JP3335424B2 - Distance measuring 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 determining a next light projecting point position according to a distance detected before.

[0002]

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

[0003] For example, in Japanese Patent Application Laid-Open No. 60-60511, focusing is performed on the closest distance among the distance measurement results from a plurality of distance measurement points sequentially measured.
Although a distance measuring device that achieves accurate focusing has been proposed, it is necessary to measure the distance over the entire area of the screen in order to completely eliminate defocus. U.S.A. S. P4
No. 943824 describes a configuration in which distance measuring points are arranged at predetermined regular intervals over the entire area of the photographing screen to measure the distance.

[0004]

However, in the above-described conventional distance measuring device, if all the distance measuring points in the photographing screen are to be measured at the same time, the number of distance measuring sensors increases and the processing circuit becomes large. Is done. In addition, a ranging device that performs multi-point ranging at the same time has a disadvantage that the S / N ratio of a circuit that configures the device is disadvantageous and costs are higher than those of a device that measures the distance in a time-division manner for each ranging point and sequentially. It was well known. For these reasons, the multi-AF type distance measuring apparatus mainly adopts a configuration in which time division is performed for each of the multi-point distance measuring points for each distance measuring point to sequentially measure the distance.

[0005] Such a conventional multipoint distance measuring apparatus (multi-A
In F), the number of distance measurement points was small, and sufficient accuracy for distance measurement could not be obtained. Therefore, in order to further improve the accuracy, even if it is possible to measure more distance measuring points, the distance is measured sequentially for each distance measuring point.
As a result, there has been a problem that the distance measurement time becomes longer and the time lag becomes longer. SUMMARY OF THE INVENTION It is an object of the present invention to provide a distance measuring apparatus which shortens the distance measuring time and realizes inexpensive and highly accurate multi-point distance measuring.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a distance measuring apparatus for sequentially measuring a plurality of points in a photographing screen in accordance with the result of the previous distance measurement. Equipped with interval determining means for determining an interval between the ranging point and the next ranging point, and determined by the interval determining means.
If the previous distance measurement result is a short distance,
Large, small when the previous distance measurement result is a long distance
A distance measuring device to be determined is provided.

[0007]

[0008]

[Function] The photographing screen is obtained by the distance measuring device having the above configuration.
When measuring multiple ranging points in
Interval for measuring distance measurement points (projection pitch of distance measurement light)
The interval determination means determines that the previous distance measurement result is
When the distance measurement is a long distance,
, The interval is determined to be small.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows and describes a conceptual configuration of a distance measuring apparatus according to the present invention. In this distance measuring device, an arithmetic and control unit (CPU) 1 for controlling the whole 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 at the time of focusing is input to the arithmetic and control unit 1 via the f input unit 8. 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. The scan pitch changing unit 4 drives the scan mechanism unit 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 view showing the appearance of a camera equipped with the above-described distance measuring device. In this camera 10, a distance measuring unit 2 that can rotate so that a subject in the direction of an arrow can measure a distance and a finder 11 are arranged above a photographing lens 9 on the front of the camera. On the top of this camera,
A release button 7 is provided.

FIG. 2B shows a screen 12 of the finder 11.
2 shows an example of the arrangement of a plurality of distance measurement points 13 provided in the inside. 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 distance measuring points as shown in FIG. 2C.

Next, the operation of the distance measuring apparatus thus configured will be described with reference to the flowchart shown in FIG. When measuring the distance while rotating in the θ direction in the distance measurement direction indicated by the arrow in FIG. 2A, first, the rotation angle (the angle of the distance measurement position) is initialized by setting the variable θ = 0. (Step S1). Next, it is confirmed by the initial position switch (not shown) that the scanning mechanism 6 is at the initial position (step S2), and the distance is measured (step S3).

Next, a position θ to be measured next is obtained from the obtained distance measurement result Lθ and the previous distance measurement position angle θ (step S4). Then, it is determined whether or not the distance measuring position angle θ has reached a predetermined distance measuring angle θ ₁ (step S5). If it is determined that the distance measuring angle θ ₁ has not reached (NO), The ranging unit 2 is scanned at the next ranging position angle θ calculated in step S4, a new ranging point is set (step S6), and the process returns to step S3.

On the other hand, if it is determined in step S5 that the obtained distance measuring position angle θ reaches the predetermined distance measuring angle θ ₁ , (YE
S), a series of scans, select the distance that would main object distance measurement result obtained by the distance measurement, and L _x (step S7).

[0015] Next, 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 end of the photographing, the scanning mechanism 6 is moved to initialize the scanning position (step S10), and the sequence ends. The above sequence is the operation control circuit (CPU)
1 controls.

Here, in the above-described sequence, the initialization is confirmed in step S2 despite the fact that the distance measurement position is initialized in step S10. In this case, the confirmation is performed again assuming a case where the transformed 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 scan actuator 5 is driven in the opposite direction to that during distance measurement to initialize the scan position, Step S3
To move to

[0017] Next, with reference to FIG. 4, the selection of the distance L _x of the main subject will be described in the step S7 shown in FIG. 4 with respect to e.g. a person 14 exists in the position of the distance L _x (a), the 4 shown in (b) the screen of the finder 11 in the case of performing distance measurement. FIG. 4C shows the relationship between the distance measurement angle θ indicating the distance measurement point and the obtained distance L when measuring the distance in the range of the arrow. In addition, the distance L ₁ to the mountain in the background, the distance L _x of to the person in the distance L ₂ to the tree,
Obtained between the angles θ _x .

