JPH0543964B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a distance measuring device, particularly an active type distance measuring device suitable for a camera.

Conventionally, in order to maintain accuracy, this type of device has performed distance measurement by emitting a small spot light and detecting the angle of the reflected light at a distance equal to the base line length.

However, with such a small spot light, reflected light may not be obtained depending on the subject conditions, and the distance measurement field of view is narrow, so for example, in a portrait of two people, the distance measurement field of view may be between the two people. As a result, there was a drawback that distance measurement was impossible or incorrect distance measurement occurred.

The present invention has been made in view of the above circumstances, and includes a plurality of light projection means for independently projecting signal light along a plurality of distance measurement axes at different angles, and a plurality of distance measurement axes for each of the plurality of distance measurement axes. a light receiving means for receiving reflected light of the signal light reflected from an object above; detecting a light receiving position of the reflected light of the light receiving means; and detecting distance measurement information regarding the object distance on each of the distance measurement axes. correcting the difference in the light receiving position of the light receiving means caused by the reflected light from objects on different distance measuring axes that are considered to be at the same distance being reflected from different distance measuring axes; A correction means for enabling the processing means to process these distances as the same distance, and a distance measurement representing a short distance among the distance measurement information for the object distance on each distance measurement axis measured by the processing means. a selection means for selecting information, prevents erroneous distance measurement by performing multiple distance measurements for different distance measurement fields of view, and forms a signal suitable for focus adjustment by comparing the distance measurement results preferentially for short distances. The aim is to provide equipment.

An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is an optical explanatory diagram of a distance measuring device according to an embodiment of the present invention. In the figure, a ₁ , a ₂ , and a ₃ are light emitters such as light emitting elements, and they are arranged in a straight line, and each of the light emitters a ₁ to a ₃ serves as a signal light emitted for distance measurement. The pulsed light pl ₁ to _{pl 3} of 2 is transmitted along the ranging axes l _{1 to l 3} at a plurality of different angles to the objects θ ₁ , θ ₂ ,
Project toward θ ₃ θ _∞ . LA is a projection lens,
It is arranged in front of the groups of light emitters _a1 to _a3 . LD is a light-receiving lens that receives reflected light of pulsed light Pl ₁ - _{pl 3} reflected from respective objects θ ₁ - _{θ ∞} on the distance measurement axes l ₁ - l ₃ .
Receives Pr ₁ ~ _{pr ∞} . _D1 , _D2 , _D3 , _D4 , _D5 , _D6 ,
Each of D ₇ is a light receiver such as an optical sensor, which is arranged in a straight line behind the light receiving lens LD, and receives the reflected light pr of the pulsed lights pl ₁ to _{pl 3} through the lens.

The light emitters a ₁ to _{a 3} groups, the lenses LA and LD, and the light receivers D ₁ to D ₇ groups are arranged as follows, for example.

In the case of a subject θ ₁ close to the lenses LA and LD, the arrangement is such that the reflected light pr ₁ by the pulsed light pl ₁ of the first light emitter a ₁ is mainly received by the fifth light receiver D ₅ , and similarly , the reflected light pr _{2 from the pulsed light Pl 2 of the second light emitter a 2 is transmitted} to the sixth light receiver D 6 and then to the third light emitter D ₆ .
The reflected light pr ₃ from the pulsed light Pl ₃ of a ₃ is reflected by the seventh light receiver.
They are arranged so that they mainly receive light at D ₇ .

In the case of a subject θ ₂ that is a little far from the lenses LA and LD, the reflected light from the pulsed light pl ₁ of the first light emitter a ₁
pr ₄ is mainly received by the fourth light receiver D ₄ , and similarly, the reflected light by the pulsed light _{pl 2 of} the second light emitter a 2
Pr ₅ is arranged so that it is mainly received by the fifth light receiver D ₅ , and the reflected light pr ₆ from the pulsed light _{pl 3 of} the third light emitter a 3 is mainly received by the sixth light receiver D ₆ .

In the case of a subject θ ₃ far from the lenses LA and LD, the reflected light pr ₇ from the pulsed light _{pl 1 of the first light emitter a 1} is mainly received by the third light receiver D ₃ and is reflected by the second light emitter a The reflected light pr ₈ from the pulsed light pl ₂ of ₂ is mainly received by the fourth photoreceiver D ₄ , and the reflected light pr ₉ from the pulsed light pl ₃ from the third light emitter a ₃ is mainly received by the fifth photoreceiver D ₅ . It is arranged so that

In the case of an object θ _∞ at infinity, the reflected light pr _∞ by the pulsed light pl ₁ of the first emitter a ₁ is mainly received by the first receiver D ₁ , and the pulse of the second emitter a ₂ They are arranged so that the light reflected by the light pl ₂ is mainly received by the second light receiver D ₂ and the light reflected by the pulsed light pl ₃ from the third light emitter a ₃ is mainly received by the third light receiver D ₃ . .

