transistor 39 and is integrated. Reference numeral 43 is a switch for initializing the integrated voltage. The integrated voltage is the INT terminal 44
Is input to the CPU 14. Then, the CPU 14 converts the integrated voltage into a digital value by the built-in A / D converter and calculates the digital value to calculate the distance of each light projecting point. Explaining this distance calculation, the outputs I ₁ and I _{2 of the} PSD ₅ are the compression diodes 30,
The voltage difference when compressed to 33 is obtained by the equation (3).

[0031]

[Equation 1]

On the other hand, when two voltage signals having the same voltage difference as this are input to the differential expansion circuit 38, the respective currents of the transistors 39 and 40 and the constant current source 41 shown in Formula 2 are
It becomes like Formula (4) and Formula (5).

[0033]

[Equation 2]

[0034]

[Equation 3]

[0035]

[Equation 4] Therefore, the current shown in the equation (6) flows through the integrating capacitor 42.

[0036]

[Equation 5] The PSD 5 has a light incident position x shown in FIG.
Output I ₁ and I ₂ that satisfy the relation of the expression (7).

[0037]

[Equation 6] Therefore, the relationship of the expression (8) is established from the expression (1).

[0038]

[Equation 7]

The relationship between the signal light from the IRED8 and P
The same applies to the I _3, I ₄ of SD5. Since the constant current source 41 is turned on for a predetermined time in synchronization with the light emission of IRED, the integrated voltage V _INT has the relationship of V _INT = A / L (9).

The initialization switch 43 changes from ON to OFF prior to the light emission of the IRED. The relationship of these sequence controls will be described with reference to the time chart of FIG. First, before projecting the IRED1, the preamplifier 2
6, 29 and the buffer circuits 34 and 37 are in the operating state,
The initialization switch 43 is turned on to initialize the integrated voltage V _INT . Next, the initialization switch 43 is turned off, the IRED 1 is caused to emit light to measure the distance in the center of the screen, and the constant current source 41 is turned on after waiting for the circuit output to stabilize due to the incident optical signal. Then, the integrating capacitor 42 receives the integrated voltage V
Appears as _INT as shown in FIG. INT in the figure
After turning off the constant current source 34 at the read timing, V
A / D convert _INT and input.

Thus, when the distance measurement at the center of the screen is completed,
Preamplifiers 26, 29, etc. are turned off, preamplifiers 27, 28
And the buffer circuits 35 and 36 in the operating state,
Distance measurement is started by D8 and PSD signals I ₃ , I ₄ .

This distance measurement is characterized in that the motor driver 21 scans the IRED 8 and repeats the above-mentioned operation.
As shown in, even if there is no main subject in the center of the screen, the correct focusing distance can be measured.

Next, the operation of the camera to which such a distance measuring device is applied at the time of photographing will be described with reference to the flowchart of FIG. The sequence described below is based on the CPU1.
4 controls.

First, in the subroutine of step S1,
The CPU 14 calculates the distance measurement result L ₀ when the preamplifiers 26 and 29 are activated and the IRED 1 emits light. Then, in step S2, the focal length detection circuit 25 of FIG.
The focal length of the shooting lens of the camera at the time of shooting is
PU14 inputs.

If the focal length f is too long, the distance measuring light in the viewfinder is enlarged as shown in FIG. 2B, and the distance measuring point 10 which is the distance measuring light projection position by the IRED 8 is Too close to the periphery of the screen. At this time, to explain with the example of FIG. 13, instead of the face of the person 3,
It may cause a problem that the hand that was sent out is in focus.

Therefore, in this flowchart, when the focal length of the taking lens exceeds 50 mm in step S3, the flow advances to step S4 to fix the data from L ₁ to Lln ₀ to ∞. Further, in step S5, L _{0 to} L _n0
The closest data, that is, L ₁ is selected from among the distances. In this way, by setting the focus distance L _P , control is performed so that focusing is performed according to the distance measurement result in step S1, that is, the distance measurement result at the center of the screen.

On the other hand, in step S3, if the focal length of the taking lens is 50 mm or less, step S1.
Proceeding to 0, the distance measurement result L ₀ at the center is compared with the closest distance L _min that can be measured by the IRED8. As described above, this range finder has a wider range range in the center by the IRED1, and the flow of steps S11 to S15 is wasted in selecting the closest step S5. _When branching to ₀ <L _min , the process proceeds to step S4.

