JP3794982B2 - Ranging device - Google Patents

Description

[0001]
BACKGROUND 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 that determines a next light projection point position according to a previously detected distance.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, when shooting with a camera, there is a camera that measures a plurality of points on the screen so that accurate focusing can be performed even when the subject is not located at the center of the shooting screen.
[0003]
For example, in Japanese Patent Application Laid-Open No. 60-60511, a distance measuring device that achieves accurate focusing by focusing on the closest distance among distance measurement results from a plurality of distance measuring points that are sequentially measured. However, in order to completely eliminate the focus error, it is necessary to measure the distance over the entire area of the screen.
[0004]
In addition, U.S. S. P4943824 describes a configuration in which distance measurement points are arranged at predetermined equal intervals over the entire area of the shooting screen.
[0005]
[Problems to be solved by the invention]
However, in the above-described conventional distance measuring device, when the distance is measured over the entire area of the screen, the background other than the person who is the main subject may be in focus, and the main subject can be detected appropriately. I could not.
[0006]
Therefore, an object of the present invention is to provide a distance measuring device that can perform distance measurement at high speed and with high accuracy .
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a photographing optical system, distance measuring means for sequentially measuring a plurality of points in a photographing screen at predetermined intervals, and a focal length at the time of photographing by the photographing optical system. Interval determining means for determining an interval between the previous distance measuring point and the next distance measuring point, and the distance determining means is configured to measure the distance when the focal length of the photographing optical system is on the telephoto side. The distance is determined based on the result of the previous distance measurement according to the position of the point previously measured by the distance means in the shooting screen, and when the focal length of the shooting optical system is on the wide angle side, A distance measuring device that determines the interval based on the distance measurement result is provided.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0010]
FIG. 1 shows a conceptual configuration of a distance measuring device according to the present invention.
[0011]
In this distance measuring apparatus, an arithmetic control unit (CPU) 1 that controls the entire system drives the focusing unit 3 based on the distance measurement value obtained by the distance measuring unit 2 to focus the photographing lens 9. The focal length f when the subject is in focus is input to the arithmetic control unit 1 via the f input unit 8. Further, when the position of the distance measuring point 13 as shown in FIG. 2B described later is changed to the position of the distance measuring point as shown in FIG. 2C, the calculation control unit 1 changes the scan pitch changing unit. 4 is input, and the scan pitch changing unit 4 drives the scan mechanism unit 6 by the scanning actuator 5. The arithmetic control unit 1 is a circuit composed of a one-chip microcomputer or the like that controls the entire sequence.
[0012]
FIG. 2A is a diagram illustrating an appearance of a camera equipped with the above-described distance measuring device. In this camera 10, a distance measuring unit 2 and a viewfinder 11 that can be rotated so that a subject in the direction of the arrow can measure a distance are disposed above the photographing lens 9 on the front side of the camera. A release button 7 is provided on the upper surface of the camera.
[0013]
FIG. 2B shows an arrangement example of a plurality of distance measuring points 13 provided in the screen 12 of the finder 11. By moving the scanning mechanism shown in FIG. 1 two-dimensionally by the scanning actuator 5, it is possible to move to the arrangement of distance measuring points as shown in FIG.
[0014]
Next, the operation of the distance measuring apparatus configured as described above will be described with reference to the flowchart shown in FIG.
[0015]
When the distance measurement direction as indicated by the arrow in FIG. 2A is rotated in the θ direction, the rotation angle (angle of the distance measurement position) is first initialized with the variable θ = 0. (Step S1). Next, it is confirmed by an initial position switch (not shown) that the scanning mechanism section 6 is in the initial position (step S2), and distance measurement is performed (step S3).
[0016]
Next, the position θ to be measured next is obtained from the distance measurement result Lθ obtained and the previous distance measurement position angle θ (step S4).
[0017]
Then, it is determined whether or not the distance measurement position angle θ has reached a predetermined distance measurement angle θ ₁ (step S5), and when it is determined that the distance measurement angle θ ₁ has not been reached (NO), The distance measuring section 2 is scanned at the next distance measuring position angle θ calculated in step S4, a new distance measuring point is set (step S6), and the process returns to step S3. On the other hand it is determined in step S5, when the distance measurement position angle theta obtained reaches a predetermined range finding angle theta ₁ is (YES), a series of scans, consider a main object distance measurement result obtained by the distance measurement The selected distance is selected as L _x (step S7).
[0018]
Then based on the selected distance L _x, the focusing unit 3, focusing of the taking lens 9 is performed (step S8), and is captured (step S9). After the photographing is finished, the scanning mechanism unit 6 is moved to initialize the scanning position (step S10), and the sequence is finished. The above sequence is controlled by the arithmetic control circuit (CPU) 1.
