JP3429547B2 - 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 distance measuring device for projecting distance measuring light onto a subject and detecting the reflected signal light position thereof to determine the focusing distance of a camera.

[0002]

2. Description of the Related Art Conventional cameras have conventionally been capable of projecting distance measuring light onto only a part of the screen, so that it is possible to focus only on a subject within the range where the light is projected. It was (missing out). On the other hand, distance-measuring light is sequentially projected to a plurality of points on the screen, and as shown in FIG. 14A, for example, a subject not present in the central portion of the screen can be correctly focused. Various techniques configured as described above have been proposed.
The technology disclosed in Japanese Patent Publication No. 201015 is known as one example (multi-AF).

On the other hand, as a technique for improving the accuracy of distance measurement at one point with the increase in the focal length of the camera lens, the number of times of distance measurement is changed as in the technique disclosed in Japanese Patent Application Laid-Open No. 63-132110 by the present applicant. A method of increasing the number is known (multiple projections).

However, both the increase in the number of distance measurements and the increase in the number of distance measurement points tend to lengthen the distance measurement time (time lag increase), and there has been a demand for a technique for solving the problem.

Therefore, the applicant of the present application has filed Japanese Patent Application Laid-Open No. 2-1587.
According to Japanese Patent Laid-Open No. 05, the distance between each point is measured in advance with a short distance and a rough accuracy, and after determining the position of the main subject, the distance can be measured with high accuracy over a long distance. Then, I proposed the technology to take measures against time lag.

In the above-mentioned Japanese Patent Application Laid-Open No. 58-201015, the same number of light projecting elements as the number of light projecting points (distance measuring points) are required. In the technique disclosed in Japanese Patent Publication No. 324807, etc., the light projecting direction of one light projecting element is switched,
It enables distance measurement of more points, reduces costs and increases the number of distance measurement points.

On the other hand, if the number of distance measuring points is increased, it is possible to take a so-called "middle-out" measure in a scene as shown in FIG. 14 (a), and it becomes possible to focus on a person. However, conversely, there is a person in a relatively distant place in the center, for example, in a scene as shown in FIG. 14B, the person in the foreground is in focus, and the person in the center cannot be focused. There was a strong tendency to have side effects.

In view of this, Japanese Patent Laid-Open No. 4-212136 discloses a technique in which a spot mode or a one-point AF mode is set with another button, and only the central object can be measured when the mode is set. Has been done. And, if such a mode is provided, FIG.
Even in the scenes shown in, you can more reliably perform the operation by placing a person in the center of the screen in advance and pressing the release button halfway down, changing the composition and pushing the release (hereinafter referred to as focus lock and focus memory). There was an advantage that the person could be focused. Needless to say, a troublesome mode setting is required prior to such an operation.

[0009]

However, in the scan-type multi-AF capable of projecting light, such as the above-mentioned Japanese Patent Laid-Open No. 4-324807, there are a plurality of projection points when the above-mentioned multiple projection techniques are combined. It was necessary to stop the movable part at each distance measuring point so as not to move during the distance measurement of the light projection.

Further, also in the above-mentioned Japanese Patent Laid-Open No. 4-212136, the shape of the cam is devised so that the projection point does not move during the distance measurement of one point. However, even if the actuator is continuously moved and the movement of the cam is repeated depending on the shape of the cam, deceleration is likely to occur at the start of the movement from the stopped state, and the method is not disclosed.
JP-A-212136 discloses a system in which light projection and light reception are integrally moved. Therefore, the size of the device is increased, and the movable part is large, which makes it difficult to increase the speed. Further, since the movable part is large, there is a noise problem during scanning.

On the other hand, as mentioned above, Japanese Patent Laid-Open No. 4-2121
According to Japanese Patent Laid-Open No. 36-36, in the scene of FIG. 14B, a one-point distance measuring mode can be set which gives priority to the distance measuring result in the central portion of the screen, but the present invention does not require such a mode setting button and is simple. The scenes shown in FIGS. 14A and 14B can be handled by operation.

The present invention has been made in view of the above problems, and an object of the present invention is to reduce the size, speed, and noise of the movable part because the movable part is only the light projecting part.
In addition, the multi-AF is performed when the release button is pressed, and the distance can be measured only in the center of the screen when the release button is half-pressed, so that the AF corresponding to the scene as shown in FIG. 14B is achieved.

Further, even in a scene where no subject exists in the center of the screen, it is possible to focus at high speed and with low noise, and it is possible to perform high-precision focusing on the subject in the center of the screen. It is possible to provide a camera with a simple structure and energy saving design. Further, a small improvement of the present invention is to enable focusing corresponding to a moving subject, that is, a moving body.