Although not shown, in the case of an object θ ₄ that is closer than the object θ _∞ at infinity and further away than the object θ ₃ that is far away, the pulsed light from the first light emitter a ₁
The light reflected by pl ₁ is mainly received by the second light receiver D ₂ , and the light reflected by the pulsed light pl 2 from the second light emitter a ₂ is received by the third light receiver D 3 , and the light reflected by the pulsed light pl ₂ from the second light emitter a 2 is received by the third light receiver D ₃ . _{The fourth} photoreceiver D4 is arranged so that the reflected light from the third pulsed light _pl3 is mainly received by the fourth photoreceiver _D4 .

Therefore, in the embodiment of FIG. 1, the subject θ ₁ ~
The far and near distance zones of θ _∞ are determined in five stages depending on the light receiving positions of the light receivers D ₁ to D ₇ groups.

FIG. 2 is a block diagram showing an embodiment of a circuit configuration for driving the light emitters a ₁ to _{a 3} group and processing the light reception signals of the light receivers D ₁ to D ₇ group of FIG. 1. Note that the same components in FIG. 2 as in FIG. 1 are given the same reference numerals. In FIG. 2, M1 is
A drive circuit for the light emitters _a1 to _a3 groups, which supplies, for example, pulsed power pp. DM1 is a demultiplexer, for example, the pulse power pp from the drive circuit M1
, the first, second, and third light emitters a ₁ , a ₂ ,
a Sort into ₃ and output. CS is a synchronization control signal output from the demultiplexer DM1. Note that each of the light emitters a ₁ to a ₃ emits and projects pulsed light pl ₁ to pl ₃ , respectively, when pulsed power pp is applied from the demultiplexer DM1.

A ₁ to _{A 7} are amplifier groups connected to each subsequent stage of each of the photodetectors D ₁ to _{D 7} to amplify and output the respective detection signals ds. MX ₁ to MX ₅ are multiplexer groups,
Each multiplexer MX ₁ ~ MX ₅ has seven amplifiers A ₁ ~
Figure 1 occurs when the detection signals ds are input from three amplifiers in A ₇ , and the distance measurement axes l ₁ to _{l 3} are different even though the subject distances are considered to be the same distance. The difference in the light receiving position of the _seven groups of light receivers D ₁ to D as explained in is corrected. That is, the first multiplexer MX ₁ receives each detection signal from the first, second, and third amplifiers A ₁ , A ₂ , and A _{3 .}
ds respectively and the second multiplexer
MX ₂ is the second, third, and fourth amplifier A ₂ , A ₃ , A ₄
Input each detection signal ds from . Similarly, the third multiplexer MX ₃ receives each detection signal from the third, fourth, and fifth amplifiers A ₃ , A ₄ , and A ₅ .
ds respectively and the fourth multiplexer
MX ₄ is the fourth, fifth, and sixth amplifier A ₄ , A ₅ , A ₆
The fifth multiplexer _MX5 receives each detection signal ds from the fifth, sixth, and seventh amplifiers _A5 , _A6 , and _A7, respectively. And further each multiplexer MX ₁ ~
The input terminals of _MX5 are switched in synchronization with the input of the control signal CS from the demultiplexer DM1. That is, the demultiplexer
The output terminal of DM1,, is →→→
..., the input terminals of each multiplexer MX ₁ to MX ₅ are switched as follows.
It can be switched as →→→...

Therefore, for example in FIG.
When the pulsed lights pl ₁ to _{pl 3} projected from the a ₁ to _{a 3} groups are all reflected at a close subject θ ₁ whose subject distances are considered to be the same distance, as described above, those reflected lights pr ₁ to pr ₃ is a different receiver D ₁ ~
The signal of the reflected light _{pr 1} of the pulsed light pl 1 by _the first light emitter a ₁ is received by the first light emitter a ₁ .
In synchronization _{with the light emission of} In synchronization with the light emission of the light emitter a ₂ , the pulsed light pl ₃ is taken in from the sixth light receiver D ₆ to the fifth multiplexer MX ₅ , and is further pulsed by the third light emitter a ₃ .
The signal of the reflected light _pr3 is taken in from the seventh light receiver _D7 to the fifth multiplexer _MX5 in synchronization with the light emission of the third light emitter _a3 .

Similarly, for objects at other distances, reflected light from objects on different ranging axes l ₁ to _{l 3} that are considered to be the same distance is received at different positions on the receivers D ₁ to _{D 7} . However, all of those signals are taken into the same multiplexers MX ₁ to MX ₅ .

As a result, the output of each multiplexer MX ₁ to MX ₅ is divided into five zones from long distance to short distance, corresponding to the absolute distance corrected for the difference in light receiving position due to the difference in the distance measurement axes _{l 1} to l 3. This represents the distance signal to the subject. In other words, the output of each multiplexer MX ₁ to MX ₅ is
The five distance zones shown in the figure correspond to object distances from long distance to short distance.

