JPH0727968A - Range-finding device for camera - Google Patents

Abstract

PURPOSE:To prevent photographing from being based on erroneous distance information by detecting glass with a photodetector for ordinary range-finding even when the regularly reflected light of IRED from the galss is made incident on a light receiving part in the case of photographing through the glass and giving a warning to a photographer when correct range-finding information is not obtained. CONSTITUTION:A CPU 2 drives and controls so that a subject is irradiated with signal light from a light projecting part 1, and the incident position of a reflected light signal from the subject is detected by the light receiving part 3. A subject distance is calculated based on output from the light receiving part 3 in a distance information arithmetic part 4, and received light quantity is calculated based on the output from the light receiving part 3 in a received light quantity arithmetic part 5. Whether or not range-finding data at such a time is correct is decided based on output from the arithmetic parts 4 and 5 in an erroneous range-finding decision part 7. Based on output from the decision part 7 and the arithmetic part 4, the subject distance is decided in a subject distance decision part 6.

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, and more particularly to an active type camera distance measuring device using semiconductor position detection as a light receiving element.

[0002]

2. Description of the Related Art Conventionally, various distance measuring devices employing an active AF (autofocus) system have been developed. The active AF method is a method in which a signal is projected onto a subject and the reflected signal light thereof is detected to detect the subject distance. Therefore, when glass is present between the subject and the camera, signal light reflection occurs on the glass surface, making it difficult to focus on the subject on the side of the glass.

[0003] Conventionally, as a measure for photographing through glass in an active distance measuring device,
For example, as disclosed in Japanese Unexamined Patent Application Publication No. 5-34580, a multi-point distance measuring device is used to measure a distance with an original combination of light emitting and receiving elements and a distance measurement with a combination of different light emitting and receiving elements. There is a method of determining that the image is captured through the glass when the received light is output when the distance measurement is performed with a combination different from the original combination. Further, when another light receiving element is arranged on the short-distance side of the original light receiving element as disclosed in JP-A-5-34581, and there is light reception output from the light receiving element, A method of determining that the image is taken through glass is known.

[0004]

However, in the method described in Japanese Patent Laid-Open No. 5-34580, when the glass is extremely close to the one, such as when the photographing lens is pressed against the glass. It was only possible to judge through the glass. That is, there is a problem that correct determination cannot be performed when the glass exists at a position slightly away from the camera and the IRED specularly reflected light from the glass enters the light receiving portion. In addition, JP-A-5-
In a method such as 34581, IR from glass is used.
There is a problem that the glass cannot be detected when the specularly reflected light of the ED does not enter the light receiving element for glass detection and is incident only on the light receiving element for normal distance measurement.

The present invention has been made in view of the above problems, and correctly determines even when the glass exists at a position slightly apart from the camera and the specularly reflected light of the IRED from the glass enters the light receiving portion. An object of the present invention is to provide a distance measuring device for a camera, which makes it possible to detect glass with a light receiving element for normal distance measurement and prevents photographing due to incorrect distance information.

[0006]

That is, the present invention comprises, as a light receiving element, a light projecting means for irradiating a subject with signal light and a semiconductor position detecting element for detecting the incident position of the reflected light from the subject. A light receiving means, a distance information calculating means for calculating information on a subject distance from an output of the light receiving means, a received light amount calculating means for calculating a light quantity of the reflected light from an output of the light receiving means, and the distance information calculating means,
An erroneous distance measurement determination means for determining whether or not the distance measurement data at this time is correct from the output of the received light amount calculation means, and the object distance is determined by the output of the erroneous distance measurement determination means and the distance information calculation means. And a subject distance determining means for determining the subject distance.

Further, according to the present invention, in the above-described distance measuring device for a camera, a plurality of the light receiving elements are arranged side by side in a direction perpendicular to the base line length direction, and an incident image of the reflected light is formed on the plurality of light receiving elements. It is characterized by comprising a light receiving means for forming an image and a received light quantity comparing means for comparing the received light quantity of the plurality of light receiving elements.

[0008]

In the camera distance measuring device of the present invention, the signal light is emitted from the light projecting means toward the subject, and the incident position of the reflected light from the subject is provided with the semiconductor position detecting element as a light receiving element. It is detected by the light receiving means. Information on the object distance is calculated by the distance information calculating means from the output of the light receiving means, while the light quantity of the reflected light is calculated by the received light quantity calculating means from the output of the light receiving means. Then, from the output of the distance information calculation means and the received light amount calculation means,
Whether or not the distance measurement data at this time is correct is determined by the erroneous distance measurement determining means, and further, by the output of this erroneous distance measurement determining means and the distance information calculating means, the object distance determining means determines the object distance. Is determined.