Generally, it is assumed that the shoulder width W of a person varies from individual to individual, but is about 40 to 50 cm. Therefore, the shoulder width W, the distance _{L x,} when the angle _{θ x, tanθ x = W /} L x ... have a relationship of (1), the range of the distance measuring angle theta indicating the distance _{L x} theta _x
But if the relationship of _{40 (cm) ≦ L x tan} θ x ≦ 50 (cm) ... (2), the distance _{L x} can be determined person, i.e. the distance to the main subject.

As described above, the method of determining the distance to the main subject of the distance measuring apparatus in the present embodiment is as follows. To obtain the relationship between the distance measuring angle θ and the distance L shown in FIG.
As shown in FIG. 5A, at a fine pitch, the ranging angle θ
The distance must be measured over time while changing the distance.

However, L _x indicating the relationship as shown in equation (2)
If it is limited to specifying θ and θ _x , as shown in FIG. 5B, the pitch can be made wider and the distance measurement time can be shortened. For example, to measure the approximate shoulder width W,
A scale with a scale of about 5 cm may be used, and a scale of mm order is not required. Therefore, when measuring the shoulder width in increments of 5 cm, if the distance L is obtained, the next ranging point is (1)
From the formula, θ = arctan (5 cm / L) (3) It is sufficient to set the position at which the angle of the distance measurement is shifted by θ obtained as follows. As is apparent from the equation (3), the closer the obtained L is, the larger the value of θ becomes, and coarse measurement becomes possible.

That is, when the distance measured at the distance measuring point of θ is L, the next distance measuring point may be θ = θ + arctan (5 cm / L) (4). Corresponds to the equation of step S4 in the flowchart of FIG.

When two persons having different distances as shown in FIG. 6A are present on the same screen, the distance measurement angle θ
FIG. 6 shows how the distance data L changes when
(B). FIG. 6C shows an example of a flowchart for determining the focusing distance in this case. However, the width W of the two persons _1, W ₂ both, 40cm~50
cm, but depending on the focal length f of the camera taking lens,
Changed the priority.

[0023] First, comparing the predetermined: focal length f _T determined in advance and the focal length f of the camera lens (Step S 1
2), given: focal length f _T than the focal length f is long focal length side, i.e. when in the telephoto side is given priority (YES), towards the person close to the center of the screen (step S14), and the distance L
Select _x .

However, when the focal length f is closer than the predetermined focal length f _T (NO), the person at the center of the screen is
The surrounding persons are assumed to be equally important subjects, and the focus is adjusted to the subject distance on the short distance side with a higher image magnification (step S13).

Generally, when photographing using a telephoto lens, the photographer's interest (the subject to be photographed) is
It tends to be in the center of the screen, but at other times, if a close-range person with a large percentage defined in the screen is in focus, it is unlikely to be a failed photo. Adopted.

FIG. 7 shows a configuration example of switching of the distance measuring points in consideration of the focal length of the photographing lens. Due to space limitations and mechanical limitations when configuring the camera, the camera taking lens 9 can be changed from θ _T to θ _W as shown in FIG. also, it is difficult to increase the range theta ₁ ranging over angle.

However, as described above, when the taking lens 9 is on the long focal length side, a main subject rarely exists other than at the center of the screen. Therefore, as shown in FIG. 7 (b), the time lag can be efficiently shortened by finely measuring the minimum pitch at the center of the screen and coarsely measuring the minimum pitch at the periphery of the screen.

On the other hand, when the taking lens is on 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 based on the focal length of the photographing lens is applied to the flowchart in FIG. 3, the operation in step S4 may be changed as in the flowchart in FIG.

The 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 S4
1). In this determination, when the taking lens 9 is on the long focus side (Y
ES), the ranging angle θ is the angle θ2 to θ3 at the center of the screen.
(Refer to FIG. 7B) (step S42). If the angle is not between the angles θ2 and θ3, that is, if it is other than the center of the screen (NO), it is expressed by the equation (3). An angle, arctan (20 cm / L), which makes the pitch coarser than that, is calculated and compared with a first predetermined angle θ01 (step S44). In this determination, the obtained calculation result is θ01
If smaller (YES), scanning is performed at a 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).

Further, when the photographing lens 9 is not on the long focal length side in step S41 (NO), and when the distance measuring angle θ is between the angles θ _{2 and} θ _{3 at} the center of the screen (YE) in step S42.
In S), the angle of the following equation, arctan (5 cm / L), is calculated and compared with the second predetermined angle θ ₀₂ (step S).
43). The predetermined angle θ ₀₂ is larger than the predetermined angle θ ₀₁ by:
This is a small value, which is a value that determines the minimum pitch at the time when the photographing lens 9 is on the wide angle side and at the center on the telephoto side.