[0014]

In order to achieve the above object, in the distance measuring device according to the first aspect of the present invention, a first switch for detecting the middle of pressing the release button and the end of pressing the release button are set. Switch means including a second switch for detecting, distance measuring means for performing distance measurement at a plurality of points within the photographing screen, determining means for determining a focusing distance based on the distance measurement results at the plurality of points, And a determining means for detecting that the switch 1 has been repeatedly operated, wherein the determining means adjusts the focus according to the detection result of the detecting means and the distance measuring result of the center portion of the photographing screen by the distance measuring means. Characterized by determining the distance. In the distance measuring device according to the second aspect, the distance measuring means is
In response to the first switch, distance measurement is performed
The stage is focused based on the distance measurement result in the center of the shooting screen.
When determining the distance, in the last shooting screen
The distance measurement result in the center and the distance measurement result in the center of the shooting screen obtained last time
When the result is compared and the two values are similar,
Determines the focusing distance based on the distance measurement result at the center of the surface
Characterized in that that. In the distance measuring device according to the third aspect,
The first switch that detects the release button being pressed
And a second switch that detects the end of pressing the release button.
Switch, including a switch, and distance measurement at the center of the shooting screen
The first distance measuring means for performing
Second distance measuring means for performing distance measurement and operation of the first switch
In the working state, the first distance measuring means is activated, and the second distance measuring means is operated.
When the switch is operating, the second distance measuring means is activated.
And a control means for controlling. Fourth state
In the distance measuring device according to the above, the first distance measuring means is
It is characterized by performing a distance measurement with higher accuracy than the distance measuring means of No. 2.
It

[0015]

[0016]

[0017]

In the distance measuring device according to the first aspect of the present invention, the first switch of the switch means detects that the release button is being pressed, and the second switch detects that the release button has been pressed. The distance measuring means measures the distances of a plurality of points in the photographing screen, and the determining means determines
The focusing distance is determined based on the distance measurement results of the plurality of points. The detection means detects that the first switch has been repeatedly operated. Then, in particular, the determining unit determines the focusing distance based on the result of the distance measurement of the center portion of the photographing screen by the distance measuring unit according to the detection result of the detecting unit. In the distance measuring device according to the second aspect, the distance measuring means responds to the first switch.
Distance measurement is performed, and the above-mentioned determination means causes the center of the shooting screen to
To determine the focusing distance based on the distance measurement result
In this case, the last distance measurement result obtained in the center of the shooting screen and
The distance measurement results obtained at the center of the captured image are compared and
If the people have similar values, the distance measurement connection in the center of the above-mentioned shooting screen
The focusing distance is determined based on the result. Third aspect
In the distance measuring device according to
The middle of pressing the release button is detected and the second switch is detected.
Button detects that the release button has been pressed.
It The first distance measuring means can measure the distance in the center of the shooting screen.
The second distance measuring means is used to make a plurality of points in the photographing screen.
And the first switch is operated by the control means.
In the operating state of, the first distance measuring means is activated and the first distance measuring means is operated.
The second distance measuring means operates when the switch 2 is in the operating state.
To be done. In the distance measuring device according to the fourth aspect,
The distance measuring means has a higher precision than the second distance measuring means.
Is done.

[0018]

[0019]

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

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

In FIG. 1, the discharging main capacitor (MC) 12 is charged up by the booster circuit 13. Then, the xenon (Xe) tube 1 for projecting the light for distance measurement emits light by the flash lighting method in which the electric charge stored in the main capacitor 12 is discharged to emit light.

At this time, the discharge path is turned on by the IGBT 7.
/ OFF is controlled. That is, the CPU 10 is the IGBT
When 7 is turned on and the AF trigger unit 6 is activated, a high voltage is applied to the Xe tube 1 to activate it and the Xe tube 1 emits light. In this way, a part of the light of the Xe tube 1 extracted by the mask 2 is condensed by the light projecting lens 3 and projected onto the subject.

These constitute the light projecting section 17, but the mask 2 is made movable and the opening (window) of the mask 2 and the principal point of the lens 3 are formed by scanning in the direction of the arrow in the figure. The angle can be changed, and the direction of light emission can be switched. The scanning mechanism 4 that scans the mask 2 corresponds to the light emitting direction switching means.

Then, the signal light projected from the light projecting unit 17 and reflected by the subject is detected by the light receiving unit 5 at the reflected signal light incident position, and the CPU 10 calculates the subject distance. The CPU 10 is an arithmetic control circuit including a one-chip microcomputer or the like that controls the sequence of the entire camera.

Further, the switches 15 and 16 connected to the CPU 10 are switches which are closed during and while the shutter release button is being pressed.
They are called 1st release switch and 2nd release switch, respectively.