If L ₀ <L _{min is} not satisfied in step S10, the process proceeds to step S11 to reset n indicating the number of distance measuring points. Next, after incrementing at step S12, the subroutine for measuring L _{n by} the IRED8 is entered at step S13. Then, until n reaches the predetermined value n ₀ in step S14, step S1
At 5, the rotation control of the motor 18, that is, the scanning of the IRED 8 is performed, and the distance measurement of n ₀ points on the screen is repeated.

When the distance measurement for the predetermined number of points is completed in step S14, the process proceeds to step S5 to perform the closest selection operation. Then, in step S6, L _{P is} focused via the lens control circuit 24, and then exposure is performed in step S7. After the exposure is completed, the reverse rotation control of the motor 18 is performed in step S8 until the initialization switch 22 detects the initial position of the IRED 8 in step S9.

Next, L _min described in the above step S10
Will be described. FIG. 8A shows the arrangement of the y-direction optical system of this distance measuring device. Assuming that the distance between the PSD 5 and the light receiving lens 4 is f _J , the baseline length between the light projecting lens 9 and the light receiving lens 8 is S _2, and the width of the PSD 5 is W, then the above L _min is given by equation (10). become.

[0051]

[Equation 8] Here, φ _J is in charge of the diameter when the distance measuring light is received, and is about 0.
Consider 4 mm. When S ₂ is 30 mm, f _J is 15 mm, and W is 1.5, L _min is about 1.3.
mm.

FIG. 10B shows the arrangement of the optical system in the x direction of this distance measuring device. When the PSD 5 covers the range of one side θ with respect to the center of the screen, the PSD length t
And f _J of the light receiving lens has a relationship of t = 2f _J tan θ + φ _J (11).

Further, the shortest detectable distance L _min c of the distance measurement by the light of the IRED 1 is S which is the base line length between the lenses 2 and 4.
_{When set to 1} , S ₁ = L _min c tan θ (12)

Here, when θ is 6 ° from the equation (11), if f _J = 15 mm and φ _J = 0.4 mm, then t
= About 3.6 mm. Further, from the above formula (12),
If S ₁ is 45 mm, then L _min c = 0.43 m.

As described above, although L _min <L _min , the subject distance is 1.3 m or less, and it is not likely that a photograph having the composition shown in FIG. 4 will be taken. There is no practical problem because the distance can be covered up to 0.4 m by the distance measurement at the center of the screen.

Further, when performing multi-AF capable of measuring a distance up to 0.43 m and covering a range of ± 6 ° with the configuration shown in FIG. 14, t is as in equation (11), and W is Since W = (S · f _J / L _min ) + φ _J (13), f _J = 15 mm, S = 45 mm, φ _J =
If it is 0.4 mm, W = 2 mm, and the area is 3.6.
It becomes × 2 (mm ² ).

On the other hand, in this embodiment, 3.6 × 1.5 (mm
² ), which shows that the area was improved. Figure 8
As is apparent from (b), the length t of PSD5 is IR
It is not used in the full range when the ED1 emits light.
This is because the light of the IRED 1 does not enter the left side of the optical axis of the light receiving lens 4.

Therefore, as shown in FIG. 9, the PSD may be divided into two parts. FIG. 9 shows a third embodiment of the distance measuring device according to the present invention.
The embodiment of FIG. 2 uses one PSD, while the PSD divided into two is used. This allows IRED
The PSD area when using 1 can be further reduced,
Further improvements are possible. Here, as shown in FIG. 9B, assuming that the PSDs divided into two are 5a and 5b and the lengths thereof are t ₁ and t ₂ , respectively, the formula (14) is obtained.

[0059]

[Equation 9] Therefore, the area of the PSD 5a is 2 × 1.5 (mm
² ) and the area of PSD5b is 1.6 × 1.5.
(Mm ² )

The PSD 5a is IRED1 and IRED8.
Signal light must be incident, and it must be a two-dimensional PSD, but only the signal light of IRED8 is incident P
SD5b may be one-dimensional instead of two-dimensional PSD.

By the way, as a further improvement, the photographed photograph is at a distance (for example, x 1/5) so that it becomes a full body image of the person.
At a distance of 0), the frequency of shooting increases, so it may be desirable to further improve the ranging accuracy near this distance. For example, with a camera having a focal length of 120 mm, it is desired to improve the distance measurement accuracy near 6 m. At this time, the basic configuration is the same as that of FIG. 1, but only the PSD 5 is configured as shown in FIG. 10A, and the configuration is such that the signal light from this distance is split at the position x _CH incident. Target.

