JP3487585B2 - Camera ranging device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-point distance measuring device mounted on a camera, and more particularly to a distance measuring device for a camera that determines a next light projecting point position according to a previously detected distance.

[0002]

2. Description of the Related Art Conventionally, when shooting with a camera, a camera for measuring a plurality of points on the screen is provided so that accurate focusing can be performed even when the subject is not located in the center of the shooting screen. is there.

For example, in Japanese Patent Laid-Open No. 60-60511, by focusing on the closest distance among distance measurement results from a plurality of distance measurement points that are sequentially measured,
Although a distance measuring device that realizes accurate focusing has been proposed, it is necessary to measure the distance over the entire area of the screen in order to completely eliminate out-of-focus.

In addition, U.S.P. S. P4943824 describes a configuration in which distance measuring points are arranged at predetermined equal intervals over the entire area of the photographing screen to measure the distance.

[0005]

However, in the above-described conventional distance measuring device, if it is attempted to measure all distance measuring points within the photographing screen at the same time, the number of distance measuring sensors increases and the processing circuit becomes large. To be done. In addition, a distance measuring device that simultaneously measures multiple points has a disadvantage in the S / N ratio of the circuit to be constructed and a higher cost than a device that sequentially measures distances by time-division for each distance measuring point. Was well known. For this reason, the multi-AF type distance measuring device is mainly configured to perform time-division for each one distance measuring point among the multi-point distance measuring points and sequentially measure the distance.

Such a conventional multi-point distance measuring device (multi A
In F), the number of distance measuring points was small, and it was not possible to obtain sufficient accuracy for distance measuring. Therefore, in order to further improve the accuracy, even if it is possible to measure a greater number of distance measuring points, the distance measuring is performed sequentially for each distance measuring point.
As a result, the distance measurement time becomes long and the time lag becomes long.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a distance measuring device which realizes a short distance measuring time and realizes inexpensive and highly accurate multi-point distance measuring.

[0008]

In order to achieve the above object, the present invention provides a shooting screen in a viewfinder in the longitudinal direction of the screen.
A plurality of distance measuring points are arranged, and in a distance measuring device of a camera for sequentially measuring the distance measuring points, among the plurality of distance measuring points, the focus of the photographing lens at the time of photographing is selected.
When the point distance is on the telephoto side, the range
The scan pitch angle between the
Angle of scan pitch between distance measuring points in the center of the array
Distance measuring point control means for controlling to be wider than
And the angle of the scan pitch between the distance measuring points is determined according to the object distance. Also, the focal length of the shooting lens at the time of shooting is set to the wide angle side.
At some point, the scan pitch between the multiple ranging points
The angle of the chi is uniform.

[0009]

[0010]

[Operation] With the distance measuring device having the above-described structure, the distance measuring point
The focal length of the taking lens is on the telephoto side.
In this case, the number of distance measuring points is large and it takes time to measure the distance.
Of the distance measuring points arranged on the shooting screen,
When there is a point distance, the distance measuring points in the periphery of the array
The scan pitch angle between the above is the above array at telephoto
From the angle of the scan pitch between the distance measuring points in the center of
Is also widely set. Also, the measuring point at wide angle
The scan pitch angle between the dots becomes uniform.

[0011]

[0012]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a conceptual configuration of a distance measuring device according to the present invention, which will be described.

In this distance measuring device, an arithmetic control unit (CPU) 1 for controlling the whole drives the focusing unit 3 based on the distance measured value obtained by the distance measuring unit 2 to focus the photographing lens 9. The focal length f when the focus is achieved is input to the arithmetic and control unit 1 via the f input unit 8. Further, when changing the position of the distance measuring point 13 as shown in FIG. 2B to be described later to the position of the distance measuring point as shown in FIG. 2C, the calculation control unit 1 changes the scan pitch changing unit. Four
The scan pitch changing section 4 drives the scan mechanism section 6 by the scan actuator 5. The arithmetic control unit 1 is a circuit composed of a one-chip microcomputer or the like that controls the entire sequence.