Further, in the camera distance measuring apparatus of the present invention, the light receiving means comprises a plurality of the light receiving elements arranged side by side in a direction perpendicular to the base line length direction, and the incident image of the reflected light is a plurality of the light receiving elements. An image is formed on the light receiving element. Then, the received light amounts of the plurality of light receiving elements are compared by the received light amount comparing means.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a block diagram showing the configuration of a distance measuring device for a camera according to a first embodiment of the present invention. Figure 1 (a)
In the above, the light projecting unit 1 emits signal light toward a subject (not shown), and is driven and controlled by the CPU 2. The light receiving section 3 detects the incident position of the reflected light signal from the subject illuminated by the light projecting section 1 and outputs the information to the distance information calculating section 4 and the received light amount calculating section 5. The outputs of the distance information calculation unit 4 and the received light amount calculation unit 5 are supplied to the subject distance determination unit 6 and the incorrect distance measurement determination unit 7 in the CPU 2.

As shown in FIG. 1B, the light receiving section 3 uses a semiconductor position detecting element (PSD) 8 for detecting the incident position of reflected light from a subject (not shown) as a light receiving element. I am configuring.

In such a structure, the light projecting section 1 driven and controlled by the CPU 2 emits signal light toward a subject (not shown). Then, the incident position of the reflected light signal from the subject emitted from the light projecting unit 1 is detected by the light receiving unit 3, and the information is output to the distance information calculating unit 4 and the received light amount calculating unit 5. The distance information calculation unit 4 calculates the subject distance from the output of the light receiving unit 3, and the received light amount calculation unit 5 calculates the received light amount from the output of the light receiving unit 3.

From the output of the received light amount calculation unit 5, the erroneous distance measurement determination unit 7 determines whether the distance measurement data at that time is affected by the reflected light from the glass. Further, the determination result of the erroneous distance measurement determining unit 7 and the subject distance from the distance information calculating unit 4 are supplied to the subject distance determining unit 6. When the distance measurement data is affected by the reflected light from the glass, the subject distance determination unit 6 performs processing such as outputting a warning to the photographer, a release lock, and a long distance shooting distance as distance information. On the other hand, when the distance measurement data is not affected by the reflected light from the glass, the output of the distance information calculation unit 4 is determined as the subject distance. This makes it possible to determine from the amount of received light whether or not distance measurement is through glass.

Here, the reason why it is possible to determine through the glass by the configuration of FIG. 1 will be described. In general, when distance measurement is performed through glass, it is considered that there is a light projecting lens with a light amount that does not affect normal distance measurement or scattered light on the inner surface of the light receiving unit in the vicinity of the emitted signal light. Harmful light is present. The amount of light reflected by glass is a few percent of the whole,
As shown in FIGS. 2A and 2B, the reflection on the glass 9 is regular reflection, and the glass 9 is located closer to the subject 10 in the distance measurement through the glass. Therefore, when the signal light and the harmful light in the vicinity thereof are reflected by the glass 9 and enter the light receiving unit 3, the received light amount becomes larger than that when the scattered reflected light at the time of normal distance measurement enters. Therefore, it is possible to determine whether or not the distance measurement is through glass, based on the amount of received light.

FIG. 3 is a block diagram showing the arrangement of a distance measuring device for a camera according to the second embodiment of the present invention. In this embodiment, a known active triangulation device is applied that projects distance measuring light onto a subject and determines the subject distance based on the incident position of the reflected signal light.

As shown in the figure, an infrared light emitting diode (IRED) 1 for projecting light through a light projecting lens 11.
2 is connected to the CPU 14 via the driver 13. Then, the output of the light position detecting element (PSD) 16 that receives the subject light incident through the light receiving lens 15 is
The differential operation circuit 23 and the current mirror circuit 24 are connected via preamplifiers 17 and 18, diodes 19 and 20, and buffers 21 and 22, respectively. The outputs of the differential operation circuit 23 and the current mirror circuit 24 are connected to the CPU 14. And this CPU1
Reference numeral 4 is connected to the focusing unit 25 to drive and control the focusing lens 26, and is also connected to a zoom encoder 28 which controls the zoom position of the zoom lens 27.

