JPH02290507A - Range finder - Google Patents

Abstract

PURPOSE:To prevent a distance from being mismeasured and to generate a signal which suits with a focus adjustment by a short-distance preferential comparison among distance measurement results by using light receivers in common and measuring plural distances in a distance measurement visual field. CONSTITUTION:The light receivers D1 - D7 are used in common to measure plural distances with narrow-width pulse light beams pl1 - pl3 along plural distance measurement axes l1 - l3, and distance measurement display operation and automatic focusing are carried out according to the results to measure the distances without being affected by the patterns and conditions of subjects theta1 - theta3. Further, the number of the light receivers D1 - D7 on a light receiving circuit side needs to be increased slightly, a circuit, specially, a demodulation part trailing a multiplexer can be shared, and the circuit does not become large so much. Further, adjustments are nearly the same as before because light emitting devices a1 - a3 are united and the light receivers D1 - D7 are united. Thus, the plural distances in different distance measurement visual fields are measured to prevent a distance from being mismeasured, and those distance measurement results are compared preferentially as to a short distance to generate the signal which suits with the focus adjustment.

Description

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

Conventionally, in order to maintain accuracy, this type of device has performed distance measurement by projecting 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, distance measurement becomes impossible or incorrect distance measurement occurs.

The present invention has been made in view of the above circumstances, and includes a light receiving means for imagining a plurality of ranging axes and receiving reflected light reflected from an object on each of the plurality of ranging axes, and a light receiving means for receiving reflected light reflected from an object on each of the plurality of ranging axes. a detection means for detecting a distance signal corresponding to an object distance on each of the distance measurement axes in response to the detection means; and a detection means for detecting a distance signal corresponding to the object distance on each of the distance measurement axes; It is equipped with a signal forming means that forms a signal for focus adjustment based on the comparison, and prevents erroneous distance measurement by performing multiple distance measurements for different distance measurement fields of view, and also adjusts the focus by preferentially comparing the distance measurement results for short distances. It is an object of the present invention to provide a distance measuring device that forms a signal suitable for adjustment.

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. ( a + + a z , a
3) are light emitters such as light emitting elements, which are arranged in a straight line, and each light emitter (a, ~a3) emits pulsed light (pβ1~a3) as a signal light projected for distance measurement.
p I2:+ ) respectively as virtual ranging axes (β, ~
Along β3), the subject (θ1.θ2θ3.θ, .:l) as the distance measurement target object on the distance measurement axis (β1 to I23)
Project towards. (LA) is a lens for projecting light, which is arranged in front of the group of light emitters (a, -83). (LD)
is a light-receiving lens, and the pulsed light (
p 12 + ~ p I2s ) reflected light (p r r
~p'66).

(D+.Dz.D3, D4.Ds.Da.Dt) are light receivers such as optical sensors, and the light receiving lens (LD
) and receive the reflected light (pr) of the pulsed light (p° C. 1 to pI 23) through the lens.

and light emitter (a. to a.) group, lens (LA, LD)
The photoreceiver group (D, ~D?) is arranged as follows, for example.

In the case of a subject (θ1) close to the lens (LA, LD),
The fifth light receiver (D5) is arranged so that the reflected light (pr+) by the pulsed light (pj2+) of the first light emitter (a1) is mainly received by the second light emitter (a1). a
The reflected light (prz) by the pulsed light (pβ2) in 2) is
The reflected light (prs) from the pulsed light (pI2,) of the third light emitter (a3) is mainly received by the sixth light receiver (Da) and the seventh light receiver (D7), respectively. Placed.

In the case of a subject (02) that is a little far from the lens (LA, LD), the reflected light (pri) from the pulsed light (p°C, ) of the first light emitter (a1) is mainly transmitted to the fourth light receiver (D4). Similarly, the reflected light (pri) by the pulsed light (pβ2) of the second light emitter (a2) is reflected by the fifth light receiver (D
6), the pulsed light (pI2.3) of the third light emitter (a3)
) is arranged so that the reflected light (pri) is mainly received by the sixth light receiver (D6).

In the case of a subject (θ3) far from the lens (LA, LD), the reflected light (pr7) from the pulsed light (pβl) of the first light emitter (a1) is mainly reflected by the third light receiver (D,). The pulsed light (pβ2) of the second light emitter (a2) is received.
) is transmitted to the fourth light receiver (D4), and reflected light (pr9) by the pulsed light (pI2s) of the third light emitter (a,) is transmitted to the fifth light receiver (D5). They are arranged so that they mainly receive light.