The CPU 10 has these switches 15, 1
When the closing of 6 is detected, the light emitting unit 17, the light receiving unit 5, the light emitting direction switching unit 4 and the like are controlled to measure the distance, and after focusing, the shutter 14 is driven to expose the camera. Take control.
A display circuit 19 including a light emitting diode (LED) or the like is also connected to the CPU 10.

When a distance measuring device having such a structure is used to measure many points many times, a discharging capacitor (M
C) There is a problem that the electric charge accumulated in 12 is immediately lost. According to the present invention, prior to photographing, distance measurement is performed only in the central portion in a so-called focus lock state in which distance measurement is performed, and multi-AF distance measurement is performed only at a timing immediately before actual photographing is performed to save energy. And

Therefore, when the 1st release switch 15 is closed, the light emission scanning operation has not started and the light emission direction is not switched. Therefore, at this timing, the distance measurement and the distance measurement values are averaged a plurality of times as described above. Since it can be performed, particularly high-precision AF can be performed on the central portion of the screen.

When the 1st release switch 15 is closed, distance measurement is performed only in the central portion of the screen.
It is also possible to perform the so-called focus lock operation described above by changing the composition while the t-release switch 15 is on and the second release switch 16 is off.

The identification of this focus lock operation is 2n.
d When the release switch is turned on, the distance from the center of the screen is measured again. Compared with the result when the 1st release switch is turned on, if the distance measurement result does not change, there is no focus lock, and if there is a change, focus locked. Can be identified.

FIG. 2 shows the distance measurement result at each distance measurement point in the scenes shown in FIGS. 14 (a) and 14 (b). Comparing FIGS. 2A and 2B, FIG. 2B shows that the data in the central portion of the screen and the data adjacent to the central portion are different, and the central portion is closer.

As a result, the scenes shown in FIGS. 14A and 14B can be discriminated. In addition, it is possible to input the user's intention to the camera by repeatedly pressing the release button halfway many times without setting the spot AF mode.

That is, the composition as shown in FIG. 14A is often used for snapshots, and is often taken relatively quickly. At this time, the half-press operation of the release button is not repeated,
It is considered that the user tends to push the release button all at once.

On the other hand, the composition as shown in FIG. 14 (b) is often used in portrait photography, and the user is carefully following the subject. Tends to wait.

If the user puts the subject in the center of the screen and repeatedly presses the release button halfway at the time of portrait photography, the user's manual should be written to extend this way of thinking. , Users will also use it.

Therefore, in the camera of such a specification, the mode setting buttons other than the release button are unnecessary, and the user only has to concentrate on the operation of the release button, which has the advantage of not missing a photo opportunity. .

Next, FIG. 3 is a time chart showing the relationship between each signal and the light emission waveform.

As shown in FIG. 3, if the boosting of the main capacitor 12 is not performed during the continuous light emission in consideration of the influence of the noise during the boosting operation on the AF operation, the potential of the main capacitor 12 will be sequentially increased. Will fall. In addition, if a boosting operation is inserted between the light emission, it is disadvantageous in terms of time lag.

Therefore, in the distance measuring apparatus of the first embodiment, it is premised that the boosting operation is not performed in consideration of the time lag and noise when continuously measuring the distance.

Hereinafter, with reference to FIG. 4, switching of the light projecting direction by the distance measuring device of the first embodiment will be described on the premise of such a configuration.

FIG. 4A shows the initial state, and when the 1st release switch 15 is turned on, the central portion C1 of the screen 18 is displayed.
To measure the distance. At this time, since the scanning mechanism 4 is not operating, the light projecting unit 17 is operated many times and the distance measurement is repeated to average the results, thereby obtaining a more reliable central distance measurement result. be able to. In the central part of the screen, the probability of existence of the main subject is as high as 80%, and at least by accurately measuring the distance, a landscape photograph or the like can be taken with correct focus.

Next, when the second release switch 16 is turned on, distance measurement around the screen is sequentially performed as shown in FIGS. 4 (b) and 4 (c), and finally distance measurement at the screen central portion C1 is performed again. After that, take a photo. 1st release switch 15
Can be pressed any number of times before shooting, but with the conventional camera, the 1st release switch 15
At the timing of N, the distance measurement of all points was performed as shown in FIG.

However, this causes a waste of energy,
When the 1st release switch 15 was pressed again, the previous distance measurement result was completely useless. In particular,
In the case of sharing the power source with the strobe of the camera as in the first embodiment, if the multi AF is performed to turn on the 1st release switch 15 and a large amount of energy is consumed, stroboscopic photography is difficult at the time of actual photographing. Will be.

As in the technique proposed in Japanese Patent Laid-Open No. 4-212136, the 2nd release switch O
When the distance measurement is performed only at the timing of N, it is impossible to focus on the person in the center in the cluttered scene as shown in FIG. 4B unless the mode is set successively.