The differential operation circuit 23 and the current mirror circuit 24 correspond to the distance information operation unit 4 and the received light amount operation unit 5 of FIG. 1, respectively. In such a configuration, when infrared light for distance measurement is emitted by the IRED 12, the infrared light is projected through the projection lens 11.
The distance measuring light is reflected on the subject, and the reflected light is condensed by the light receiving lens 15 and is incident on the PSD 16. Then, based on the known principle of triangulation, the object distance is calculated based on the incident position of the reflected signal light on the PSD 16.

[0018] The PSD16, as shown in FIG. 4, two current signals depending on the position of the signal light i _a, but outputs a i _b, the current signal i _a, i _b is (1) as equation It becomes a relationship.

[0019]

[Equation 1] Then, from the relationship of m + n = t (t: length of PSD) (2), the equation (3) is established.

[0020]

[Equation 2] The m is the light incident position, since t is a constant, by calculating a _{i a / (i a + i} b) ... (4), the incident position m of the reflected signal light can be computed, subject distance Can be asked. Furthermore,
The current signals i _a and i _b of the PSD 16 are amplified by the preamplifiers 17 and 18 and flow into the compression diodes 19 and 20. Then, the buffer circuits 21 and 22 are
The V _ref reference potentials of the compression diodes 19 and 20 are output to the differential operation circuit 23.

FIG. 5 is a circuit configuration diagram showing the details of the differential operation circuit 23. In FIG. 5, 29 is a current value i ₀
Of the NPN transistors 30 and 31 whose emitters are commonly connected. Let these collector currents be i ₁ and i ₂ . When the amplification factor of the preamplifier and beta, the output potential V _A of the compression diode, V _B is as equation (5).

[0022]

[Equation 3] From the same equation, the relationships of equations (6) and (7) are established between i ₁ and i ₂ and _VA and V _B.

[0023]

[Equation 4]

I _a / i _b = i ₂ / i ₁ (7) On the other hand, the expression (10) is obtained from the expressions (8) and (9). i ₁ + i ₂ = i ₀ (8)

[0025]

[Equation 5]

[0026]

[Equation 6] Therefore, .gamma.i ₂ converted into voltage i ₂ with resistor 32
Is expressed by equation (11).

[0027]

[Equation 7]

That is, since γ, i ₀ , and t are fixed values, PSD1 is calculated from γi ₂ shown in the above equation (11).
The incident position m of the signal light on 6 can be obtained. Next, regarding the received light amount, the detailed circuit configuration of the current mirror circuit 24 for calculating this is as shown in FIG. In FIG. 6, NPN transistors 33 and 34
Are compression diodes 19 and 2 respectively shown in FIG.
0 constitutes a current mirror circuit. Therefore, NP
The collector currents of the N transistors 33 and 34 are β
i _a, beta I _b, and the current flows in βi _a + βi _b the resistor 35. Then, γ (βi _a + βi _b ) obtained by converting this current into a voltage by the resistor 35 is used as the received light amount and the CPU 14
Output to.

The CPU 14 outputs the output signal voltage from the distance information calculating means and the received light amount calculating means (see the distance information calculating section 4 and the received light amount calculating section 5 in FIG. 1) to A / D by the built-in A / D converter. D-convert and input. Then, the signal is used for focusing control by a predetermined algorithm. At this time, the focusing lens 26 is controlled via the focusing unit 25.

Next, referring to the flow chart of FIG.
The operation of the embodiment will be described in detail. First, step S1
The IRED12 is caused to emit light at step S2, S
At 3, the subject distance L and the received light amount V are calculated. Then, in step S4, it is determined whether or not the received light amount V is smaller than a predetermined value V ₀ . In step S5, focusing is performed based on the subject distance L. On the other hand, if V> V ₀ in step S4, step S6
Go to and determine that the distance measurement is through glass, and notify the photographer that distance measurement is not correct with a warning or release lock, or turn off the flash and focus at the distance for long-distance shooting. And the like.

Here, when it is determined that the distance measurement is through glass, focusing on the long-distance shooting distance with the strobe off is performed in the case of shooting through the glass and shooting a long-distance subject such as a landscape. This is because there are many things to do. The reason why the flash is turned off is to prevent the flash light from being reflected by the glass when the flash is fired when shooting through glass, and in particular when shooting night scenes, the subject is not covered by the flash light. is there.

