JPH08210840A - Range finder of camera - Google Patents

Abstract

PURPOSE: To perform the triangular distance measurement by a binocular AF by using a xenon tube for a strobe so as to obtain the highly accurate AF at a low cost. CONSTITUTION: In the distance measurement for an object in a short distance, a CPU 8 makes a light projecting part 2 utilizing IRED emit light. The reflected light from the object is detected with photodetectors 5 and 6 through light receiving lenses 3 and 4. The distance to the object is obtained by an AF circuit 7 and the CPU 8. Meanwhile, when the object is located in the long distance, the light from a strobe circuit 9 is utilized, and the distance is measured by the principle of triangular distance measurement. The output light from the strobe circuit 9 can be switched to two ways of the case, wherein a part of the object is illuminated, and the case, wherein the entire object is illuminated, by a ray switching circuit 10. In the AF circuit 7 in a range finder 1, the distance to the object is obtained based on the position of the light, which is cast on the photocletectors 5 and 6 through two light receiving lenses 3 and 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera distance measuring device (A
F) particularly relates to a distance measuring device for a camera that projects distance measuring light on a subject and determines the subject distance by reflected signal light.

[0002]

2. Description of the Related Art Distance measuring means for projecting a distance measuring light to a subject to obtain a subject distance has been proposed for a long time.
There are known ones that utilize the speed, one that uses the amount of reflected signal light, and one that uses triangulation.

An infrared light emitting diode (IRED) is generally used as a light source for the light source. For example, Japanese Patent Laid-Open No. 58-95716 discloses a flash device which also assists the exposure of the camera. Is listed. Further, a technique having a xenon discharge tube (Xe tube) in addition to the one for exposure is disclosed in, for example, Japanese Utility Model Laid-Open No. 62-151530.

[0004]

The light emitting diode is small in size, can operate at a low voltage, can continuously emit light, and is excellent in life, so that it is easy to handle, but the light amount is small compared to the large light amount of the Xe tube. Conversely, the Xe tube has a large amount of light,
Continuous emission is not possible. In addition, there is a problem that a high voltage is required and the life is inferior to that of a diode.

That is, an infrared light emitting diode (IRED)
Then, you cannot expect the large amount of light as the Xe tube. On the other hand, in order to have a Xe tube dedicated to distance measurement, a boosting light emitting circuit for the Xe tube is required, which is a great disadvantage in terms of cost and space.

Therefore, a technique using an electronic flash for exposure control like the above-mentioned Japanese Utility Model Application Laid-Open No. 58-95716 can be considered. However, in the AF which determines the distance by the magnitude of the reflected signal light as in the present invention, the object is detected. Depending on the reflectance of
There is a problem in that the distance measurement signal is confused depending on the size of the subject.

Further, when a huge amount of light of the Xe tube is used, even if a long distance can be measured correctly, a photocurrent value becomes too large at a short distance, causing a problem such as circuit saturation, which cannot be ignored.

The present invention has been made in view of the above-mentioned problems, and uses the large amount of light of the Xe tube to achieve high precision, and also has a cost problem, a space problem, a reflectance problem, and a circuit saturation at a short distance. An object of the present invention is to provide a distance measuring device for a camera capable of solving the above problem.

[0009]

That is, the present invention is directed to a light projecting means for projecting light for distance measurement onto a subject and reflected light from the subject on two different optical paths, and their respective incident positions. Further comprises a light receiving means for detecting the distance to the subject and a strobe means for adjusting the exposure amount of the subject, and when the distance measurement result by the light projecting means is a long distance, the strobe light is used. The distance to the subject is detected again based on the output of the light receiving means when the means emits light.

Further, according to the present invention, a light emitting diode for projecting distance measuring light to a subject and reflected light from the subject are received by two different optical paths, and the distance from each incident position to the subject is determined. The light receiving means for detecting, the photometric means for detecting the brightness of the subject, and the strobe means for adjusting the exposure amount of the subject are provided, and when the output signal of the photometric means is equal to or higher than a predetermined brightness. Is characterized in that the strobe means and the light receiving means are operated, and when the output signal of the light measuring means is below a predetermined brightness, the light emitting diode and the light receiving means are operated to perform distance measurement. To do.

