JPH10197917A - Multipoint range finder for camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multipoint range finder where accurate range-finding is performed wherever a subject is positioned within an image plane. SOLUTION: Light for range-finding is projected to the subject by a light projecting means 51, and reflected signal light from the subject is received by a light receiving means 52. Then, light receiving position information or incident light quantity information are calculated based on the output of the light receiving means 52 by a light receiving position arithmetic means 54 or an incident light quantity arithmetic means 55. The light emission state of the projecting means 51 is switched by an arithmetic result. The range-finding is performed by the emitted light of the projecting means 51 switched.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multipoint distance measuring apparatus for a camera, and more particularly to a method for projecting distance measuring light to a plurality of points on a photographic subject on a subject and based on the reflected signal light. And a multi-point distance measuring device for a camera that determines a subject distance.

[0002]

2. Description of the Related Art A conventional camera having a built-in multi-point distance measuring device of a type capable of measuring a plurality of points of a subject can perform focusing regardless of the position of the subject.
However, if any of the plurality of points is erroneously measured, a failure photograph is taken due to the influence.

In order to solve the above-mentioned problem, Japanese Unexamined Patent Publication No. 4-65630 proposed by the applicant of the present invention discloses a multi-AF distance measurement, that is, a method of comparing the results of distance measurement of a plurality of points. Then, the wrong result is canceled and the correct subject distance is selected. In other words, when it is considered that spots are missing at a plurality of points of the ranging light, or when the ranging result is a short distance even if there is no spot missing, the ranging results are treated as erroneous ranging data. .

As a technique for correcting an erroneous distance measurement, a camera distance measuring apparatus disclosed in Japanese Patent Application Laid-Open No. 4-50610 also proposed by the present applicant considers the intensity of reflected signal light. This is to prevent erroneous distance measurement. That is, when there is a spot missing in the distance measurement light, the correction is performed.

Here, the outline of the distance measuring process in the conventional multi-point distance measuring (multi-AF distance measuring) apparatus will be described with reference to the flowchart of FIG. 11. In step S101, an object in the photographing screen 101 shown in FIG. For 102
Beam spot 103 at three ranging points in the screen
L, 103C and 103R are projected. Pre-ranging of each ranging point is performed with coarse accuracy by the reflected light. In step S102, a subject ranging point of a spot that outputs the closest distance is selected from the three points. Then, in the last step S103, the main ranging is performed on the selected ranging point.

FIG. 13 is a time chart of the emission pulse waveform of the infrared light emitting diode (IRED) during the pre-ranging and the main ranging. In the pre-distance measurement, short-time distance measurement is performed by light-emitting pulses PL, PC, and PR of the beam spots 103L (left side), 103C (center), and 103R (right side) with a small number of light emission times. In the main ranging, ranging is performed over a long time by a plurality of emission pulses MC of a beam spot on a selected single ranging point, for example, the spot 103C, and the AF circuit (AFIC) repeatedly performs data measurement. And averaging the captured data to improve the accuracy.

However, depending on the position of the subject 102, spots may be missing like the beam spots 103L and 103R in FIG. When the beam spot is chipped, as will be described later with reference to the optical path diagram of the distance measuring light in FIG. Could be.

[0008]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Laid-Open No. 4-65 is disclosed.
The camera distance measuring apparatus disclosed in Japanese Patent No. 630 cancels erroneous distance measurement information and selects only correct subject distance information as described above. However, in this technique, only a simple comparison of distance measurement results is performed. Therefore, there is a possibility that the case of erroneous distance measurement and the case of correct distance measurement may be erroneously determined. The camera distance measuring device disclosed in Japanese Patent Laid-Open No. 4-50610 described above takes into consideration the intensity of the reflected signal light as described above,
Although it is intended to prevent erroneous distance measurement, the description to the application to the multi-AF for measuring the distance of a plurality of points is insufficient.

In view of the above points, the present invention can measure the distance to a plurality of points on an object on a photographing screen, has a small erroneous distance measurement, and can detect an object anywhere in the screen. It is an object of the present invention to provide a camera multi-point distance measuring device capable of performing a correct distance measurement.

[0010]

According to a first aspect of the present invention, there is provided a multi-point distance measuring apparatus for a camera, which sequentially projects a light beam toward a plurality of distance measuring points arranged on a subject within a field of view. Light-emitting means, receiving reflected light from the subject by the light-emitting,
A light receiving unit that outputs the incident position information and the incident light intensity information, and sequentially controls the light projection by the light projection unit,
Control means for selecting one of the plurality of distance measurement points in response to an output from the light receiving means and calculating a distance to a subject located at the distance measurement point. In the multi-point ranging device of the camera, first, pre-ranging is performed by sequentially projecting light to all the ranging points, and a single ranging point is selected based on the output of the light receiving means at that time. Then, the distance to the selected single ranging point is measured again to determine the subject distance.