Next, a third embodiment of the present invention will be described. FIG. 8 is a block diagram showing the configuration of a distance measuring device for a camera according to the third embodiment of the present invention. As shown in the figure, in the third embodiment, two PSDs arranged side by side in the direction perpendicular to the base line length direction are used as a light receiving element with respect to the second embodiment. And two PS
The amount of received light of D8a, 8b and the two PSDs 8a, 8
The distance measurement through the glass is determined according to the level of the sum of the received light amounts of b. In addition, in FIG.
The same components as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

As described above, since harmful light exists around the signal light emitted toward the subject and the reflection on the glass surface is specular reflection, the angle of the glass with respect to the camera causes a change in FIG. As shown in (a) and (b),
Even if the distance to the glass 9 is the same, the direction (angle) of incidence on the light receiving unit 3 changes.

That is, the scattered reflected light spot image in the normal distance measurement moves according to the object distance only in the direction parallel to the base line length direction, and does not move in the direction perpendicular to the base line length direction. However, when the distance is measured through the glass,
In the case where the camera 37 and the glass 9 are inclined as shown in (a), the specular reflection light spot image 38 is located above the normal scattered reflection light spot image as shown in FIG. Shift to. Similarly, in the case of the inclined arrangement as shown in FIG. 9B, the spot image shifts downward as shown in FIG. 9E, so whether the spot image is shifted upward or downward is determined. Can be detected. As a result, it is possible to determine whether the distance measurement is through glass.

Incidentally, FIG. 9 (c) shows an arrangement in which the camera 37 and the glass 9 are opposed to each other without being tilted. In this case, as shown in FIG. 9 (f), the two PSDs 8a and 8b are disposed in the middle. The specular reflection light spot image 38 is located.

That is, in this embodiment, as shown in FIG. 10C, the spot lights are incident on the two PSDs 8a and 8b at the same ratio, that is, the PSDs 8a and 8b.
It is adjusted in advance so that the received light quantities V _A and V _{B of} b are the same. Then, spot light is incident on the positions shown in FIGS. 10A and 10B, and V _A > V _B and V _A <V
_When it becomes _B , it is determined that the distance measurement is through glass.
However, the specularly reflected light from the glass is shown in FIG. 10C when the glass 9 and the camera 37 are in a positional relationship as shown in FIG. 9C.
As shown in (3), the light is incident on the position where V _A = V _B. Therefore, the above-mentioned determination alone means that the distance measurement is normal.

Therefore, even when the spot light is incident on the position where V _A = V _B , the total received light amount, that is, V
When _A + V _B is greater than the predetermined level, like the second embodiment described above, by determining that the through glass, glass 9 and camera 37 in a positional relationship as shown in FIG. 9 (c) Even if there is, it is possible to determine through the glass.

FIG. 11 is a block diagram showing the detailed construction of the distance measuring device for a camera according to the third embodiment. In the distance measuring device of the second embodiment shown in FIG. 3 described above. The processing circuit on the light receiving side is added by one PSD.

That is, the processing circuit on the light receiving side will be described. The outputs of the light position detecting elements (PSD) 16a and 16b for receiving the subject light incident through the light receiving lens 15 are the preamplifiers 17a, 18a and 17b, 18b. ,
The diodes 19a, 20a and 19b, 20b and the buffers 21a, 22a and 21b, 22b are connected to the differential operation circuits 23a and 23b and the current mirror circuit 24, respectively. The outputs of the differential operation circuits 23a and 23b and the current mirror circuit 24 are C
It is connected to the PU 14.

The range finder of the embodiment has the following structure.
The configuration of the second embodiment described above may be switched in time series to process the outputs of the two PSDs. Next, the operation of the third embodiment will be described in detail with reference to the flowchart of FIG.

First, in step S11, the IRED 12 is caused to emit light. Then, in step S12, the PSD 16a,
The subject distance L is calculated from the average position m _AVE of the reflected light spot center of gravity positions m _A and m _B of 16 b. Then, in step S13, the received light amounts V _A and V _B of the PSDs 16a and 16b are received.
To calculate.

Next, in step S14, V _A and V
It is determined whether or not the magnitude of the difference in _B is smaller than the predetermined value V ₁ . Here, | determines that <When the relationship of V ₁ was, reflected light spot image is in the normal position as shown in FIG. _{10 (c) | V A -V} B. Therefore, step S
In step 15, it is determined whether the sum of the received light amounts of the PSDs 16a and 16b is smaller than the predetermined value V ₀ . V _A + V _B <V
_If the relationship is ₀ , it is determined that the distance is normal, and the process proceeds to step S16 to focus on the basis of the subject distance L.