The distance measuring operation of the first embodiment will be described below with reference to the flow charts shown in FIGS. Figure 1
4 (a) and 4 (b) show that the subject distance in the center of the screen is a long distance and the subject distance in the surroundings is a short distance. Therefore, which one of them, the long distance side or the short distance side, is to be focused is selected. It was a difficult scene to judge.

In this embodiment, these scenes are dealt with by the following logic.

(1) Before taking a picture (before turning on the second release switch 16), the 1st release switch is repeatedly turned on.
If the result is N, and the distance measurement results at the center of the screen at that time show almost the same result, the priority is given to the center.

(2) When the distance between adjacent points in the center is greater than the distance in the center, priority is given to the center (see FIG. 11).

(3) 1st release switch 15 to 2n
If there is a composition change between the inputs of the d-release switch 16, the central priority before the change is given.

(4) Except in the cases of (1), (2), and (3), the data indicating the shortest distance is set as the focusing distance (closest selection).

In this sequence, when the CPU 10 detects that the 1st release switch 15 is ON (step S
1) It is checked whether the scanning mechanism 4 is at the initial position so that the light projection point is located at the center of the screen. If the scanning mechanism 4 is not at the initial position, this is initialized (step S2). And
In order to improve the distance measurement accuracy by repeatedly measuring the center of the screen, a variable n indicating the number of times of the repeated distance measurement is initialized (step S3).

Next, the CPU 10 increments this n (step S4), and repeats the distance measuring subroutine until the four repeated distance measuring operations are completed (step S4).
5, S6). Then, the CPU 10 averages the distance measurement results of l ₁ to l ₄ obtained by the repeated distance measurement, and sets the distance measurement result l _{C1 at the} center of the screen as a more reliable result (step S7).

Subsequently, the CPU 10 inputs the time T at the end of the central distance measurement at the ON timing of the 1st release switch 15 (step S8), and stores the distance measurement result l _C1 as l _C1 (T). (Step S9).
When the 1st release switch 15 is turned on many times, the CPU 10 can detect how the central distance measurement result l _C1 changes at each time by this step S9. This corresponds to the above logic (1).

Then, the O of the second release switch 17 is turned on.
When N / OFF is detected (step S10), and when ON of the switch 17 is detected, the operation of the scan mechanism 4 is started (step S14), and the subsequent multi-AF sequence is started.

On the other hand, in step S10, when the second release switch 17 is not turned on, it is assumed that the photographer has no intention of photographing, and the CPU 10 causes the booster circuit 13 to conserve the energy used in step S6. To charge the main capacitor 12 (step S1
1). Then, the input state of the 1st release switch 15 is checked again (step S12), and when the 1st release switch 15 is turned on, the photographer waits for the timing of photographing and returns to step S10.

On the other hand, when the photographer releases his / her finger from the release button and the OFF of the 1st release switch 15 is detected in step S12, the flag F for re-pressing the 1st release switch 15 is set to "1", and the step S1 is executed.
It returns to (step S13). Next, the sequence from step S14 will be described.
The variable m indicating the distance measurement point of is initialized (step S1
5) After incrementing this (step S1
6) Then, the distance measurement is repeated in step S18 until the distance measurement points are completed for the surrounding 6 points as shown in FIGS. 4B and 4C (step S17). Step S19
Is a step of a timer for gaining the timing from the distance measurement of a certain point to the distance measurement of the next point.

Subsequently, the CPU 10 determines again whether or not the scanning mechanism 4 has reached a position where the center point can measure the distance (step S20), and if the distance can be measured in the center, the center is measured again in step S21. Then, the result is set as l _C2 .

Thus, the multi-AF sequence is
Since it is performed after the input of the second release switch 17, the user operates the 1st release switch 1 according to the first embodiment.
Even if the shooting is interrupted many times after the input of 5, the risk that all the energy of the main capacitor 12 is used up by the multi AF is avoided.

Next, the above-mentioned 1st release switch 1
The re-detection detection flag F of No. 5 is determined (step S2
2) If the flag is "1", finally step S8
At least one central distance measurement result l _C1 obtained from the time T input at 1 minute before is read,
_C1 (T-1) is set (step S23).

Then, the CPU 10 causes the l _C1 (T-
1) is compared with the last obtained l _C1 (T), and if this is a similar value, it is repeated many times (step S24), and it is assumed that the user is trying to photograph the same subject, and The distance measurement result l _C1 is set as the focusing distance l _P (step S
26).