In the case of a subject (θ.) at infinity, the first light emitter (a
．． ) reflected light (proo) by pulsed light (pj2+)
is mainly received by the first photoreceiver (D1), and the second
The reflected light from the pulsed light (1) I22) of the light emitter (a2) is transmitted to the second light receiver (D2) and the third light emitter (a,).
The reflected light from the pulsed light (pβ3) is transmitted to the third light receiver (
D3) are arranged so that the light is mainly received. Although not shown, an object at infinity (θoo)
In the case of an object (θ4) that is closer and further away than the object (θ3), the reflected light from the pulsed light (pI2+) of the first light emitter (a,) is mainly reflected by the second light receiver (D2). ), and the reflected light from the pulsed light (p12z) of the second light emitter (a2) is reflected by the third light receiver (
D3), the pulsed light (p°C, ) of the third light emitter (a3)
The fourth light receiver (D4) is arranged so that the reflected light is mainly received by the fourth light receiver (D4).

Therefore, in the embodiment shown in FIG. 1, the far and near distance zones of the subject (θ, ~θD) are determined in five stages depending on the light receiving position of the light receiver (D, ~D?) group. .

FIG. 2 is a block diagram showing an example of a circuit configuration for driving the light emitter (a l"a 3) group and processing the light reception signal of the light receiver (D. to D,) group in FIG. 1. 2 is a circuit diagram. In FIG. 2, the same components as in FIG. 1 are given the same reference numerals. In FIG. The circuit supplies, for example, pulsed power (pp). (DMI) is a demultiplexer that supplies pulsed power (pp) from, for example, the drive circuit (M).
), sequentially the first, second and third light emitters (a, .a2
, a3) and output them. (CS) is a synchronization control signal output from the demultiplexer (DMI). Note that each light emitter (a1. to a,) emits and projects pulsed light (p°C1 to pI2,) when pulsed power (pp) is applied from the demultiplexer (DMI).

(AI-A?) is an amplifier group, and each photoreceiver (DI-Dt
) is connected to each subsequent stage of the detection signal (ds
) is amplified and output.

(MX, -MX.) is a group of multiplexers, and each multiplexer (MXI~MX,) has seven amplifiers (A.
- A, ), the detection signals (ds) are input from three amplifiers, respectively, and the detection signal (ds) is detected due to the fact that the distance measurement axes (41 to β3) are different even though the subject distances are considered to be the same distance. A photoreceiver as explained in Figure 1 (
DI to D,) corrects the deviation in the light receiving state of the groups. In other words,
The first multiplexer (MX+) has the first, second and third
The second multiplexer (Mx2) inputs each detection signal (ds) from the amplifiers (A I, A 1, A 3 ) of the second multiplexer (Mx2). The third and fourth amplifiers (A2.
A3. Input each detection signal (ds) from A4). Similarly, the third multiplexer (MXi is the third, fourth, and fifth amplifier (A 3, A 4, A
The fourth multiplexer (MX.) receives each detection signal (ds) from the fourth, fifth,
Each detection signal (ds) from the sixth amplifier (A 4i A a, A s ) is inputted to the fifth multiplexer (MXS). The seventh amplifier (A
s, A a. Each detection signal (ds) from A t )
Enter each. And each multiplexer (
MXr to MXs) are the input terminals ■, ■. ■ is the control signal (CS) from the demultiplexer (DMI)
can be switched in synchronization with the input. In other words, the output terminal of the demultiplexer (DM1) ■. ■． ■But ■1■1■
The input terminals of each multiplexer (MX+ to MX.) correspond to the input terminals of the multiplexers (MX+ to MX.). ■． ■
is switched as ■1■1■1■...

Thus, for example, in FIG.
When the pulsed lights (pβ1 to pβ,) projected from the aS) group are all reflected by a close subject (θl) whose subject distance is considered to be the same distance, as described above, those reflected lights (pr+ to prs ) are different receivers (D
, ~D,), but the signal of the reflected light (pr+) of the pulsed light (pI2.,) by the first light emitter (a,) is the light emitted by the first light emitter (a,). The pulsed light (
The signal of the reflected light (pry) of pβ2) is transmitted to the second light emitter (
a2) synchronizes with the light emission from the sixth receiver (D6) to the fifth receiver (D6).
It is incorporated into the multiplexer (MXS) of
The signal of the reflected light (pr3) of the pulsed light Cpl2s) by the third light emitter (a,) is transmitted from the seventh light receiver (D7) to the fifth light receiver (D7) in synchronization with the light emission of the third light emitter (a3). Incorporated into multiple plexer (MX!).