According to a second aspect of the present invention, as a result of the pre-distance measurement performed by the control means of the multi-point distance measuring apparatus of the first aspect, the closest object distance is indicated. The distance measuring point is used as the current reference position, the incident light amount information at the distance measuring points adjacent to this point is compared with each other, and the distance measuring point having the larger incident light amount is selected, and the distance measuring is performed for the distance measuring point. Will be

According to a third aspect of the present invention, in the control means of the multi-point distance measuring apparatus according to the first aspect, the pre-distance measurement is performed with the infinity determination level as the first level. A ranging point is selected according to the result, and the infinity determination level is set to a second level lower than the first level, and then ranging is performed again.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. Prior to the detailed description of the embodiments of the present invention, a description will be given of the outline of the multi-point distance measuring apparatus of the camera of the present invention. Is an active-type multi-point distance measuring (multi-AF) device that projects distance measuring light and determines a subject distance based on the reflected signal light.

FIG. 1 is a main block configuration diagram of the multipoint distance measuring apparatus. Light for distance measurement is projected from the light projecting means 51 toward the subject, and signal light reflected from the subject is received by the light receiving means 52. Based on the output of the light receiving means 52, the light receiving position calculating means 54 calculates the light receiving position information, and the incident light amount calculating means 55 calculates the incident signal light amount information.
The calculation results are input to the selection means 58a built in the calculation control means 58. Selection means 58a
Performs switching control of the light emission switching unit 53 based on the calculation result.

Operation control means 58 composed of a CPU and the like
The light receiving position calculating means 54 and the incident light amount calculating means 55
The distance of the object is measured based on the result of the calculation, and the focusing control unit 57 is controlled based on the distance measurement information to perform focusing. The selecting means 58a of the arithmetic control means 58
By controlling the light emission switching means 53 by
The projection direction and the number of projections of the projection unit 51 are switched, and a plurality of points on the subject within the shooting angle of view are measured with different precisions. By increasing the number of light projections in this way, the result of distance measurement can be averaged to cancel random noise, and accuracy can be improved.

When the amount of signal incident on the light receiving means 52 is small, the reliability of the result of calculation of the light incident position is reduced. Therefore, the signal amount is compared with a predetermined level. The ∞ determination means 23 is provided for invalidating the position calculation result and setting the distance measurement value to infinity (hereinafter, referred to as ∞). The predetermined level can be switched by the arithmetic control means 58.

If the projected distance measuring beam does not properly hit the subject, erroneous distance measurement will occur. Therefore, before the main distance measurement for obtaining focusing data, pre-range measurement with a small number of light projections and coarse accuracy is performed. The calculation control means 58 determines whether or not the focus of the distance measurement is appropriate in accordance with the result of the light amount calculation at the time of the pre-range measurement and the result of the ∞ determination.

Hereinafter, a multipoint distance measuring apparatus according to an embodiment of the present invention will be described. FIG. 2 shows a main block configuration diagram of a camera in which the multipoint distance measuring apparatus of the present embodiment is incorporated. The control circuit of the camera includes a CPU 10 which is an arithmetic control circuit such as a one-chip microcomputer as a control means for mainly controlling each component, a photographic lens 17, and a focusing lens unit of the photographic lens 17. , A winding control unit 13 for controlling winding of the film 12, and infrared light emitting diodes (hereinafter referred to as IREDs) 1a, 1b, 1c as light projecting means.
A selection driver 5 as selection means for selectively switching the light emission of each IRED, a light projecting lens 2 for condensing light emitted from each IRED and projecting it as a distance measuring beam toward the subject, A light receiving lens 3 for condensing the reflected light of the distance measuring beam from the camera, and a semiconductor light position detecting element (hereinafter referred to as PSD) 4 which is a light receiving means for receiving the reflected light.
a, 4b, and 4c, an AFIC 8 that takes in the output signals of the PSDs and outputs a ranging signal, a release switch 14, and the like.

The AFIC 8 includes a preamplifier array 6 to which the output of each PSD is input, a switch element 7 for switching the output of the preamplifier, a ratio calculation circuit 20 for calculating the incident position, and a light amount calculation for calculating the incident light amount. Circuit 21
A level switching circuit 23 composed of an A / D converter that outputs a judgment level voltage Vc;
This is an auto-focusing (AF) integrated circuit including a comparator 22 and the like for comparing c with a light quantity calculation output voltage.

When the distance measurement of an object is performed by the camera having the above-described configuration, first, the IRE is selected via the selection driver 5 while being selectively controlled by the CPU 10.
D1a, 1b and 1c are driven. The ranging light emitted from each IRED is condensed by the light projecting lens 2 and projected as beam spots 15a, 15b, and 15c at three ranging points in the photographing screen 17.

When the subject 16 is located on the beam spot area, the distance measuring light is reflected and enters the PSDs 4a, 4b and 4c via the light receiving lens 3 as reflected signal light. As will be described later, the incident position of the reflected signal light changes according to the principle of triangulation, so that if the incident position is detected by the PSD, the subject distance at each distance measurement point can be obtained.