Further, even when branching to "N" in steps S22 and S24, if the distance measurement result of the point adjacent to the center of the screen is far from l _C1 in step S25, refer to FIG. l _C1 is set as the focusing distance (step S26), and focusing is performed (step S3).
0). Note that FIGS. 2A and 2B shown above are respectively shown in FIG.
4A and 4B are distance measurement results corresponding to the respective scenes. Similarly, although the center part of the screen outputs the distance measurement result of the short distance in the peripheral part of the screen, the data in the center part of the screen is slightly different as shown in FIG. 2 (b) in the scene of FIG. 14 (b). It can be seen from the distance measurement data of the adjacent portions that the short distance is indicated.

Therefore, in step S25, in consideration of this point, the scene of FIG. Further, in the case of branching from step S25 to S27, in step S27, the result of distance measurement at the center when the 1st release switch 15 is turned on _C1 and the result of distance measurement at the center of the screen after the second release switch 17 is turned on l _C2 When the values do not match, the photographer changed the composition after the 1st release. That is, it is determined that the focus is locked, and the process branches to the step of step S28 that gives priority to the center. At other times, the process branches from step S27 to step S29, and the closest subject distance is selected from l _C1 , l _{l to l 6} to correspond to the hollow image scene.

Then, l _P is focused (step S31), and the photographic film is exposed (step S3).
2) After resetting the flag (step S33), the scan mechanism 4 is controlled to initialize the scan position, and the entire sequence is completed.

As described above, in the distance measuring apparatus according to the first embodiment, even if there is no subject in the center of the screen, it is possible to focus on the subject in the center of the screen. Even if there is, or if you want to focus on an arbitrary subject by the focus lock, you can easily correct and focus.

Since the accuracy of the central portion of the screen can be improved by repeatedly measuring the distance, high-precision focusing can be performed on a photograph having a main subject in the central portion of the screen, which occupies 80% or more of a general photograph.

Further, the non-stop scan type multi-AF can provide a multi-AF camera with an extremely small release time lag.

Further, since the multi-AF is performed only when taking a picture, it is possible to reduce the energy consumed in one shooting. When the stored distance measurement result at the center of the screen when the 1st release switch 15 is turned on is used as in the processes of steps S26 and 29 in the sequence of FIG. 6, the screen 18 of FIG. Bottom 20
Needless to say, if the display is displayed in the viewfinder of the camera as shown in FIG.

Next, FIG. 7 is a diagram showing the structure of the distance measuring apparatus according to the second embodiment.

In FIG. 7, the light projecting unit 17 and the strobe circuit 39 are the same as the components shown in FIG. Further, regarding the light receiving section 5, more specifically, a pair of light receiving lenses 30a and 30b, semiconductor light position detecting elements (PSD) 31a and 31b, and the PSDs 31a and 3b.
It is shown as an integrated circuit 32 which receives the output current of 1b and converts it into an output signal depending on the subject distance.

Further, the CPU 10, the first release switch 15, the second release switch 16 and the shutter 1
4 is the same as the component shown in FIG. Further, for switching the light emitting direction, the CPU 10 rotates the motor 34 via the motor driver (MD) 33,
This is performed by sliding the mask 2 integrally with the movable portion 37 by the feed screw 36. These form a light emitting direction switching unit.

Next, FIG. 8 shows the principle of switching the light projecting direction according to the present embodiment.

FIG. 8A shows a state in which the mask 2 is set at the initial position of the scanning mechanism of the present invention, that is, at the position where the distance measuring light is projected on the center of the screen.

At this time, the light from the Xe tube 1 is transmitted through the window 2a of the mask 2.
Is emitted as distance measuring light, and the distance measuring light is projected along the optical axis of the lens 3. At this time, the initial position detection switch 35 is turned on as shown in the figure.

Next, when the mask 2 slides in the direction of the arrow, the window 2a becomes the position of X _S1 with respect to the optical axis, and when the focal length of the light projecting lens is f _T ,

[Equation 1] The distance measuring light is projected at an angle of.

When this X _S1 becomes large, the distance measuring point moves accordingly, as shown in FIG. 4 (b). At this time, the initial position detection switch 35 is turned off.

Further, when the window 2a moves to X _S2 , this time, the window 2b in front of the Xe tube 1 becomes (-
X _S3 ), and (-X _S3 ) in X _S1 of the above formula (1).
The distance measuring light is projected at an angle θ in which is substituted. At this time, the distance measuring point moves as shown in FIG. Therefore, from FIG. 8 (b) to FIG. 8 (c), the motor 34 rotates non-stop in the same direction, and as shown in FIG. 4 (b) to FIG. It will be possible.

Next, the structure of the light receiving portion and the principle of distance measurement will be described with reference to FIG.

If the focal lengths of both light receiving lenses 30a and 30b are both f _J and the distance between the principal points is S, then C1 of distance l
The light reflected from the place is PSD 31a, 31b, respectively.
Incident on the positions of x _1a and x _1b as shown in the figure.