Further, according to the present invention, the first light projecting means for projecting the light for distance measurement toward a plurality of points on the screen and the reflected light from the subject are received to determine the distance to the subject. And a second light projecting unit configured by a member different from the first light projecting unit and configured to project light in a range wider than the projection range of the first light projecting unit, When the distance measurement results of the plurality of distance measurement points obtained by the operation of the first light projecting unit are all farther than the predetermined distance, the second light projecting unit is operated to detect the distance. It is characterized by

[0012]

In the distance measuring device of the camera of the present invention, the distance measuring light is projected from the light projecting means onto the object, and the reflected light from the object is received by the light receiving means through two different optical paths. Then, the distance from each incident position to the subject is detected. Further, the exposure amount of the subject is adjusted by the strobe means. When the distance measured by the light projecting means is a long distance, the distance to the subject is detected again based on the output of the light receiving means when the strobe means emits light.

Further, in the camera distance measuring device of the present invention,
Light for distance measurement is projected from the light emitting diode to the subject, and the reflected light from the subject is received by the light receiving means through two different optical paths, and the distance from the respective incident positions to the subject is detected. The brightness of the subject is detected by the photometric means, and the exposure amount of the subject is adjusted by the strobe means. When the output signal of the photometric means is equal to or higher than a predetermined brightness, the strobe means and the light receiving means are operated to perform distance measurement. On the other hand, when the output signal of the photometric means is below a predetermined luminance, the light emitting diode and the light receiving means are operated to perform distance measurement.

Further, in the distance measuring device of the camera of the present invention, the distance measuring light is projected from the first light projecting means toward a plurality of points on the screen, and the reflected light from the subject is generated. The light is received by the light receiving means and the distance to the subject is detected. Further, the second light projecting means constituted by a member different from the first light projecting means projects the light in a range wider than the projection range of the first light projecting means. When the distance measurement results of the plurality of distance measurement points obtained by the operation of the first light projecting means are all farther than a predetermined distance, the second light projecting means is operated. The distance is detected by.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a conceptual embodiment of a distance measuring device for a camera according to the present invention.

In FIG. 1, in the distance measuring device 1, a light projecting section 2 as a light projecting means, a light receiving lens 3 as a light receiving means,
4 and light receiving elements 5 and 6 are provided. Light receiving element 5,
6 is controlled by an arithmetic control circuit (CPU) 8 including a one-chip microcomputer or the like via an AF (autofocus) circuit 7. The arithmetic control circuit 8 includes a strobe circuit 9 for supplementing the exposure of the subject.
In addition to the light beam switching circuit 10 for switching when illuminating a part or the whole of the subject, the light projecting unit 2 in the distance measuring device 1 is connected and controlled.

In such a structure, the CPU 8 detects the infrared light emitting diode (I
The light projecting unit 2 using RED) is caused to emit light. Then, reflected light from a subject (not shown) is detected by the light receiving elements 5 and 6 via the light receiving lenses 3 and 4, and the AF circuit 7 and CP
The distance to the subject is obtained at U8.

On the other hand, when the subject is a long distance, the light from the strobe circuit 9 is used to measure the distance according to the principle of triangulation. The output light from the strobe circuit 9 can be switched between two ways, one for illuminating a part of the subject and the other for illuminating the entire subject by the light beam switching circuit 10. In the AF circuit 7 in the distance measuring device 1, the subject distance is obtained from the position of the light that has passed through the two light receiving lenses 3 and 4 and is incident on the light receiving elements 5 and 6.

Here, with reference to FIG.
The principle of triangulation will be described. In FIG. 2, the light receiving elements 5 and 6 are composed of semiconductor position detecting elements (PSD) for detecting the position of incident light.
Then, a state in which the light of the IRED 2b is projected onto the subject 11 via the light projecting lens 2a is shown.

As shown in FIG. 2, assuming that the reflected signal light incident positions on the PSDs ₅ and 6 are x ₁ and x ₂ , respectively, the object distance L is the distance between the light emitting and receiving lenses S ₁ and S ₂ and the light receiving lens. From the distances f _j between 3 and 4 and PSDs 5 and 6, L = S ₁ · f _j / x ₁ = S ₂ · f _j / x ₂ (1) From the above formula (1), S ₁ + S ₂ = (L · x ₁ / f _j ) + (L · x ₂ / f _j ) = S ∴ L = (S · f _j ) / (x ₁ + x ₂ ) ... (2) As described above, the subject distance L is obtained only from the distance S between the two light receiving lenses regardless of the distance between the light projecting lens and the light receiving lens. This means that the projection lens may be provided at any position.