Similarly, for objects at other distances, the reflected light from objects on different ranging axes (ρ1 to f23) that are considered to be the same distance is received at different positions on the receiver (D. to D7). However, all of those signals are taken into the same multiplexer (M x r NM x s ).

This allows each multiplexer (M X l to MX.
The output of ) represents the distance signal to the subject divided into five zones from long distance to short distance corresponding to the absolute distance corrected for the deviation in the light reception state due to the difference in the distance measurement axes (β1 to β3). become. That is, each multiplexer (
MX. ~MX. The outputs of ) correspond to the object distances from long distance to short distance in the five distance zones shown in FIG. 1, respectively.

(DA+~DAM) is a detection circuit group consisting of a synchronous detector and a comparator given a desired threshold level, and each multiplexer (MXI~M
The detection signals (ds') from the multiplexers (MXI-MXs) are synchronously detected by the output from the drive circuit (Ml) using their respective synchronous detectors, and the The signal level is compared with the threshold level by a comparator, and only when the threshold level is exceeded, that is, when the subject distance signal is output from the multiplexer (Mxl-Mxs), a high level detection signal (dts) is output. Output. (F F l - F F s ) is a group of frits for storage, which is connected to the latter stage of each detection circuit (DA l to DAa), and is set when a high level detection signal (dts) is input. High level distance signal (d+~a
S) is output. In addition, each fritub flop (FF
l-F F s ) is reset by a reset signal (puc) output from means not shown. (PEI) is an encoder having a priority function, which is connected to the rear stage of the flip-flop group (FF l"F Enter the
Distance data (dd) corresponding to the distance signal is output.

This distance data (dd) may be digital or analog. For example, the distance signal (dI) corresponds to the farthest zone. In other words, the subject at infinity (θ
i). ), the distance signal (d1) is transmitted to the encoder (P
EI), and infinite distance data (dd) is output from the encoder (PEI). The distance signal (ds) corresponds to the nearest zone, and similarly in this case, the encoder (PEI) outputs distance data (dd) indicating the nearest distance.

Note that a plurality of distance signals (d1 to da) are encoded by the encoder (
PEI), the corresponding encoder (PEI)
The priority function works and the distance signal (ct
．． ~dl1) is selected, and the distance data (dd) corresponding to the distance signal (d.~ds) is output.

In addition, like a MOS photo sensor, the light receiver (D.~
D? ) When using a sensor that has an accumulation effect and can be selectively read out, the multiplexer (MXt~MXS) in the embodiment is configured in the sensor and the first stage amplifier (AI-A?) is used. It can also be omitted. As explained above, according to this embodiment, the light receiver (D.
~D7) [Including first-stage amplifiers (Al~A, By measuring the distance and using the results to display the distance measurement and autofocus, it becomes possible to measure the distance without being influenced by the pattern or conditions of the subject (01 to θD). (DI~D,) The number increases only a little, and the circuit, especially the multiplexer (M
There is an advantage that the demodulators from 1 to MXI1) onward can be shared, and the circuit does not become too large.

Further, by integrating a plurality of light emitters (a+ to as) and integrating a light receiver (DI-'D?), there is an advantage that adjustment is almost the same as in the past.

As described above, according to the present invention, multiple distance measurements are performed for different distance measurement fields of view, and erroneous distance measurements are prevented. ,
By comparing these distance measurement results with priority given to short distances, it is possible to provide a distance measurement device that forms a signal suitable for focus adjustment, and its effectiveness is extremely high.

[Brief explanation of drawings]

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. 01~θ,...Subject, 81~a,...Light emitter, β,~β,...Distance measuring axis, pβ1~p12s...Pulse light, D,~D,...
・Photoreceiver, pr...Reflected light, MX. ~Mxs...Multiplexer.

Claims (1)

[Claims] 1. A light receiving means for imagining a plurality of distance measuring axes and receiving reflected light reflected from an object on each of the plurality of distance measuring axes; a detection means for detecting a distance signal for the object distance above; and a signal for focus adjustment based on a short distance preferential comparison of the distance signals corresponding to the respective distance measurement axes detected by the detection means. A distance measuring device comprising a signal forming means for forming a signal.