Using these x _a1 and x _1b , the distance l is

[Equation 2] Is required as.

On the other hand, the PSDs 31a and 31b have signal currents I _1a , I _2a , I _1b and I _2b depending on x _1a and x _1b , respectively.
Is an element that outputs. That is,

[Equation 3] Becomes Here, I _1a + I _2a and I _1b + I _2b are both PSD
Since the total amount of signal photocurrent I _{P is}
If D, then I _1a + I _2a = I _1b + I _2b = I _P (4) Therefore, if both equations (3) above are added,

[Equation 4] And I _2a + I _2b = 2I _P − (I _1a + I _1b ) ... (6) Therefore, both outputs of each PSD are individually springed to generate AFI.
By inputting into C32, (x _1a + x _1b ) is obtained from the above equations (5) and (6).

That is, (I _1a + I _1b ), (I _2a + I _2b ).
Than,

[Equation 5] Becomes From this (x _1a + x _1b ), the distance 1 can be obtained from the above equation (2).

The advantage of the system having two light receiving lenses and elements is that even if the light projecting point deviates from C1 to C2, the two light receiving systems cancel each other out and the above equation (2) is used as it is. The point is that the correct distance 1 can be calculated. Therefore, even if the mask 2 is loosened during scanning, the distance can be correctly measured.

The distance measuring operation of the distance measuring apparatus according to the second embodiment will be described below with reference to the flow charts of FIGS. 11 and 12. Incidentally, here, only the sequence different from that of the first embodiment will be explained, and the explanation of the other steps which are not different will be omitted.

In this sequence, the 1st release switch 1
In step S107 and S10, the central distance measurement with improved accuracy is performed by illuminating multiple times and averaging when 5 is ON.
Step 8 is a step of resetting the timer for starting the time measurement from the distance measurement when the 1st release switch 15 is ON and starting the time measurement.

Then, the O of the second release switch 16
When N is detected (step S110), the scan-type multi-AF sequence is started (steps S113 to S117), similar to the sequence of the first embodiment. Then, the CPU 10 measures the distance again in the central portion (step S11).
(8, S119), the clocking of the timer reset in step S107 is completed, and the result is set to Δt (step S120).

A timing chart showing the above sequence is shown in FIG.

As shown in FIG. 10, when the 1st release switch 15 is turned on, the Xe tube 1 emits light four times.
At this time, the projection direction is toward the center at this time, the initial position switch 35 is ON, and the motor driver (M
D) 33 is not working. When the second release switch 16 is turned on, the MD 33 is activated, the mask 2 is slid, and the initial position setting switch 35 is turned off.
F, the projection direction changes as shown in the figure (Fig. 4 (a)).
Through (c)).

When the distance measurement of the peripheral 6 points is completed while changing the light emitting direction in this way, the MD 33 is stopped and the distance measurement of the center is performed again. At this time, since the window 2b of the mask 2 is used, the switch 35 remains off. Then, the CPU 10 detects a time Δt from the time when the central four light emission ends to the time when the distance to the center is measured again.

When the distance measuring apparatus according to the second embodiment measures a moving object (moving object) as shown in FIG. 13, since the object distance changes within Δt, the first central distance measuring result is obtained. The distance measurement result l _C2 is different from l _C1 . Especially, since there are many opportunities to be photographed because the subject is close to the camera, compared with l _C1 and l _C2 (step S121), moving object distance measurement is performed only when l _C2 is closer.

This moving object distance measurement considers the time lag t _S from the time point of distance measurement to l _C2 until the shutter 14 is actually released,
Assuming that also the moving object between the time lag t _S is approaching at the same speed, a distance measurement to perform focusing in consideration of the object distance changes during this time lag t _S. Therefore,
The result calculated by l _C1 , l _C2 , Δt, t _S is set as the focusing distance l _P (step S122).

If l _C2 and l _C1 are different, the user locks the focus and branches to step S125 assuming that the composition has been changed, and l _C1 is the focusing distance. Further, when the process branches to “Y” in step S123, the object distance is the closest one from l _C1 and l _{1 to} l ₆ . l _C2
Is not used here because it is not as accurate as l _C1 .

Next, the CPU 10 performs focusing (step S126), performs exposure (step S49), reverses the motor 34 until the switch 35 is turned on, initializes the scan position (mask position), and ends the sequence. Yes (step S50).

As described above, according to the second embodiment, it is possible to provide a camera with a high-speed multi-AF, which enables accurate focusing even if the subject is a moving body. In addition, since the central portion of the screen where the main subject is likely to exist is averaged over a plurality of times of distance measurement and used as focusing data, A
It becomes F. Further, since the distance measurement at the center is repeated, the intention of the user to lock the focus can be determined, and the distance can be accurately measured at the point at which the user wants to focus more accurately.