FIG. 2A is a diagram showing the external appearance of a camera equipped with the distance measuring device described above. In this camera 10, a finder 11 and a rotatable distance measuring unit 2 are arranged above the taking lens 9 on the front surface of the camera so as to measure the distance of the object in the direction of the arrow. On the top of this camera,
A release button 7 is provided.

FIG. 2B shows a screen 12 of the finder 11.
An example of arrangement of a plurality of distance measuring points 13 provided inside is shown. By moving the scanning mechanism shown in FIG. 1 two-dimensionally by the scanning actuator 5, it becomes possible to move to the arrangement of the distance measuring points as shown in FIG. 2C.

Next, the operation of the distance measuring device constructed as described above will be described with reference to the flow chart shown in FIG.

When the distance measuring direction as shown by the arrow in FIG. 2A is measured while rotating in the θ direction, first, the rotation angle (angle of the distance measuring position) is set to the variable θ = 0. Is initialized (step S1). Next, it is confirmed by an initial position switch (not shown) that the scanning mechanism unit 6 is in the initial position (step S2), and distance measurement is performed (step S).
3).

From the distance measurement result Lθ obtained next and the previous distance measurement position angle θ, the position θ to be measured next is obtained (step S4).

Then, it is judged whether or not the distance measuring position angle θ has reached a predetermined distance measuring angle θ1 (step S
5) When it is determined that the distance measurement angle θ1 has not been reached (NO), the distance measurement unit 2 is scanned to the next distance measurement position angle θ calculated in step S4, and a new distance measurement point is set. Then (step S6), the process returns to step S3. On the other hand, when the determined distance measurement position angle θ reaches the predetermined distance measurement angle θ1 in the determination of step S5 (YES), it is considered to be the main subject from the distance measurement results obtained by a series of scans and distance measurement. A distance is selected and set as Lx (step S7).

Next, based on the selected distance Lx, the focusing section 3 focuses the photographing lens 9 (step S8) and photographs it (step S9). After the end of the photographing, the scan mechanism unit 6 is moved to initialize the scan position (step S10), and the sequence is finished. The above sequence is the arithmetic control circuit (CPU)
1 controls.

Here, in the above-mentioned sequence, although the distance measuring position is initialized in step S10, the initialization confirmation is performed in step S2, for example, when the camera is carried. The confirmation is performed again assuming the case where the digitized position is displaced due to vibration or the like. That is, when the initialized position is deviated and it is not possible to confirm the initialization in step S2, the scanning actuator 5 is driven in the direction opposite to that during distance measurement to initialize the scanning position, and then Step S3
To move to.

Next, the selection of the distance Lx of the main subject in step S7 shown in FIG. 3 will be described with reference to FIG.

FIG. 4B shows a screen in the finder 11 when the distance measurement is performed on, for example, the person 14 present at the position of the distance Lx as shown in FIG. 4A. FIG. 4C shows the relationship between the distance L obtained and the distance L that indicates the distance measuring point when measuring the range of the arrow. In addition, the distance L1 to the person in the distance L1 to the mountain in the background and the distance L2 to the tree
Is obtained between the angles θx.

Generally, the shoulder width W of a person is assumed to be about 40 to 50 cm, although there are individual differences. Therefore, assuming that the shoulder width W, the distance Lx, and the angle θx, there is a relationship of tan θx = W / Lx (1), and the range θx of the distance measuring angle θ indicating the distance Lx is 40 (cm) ≦ Lxtan θx ≦ 50 (cm ) (2), the distance Lx can be determined to be the distance to the person, that is, the main subject.

As described above, the method of determining the distance to the main subject of the distance measuring apparatus in this embodiment is as follows.
To obtain the relationship between the distance measurement angle θ and the distance L shown in FIG. 4C, as shown in FIG. 5A, the distance measurement angle θ is changed at a fine pitch while the distance measurement is performed over time. Must be done.