Further, if the signal distance is the same, even if the signal light is not reflected at the position of the subject 11a and is reflected at the position of the subject 11b, the deviation amount Δx of the incident position cancels out on each light receiving element. Therefore, from the relationship of x ₁ + Δx + x ₂ −Δx = x ₁ + x ₂ , even if no special correction is made, the above (2)
Correct distance measurement is possible from the formula.

FIG. 3 is a diagram showing a schematic structure of a camera to which the distance measuring optical system having such a structure is applied. An Xe tube 9a that can pop up in the direction of the arrow shown is provided on the top of the camera body 12. And this camera body 12
On the front surface of the, a taking lens 13 is provided at a substantially central portion thereof. On the other hand, on the front surface of the Xe tube 9a, a light projecting lens 14 that transmits the light from the Xe tube 9a in a state where the Xe tube 9a is housed is provided. On the other hand, the light projecting lens 2a and the light receiving lenses 3 and 4 are provided on the front surface of the camera body 12, and the IRED 2b and PSDs 5 and 6 are built in the camera body, respectively.

According to the camera to which the distance measuring optical system having such a structure is applied, even if the distance measuring light is projected from the light projecting lens 2a for the IRED 2b, the light from the Xe tube 9a that does not pop up. The subject distance L can be correctly calculated from the outputs of the two PSDs 5 and 6 by using the above equation (2) regardless of whether the light is projected through the light projecting lens 14.

FIG. 4 shows the AF adopted in the camera of FIG.
It is a block diagram shown in more detail. In FIG. 4, the pop-up means 16 is for popping up the Xe tube 9a from the camera body, and is controlled by the CPU 8.
By this pop-up means 16, the camera body 12
(See Fig. 3).
When a is controlled to emit light, the entire subject is illuminated and serves as an auxiliary light source during exposure.

On the other hand, the Xe tube 9a is attached to the camera body 12
In the state of being housed in C, as shown in FIG. 4, the light is condensed and projected by the slit 17 and the projection lens 14,
.. D, the light 18 having an elongated shape having a spread on the screen is projected onto the subject.

PSDs 5 and 6 are received through the light receiving lenses 3 and 4.
Shows the angle of view between A and B shown in FIG. 5 (a), but C to D from the strobe light projection unit (Xe tube 9a).
When a light having a spread is projected, it is possible to measure the distance of the subject present in the shaded area in the figure.

That is, as shown in FIG. 5 (a), even if the strobe light projecting portion is arranged at a position distant from the light receiving lens, the width of the projected light is widened so that L ₁ to L ₂ The distance can be measured. IRED near L ₁
Distance measurement is performed with light from 2b.

The Xe tube 9a discharges the electric charge of the capacitor 20 boosted and charged to about 300V by the booster circuit 19 to emit light, but the circuit for ionizing the tube is not shown. Further, a current switching element (IGBT or the like) is inserted in the discharge path, and the capacitor 2
This prevents the zero electric charge from being consumed by one emission. That is, the CPU 8 controls the switching element (SW) 21 to end the discharge at a predetermined time and end the distance measurement light emission.

Since the PSDs 5 and 6 respectively output two signal currents depending on the incident position of light, the AF circuit 2
Reference numerals 2 and 23 amplify them and perform an arithmetic operation to input an output depending on the light incident positions x ₁ and x ₂ to the CPU 8.

From these outputs, the CPU 8 uses the above (2)
The calculation based on the formula is performed to obtain the subject distance L. Also, C
The PU 8 controls these above-mentioned means in accordance with the input states of the release switches 24 and 25 incorporated in the release button of the camera to selectively use the light of the Xe tube 9a for distance and exposure.

FIG. 5B is a timing chart showing a simple operation of this embodiment. PSD flash popup previous emission from birds applied to the Xe tube 9a, the switching element 21 is between the T ₁ of the up-off, is performed by about 80Myusec, reflected signal light from the object of the light
The light is received at 5 and 6 and distance measurement is performed. At this time, the light from the Xe tube 9a is focused on the center of the screen by the slit 17 and the light projecting lens 14.