Further, in step S14, | V
_A -V _B | when a> V _1, when a V _A + V _B> V ₀ In step S15, the flow advances each determined to be a distance measurement through the glass to the step S17. And
In step S17, processing such as warning, release lock, or strobe off for focusing at a distance for long-distance photography is performed.

Next explained is the fourth embodiment of the invention. In the case of the signal light irradiation type triangulation, correct distance measurement cannot be performed unless the signal light is properly irradiated to the subject. In the embodiment, a spot defect is determined in addition to the determination through the glass. Here, the spot lacking is a state as shown in FIG. 13 in a state where the signal light does not correctly hit the subject.

The fourth embodiment has the same structure as that of the third embodiment described above, and in addition to the amount of received light, the PSD 16a,
The normal distance measurement, the distance measurement through glass, and the spot defect are determined by also taking into consideration the gravity center positions m _A and m _B of the reflected light spot of 16 b.

When a spot is obliquely cut off as shown in FIG. 14 (a), the barycentric positions m _A and m _B of the reflected light spots of PSDA and B have the difference as shown in FIG. Generated and received light amount V _A and V of PSD A and B
_{B is} also equal. From this, the normal distance measurement or spot deficient light is determined, and the total received light amount V _A + V _B
Judgment is made according to the size of.

The operation of the fourth embodiment will be described in detail below with reference to the flowchart of FIG. First, in S21 to S23, the IRED is caused to emit light and the PSD
The positions m _A and m B of the reflected light spot centroids of _A and _B and the received light amounts V _A and V _B are calculated. Then, in step S24, it is determined whether or not the difference between V _A and V _B is smaller than the predetermined value V ₁ . If the difference between V _A and V _B is smaller than V ₁ , the process proceeds to step S25 and it is determined whether the total received light amount V _A + V _B is smaller than a predetermined value V ₀ .

At step S25, V _A + V _B is V
When it is smaller than ₀ , it is determined that the distance measurement is normal, and the process proceeds to step S26 to calculate the subject distance L by the average m _AVE of m _A and m _B. Then, in step S27, the focus is adjusted by L. In step S24, | V
_A -V _B | when a> V _1, the process proceeds to step S28.

Then, in this step S28, V _A +
When V _B is smaller than V ₂ , it is determined that the spot is missing and the process proceeds to step S29. In this step S29, m _A and m
_If the magnitude of the difference in _B is larger than the predetermined value m ₀ , a warning or release lock is given to the photographer in step S30 to inform the photographer that correct distance measurement has not been performed. On the other hand, when | m _A −m _B | <m _{0 in} the above step S29, FIG.
It is determined that the spot is missing in the direction parallel to the base line length direction as shown in (4), and the process proceeds to steps S26 and S27 to perform the above-described processing.

In step S28, V _A + V _B
Is larger than the predetermined value V ₂ , and V is obtained in step S25.
When the _A + V _B> V _0, determines that it would be through glass ranging turns off the flash at step S31, focus on distance for long range imaging.

Next explained is the fifth embodiment of the invention. As described in each of the above-described embodiments, when the amount of received light is larger than the predetermined level, it is determined that the distance measurement is through the glass and the distance for long-distance shooting is focused, for example, over the show window. If you shoot a subject at a short distance through the glass, such as when shooting an interior display, you will end up with a very blurry picture.

The fifth embodiment has the same structure as the above-mentioned third and fourth embodiments, and the position m of the center of gravity of the reflected light spots of PSDs A and B when it is judged that the light is received through the glass. By comparing _A and m _B , it is determined whether or not short-distance photography through glass is performed. If it is determined that the subject is a close-up shot through glass, a warning or a release lock is used to inform the photographer that correct distance measurement has not been performed, and the subject is present at a short distance. It focuses on long distances and prevents you from taking large, blurry photos.

When a short-distance subject is measured through glass, two spot images of specular reflection light from the glass and reflection light from the subject are displayed on PSDs A and B as shown in FIG. The positions of the spot centroids of the formed PSDs A and B are different depending on the baseline length and the vertical shift of the incident position of the specularly reflected light from the glass, as shown in FIG.