FIG. 10 shows the construction of the fourth embodiment of the distance measuring apparatus of the present invention. Here, the length of the PSD 5b is (1 when the constant of the third embodiment described above is taken as an example.
It becomes like the formula 5).

[0063]

[Equation 10] On the other hand, the length of the PSD 5a is 3.6 mm-1.9 mm =
It becomes 1.7 mm.

Further, in the vicinity of 6 m, as shown in FIG. 10B, the spots of the signal light have two PSDs 5a and 5d.
Although it is designed to be applied to both b, by measuring the ratio of the signal light incident on each light receiving surface, it becomes possible to measure the incident position of the reflected signal light, that is, the object distance with high accuracy. . The reason why the accuracy is high is that the spot of the signal light slightly moves on the PSD in the x direction according to the change of the subject distance, and the ratio of the spot incident on each PSD largely changes. For example, when the spot φ _J is 0.4 m, the output ratio changes by 0.1 / 0.4 = 1/4 when the spot is moved by 0.1 mm.

For example, in the PSD 5a with t ₁ = 2 mm of the third embodiment (FIG. 9), 2 mm × 1/4 = 0 for the output ratio of I ₁ and I ₂ to change by 1/4. It is necessary to move the spot by 0.5 mm. However, when the subject distance is determined by such a method, there is a fear that the range in which the distance can be measured becomes narrow. That's because both PSDs need to be spotted,
Using the above constants, as shown in FIG. 10 (c), the closest distance at which the spots are applied to both PSDs is (1
It becomes like the formula 6).

[0066]

[Equation 11] At a closer distance, the spot will be completely placed on the PSD 5a, so the output current I from both ends of the PSD 5a
_Although it is possible to measure the distance from ₁ and I ₂ , the distance measurement result becomes discontinuous in the vicinity of 2.25 m. Therefore, in the same embodiment, as shown in Table 1, the signal light of the movable IRED 8 is used for the distance around 2 m to 3 m in the center of the screen.

[0067]

[Table 1]

FIG. 11 shows the structure of the light receiving portion of the fourth embodiment. The configuration of the light projecting system (not shown) conforms to that of FIG. 1 and is omitted here. Figure 1
In 1, the reference numeral 5a is a two-dimensional PSD, and the reference numeral 5b is a one-dimensional PSD capable of detecting the light position in the y direction. These two PS
The output currents of the electrodes D5a and 5b are absorbed and amplified by the preamplifiers 45, 46, 47, 48, 49 and 50, respectively. The signals amplified by the preamplifiers 45 and 46 are supplied to the ratio calculation circuit 53 and the preamplifiers 47 and 4 respectively.
The signals amplified by 8, 49 and 50 are added by adding circuits 51 and 5
2 and ratio calculation circuits 54, 55 and 56.

This ratio calculation circuit corresponds to the portion composed of the compression diodes 30, 33, the buffer circuits 34, 37 and the expansion calculation circuit 38 of FIG. Therefore, when the inputs of these circuits are I ₁ and I ₂ , the calculation as in the above equation (6) is performed, and the output depending on the distance L is obtained in the form of the equation (9).

The adder circuits 51 and 52 are circuits for adding the two amplified signal currents, and the adder circuit 51 corresponds to I ₃ and + I ₄ , and the adder circuit 52 corresponds to currents I ₅ and + I _6. Output a signal. Therefore, the ratio calculation circuit 56 which inputs these outputs performs a calculation for calculating a ratio corresponding to (I ₃ , + I ₄ ) / (I ₃ , + I ₄ + I ₅ + I ₆ ).

This calculation corresponds to the ratio of the area of each PSD of the signal light spot incident on the PSD as shown in FIG. 10B, and as described above, the signal thus obtained. The incident position of the signal light spot is obtained from the ratio of light.

Table 1 summarizes the distance measuring spots and the range of coverage according to the configuration of FIG.
Is. As described above, in the fourth embodiment, the long distance (3 m to ∞) at the center of the screen is measured by the ratio of the signal light incident on the two PSDs. The IRED used at this time is 1, and the ratio calculation circuit used by the CPU 14 is 56.

The short distance in the center is IRED1 and PSD.
The ratio calculation circuit 53 of I ₁ and I ₂ of 5a is used. 2 in the center
Around m is a discontinuity point of these perspective switching, so
1.3 m to 3 m is measured using the IRED8, PSD5b, and the ratio calculation circuit 55. Further, the distance measurement other than the center of the screen is performed using the IRED8. This IRED8
Is based on the premise that the distance measuring light can be scanned by the motor 18 as shown in FIG.