Next, the mechanism 8 of the pop-up circuit 16 is driven to cause the strobe portion to pop out from the camera body as shown in FIG. 3 to emit light during exposure of the camera. At this time, the entire photographic screen must be illuminated, so the slit 17 or the like is not used.

The light emission time T ₂ is controlled according to the measured subject distance, the diaphragm of the taking lens, and the sensitivity of the film. Generally, this T ₂ is longer than T _1. Become.

As described above, in this embodiment, the energy consumption is suppressed by the triangulation using two light receiving lenses, the projection of a long and narrow slit, and the discharge path switching means. As a result, it is possible to provide a high-precision, wide-range, low-power-consumption camera AF with a very simple configuration.

In addition, since the principle of triangulation is used, the distance measuring light is focused and projected without depending on the reflectance of the object, so that the light energy is effectively applied to the object. It has the advantage of being able to project, improving the S / N, and being able to correctly measure the distance to only the targeted subject.

Next, another example of light beam switching in the camera distance measuring device of the present invention will be described. FIG. 6A shows
It is the figure which showed the state which has projected the light for distance measurement with respect to a to-be-photographed object. In the figure, a reflecting umbrella 27 is arranged behind the Xe tube 9a. A slit-shaped window 27a is formed in the reflecting umbrella 27, and the light emitted from the window 27a is
The light is focused on the subject 11 via the mirror 28 and the light projecting lens 14.

In this way, the distance measuring light focused and projected on the subject 11 is reflected on the subject 11. And, although not shown in FIG.
An image is formed on D.

At this time, the emitted light is the main subject 1
1 and the subject 11b in the background, and the photographing lens 30
These images are exposed on the film 31 via.
Here, at the time of distance measurement shown in FIG.
Light is emitted in a direction different from that of the subject 11, and distance measuring light is emitted only to the main subject 11. At this time, it is important that the distance measurement light is not emitted to the background subject 11b. This is because when the distance measuring light hits the subject 11b in the background, P (not shown)
This is because two distances of light are simultaneously incident on the SD, which causes interference of optical signals, resulting in erroneous distance measurement.

When the CPU 8 rotates the motor 33 via the driver 32, the driving force is transmitted to the gear 27b provided on the reflector 27, and the Xe tube 9a is provided as shown in FIG. 6B. The irradiation direction of the light beam can be switched.

At the time of exposure shown in FIG. 6 (b), it is important that the entire photographing screen of the camera is irradiated with strobe light. Next, regarding the operation of the camera having the above-mentioned configuration,
This will be described with reference to the flowchart of FIG. This sequence is performed by the CPU 8.

First, in step S1, the state of the switch 24 which is closed by half-pressing the release button of the camera is detected. When this switch 24 is turned on, the following step S
In 2, the photometry of the subject is performed using a photometric means (not shown). If the photometric result is less than or equal to a predetermined value, it is necessary to make the strobe emit light to supplement the light. Therefore, in the next step S3, it is determined whether or not the strobe is necessary.

If a strobe is required, the process branches to step S4, and the St flag, which is a flag for storing the strobe light emission, is set to 1. In a dark scene,
Since the subject is not far away, the Xe tube 9a
AF is not performed, and in step S5, IRED2
AF is performed by causing b to emit light. Then, step S6
Then, this distance measurement result is used as the focusing distance.

On the other hand, if it is determined in step S3 that the strobe light emission is unnecessary, the process proceeds to step S7, where the strobe light emission flag (St flag) is reset,
In the next step S8, the IRED 2b is caused to emit light to measure the distance. Next, at step S9, this distance measurement result L
_It is determined whether _I is greater than the predetermined distance L ₀ .

If L _I is longer than the predetermined distance L ₀ , the S / N is insufficient with the light amount of the IRED 2b, the process proceeds to step S10, and the light of the Xe tube 9a is projected through the light projecting lens 14. Then, distance measurement is performed. The distance measurement result is set as the focusing distance L _p .

On the other hand, if L _I is shorter than the predetermined distance L _{0 in} step S9, S / N is considered to be sufficient, and as a result L _I
Is the focusing distance L _p . Next, step S1
If the switch 25 does not detect that the release button of the camera is pressed in 2, the process proceeds to step S13 and the state of the switch 24 is detected again.

When it is detected that the switch 25 is turned on in step S12, the process proceeds to step S14, and the focusing distance L _p obtained as described above is focused. Next, in step S15, the St flag is determined.