However, Lx showing the relationship as shown in equation (2)
If it is limited to specify θx and θx, it is possible to shorten the distance measurement time by roughening the pitch as shown in FIG. 5B. For example, to measure the approximate shoulder width W,
A scale with a scale of about 5 cm is sufficient, and a scale on the order of mm is not necessary. Therefore, when measuring the shoulder width in steps of 5 cm, if the distance L is obtained, the next distance measurement point is (1)
From the equation, it is sufficient to set the position where the distance measurement angle is changed by θ obtained as θ = tan ⁻¹ (5 cm / L) (3). As is clear from the equation (3), the closer the obtained L is, the larger θ becomes, and the rough measurement becomes possible.

That is, when the result of distance measurement at the distance measuring point of θ is L, the next distance measuring point should be θ = θ + tan ⁻¹ (5 cm / L) (4) This corresponds to the equation of step S4 in the flowchart of FIG. Further, when two persons having different distances as shown in FIG. 6A are present in the same screen, the change in the distance data L when the distance measuring angle θ is changed is shown in FIG. It becomes like b). FIG. 6C shows an example of a flowchart for determining the focusing distance in this case. However, the width W1 and W2 of two persons is 40 cm.
It is set to -50 cm, but the priority is changed according to the focal length f of the camera taking lens.

First, the focal length f of the camera lens is compared with a predetermined focal length fT (step S2).
1) When the focal length f is on the long focal length side, that is, on the telephoto side with respect to the predetermined focal length fT (YES), the person closer to the center of the screen is prioritized (step S12), and this distance Lx
Select.

However, when the focal length f is closer to the predetermined focal length fT (NO), the person in the center of the screen
It is assumed that the surrounding persons are equally important subjects, and the focus is adjusted to the subject distance on the near distance side where the image magnification is larger (step S13).

Generally, when a photograph is taken using a telephoto lens, the photographer's interest (the subject to be photographed) is
It tends to exist in the center of the screen, but at other times, if a person at a short distance with a large proportion defined on the screen is in focus, it will not be a failed photo, so switch as above. Adopted.

FIG. 7 shows an example of the structure for switching the distance measuring points in consideration of the focal length of the photographing lens.

Due to space limitations and mechanical restrictions when constructing the camera, the camera taking lens 9 is changed from θT to θW as shown in FIG. 7A in accordance with the switching of its focal length. However, it is difficult to make the range θ1 for distance measurement larger than the angle of view.

However, as described above, when the taking lens 9 is on the long focus side, the main subject is rarely present outside the central portion of the screen.

Therefore, as shown in FIG. 7B, the minimum pitch is finely measured in the central portion of the screen and the minimum pitch is roughly measured in the peripheral portion of the screen, so that the time lag can be effectively shortened. it can.

On the other hand, when the taking lens is on the wide angle side,
As shown in FIG. 7C, the distance measuring unit is scanned within the entire distance measuring range θ1 without changing the minimum pitch. When such a change of the scan pitch of the distance measuring unit according to the focal length of the photographing lens is applied to the flowchart of FIG. 3, the operation of step S4 may be changed as shown in the flowchart of FIG.

It is judged whether the setting f of the focal length of the taking lens 9 based on the distance Lθ obtained in step S3 of FIG. 3 is longer or shorter than the predetermined focal length f1 (step S41).

In this determination, when the taking lens 9 is on the long focal point side (YES), the distance measuring angle θ is the angle θ2 of the center of the screen
It is determined whether or not the angle is between θ3 (see FIG. 7B) (step S42), and it is not between the angles θ2 and θ3, that is, (NO) in the area other than the center of the screen, as shown by the equation (3). An angle that results in a coarser pitch than tan ^-1 (20 cm
/ L) is calculated and compared with the first predetermined angle θ01 (step S44). In this determination, when the obtained calculation result is smaller than θ01 (YES), scanning is performed at the pitch of θ01 (step S45). That is, the minimum pitch of the peripheral portion of the screen is determined. However, when the calculation result is larger than θ01 (NO), the distance on the subject is measured at intervals of 20 cm (step S46).