Further, since a pair of the light receiving lens and the light receiving element are prepared to measure the distance in such a manner as to offset the deviation of the light emitting point, even if the light emitting position is shifted during the distance measurement in the non-stop scan distance measurement. Correct distance measurement is possible.

A technique for focusing on a moving object by a plurality of distance measurements is disclosed in Japanese Patent Laid-Open No. 63-118133.
Although it is already known in the technology disclosed in Japanese Patent Laid-Open Publication No. JP-A-2003-264, there is no example that effectively combines high-speed multi-AF as in the present invention. In addition, since the movable part is only a mask with slits (windows), beam scanning is possible at high speed and low noise.

As described in detail above, according to the present invention, the distance measurement in the central portion of the screen where the existence probability of the subject is high is highly accurate, and the distance measurement in the peripheral portion of the screen is high speed and low noise. Can be provided. Further, since the peripheral distance measurement is performed only immediately before photographing, wasteful energy is not consumed every time photographing is interrupted due to a composition change or the like. Furthermore, since the distance to the center is measured and stored in memory before the release button is pressed, it is possible to apply focus adjustment with priority to the center of the screen, such as focus lock and AF for moving objects, according to the stored information. It is possible to provide a camera with a focusing function that corresponds to the scene.

Further, the S / N ratio is improved by using a xenon tube as a light source, which is capable of taking out a light amount several tens of times that of an infrared light emitting diode (IRED) used as a conventional light source for distance measurement, Sufficient distance measurement accuracy can be obtained without projecting a plurality of times.

According to the above embodiment of the present invention, the following constitution can be obtained.

(1) Projecting means for projecting a distance measuring light beam toward an object, light emitting direction switching means for switching the light emitting direction of the distance measuring light beam, and the distance measuring light beam from the object. Light receiving means having a light receiving element for receiving reflected light and outputting a photoelectric conversion signal according to the light receiving position, switch means for opening in response to operation of a release button, and up to the subject based on the photoelectric conversion signal Comprising a calculation means for calculating a distance and a control means for detecting the operation of the switch means to start a distance measuring operation. In the stopped state before the operation of the light emitting direction switching means, the center of the photographing screen is provided. A distance measuring device characterized by detecting a distance of a subject corresponding to a section.

(2) The switch means is composed of a first switch which is opened while the release button is being pressed, and a second switch which is opened when the release button is completely pressed, and the control means is the first switch. The distance measuring apparatus according to (1) above, wherein the focusing distance of the camera is determined based on a comparison calculation of the distance measuring result when the camera is opened and the distance measuring result when the second switch is opened.

(3) The switch means has at least a first switch which is opened during the pressing of the release button, and the control means stops the projection direction switching means in response to the opening of the first switch. Multiple times in the state,
The distance measuring device according to (1) or (2) above, wherein the distance measuring operation is repeated and the added value or average value of a plurality of distance measuring results is used for focusing.

(4) The light receiving means is composed of a pair of light receiving elements, and the computing means determines the subject distance according to the incident position of each of the reflected lights. The distance measurement described in (1) to (3) above. apparatus.

(5) Projecting means for projecting the distance measuring light beam toward the object, light emitting direction switching means for switching the light projecting direction of the distance measuring light beam, and the distance measuring light beam from the object. Light receiving means having a light receiving element for receiving reflected light and outputting a photoelectric conversion signal according to a light receiving position, switch means having first and second switches opened in response to operation of a release button, and the first First detection means for detecting the distance to the subject in a state in which the switching of the light projecting direction by the light projecting direction switching means is stopped in response to the opening of the switch;
A distance measuring device comprising: a second detecting unit that detects a distance to a subject while switching the light projecting direction by the light projecting direction switching unit in response to opening of the second switch.

(6) The distance measuring apparatus according to (5), wherein the first detecting means repeatedly detects the distance of the object in the same direction a plurality of times.

(7) The distance measuring device according to (5) or (6), wherein the first detecting means detects the distance to the subject corresponding to the center of the photographing screen.

(8) The second detecting means performs distance measurement once for each distance measuring point while switching the light emitting direction by the light emitting direction switching means. ) The distance measuring device described in.

(9) The light projecting direction switching means has a mask having a plurality of slit windows arranged in front of the light projecting means, and a scanning means for scanning the mask (5) to (8). ) The distance measuring device described in.

(10) The distance measuring device according to (9), wherein any one of the plurality of slit windows faces the optical axis direction of the taking lens in the stopped state.