If the St flag is "1", the flow advances to step S16 to switch the optical path of the strobe for exposure assistance, and the light emission and exposure operations are performed in step S17. After the light emission, this optical path is returned to the original position in step S18.

On the other hand, in step S15, St
If the flag is reset to "0", the process proceeds to step S19, the exposure without stroboscopic light emission is performed, and this sequence is ended.

As described above, according to the embodiment according to the flow chart of FIG. 7, the energy for Xe tube emission is used for distance measurement when it is bright, and the energy for Xe tube emission when it is dark. Is used for strobe emission for exposure assistance, so by using energy for AF,
The flash reach will not be shortened.

Further, since stroboscopic light emission at the time of exposure is meaningless for a photograph of a landscape or the like, an embodiment in which the result of distance measurement is taken into consideration in determining the necessity of stroboscopic light is also possible, as in the flowchart of FIG. .

That is, when it is determined in step S21 that the release button is half-pressed, IRE is determined in step S22.
Distance measurement is performed by D2b, and then photometry is performed in step S23. Then, based on the results of the distance measurement and the photometry, the necessity of the strobe at the time of exposure is determined in step S24.

That is, when the distance is longer than the predetermined distance, the light from the strobe does not reach and the strobe at the time of exposure is unnecessary.
Also, even in a sufficiently bright environment, a strobe is not necessary either. If a strobe is required by such a determination, the process branches to step S25, and the St flag is set to 1. Then, in step S26, the above step S2
The distance measurement result of 2 is set as the focusing distance.

On the other hand, if it is determined in step S24 that the strobe is unnecessary, the St flag is reset in step S27, and then the Xe tube 9a emits light according to the distance measurement result L _{I in} step S22. Whether or not distance measurement is performed is determined in step S28.

The following sequence of steps S29 to S38 is the same as step S10 in the flowchart of FIG.
Since it is the same as the processing operation of to S19, description thereof will be omitted here.

According to the embodiment according to the flow chart of FIG. 8, the conditions for stroboscopic light emission can be further restricted, so that it is possible to design a camera with further energy saving. In these examples, the optical path switching of the Xe tube is performed as shown in FIG.
Although a pop-up method as shown in FIG. 6 and a rotation method as shown in FIG. 6 can be considered, the present invention is not limited to these. For example, a switching method as shown in FIG. 9 may be adopted.

9 (a) and 9 (b) are views showing a method of controlling the inclination of the reflection plate 35 of the Xe tube 9a to switch the light collecting state. 9C and 9D show the Xe tube 9a.
Control the rotation of the slit 36 with a window that rotates around the
The method of switching according to the position of the window is shown. FIG. 7C shows the state of light emission for exposure, and FIG. 8D shows the state of spot projection for AF. During spot light projection, light is condensed through the mirror 28 and the light projection lens 14.

FIG. 10 is a diagram showing the configuration of a second embodiment in which the distance measuring device for a camera of the present invention is applied to multi-AF. A general AF camera has a specification capable of measuring the distance only in the center of the screen, but cannot focus when the subject is not in the center of the screen.

Therefore, various types of AF capable of measuring the distances to a plurality of points on the screen have been proposed, and this is the multi-AF. In FIG. 10, IRED2b and PSD
Each of 5 and 6 is composed of three sets, and distances can be measured at three points on the photographing screen. That is, PSDs 5 and 6 are indicated by broken lines 38, 39 and 4
I stared at the part of 0, IRED2b 38a, 39
Light is projected on each of the right, center, and left portions of the screens a and 40a.

Therefore, these 38a, 39a, 4
If the subject exists at any position of 0a, the subject can be focused. Each of the three outputs of PSDs 5 and 6 has a switch 41 switchable by the CPU 8,
It is selected by 42 and input to the AF circuit (AFIC) 7. In the configuration example of FIG. 4, the calculation results are added by the CPU 8 using two of the AF circuits, but in the configuration example of FIG. 10, the outputs of the PSDs 5 and 6 are bundled into the AFIC.
Input to 7 and add before calculation, x ₁ + in the above equation (2)
The calculation of x ₂ is performed. Therefore, AFIC7 is x
_Since the signal depending on ₁ + x ₂ is output, the CPU 8 determines the subject distance L according to the equation (2).