On the other hand, in the case of long-distance photography through glass,
Normally, the reflected light from the subject does not enter, but the amount of light is small compared to the specularly reflected light from the glass, so P
The centers of gravity of the spots of SDA and B are almost at the same position. From this, in the fifth embodiment, when it is determined that the image is taken through the glass, it is determined whether or not the close-range image is taken through the glass.

The operation of the fifth embodiment will be described below with reference to the flowchart of FIG. In the flowchart of FIG. 17, steps S41 to S50 are the same as steps S21 to S21 of the fourth embodiment of FIG. 15 described above.
The same process as S30 is performed. Then, if it is determined in step S48 that the total received light amount V _A + V _B is larger than the predetermined value V _{2 and the} light is through the glass, the process proceeds to step S51.
In step S51, it is determined whether or not the magnitude of the difference between the reflected light spot barycentric positions m _A and m _B of the PSDs A and B is larger than a predetermined value m ₁ .

Here, when the difference between m _A and m _B is larger than the predetermined value m _1, it is determined that the close-up photography through the glass is performed. Therefore, the process proceeds to step S50, and the photographer is informed that correct distance measurement has not been performed by a warning or a release lock. On the other hand, in step S51,
When | m _A −m _B | <m ₁ , it is determined to be long-distance photography through glass. Next, in step S52, the flash is turned off and the long-distance shooting distance is focused.

FIG. 18 is a flow chart showing a modified example of the fifth embodiment. That is, in the flowchart of FIG. 17, when it is determined in step S51 that the close-up photography through glass is performed, step S5 is performed.
I proceeded to 0 and alerted the photographer that the distance could not be measured correctly by warnings and release locks.

However, in the modification of FIG. 18,
In the case of short-distance shooting through glass, the focus is on the short distance. That is, in step S51, the magnitude of the difference between m _A and m _B is the predetermined value m ₁
If it is larger, it is determined that the close-up photography through the glass is performed, and the process proceeds to step S53. Then, in this step S53, the photographing can be performed by focusing on the short-distance photographing distance.

Next explained is the sixth embodiment of the invention. In the sixth embodiment, correct distance measurement data can be obtained even when a spot defect occurs, and as shown in FIG.
An SD8 'is used which is arranged side by side in the direction perpendicular to the base line length direction. Here, as shown in FIG. 14C, when a spot is missing in the direction perpendicular to the base line length direction, correct distance measurement data cannot be obtained with the configuration of the sixth embodiment.

Therefore, the spot shape is made to be elongated in the vertical direction as shown by the specular reflection light spot image 39 in FIG. 19 so that the spot chipping in the vertical direction does not occur. Then, the spot barycentric positions of adjacent PSDs are compared, and when two or more barycenters are at the same position, the subject distance L is calculated based on the positions and focusing is performed. For example, in the case shown in FIG. 20 (a), since the gravity center positions m ₁ and m ₂ are at the same position, m ₁
And the object distance L is calculated based on the positions of m ₂ and m ₂ . Further, in the case as shown in FIG. 20B, the center of gravity position m
_{Since 1} , m ₂ and m ₃ are at the same position, m ₁ , m ₂ and m ₃
The subject distance L is calculated based on the position of.

The operation of this embodiment will be described below with reference to the flowchart of FIG. First, in steps S61 to S63, the IRED is caused to emit light, and the positions m _{1 to} m _{5 of} the center of gravity of the reflected light spot of each PSD and the total received light amount V are calculated. Then, in step S64, it is detected that the difference between the barycentric positions of the adjacent PSDs is within a predetermined difference. The subroutine of step S64 will be described later.

Next, in step S65, the magnitude of the total received light amount V and the predetermined value V ₀ is determined. Here, when the total received light amount V is larger than the predetermined value V _0, it is determined to be through the glass, the process proceeds to step S73, the strobe is turned off, and the distance for long-distance photography is focused. On the other hand, if V <V _{0 in} step 65, the process proceeds to step S66, and it is determined whether the barycentric positions of all PSDs are within a predetermined difference.

In step S66, if the barycentric positions of all PSDs are within the predetermined difference, it is determined that the distance measurement is normal, and the flow advances to step S67. Then, the subject distance L ₁ is calculated based on the average position of all the centers of gravity, and then step S68.
Go to and focus on L ₁ . On the other hand, if the position of the center of gravity is not within the predetermined difference in step S66,
In step S69, it is determined whether the barycentric position is within the predetermined difference.