DA ₁ to _{DA 5} are detection circuit groups each consisting of a synchronous detector and a comparator given a desired threshold level, and each multiplexer MX ₁
~ MX ₅ are respectively connected to the subsequent stages, and the detection signals ds' from the multiplexers MX ₁ to MX ₅ are synchronously detected by the output from the drive circuit M1 using their respective synchronous detectors, and the signal level after the detection is A comparator compares it with a threshold level, and outputs a high-level detection signal dts only when the threshold level is exceeded, that is, only when subject distance signals are output from multiplexers _MX1 to _MX5 .

FF ₁ to FF ₅ are flip-flop groups for memory.
It is connected after each detection circuit DA ₁ to DA ₅ , and is set when a high level detection signal dts is input.
Outputs high-level distance signals _d1 to _d5 . In addition,
Each flip-flop FF ₁ to _{FF 5} is reset by a reset signal PUC output from means not shown.

PE1 is an encoder having a priority function, which is connected to the rear stage of the ₅ groups of flip-flops _FF1 to FF, and inputs any one of the distance signals _d1 to _d5 corresponding to the five far and near distance zones. Outputs distance data dd corresponding to the distance signal. This distance data dd may be digital or analog. For example, distance signal d ₁ corresponds to the farthest zone. In other words, in the case of the object θ _∞ at infinity in FIG. 1, the distance signal d ₁ is input to the encoder PE1, and the encoder PE1 outputs distance data dd at infinity. And the distance signal d ₅ is
Corresponding to the nearest zone, similarly in this case, the encoder PE1 outputs distance data dd indicating the nearest distance.

Note that a plurality of distance signals d ₁ to _{d 5} are encoded
When input to PE1, the priority function of the encoder PE1 works and the distance signal d ₁ indicating the short distance is
to _d5 is selected, and the distance data dd corresponding to the distance signals _d1 to _d5 is output, and distance measurement display and automatic focus adjustment are performed.

In addition, like the MOS type photo sensor, the receiver
When using a sensor that has an accumulation effect and can be selectively read out as D ₁ to D ₇ itself, the multiplexers MX ₁ to _{MX 5} in the embodiment are configured in the sensor and the first stage amplifiers A ₁ to _{A 7} are used. can also be omitted.

As explained above, according to this embodiment, the photoreceivers D ₁ to D ₇ [including the first stage amplifiers A ₁ to A ₇ ] are shared, and narrow range measurement along the plurality of distance measurement axes l ₁ to _{l 3} is performed. width pulse light
By performing multiple distance measurements using pl ₁ to _{pl 3} and performing distance measurement display and automatic focusing based on the results, distance measurement that is less influenced by the patterns and conditions of the objects θ ₁ to _{θ ∞} becomes possible.

Moreover, the number of receivers D ₁ to D ₇ on the receiver circuit side increases only slightly, and the circuit, especially the multiplexer
The demodulators from MX ₁ to MX ₅ onwards can be shared, and the advantage is that the circuit does not become too large.

In addition, it is possible to integrate multiple light emitters a ₁ to _{a 7} and
By integrating D ₁ to D ₇ , there is an advantage that adjustment is almost the same as before.

In the above embodiments, the light emitters _a1 to _a7 and the light projecting lens LA correspond to the light projecting means of the present invention,
The light receivers _D1 to _D7 groups and the light receiving lens LD correspond to the light receiving means of the present invention, the detection circuits _DA1 to _DA5 groups and the flip-flop groups _FF1 to _FF5 correspond to the processing means of the present invention, The multiplexers _MX1 to _MX5 correspond to the correction means of the present invention, and the encoder PE1 corresponds to the selection means of the present invention.

As explained above, according to the present invention, a plurality of distance measurements are performed for different distance measurement fields of view to prevent erroneous distance measurements, and a signal suitable for focus adjustment is formed by comparing the distance measurement results with priority given to short distances. A distance measuring device can be provided, and its effectiveness is extremely high.

[Brief explanation of the drawing]

FIG. 1 is an optical explanatory diagram of a distance measuring device according to an embodiment of the present invention, and FIG. 2 is a block circuit diagram of the same embodiment. θ ₁ - θ ₃ ... Subject, a ₁ - _{a 3} ... Light emitter, l ₁ - _{l 3}
...Range axis, pl ₁ to _{pl 3} ...Pulse light, D ₁ to _{D 7} ...
Receiver, pr...Reflected light, MX ₁ to MX ₅ ...Multiplexer, DA ₁ to _{DA 5} ...Detection circuit, FF ₁ to _{FF 5}
...Flip-flop, PE1...Encoder.

Claims (1)

[Claims] 1. A plurality of light projecting means for independently projecting signal light along a plurality of distance measurement axes at a plurality of different angles, and a signal light reflected from an object on each of the plurality of distance measurement axes. a light receiving means for receiving reflected light of the signal light; detecting a light receiving position of the reflected light of the light receiving means;
processing means for forming distance measurement information for object distances on each of the distance measurement axes; a correction means for correcting the difference in the light receiving position of the light receiving means that occurs due to the difference in the light receiving position so that the processing means can process them as the same distance; and objects on the respective ranging axes measured by the processing means. A distance measuring device comprising a selection means for selecting distance measuring information representing a short distance from among distance measuring information regarding distances.