When the taking lens 9 is not on the long focus side in step S41 (NO), and when the distance measurement angle θ is between the angles θ2 to θ3 at the center of the screen in step S42 (YE).
In S), the angle of the following equation, tan ⁻¹ (5 cm / L), is calculated and compared with the second predetermined angle θ02 (step S4).
3). The predetermined angle θ02 is a value smaller than the predetermined angle θ01, and is a value that determines the minimum pitch when the taking lens 9 is on the wide angle side and in the center portion on the telephoto side.

In this comparison, when the second predetermined angle θ02 is larger than the calculation result (YES), scan distance measurement is performed at the minimum pitch (step S48). However, when the second predetermined angle θ02 is smaller than the calculation result (NO), the scan distance measurement is performed at the same pitch as described in the equation (4) (step S47).

Therefore, in this embodiment, in addition to changing the pitch according to the focal length, as a measure against the pitch calculated by the equation (4) being too fine, a predetermined angle θ01,
The minimum pitch is restricted by θ02 or the like.

FIG. 9 shows an example of a specific configuration of the distance measuring device as described above.

In this range finder, an arithmetic control circuit (CPU) 1'comprising a one-chip microcomputer or the like is used.
The functions of the arithmetic control unit 1 and the scan pitch changing unit 4 shown in FIG. The CPU 1'is provided with a switch 7 for starting the distance measurement and a switch 31 for detecting the initial position of the distance measurement angle θ of the distance measuring device.

This distance measuring device is provided with the light emitting / receiving lenses 20, 2
3, infrared light emitting diode (IRED) 21, light position detection element (PSD) 24, IRED driver 22, and P
The AFIC 25 and the like for calculating the SD output are integrally configured and mounted in the unit body 30.

The unit body 30 is connected by a motor 26 controlled by a driver 27 by a gear so as to rotate about a shaft 32. The rotation angle is determined by a signal from the switch 31 that is turned on / off by a lever portion 30a provided outside the unit body 30 and a signal from a gear 29 that is connected to a gear portion 30b of the unit body 30. Entered in.

The signal of the gear 29 is a signal in which a black-and-white pattern is provided on the gear 29 in accordance with the rotation, and the difference in reflectance due to the rotation is detected by the photo reflector 28 in a non-contact manner. The rotation position of the unit main body 30 is detected by the CPU 1 ′ detecting the change in the electric signal of the photo reflector 28 due to the rotation of the gear 29.

Then, the driver 22 is driven by the instruction of the CPU 1 ', and the distance measuring light is projected from the IRED 21 through the light projecting lens 20 toward a subject (not shown). The reflected signal light of the distance measuring light reflected from the subject passes through the light receiving lens 23 and is received by the PSD 24.
Here, the distance (baseline length) S between the principal points of the projection and reception lenses 20 and 23 is fixed, and the object distance L and the signal light incident position x received by the PSD 24 are set by the principle of triangulation.
Has the following relationship with the distance f between the light receiving lens 20 and the PSD 24.

X = s · f / L (5) Here, s · f are both fixed values, and if the AFIC 25 detects the signal light incident position x from the output of the PSD 24,
The subject distance L is obtained by the calculation of the above equation. The PSD 24 outputs two current signals i1 and i2 depending on the signal light incident position x, more specifically, AF.
The IC 25 is a circuit that calculates x from i1 and i2.

With the above configuration, the CPU 1'is
The object distance L is calculated from the output of the AFIC 25 when the IRED 21 emits light, and the motor 26 is operated via the driver 27.
By controlling the rotation of the camera, the distance measurement of the camera and the photographing sequence are performed by the operation described in the flowchart of FIG.

Step S in the flowchart of FIG.
The initial position confirmation of 2 is performed by checking the state of the switch 31, and the scanning to the position of the distance measuring angle θ in step S6 is performed by detecting the number of rotations of the gear 29 having the black-and-white pattern by the photo reflector 28. This is performed while monitoring the angle of the unit body 30.

Next, FIG. 10 shows another example of the specific construction of the distance measuring apparatus according to the present invention.