[0019]
Here, in the above-described sequence, although the distance measurement position is initialized in step S10, initialization is confirmed in step S2, for example, when the camera is being carried. The confirmation is performed again assuming that the position is shifted due to vibration or the like. In other words, when the initialized position is shifted and the initialization in step S2 cannot be confirmed, the scanning actuator 5 is driven in the opposite direction to that during distance measurement, the scan position is initialized, and the next The process proceeds to step S3.
[0020]
Referring now to FIG. 4, the selection of the distance L _x of the main subject will be described in the step S7 shown in FIG.
[0021]
FIG. 4B shows a screen in the finder 11 when distance measurement is performed on, for example, the person 14 existing at the position of the distance L _x as shown in FIG. FIG. 4C shows the relationship between the distance measurement angle θ indicating the distance measurement point and the distance L obtained when measuring the range of the arrow. The distance L _x to a person in the distance L _1, the distance to trees L ₂ to the mountain of the background is obtained between the angle theta _x.
[0022]
Generally, the shoulder width W of a person is assumed to be about 40 to 50 cm, although there are individual differences. Therefore, if shoulder width W, distance L _x , and angle θ _x are given,
tan θ _x = W / L _x (1)
The have a relationship, the distance L range of the distance measuring angle theta showing the _x theta _x is,
40 (cm) ≦ L _x tan θ _x ≦ 50 (cm) (2)
In this relationship, the distance L _x can be determined as the distance to the person, that is, the main subject.
[0023]
As described above, the distance determination method according to the present embodiment is a method for determining the distance to the main subject. In order to obtain the relationship between the distance measurement angle θ and the distance L shown in FIG. As shown in a), it is necessary to perform distance measurement over a long time while changing the distance measurement angle θ at a fine pitch.
[0024]
However, if it is limited to specifying L _x and θ _x indicating the relationship as in the equation (2), the pitch is increased as shown in FIG. 5B to shorten the distance measurement time. be able to. For example, in order to measure an approximate shoulder width W, a scale with a scale of about 5 cm may be used, and a scale with a mm order 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
θ = arctan (5 cm / L) (3)
As long as θ is obtained, the position of the distance measurement may be changed. As is clear from the equation (3), the closer the obtained L is, the larger the θ becomes, and a rough measurement becomes possible.
[0025]
In other words, when the result of distance measurement at the distance measurement point of θ is L, the next distance measurement point is
θ = θ + arctan (5 cm / L) (4)
This equation corresponds to the equation of step S4 in the flowchart of FIG.
Further, when two persons having different distances as shown in FIG. 6A exist in the same screen, the change in the distance data L when the distance measuring angle θ is changed is as 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 widths W ₁ and W _{2 of the two} persons are 40 cm to 50 cm, but the priority is changed according to the focal length f of the camera photographing lens. First, compared with the predetermined: focal length f _T determined in advance and the focal length f of the camera lens (step S12), the predetermined: focal length f _T than the focal length f is long focal length side, i.e. when in the telephoto side (YES), priority is given to the person closer to the center of the screen (step S14), and this distance _Lx is selected.
[0026]
However, when a predetermined: focal length f _T than the focal length f is on the short distance side and (NO), the center of the screen of the person, the peripheral of the person, as important, assuming the subject, large more image magnification The subject distance on the short distance side is focused (step S13).
[0027]
In general, when shooting using a telephoto lens, the photographer's interest (the subject to be shot) tends to be in the center of the screen, but at other times, the ratio of the ratio set in the screen Since it is difficult for a photograph to be a failure if it is in focus on a large close-up person, the above switching is adopted.
[0028]
Further, FIG. 7 shows a configuration example of switching of the distance measuring point in consideration of such a photographing lens focal length.
[0029]
Due to space limitations and structural limitations when configuring the camera, the camera photographing lens 9 can be changed from θ _T to θ _W according to the switching of the focal length, as shown in FIG. However, it is difficult to make the distance measurement range θ ₁ larger than the angle of view.
[0030]
However, as described above, when the photographic lens 9 is on the long focal side, there are few main subjects other than the center of the screen.
[0031]
Therefore, as shown in FIG. 7B, the time lag can be shortened efficiently by finely measuring the minimum pitch in the center of the screen and roughly measuring the minimum pitch in the periphery of the screen.
[0032]
On the other hand, when the photographing lens is at the wide-angle side, as shown in FIG. 7 (c), among all the distance measurement range theta _1, so as to scan the distance measuring unit without changing the minimum pitch. When such a change in 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.