Further, if the three IREDs 2b are driven simultaneously, the light quantity may decrease, so that they are sequentially emitted. Then, the corresponding PSDs 5 and 6 are connected to the switch 4
The signal is sequentially switched by 1, 42, and the signal is AFIC.
It is designed to be input to 7.

Further, the CPU 8 emits light from the Xe tube 9a via the light emitting circuit 43. When the light of the Xe tube 9a is used for distance measurement, the light projected from the Xe tube 9a is slit (not shown). ) And a light projecting lens 14 to project light in a spot shape as indicated by 44. This spot 4
4 is slightly larger than the spot 39a formed by IRED2b. This is for the following reason.

In the light emitting diode, in order to increase the density of light per area, it is necessary to flow a large amount of current in a small light emitting area. Therefore, if the light emitting area is increased as it is, the light density is reduced even if the spot diameter is increased. On the other hand, in order to increase the spot diameter while maintaining the light density, it is necessary to flow a large current in proportion to the area. However, it cannot be easily realized due to the limitation of the battery of the camera.

Further, since the Xe tube is used to project the original large amount of light by masking it, that is, by squeezing it with a slit or a window, the size of the projected spot can be arbitrarily selected.

Therefore, in the second embodiment, IRED2b
By making the diameter of the light projecting spot 44 by the Xe tube 9a larger than that of the light projecting spot 39a, it is possible to focus the scene as shown in FIG.

In FIG. 11, spots 38a and 39 are formed.
Although a and 40a are light projecting points by the IRED 2b, in this case, in the case of a photograph in which the longitudinal direction is vertical, neither beam hits the main subject 11, so correct focusing was impossible.

However, when the projection of the Xe tube 9a capable of projecting light to the spot 44 having a large area is also used as in the same embodiment, the reflected signal light from the portion 44a on the subject 11 is PSD 5,6. It is possible to focus on the person 11, which is the main subject.

Here, the merit of the binocular light receiving AF that can perform correct distance measurement without applying all the beams to the PSD is applied. That is, as described with reference to FIG. 2, for subjects at the same distance, the light starts from the point 11a at the PSD.
Whether it is incident on or from point 11b,
This is based on the principle that the distance measurement results will be the same.

FIG. 12 is a flow chart for explaining the operation of this second embodiment. First, in step S41, the distance measurement is started by detecting the state of the switch 24 which is closed in conjunction with the half-pressing of the release button of the camera. When this switch 24 is turned on, IRED2
From b, the distance measuring light is projected onto the spots 40a, 39a, and 38a. Thereby, in step S42,
In S43 and S44, distance measurement is performed for the left, center, and right within the shooting screen.

From these distance measurement results L _L , L _C and L _R , the closest distance L _p is selected in step S45. Next, in step S46, it is determined whether or not this L _p is longer than the predetermined distance L ₀ .

If it is determined that L _p is longer than the predetermined distance L ₀ , the process proceeds to step S47 and the Xe tube 9a emits light, and the result is the focusing distance L _p . On the other hand, when it is determined in step S46 that L _p is shorter than the predetermined distance L ₀ , the result obtained in step S45 is set as the focusing distance, and the process proceeds to step S48.

Step S48 is a step of determining whether or not the release button of the camera has been pressed, and the subsequent steps S49.
Since steps S55 to S55 are the same as the processing operations of steps S13 to S19 in the flowchart of FIG. 7 described above, description thereof will be omitted here.

As described above, according to the second embodiment, the spot of the light projected by the Xe tube can be accurately measured to a far distance by the powerful light of the Xe tube as compared with the conventional multi-AF by the IRED. Since the size of the camera is increased, it is possible to provide a distance measuring device for a camera that can correctly focus on the main subject 11 even in a scene as shown in FIG. 11, for example.

In the conventional multi AF, 38a, 39a,
Correct focus cannot be achieved if the subject does not exist at any of the points 40a (see FIG. 11). However, since the subject existing in the spot portion of 44 can be focused by this embodiment, the focus is far better. It is possible to provide a multi-AF camera with a high rate.

Further, as shown in FIG. 6, it is determined from the result of the multi-AF whether or not the subject 11b exists in the background, and if there is, the large-area stroboscopic light emission is stopped to take measures against interference. You may do it.