In step S69, if the barycentric position is within the predetermined difference, the process proceeds to step S70, and the object distance L ₂ is calculated based on the average position of the barycentric positions within the predetermined difference. Then, in step S71, focusing is performed based on L ₂ . On the other hand, when the center of gravity position is not within the predetermined difference in step S69, the process proceeds to step S72 to notify the photographer by the warning or the release lock that the distance cannot be correctly measured.

Next, referring to the subroutine of FIG.
The processing operation of step S64 will be described in detail. First, in step S82, i representing the PSD number is set to 1, and then the PSD represented by i in step S82.
I + 1, that is, 2, is set to j representing the number of the PSD next to. Then, in step S83, the positional difference m _ij between adjacent centers of gravity is obtained, and in step S84 m _ij and the predetermined value m _0.
And determine the size of.

Here, when m _ij is smaller than the predetermined value m _0, it is determined that the PSDs represented by i, j are not affected by the spot defect, and the combination (i, j) is determined in step S85. After storing, proceed to step S86. On the other hand, if m _ij > m ₀ in step S84,
It is determined that the PSD represented by i, j is affected by the spot defect, and the process proceeds to step S86 without storing the combination (i, j).

In step S86, i + 1, j
To j + 1. Next, in step S87, it is determined whether or not the final combination has been completed. Here, if the final combination has not been completed, the process returns to step S83, the above-described processes of steps S83 to 87 are repeated, and if completed, the process returns.

The present invention is not limited to the above embodiment. For example, the PSD 8 ″ and the specular reflection light spot image 40 having the configuration shown in FIG. 23 can be used to apply to multi-point distance measurement.

Further, when a circuit in which the light amount output is saturated when the received light amount is large is used, a gain control circuit for lowering the gain of the IRED according to the received light amount is added to the configuration of the distance measuring device. It goes without saying that such applications and modifications are possible.

[0070]

As described above, according to the present invention, by using one or a plurality of semiconductor position detecting elements, the amount of received light and the position of the center of gravity of the reflected light incident on the semiconductor position detecting elements are passed through the glass. Since the shooting and spot missing are determined, it is possible to prevent shooting using incorrect distance measurement information when shooting through glass or when spot missing occurs,
Even in such a case, it is possible to provide a distance measuring device for a camera that is in focus.

[Brief description of drawings]

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

FIG. 2 is a diagram showing specular reflection light from glass when distance measurement is performed through the glass.

FIG. 3 is a block diagram showing a configuration of a distance measuring device for a camera according to a second embodiment of the present invention.

FIG. 4 is a diagram showing details of the PSD 16 of FIG.

5 is a circuit configuration diagram showing details of a differential operation circuit 23 in FIG.

6 is a detailed circuit configuration diagram of a current mirror circuit 24 of FIG.

FIG. 7 is a flowchart illustrating the operation of the second embodiment.

FIG. 8 is a block diagram showing a configuration of a distance measuring device for a camera according to a third embodiment of the present invention.

9A to 9C are diagrams showing an example of the positional relationship between the camera 37 and the glass 9, and FIGS. 9D to 9F are positional relationships shown in FIGS. It is a figure showing the position of the specular reflection light spot image 38 in the case of.

FIG. 10 is a diagram showing two PSDs 8a and 8b and an incident state of spot light according to a third embodiment.

FIG. 11 is a block diagram showing a detailed configuration of a distance measuring device for a camera according to a third embodiment.

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

FIG. 13 is a diagram showing an example of a spot missing state in a signal light irradiation type triangulation.

FIG. 14 is a diagram showing an example of a spot missing state for two PSDs.

FIG. 15 is a flowchart illustrating the operation of the fourth embodiment.

FIG. 16 shows two spot images of specular reflection light from glass and reflection light from the subject formed on PSDs A and B, when a short-distance subject is measured through glass.
It is the figure which showed the position of the spot gravity center of SD A and B.

FIG. 17 is a flowchart illustrating the operation of the fifth embodiment.

FIG. 18 is a flowchart illustrating an operation of a modified example of the fifth embodiment.

FIG. 19 is a diagram showing a configuration of a sixth embodiment of the present invention and is a diagram showing an example in which a plurality of PSDs 8'as light receiving elements are arranged in parallel in a base line length direction and a vertical direction.

20 is a diagram showing the relationship between the specular reflection light spot image 39 and the position of the center of gravity in FIG.