[0033]
Focal length setting f of the imaging lens 9 based on the obtained distance Lθ in step S3 in FIG. 3 determines whether longer or shorter than the predetermined focal length f _t (step S41).
[0034]
In this determination, when the photographing lens 9 is on the long focal side (YES), it is determined whether or not the distance measuring angle θ is between the angles θ _{2 to} θ _{3 in} the center of the screen (see FIG. 7B). (Step S42), which is not between the angles θ _{2 to} θ ₃ , that is, other than the center portion of the screen (NO), an angle that gives a coarser pitch than the case expressed by the expression (3),
arctan (20cm / L)
Is calculated and compared with the first predetermined angle θ ₀₁ (step S44). In this determination, when the obtained calculation result is smaller than θ ₀₁ (YES), scanning is performed at a pitch of θ ₀₁ (step S45). That is, the minimum pitch at the periphery of the screen is determined. But when the calculated result is greater than theta ₀₁ (NO), the to distance measurement on the subject at intervals of 20 cm (step S46).
[0035]
When the photographing lens 9 is not on the long focus side in step S41 (NO), and when the distance measuring angle θ is between the angles θ _{2 to} θ _{3 in} the center of the screen (YES) in step S42, The angle of the expression,
arctan (5cm / L)
Is calculated and compared with the second predetermined angle θ ₀₂ (step S43). The predetermined angle θ ₀₂ is smaller than the predetermined angle θ ₀₁ , and is a value that determines the minimum pitch at the center portion on the telephoto side when the photographing lens 9 is on the wide angle side.
[0036]
In this comparison, when the second predetermined angle theta ₀₂ is greater than the calculated result (YES), the scan distance measurement with a minimum pitch is performed (step S48). But when the second predetermined angle theta ₀₂ is smaller than the calculated result (NO), the (4) scanning the distance measuring at the same pitch as described in formula is performed (step S47).
[0037]
Therefore, in this embodiment, in addition to changing the pitch depending on the focal length, as a countermeasure when the pitch calculated by the equation (4) is too fine, the minimum pitch is limited by a predetermined angle θ ₀₁ , θ ₀₂ or the like. It has been broken.
[0038]
FIG. 9 shows an example of a specific configuration of the distance measuring apparatus as described above.
[0039]
In this distance measuring apparatus, an arithmetic control circuit (CPU) 1 ′ composed of a one-chip microcomputer or the like, which controls 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 distance measurement and a switch 31 for detecting the initial position of the distance measuring angle θ of the distance measuring device.
[0040]
This distance measuring device is configured integrally with light projecting / receiving lenses 20, 23, an infrared light emitting diode (IRED) 21, a light position detecting element (PSD) 24, an IRED driver 22, an AFIC 25 for calculating PSD output, and the like. It is mounted in the unit main body 30.
[0041]
The unit main body 30 is connected by a gear so as to rotate about a shaft 32 by a motor 26 controlled by a driver 27. The rotation angle is determined by the CPU 1 ′ by a signal from the switch 31 that is turned on / off by a lever portion 30 a provided outside the unit main body 30 and a signal from the gear 29 that is connected to the gear portion 30 b of the unit main body 30. Is input.
[0042]
The signal of the gear 29 is a signal in which a black and white pattern is provided on the gear 29 according to the rotation, and the difference in reflectance due to the rotation is detected by the photo reflector 28 in a non-contact manner. When the CPU 1 ′ detects a change in the electrical signal of the photo reflector 28 accompanying the rotation of the gear 29, the rotational position of the unit body 30 is detected.
[0043]
Then, the driver 22 is driven by the command 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 ranging 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 light projecting and light receiving lenses 20 and 23 is constant, and the subject distance L and the signal light incident position x received by the PSD 24 are received by the principle of triangulation. The following relationship is established between the distance 20 between the lens 20 and the PSD 24.
[0044]
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 can be obtained from the calculation of the above-described equation. The PSD 24 outputs two current signals i ₁ and i ₂ depending on the signal light incident position x. More specifically, the AFIC 25 is a circuit that calculates x from i ₁ and i ₂ .
[0045]
With the above-described configuration, the CPU 1 ′ calculates the subject distance L from the output of the AFIC 25 when the IRED 21 emits light, and controls the rotation of the motor 26 via the driver 27, whereby the operation described in the flowchart of FIG. To perform camera distance measurement and shooting sequence.