(11) The light projecting means for projecting the distance measuring light beam toward the subject, and the initial position in the light projecting direction of the distance measuring light beam by the light projecting means is near the center of the photographing screen. It has a projection direction switching means for sequentially switching the projection direction of the distance measuring light beam, and a light receiving element for receiving the reflected light of the distance measuring light beam from the subject and outputting a photoelectric conversion signal according to the light receiving position. A distance measuring device comprising: a light receiving unit; and a calculating unit that calculates a distance to the subject based on the photoelectric conversion signal.

(12) The projection direction switching means includes a mask having a plurality of holes arranged in front of the projection means,
The distance measuring apparatus according to (11) above, including this mask and a scanning unit that relatively scans the light projecting element of the light projecting unit.

(13) Any one of the plurality of holes is
The distance measuring device according to (12), which is oriented in a direction corresponding to a substantially central portion of the photographing screen in the stopped state.

(14) In the stopped state, the light projecting direction switching means directs the light projecting direction of the distance measuring light beam of the light projecting means in a direction corresponding to a substantially central portion of the photographing screen. In accordance with the start of the switching operation of the light projecting direction, the light projecting direction is sequentially switched within the scanning range, and finally the direction is returned to the direction corresponding to the substantially central portion of the photographing screen (11) to (). The distance measuring device according to 13).

[0114]

According to the present invention, high-accuracy distance measurement with improved S / N is possible, downsizing of moving parts, high speed, and low noise are achieved, and further, energy saving design is made with a simple structure. It is possible to provide a distance measuring device that realizes the above and can also perform distance measurement corresponding to a moving object.

[Brief description of drawings]

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

2 (a) and (b) are respectively FIG. 14 (a),
It is a figure which shows the result of having measured the object shown to (b).

FIG. 3 is a time chart showing a relationship between each signal and a light emission waveform.

FIG. 4 is a diagram for explaining switching of a light projecting direction by the distance measuring device according to the first embodiment.

FIG. 5 is a flow chart for explaining a distance measuring operation of the first embodiment.

FIG. 6 is a flowchart for explaining a distance measuring operation of the first embodiment.

FIG. 7 is a diagram showing a configuration of a distance measuring device according to a second embodiment.

FIG. 8 is a diagram for explaining a principle of switching a light emitting direction.

FIG. 9 is a diagram for explaining a configuration of a light receiving unit and a distance measuring principle.

FIG. 10 is a timing chart showing the operation of the second embodiment.

FIG. 11 is a flowchart showing a distance measuring operation of the distance measuring apparatus according to the second embodiment.

FIG. 12 is a flowchart showing a distance measuring operation of the distance measuring apparatus according to the second embodiment.

FIG. 13 is a diagram showing an example of a moving subject.

FIG. 14A is a subject that does not exist in the center of the screen,
(B) is a diagram showing a state of a subject existing in the central portion of the screen.

[Explanation of symbols]

1 ... Xe tube, 2 ... Mask, 3 ... Lens, 4 ... Scan mechanism, 5 ... Light receiving part, 6 ... AF trigger part, 7 ... IGBT, 8
... Xe tube, 9 ... IGBT, 10 ... CPU, 11 ... Strobe trigger section, 12 ... Main capacitor, 13 ... Booster circuit, 14 ... Shutter, 15 ... 1st release switch,
16 ... 2nd release switch, 17 ... Projector, 19 ...
Display section.

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01C 3/06 G01B 11/00 G02B 7/28 G02B 7/32 G03B 13/36

Claims (4)

(57) [Claims] 1. A switch means including a first switch for detecting a halfway pressing of a release button and a second switch for detecting the end of pressing the release button, and a distance measuring for measuring a plurality of points on a photographing screen. Means, determining means for determining a focusing distance based on the distance measurement results of the plurality of points, and detecting means for detecting that the first switch has been repeatedly operated, the determining means comprising: A distance measuring device characterized in that the focusing distance is determined based on the result of distance detection of the central portion of the photographing screen by the distance measuring means according to the detection result of the detecting means. 2. The distance measuring means responds to the first switch.
In response, the distance is measured, and the determination means is
When determining the focusing distance based on the distance measurement results
The last obtained distance measurement result in the center of the shooting screen and
Compared with the distance measurement result in the center part of the shooting screen, the two are similar
If the value is
A claim characterized in that the focusing distance is determined based on
The distance measuring device according to Item 1. 3. A method for detecting a halfway pressing of a release button
Detecting the end of pressing the switch 1 and the release button
Switch means including a second switch, a first distance measuring means for performing distance measurement at a central portion within the photographing screen, and a second distance measuring means for performing distance measurement at a plurality of points within the photographing screen.
And the first distance measuring means in the operating state of the first switch.
Is activated, and when the second switch is in the operating state,
And a control means for operating the distance measuring means of 2.
Distance measuring device characterized by. 4. The first distance measuring means is the second distance measuring means.
The distance measurement is performed with higher accuracy than the means.
The distance measuring device according to item 3.