As is clear from FIG. 10A, the reflected signal light from the right side of the screen is incident on the PSD 5a. Therefore, the ratio calculation circuit used is 54. On the other hand, since the reflected signal light from the left side of the screen is incident on the PSD 5b, CP
The ratio calculation circuit used by U14 is 55.

As described above, according to this embodiment,
The area of each PSD can be reduced, S / N deterioration due to incidence from other than the signal light can be prevented, the distance measurement system at the center of the screen can be improved, and two IREDs can be effectively used in combination. This enables wide-range distance measurement.

[0076]

As described above, according to the present invention, the degree of freedom in space of the structure of the device is not sacrificed, the light receiving element is not upsized, and there is no S / N disadvantage. An inexpensive distance measuring device can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing a concept of a distance measuring device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a finder and a distance measuring point.

FIG. 3 is a diagram showing an arrangement on a camera of a light emitting / receiving system of the distance measuring device having the configuration of FIG.

FIG. 4 is a diagram showing a scene that requires multi-AF.

FIG. 5 is a diagram showing a configuration of a distance measuring device according to a second embodiment of the present invention.

6 is a time chart showing the relationship of sequence control of the distance measuring device of FIG.

7 is a flowchart illustrating an operation of a camera to which the distance measuring device of FIG. 5 is applied during shooting.

8A is a diagram showing an arrangement of a y-direction optical system of the distance measuring device, and FIG. 8B is a diagram showing a relationship between IRED and PSD.

FIG. 9 is a diagram showing the configuration of a third embodiment of the distance measuring device according to the present invention.

FIG. 10 is a diagram showing the configuration of a fourth embodiment of the distance measuring device according to the present invention.

FIG. 11 is a diagram showing a configuration of a light receiving portion of a fourth embodiment.

FIG. 12 is a diagram showing the principle of an active triangular side distance method.

FIG. 13 is a diagram showing a relationship between a distance measuring frame and a distance measuring point in a conventional general camera finder.

FIG. 14 is a diagram showing a configuration of a conventional distance measuring device, showing a device capable of fixing the distance measuring light for measuring the center portion of the screen and scanning the other distance measuring light. Is.

[Explanation of symbols]

1, 8 ... Infrared light emitting diode (IRED), 2, 9 ... Projection lens, 3 ... Subject, 4 ... Light receiving lens, 5 ... Semiconductor position detection element (PSD), 6 ... Finder, 7, 10 ... Distance measuring point , 11 ... camera body, 12 ... shooting lens,
13 ... Objective lens, 14 ... Arithmetic control circuit (CPU), 1
5, 16 ... driver, 17 ... movable member, 18 ... motor,
19 ... Feed screw, 20 ... Rail, 21 ... Motor driver, 22 ... Switch, 24 ... Lens control circuit, 25 ... Focal distance detection circuit, 26, 27, 28, 29 ... Preamplifier, 30, 31, 32, 33 ... Compression Diode, 34,
35, 36, 37 ... Buffer circuit, 38 ... Differential expansion circuit, 39, 40 ... Transistor, 41 ... Constant current source, 42
… Integration capacitor, 43… Initialization switch, 44… IN
T terminal.

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] November 11, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction content]

On the other hand, the photographic lens of the camera is from the directional user, becoming longer focal compatible zoom lens to a distance mainstream wants more shooting distant subjects increased.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

On the other hand, the projection direction of the distance measuring light by the IRED 1 and the light projecting lens 2 is fixed so that light can be projected onto the distance measuring point 7 at the center of the finder 6. Considering Parara click scan finder and projection lens, these optical axes shall be designed to cross at 5 to 6 m.

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 13

[Correction method] Change

[Correction content]

[Fig. 13]

Claims (1)

[Claims] 1. A first and second light projecting means for projecting a plurality of distance measuring lights onto a subject, a control means for successively projecting the first and second light projecting means, and the first to second projecting means. 1st and 2nd
In the distance measuring device, the distance measuring light is received by the light projecting means and the reflected signal light from the subject is received, and the incident position can be two-dimensionally received and detected. 1. A distance measuring device, characterized in that a direction connecting one light projecting means and the light position detecting means and a direction connecting the second light projecting means and the light position detecting means are arranged substantially orthogonal to each other.