[0046]
The initial position confirmation in step S2 in the flowchart of FIG. 3 is performed by checking the state of the switch 31, and the scan to the position of the distance measuring angle θ in step S6 is performed by rotating the gear 29 having a monochrome pattern by the photo reflector 28. This is performed while monitoring the angle of the unit body 30 by detecting the number.
[0047]
Next, FIG. 10 shows another example of a specific configuration of the distance measuring apparatus according to the present invention.
[0048]
In the configuration example of FIG. 9 described above, the light projecting unit and the light receiving unit are moved as a unit. By changing at 47, the ranging light projection position is changed.
[0049]
The feed screws 45 and 47 are rotated by motors 44 and 46 driven by a driver 48. The driver 48 is controlled by the CPU 1 '. The rotation speeds of the feed screws 45 and 47 are counted by a rotation speed monitor circuit 49 and input to the CPU 1.
[0050]
Therefore, in this configuration, the IRED 41 can be moved in the x and y directions under the control of the CPU 1 ', and the distance measurement points can be set two-dimensionally within the screen as shown in FIG. 2 (c). ing.
[0051]
Further, in order to receive the reflected signal light of the ranging light projected in a two-dimensional direction, the light receiving element (PSD) 51 has a larger area than the light receiving element (PSD) 24 shown in FIG. I use something.
[0052]
As described above, the distance measuring device of the present embodiment can set a larger number of distance measuring points at arbitrary positions than the conventional multi-point distance measuring device (multi AF), and realizes sufficient accuracy for distance measurement. Further, by arranging the distance measuring points at an efficient position, the distance measurement time can be shortened (speeded up) and the focus can be adjusted with high accuracy.
[0053]
Further, the present invention is not limited to the above-described embodiments, and various modifications and applications can be made without departing from the scope of the invention.
[0054]
【The invention's effect】
As described above in detail, according to the present invention, it is possible to provide a distance measuring device that can perform distance measurement at high speed and with high accuracy .
[Brief description of the 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 an example of arrangement of distance measuring points.
FIG. 3 is a flowchart for explaining the operation of the distance measuring apparatus shown in FIGS. 1 and 2;
4 is a diagram for describing selection of a distance L _x of a main subject in step S7 in the flowchart of FIG. 3;
FIG. 5 is a diagram illustrating an example of arrangement of distance measurement points.
FIG. 6 is a diagram for explaining distance measurement when two persons having different distances exist in the same screen.
FIG. 7 is a diagram for explaining distance measuring points at the time of shooting on the telephoto side and the wide-angle side.
FIG. 8 is a flowchart for explaining the change of the scan pitch of the distance measuring unit according to the photographing lens focal length;
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 a distance measuring device according to the present invention.
[Explanation of symbols]
1. Calculation control unit (CPU)
2. Distance measuring unit 3 Focusing unit 4 Scan pitch changing unit 5 Scanning actuator 6 Scan mechanism unit 7 Release button (switch)
8 ... f (focal length) input unit 9 ... taking lens 10 ... camera 11 ... finder 12 ... finder screen 13 ... ranging point

Claims (5)

Photographic optics,
Distance measuring means for sequentially measuring a plurality of points in the shooting screen at predetermined intervals;
And interval determining means for determining the distance between the last time distance measurement point and the next distance measurement points,
Equipped with,
When the focal length of the photographing optical system is on the telephoto side, the interval determining means is based on the result of the previous distance measurement according to the position of the point measured by the distance measuring means in the photographing screen. A distance measuring apparatus, wherein the distance is determined, and when the focal length of the photographing optical system is on the wide angle side, the distance is determined based on the previous distance measurement result . When the focal length of the imaging optical system is on the telephoto side and the point previously measured by the distance measuring unit is in the peripheral area in the imaging screen, the interval determining unit is The distance measuring apparatus according to claim 1, wherein the distance is determined by comparing a first distance determined based on an output with a predetermined second distance. The interval determining means determines the second interval as the interval when the first interval is smaller than the second interval, and the first interval is larger than the second interval. In this case, the distance measuring device according to claim 2 , wherein the first interval is determined as the interval . The distance determining means is the distance measuring means when the focal length of the photographing optical system is on the wide-angle side or the point previously measured by the distance measuring means is in the central area in the photographing screen. A third interval that is determined based on the output of the first interval and is smaller than the first interval, and a fourth interval that is predetermined and smaller than the second interval; The distance measuring apparatus according to claim 1 , wherein the distance is determined by comparing the two . The interval determination means determines the fourth interval as the interval when the third interval is smaller than the fourth interval, and the third interval is larger than the fourth interval. In this case, the distance measuring device according to claim 4 , wherein the third interval is determined as the interval .

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