In this comparison, when the second predetermined angle θ ₀₂ is larger than the calculation result (YES), scan distance measurement with the minimum pitch is performed (step S48). However, when the second predetermined angle θ ₀₂ is smaller than the calculation result (NO), scan distance measurement is performed at the same pitch as described in the above equation (4) (step S47).

Therefore, in the present embodiment, in addition to the pitch change based on the focal length, as a countermeasure when the pitch calculated by the equation (4) is too fine, predetermined angles θ ₀₁ and θ _{02 are set.}
Etc., the minimum pitch is restricted.

FIG. 9 shows an example of a specific configuration of the distance measuring apparatus as described above. In this distance measuring device, an arithmetic control circuit (CPU) 1 'composed of a one-chip microcomputer or the like is responsible for the operation 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 an initial position of the distance measurement angle θ of the distance measurement device.

The distance measuring device includes light emitting and receiving lenses 20, 2
3, infrared light emitting diode (IRED) 21, light position detecting element (PSD) 24, IRED driver 22, and P
The AFIC 25 for calculating the SD output and the like are integrally formed and mounted in the unit main body 30.

The unit main 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 angle of this rotation is determined by the CPU 1 ′ based on a signal from the switch 31 which is turned on / off by a lever portion 30 a provided outside the unit main body 30 and a signal from the gear 29 connected to the gear portion 30 b of the unit main body 30. Is input to

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 photoreflector 28 in a non-contact manner. The rotation position of the unit main body 30 is detected by the CPU 1 ′ detecting a change in an electric signal of the photoreflector 28 accompanying the rotation of the gear 29.

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 the 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 (base line length) S between the principal points of the projecting and receiving lenses 20 and 23 is fixed, and the subject distance L and the incident position x of the signal light received by the PSD 24 are determined by the principle of triangulation.
Satisfies the following relationship with the distance f between the light receiving lens 20 and the PSD 24.

X = s · f / L (5) Here, both s · f are 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 from the calculation of the above equation. The PSD 24 outputs two current signals i ₁ and i ₂ depending on the signal light incident position x.
The IC 25 is a circuit that calculates x from i ₁ and i ₂ .

With the above configuration, the CPU 1 '
While calculating the subject distance L from the output of the AFIC 25 when the IRED 21 emits light, the motor 26
By controlling the rotation of the camera, the distance measurement and the photographing sequence of the camera 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 ranging 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 a specific configuration of the distance measuring apparatus according to the present invention, which will be described. FIG. 9 described above.
In the example of the configuration, the light projecting unit and the light receiving unit move integrally, but in this example of the configuration, only the light projecting unit,
By changing the relative relationship between the lens and the light projecting lens 42 using the feed screws 45 and 47, the light projection position for distance measurement is changed.

The feed screws 45 and 47 are connected to a driver 48
The motor is rotated by motors 44 and 46 driven by the motor. The driver 48 is controlled by the CPU 1 '. The rotation speeds of the feed screws 45 and 47 are counted by the rotation speed monitor circuit 49 and input to the CPU 1.

Therefore, in this configuration, the CPU 1 '
By controlling the IRED 41, the IRED 41 can be moved in the x and y directions, and a distance measuring point can be set two-dimensionally on the screen as shown in FIG.

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
No. 1 uses a light receiving element (PSD) 24 having a larger area than the light receiving element (PSD) 24 shown in FIG.

As described above, the distance measuring apparatus according to the present embodiment can set a larger number of distance measuring points to arbitrary positions than the conventional multi-point distance measuring apparatus (multi-AF), and has sufficient accuracy for distance measuring. Realize. Further, by arranging the distance measuring points at an efficient position, the distance measuring time can be shortened (speeded up) and the focusing can be performed with high accuracy. In addition, the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications and applications are possible without departing from the spirit of the invention.

[0046]

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

[Brief description of the drawings]

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

2 (a) shows the appearance of a camera equipped with the distance measuring device shown in FIG. 1, and FIGS. 2 (b) and 2 (c) show examples of the arrangement of distance measuring points.

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

4 is a diagram illustrating the selection of a distance L _x of the main subject in step S7 in the flowchart of FIG.

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

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

FIG. 7 is a diagram for explaining distance measurement points in photographing on the telephoto side and the wide-angle side.

FIG. 8 is a flowchart illustrating a change of a scan pitch of a distance measuring unit according to a focal length of a 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 apparatus according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Calculation control part (CPU), 2 ... Distance measuring part, 3 ... Focusing part, 4 ... Scan pitch change part, 5 ... Scan actuator, 6 ... Scan mechanism part, 7 ... Release button (switch), 8 ... f (focal length) input unit, 9: photographing lens, 10: camera, 11: finder, 12: finder screen, 13: distance measuring point.

Claims (1)

(57) [Claims] 1. A distance measuring apparatus for sequentially measuring a plurality of points in a photographing screen, wherein an interval between the previous distance measuring point and the next distance measuring point is determined according to a result of the previous distance measuring. It includes a interval determination means
And, intervals determined by the interval determining means, for the previous
When the result of distance measurement is close, the distance is large.
A distance measuring device, which is small when the result is a long distance.