FIG. 13 is a diagram showing the configuration of the third embodiment of the present invention. In FIG. 13, the distance measuring apparatus 1 guides the luminance distribution information of the subject 11 from the light receiving lenses 3 and 4 which are two different fields of view to the PSDs 5 and 6 and observes it, and correlates the degree of deviation to correlate the subject. This is a so-called passive type distance measuring means for measuring the distance. This distance measuring device 1
Is controlled by the CPU 8 together with the light projecting circuit 2c, the light emitting circuit 43 and the photometric circuit 45.

The passive type distance measuring device 1 needs to perform distance measurement using auxiliary light under low brightness or when the subject has no contrast (low contrast). Two
When the correlation of the luminance distribution information by the two visual fields cannot be obtained, the AF means for outputting the default signal is used.

FIG. 14 is a flow chart for explaining the operation of the distance measuring device shown in FIG. First, step S
At 61, the state of the switch that is closed by pressing the release button of the camera halfway is detected. When this switch is turned on, in step S62, the photometric circuit 45 performs photometry on the subject 11. Next, in step S63, distance measurement is performed.

Here, if it is determined in step S64 that it is the default, the process proceeds to step S65, and the auxiliary light is emitted by the light emitting diode. Then, if it is determined in step S67 that the default is still maintained, the process proceeds to step S67, and the Xe tube 9a emits light as auxiliary light.

Subsequent steps S68 to S75 are steps S12 to S19 in the flowchart of FIG. 7 described above.
Since the processing operation is the same as that of (1), description thereof will be omitted here. Further, switching to LED auxiliary light at low contrast and strobe auxiliary light at low brightness can be considered.

FIG. 15 is a flow chart for explaining the operation of such a distance measuring device. When the switch by the release button of the camera is turned on in step S81, the photometric circuit 45 performs photometry of the subject 11 in subsequent step S82, and the distance measurement is performed in step S83.

If it is determined in step S84 that the brightness is default, it is subsequently determined in step S85 whether or not the brightness is low. Here, if the brightness is low, the process proceeds to step S86, and re-ranging is performed with the strobe auxiliary light, while if it is not low, re-ranging is performed with the light emitting diode auxiliary light.

Subsequent steps S88 to S95 are steps S12 to S19 in the flowchart of FIG. 7 described above.
Since the processing operation is the same as that of (1), description thereof will be omitted here. Thus, according to this embodiment, the LED illumination and X
It is possible to provide a distance measuring device for a camera capable of more reliable distance measurement by switching the illumination of the e tube.

According to the embodiment of the present invention as described in detail above, the following constitution can be obtained. That is, (1) light projecting means for projecting light for distance measurement to a subject and reflected light from the subject are received by two different optical paths, and the distance from each incident position to the subject is detected. The light receiving means and the strobe means for adjusting the exposure amount of the subject are provided, and when the distance measurement result by the light projecting means is a long distance, the light receiving means at the time of the light emission of the strobe means. A distance measuring device for a camera, wherein the distance to the subject is detected again based on the output of 1.

(2) The strobe means switches the condensing state between the light emission when adjusting the exposure amount and the light emission when detecting the subject distance.
The distance measuring device for the camera described in.

(3) The strobe means switches the light emission time between light emission when adjusting the exposure amount and light emission when detecting the subject distance.
The distance measuring device for the camera described in.

(4) A light emitting diode for projecting light for distance measurement to a subject and reflected light from the subject are received by two different optical paths, and the distance from each incident position to the subject is detected. The light receiving means, the photometric means for detecting the brightness of the subject, and the strobe means for adjusting the exposure amount of the subject are provided, and when the output signal of the photometric means is equal to or higher than a predetermined brightness, A camera characterized in that the strobe means and the light receiving means are operated, and when the output signal of the light measuring means is below a predetermined brightness, the light emitting diode and the light receiving means are operated to perform distance measurement. Ranging device.

(5) The first light projecting means for projecting the distance measuring light toward a plurality of points on the screen and the reflected light from the subject are received to detect the distance to the subject. The light receiving means and a second light projecting means configured by a member different from the first light projecting means and projecting light in a range wider than the projection range of the first light projecting means, When the distance measurement results of the plurality of distance measuring points obtained by the operation of the first light projecting unit are all longer than the predetermined distance, the second light projecting unit is operated to detect the distance. Characteristic camera distance measuring device.