In the configuration example of FIG. 9 described above, the light projecting section and the light receiving section move integrally, but in this configuration example, only the light projecting section,
That is, by changing the relative relationship between the light projecting element 41 and the light projecting lens 42 with the feed screws 45 and 47, the distance projection light projection position is changed.

The feed screws 45 and 47 are screwdrivers 48.
It is rotated by motors 44 and 46 driven by. The driver 48 is controlled by the CPU 1 '. The number of rotations of the feed screws 45 and 47 is counted by the rotation number monitor circuit 49 and input to the CPU 1.

Therefore, in this configuration, the CPU 1 '
The IRED 41 can be moved in the x- and y-directions, and the distance measuring points can be two-dimensionally set within the screen as shown in FIG. 2 (c).

Further, in order to receive the reflected signal light of the distance measuring light projected in the two-dimensional direction, the light receiving element (PSD) 5
1 has a larger area than the light receiving element (PSD) 24 shown in FIG.

As described above, the distance measuring device of this embodiment can set a large number of distance measuring points at arbitrary positions as compared with the conventional multi-point distance measuring device (multi-AF), and has sufficient accuracy for distance measuring. To be realized. Further, by arranging the distance measuring points at efficient positions, it is possible to shorten the distance measuring time (speed) and to focus with high accuracy.

Further, the present invention is not limited to the above-mentioned embodiment, and it is needless to say that various modifications and applications can be made within the scope not departing from the gist of the invention.

[0058]

As described above in detail, according to the present invention, it is possible to provide a distance measuring device which realizes a short distance measuring time and realizes inexpensive and highly accurate multi-point distance measuring.

[Brief description of drawings]

FIG. 1 is a diagram showing a conceptual configuration of a distance measuring device according to the present invention.

2A is an external view of a camera equipped with the distance measuring device shown in FIG. 1, and FIGS. 2B and 2C are diagrams showing examples of arrangement of distance measuring points.

FIG. 3 is a flowchart for explaining the operation of the distance measuring device shown in FIGS. 1 and 2.

FIG. 4 is a diagram for explaining selection of a distance Lx 1 of the main subject in step S7 of the flowchart of FIG.

FIG. 5 is a diagram showing an arrangement example of distance measuring points.

FIG. 6 is a diagram for describing distance measurement when two persons having different distances are present in the same screen.

FIG. 7 is a diagram for describing distance measuring points at the time of shooting on the telephoto side and the wide-angle side.

FIG. 8 is a flowchart for explaining how to change the scan pitch of the distance measuring unit according to the focal length of the photographing lens.

FIG. 9 is a diagram showing an example of a specific configuration of a distance measuring device according to the present invention.

FIG. 10 is a diagram showing another example of a specific configuration of the distance measuring device according to the present invention.

[Explanation of symbols]

1 ... Arithmetic control unit (CPU) 2. Distance measuring unit 3 ... Focusing section 4 ... Scan pitch change section 5 ... Scan actuator 6 ... Scan mechanism section 7. Release button (switch) 8 ... f (focal length) input section 9 ... Shooting lens 10 ... Camera 11 ... Finder 12 ... Finder screen 13 ... distance measuring point

Claims (2)

(57) [Claims] 1. A longitudinal direction of a screen displayed on a shooting screen in a viewfinder.
A plurality of distance measuring points are disposed in the distance measuring device, and a distance measuring device for a camera that sequentially measures the distance measuring points .
Distance measurement at the periphery of the above array when the focal length is on the telephoto side
The angle of the scan pitch between the points is
Of the scan pitch between the distance measuring points in the center of the above array
Distance measuring point control hand that controls to be wider than the angle
A distance measuring device for a camera having steps, wherein the angle of the scan pitch between the distance measuring points is determined according to the subject distance. 2. The distance measuring device of the camera, wherein when the focal length of the photographing lens at the time of photographing is on the wide angle side, the angle of the scan pitch between the plurality of distance measuring points becomes uniform.
The measurement of the camera according to claim 1, wherein
Distance device.