FIG. 21 is a flowchart illustrating the operation of the sixth embodiment.

FIG. 22 is a subroutine for explaining in detail the processing operation of detecting the center of gravity within the position difference predetermined difference in step S64 of FIG.

FIG. 23 is a diagram showing an example of a PSD 8 ″ and a specular reflection light spot image 40 when applied to multi-point distance measurement.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Projector, 2, 14 ... CPU, 3 ... Light receiving part, 4 ... Distance information calculating part, 5 ... Received light amount calculating part, 6 ... Subject distance determining part, 7 ... False distance determining part, 8 ... Semiconductor position Detection element (PS
D), 9 ... glass, 10 ... subject, 11 ... projection lens,
12 ... Infrared light emitting diode (IRED), 13 ... Driver, 15 ... Light receiving lens, 16 ... Optical position detection element (PS)
D), 17, 18 ... Preamplifier, 19, 20 ... Diode, 21, 22 ... Buffer, 23 ... Differential operation circuit, 24
... current mirror circuit, 25 ... focusing section, 26 ...
Focusing lens, 27 ... Zoom lens, 28 ... Zoom encoder.

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[Procedure amendment]

[Submission date] November 8, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

The present invention will be described below with reference to FIGS. 3 to 7.
The first embodiment will be described in detail. In this embodiment, a known active triangulation device is applied that projects distance measuring light onto a subject and determines the subject distance based on the incident position of the reflected signal light.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

As shown in FIG . 3 , an infrared light emitting diode (IRED) 1 for projecting light through a light projecting lens 11 is provided.
2 is connected to the CPU 14 via the driver 13. Then, the output of the light position detecting element (PSD) 16 that receives the subject light incident through the light receiving lens 15 is
The differential operation circuit 23 and the current mirror circuit 24 are connected via preamplifiers 17 and 18, diodes 19 and 20, and buffers 21 and 22, respectively. The outputs of the differential operation circuit 23 and the current mirror circuit 24 are connected to the CPU 14. And this CPU1
Reference numeral 4 is connected to the focusing unit 25 to drive and control the focusing lens 26, and is also connected to a zoom encoder 28 which controls the zoom position of the zoom lens 27.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

[0019]

[Equation 1] Then, from the relationship of m + n = t (t: length of PSD) (2), the equation (3) is established.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0042

[Correction method] Change

[Correction content]

Next, in step S14, V _A and V
It is determined whether or not the magnitude of the difference in _B is smaller than the predetermined value V ₁ . Here, | determines that <When the relationship of V ₁ was, reflected light spot image is in the normal position as shown in FIG. _{10 (c) | V A -V} B. Therefore, step S
In step 15, it is determined whether the sum of the received light amounts of the PSDs 16a and 16b is smaller than the predetermined value V ₀ . V _A + V _B <V
_If the relationship is ₀ , it is determined that the distance measurement is normal, and the process proceeds to step S16 to focus on the basis of the subject distance L.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0046

[Correction method] Change

[Correction content]

When a spot is obliquely cut off as shown in FIG. 14 (a), the barycentric positions m _A and m _B of the reflected light spots of PSDA and B have the difference as shown in FIG. Generated and received light amount V _A and V of PSD A and B
_B is also not equal. From this fact, the normal distance measurement or spot missing light is determined, and whether the light is passing through the glass is determined by the total received light amount V _A.
Judgment is made according to the magnitude of + V _B.

Claims (2)

[Claims] 1. A light projecting means for irradiating an object with signal light, a light receiving means having a semiconductor position detecting element as a light receiving element for detecting an incident position of reflected light from the object, and an output of the light receiving means. From the output of the distance information calculation means for calculating the information on the subject distance, the received light amount calculation means for calculating the light amount of the reflected light from the output of the light receiving means, the distance information calculation means, and the output of the received light amount calculation means. An erroneous distance measurement determining means for determining whether or not the distance measurement data at this time is correct, and an object distance determining means for determining the object distance by the output of the erroneous distance measurement determining means and the distance information calculating means. A distance measuring device for a camera, characterized by: 2. A light receiving means, wherein a plurality of the light receiving elements are arranged side by side in a direction perpendicular to a base line length direction, and an incident image of the reflected light is formed on the plurality of light receiving elements, and the plurality of light receiving means. 2. The camera distance measuring device according to claim 1, further comprising: a received light amount comparison means for comparing received light amounts of the light receiving elements.