[0088]

As described above, according to the present invention, it is possible to perform distance measurement with high accuracy even at a long distance, do not depend on the reflectance and size of the subject, and do not require a large space for energy consumption.
A distance measuring device for a camera can be provided. Further, as in the conventional AF, the light emitting diode is used at a short distance, so that the problem of the circuit dynamic range does not occur and correct focusing can be performed from a short distance to a long distance.

[Brief description of drawings]

FIG. 1 is a block diagram showing a conceptual embodiment of a distance measuring device for a camera according to the present invention.

FIG. 2 is a diagram for explaining the principle of triangulation with two light receiving lenses.

3 is a diagram showing a schematic configuration of a camera to which a ranging optical system having a configuration according to the principle of triangulation of FIG. 2 is applied.

FIG. 4 is a configuration diagram showing the AF adopted in the camera of FIG. 3 in more detail.

5A is a view showing the angle of view of the PSD and the angle of view of the strobe light projecting portion, and FIG. 5B is a timing chart showing a simple operation of the camera of FIG.

FIG. 6 is a view for explaining another example of light ray switching in the distance measuring device for a camera of the present invention, (a) showing a state in which distance measuring light is projected onto a subject; (B) is a figure showing a state at the time of exposure.

FIG. 7 is a flowchart illustrating an operation of the camera having the above-described configuration.

FIG. 8 is a flowchart illustrating an operation of an embodiment in which a result of distance measurement is added to determination of necessity of a strobe.

FIG. 9 is a diagram illustrating still another example of light ray switching in the distance measuring device for a camera according to the present invention.

FIG. 10 is a diagram showing a configuration of a second embodiment in which the distance measuring device for a camera of the present invention is applied to multi-AF.

FIG. 11 is a diagram showing an example of a shooting scene according to a second embodiment.

FIG. 12 is a flowchart illustrating the operation of the second embodiment.

FIG. 13 is a diagram showing a configuration of a third exemplary embodiment of the present invention.

FIG. 14 is a flowchart illustrating the operation of the distance measuring device shown in FIG.

FIG. 15 is a flowchart illustrating another operation example of the distance measuring apparatus according to the third embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Distance measuring device, 2 ... Projector, 2a, 14 ... Projector lens,
2b ... Infrared light emitting diode (IRED), 2c ... Emitter circuit, 3, 4 ... Light receiving lens, 5, 6 ... Light receiving element (semiconductor position detecting element, PSD), 7, 22, 23 ... AF (autofocus) circuit , 8 ... Arithmetic control circuit (CPU), 9 ...
Strobe circuit, 9a ... Xenon tube (Xe tube), 10 ... Ray switching circuit, 11, 11a, 11b ... Subject, 12 ... Camera body, 16 ... Pop-up means, 17 ... Slit,
19 ... Booster circuit, 24, 25 ... Release switch.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G02B 7/32 G03B 13/36

Claims (3)

[Claims] 1. A light projecting means for projecting light for distance measurement to a subject, and reflected light from the subject is received by two different optical paths, and the distance from each incident position to the subject is detected. The light receiving means and the strobe means for adjusting the exposure amount of the subject are provided, and when the distance measurement result by the light projecting means is a long distance, the light receiving means when the strobe means emits light. A distance measuring device for a camera, wherein the distance to the subject is detected again based on the output of 1. 2. A light emitting diode for projecting light for distance measurement to a subject and a light receiving device for receiving reflected light from the subject through two different optical paths and detecting a distance from each incident position to the subject. Means, photometric means for detecting the brightness of the subject, and strobe means for adjusting the exposure amount of the subject. When the output signal of the photometric means is equal to or higher than a predetermined brightness, When the strobe means and the light receiving means are operated and the output signal of the photometric means is below a predetermined brightness,
A distance measuring device for a camera, characterized in that the light emitting diode and the light receiving means are operated to perform distance measurement. 3. A first light projecting means for projecting light for distance measurement toward a plurality of points on a screen, and a light receiving means for receiving reflected light from the subject and detecting a distance to the subject. And a member different from the first light projecting unit,
A second light projecting means for projecting light in a range wider than the projection range of the first light projecting means, and distance measurement of a plurality of distance measuring points obtained by the operation of the first light projecting means. A distance measuring device for a camera, wherein when any of the results is longer than a predetermined distance, the second light projecting means is operated to detect the distance.