The PSDs 4a, 4b, and 4c output two photocurrents depending on the light intensity and the incident position, respectively.
These amplified outputs are selected by the changeover switch element 7 as selection means and input to the ratio calculation circuit 20 and the light quantity calculation circuit 21. The ratio calculation circuit 20 is a circuit that calculates the ratio between the output signals of the two PSDs and converts the ratio into a signal based on the signal light incident position. Also, the light amount calculation circuit 21
Is a circuit for converting the above two output signals of the PSD into a signal depending on the amount of incident signal light.

When photographing with this camera, the CPU 1
0 controls the selection driver 5 and the selection means 7 in response to the operation of the release switch 14 to switch the distance measurement point and measure the distance at each point. Then, the distance to the subject 16 is selected and calculated in accordance with the outputs of the ratio calculation circuit 20 and the light amount calculation circuit 21, and the feeding control means is controlled based on the result to control the feeding position of the focusing lens unit in the photographing lens 11. To adjust. After the photographing is completed, the film 12 is wound by the winding controller 13.

If the amount of light incident on the PSDs 4a, 4b, 4c is small, the output photocurrent is reduced and correct ratio calculation cannot be performed. The output of the calculating means 20 is devised so as to be invalidated, thereby preventing erroneous distance measurement. That is, in the example of the present embodiment, the comparator 22 compares the output of the light amount calculation circuit 21 with the predetermined ∞ judgment level voltage Vc output from the level switching circuit 23. Treat the result of the ratio operation as equivalent to ∞ distance. The level voltage Vc is determined by the CPU
Switching to a high level or a low level can be performed through the level switching circuit 23 according to the instruction of 10. However, the light amount output level to be compared with the predetermined level voltage Vc does not necessarily have to be the output of the light amount calculation circuit 21.
The direct output of the preamplifier array 6 may be used.

Here, the light projection triangulation method will be described in detail with reference to the optical path diagrams of the distance measurement light to the object shown in FIGS. 3A and 3B. 3 (A) and (B)
One set of IRED1 among a plurality of sets of IRED and PSD
a and PSD 4a, but other IREs
The same applies to D1b, 1c and PSDs 4b, 4c.

Since the light emitting section of the IRED 1a has a predetermined area size, the beam spot 15a for providing a distance measuring point has a certain area, not a point.
The area of this beam spot 15a is all shown in FIG.
When the totally reflected light impinges on the light receiving lens 3 as described above, it is not necessary to particularly consider the area of the spot, but the center of gravity of the reflected light beam. Then, as shown in the above-mentioned figure, the processing may be performed assuming that the beam simply enters the PSD 4a along the triangular shape ranging optical path.

Accordingly, the subject distance L, the base length S between the light projecting and receiving lenses 2 and 3, and the focal length f on the light receiving lens 3 side
The relationship L: S = f: x (1) holds between the signal and the signal light incident position data x that gives the incident position of the reflected distance measuring light on the PSD 4a. Therefore, the subject distance L can be obtained from the relational expression for the signal light incident position data x, L = S · f / x (2).

The PSD 4a having the effective length t of the light receiving section outputs the following two signal light currents i1 and i2 according to the incident position data x due to the current shunting effect of the surface resistive layer. That is, as the total signal light current ip, two signal light currents of i1 = ip × x / t (3) i2 = ip × (1-x) / t (4) are output. And the above i1
The value of + i2 is equal to the total signal light current ip which is the light amount calculation value. That is, i1 + i2 = ip (5). The total signal light current ip increases in proportion to the amount of incident light.

From the ratio of i1 and i1 + i2, the incident position data x, which is a ratio operation value, is obtained. That is, x = i1 / (i1 + i2) .times.t (6) The calculation based on the above equation (5) is performed by the light amount calculation circuit 21 in FIG. The analog operation based on the expression (6) is performed by the ratio operation circuit 20 in FIG.

As shown in FIG. 3A, in a state where the beam spot 1a of the distance measuring light is completely incident on the subject 16, correct distance measurement can be performed by performing calculations according to the above equations (5) and (6).

However, as shown in FIG. 3B, when the beam spot 1a of the distance measuring light does not completely hit the subject 16 and a part of the spot is missing, the distance measuring optical path assumed by the equation (1) is used. However, the triangle does not form a triangle, and the reflected signal light shifts to a shorter distance side than the expected position as shown by the dotted line. That is, in this “spot missing” state, the AFIC
In No. 8, a correct distance measurement result cannot be output.

In the conventional camera capable of measuring three points in the screen shown in FIG. 12, even if there is a subject in the center, if the left and right distance measuring points are in the above-mentioned spot missing state, erroneous distance measurement will occur. Then, accurate focusing cannot be performed. Therefore, in the multipoint distance measuring apparatus according to the present embodiment, the side effect of the erroneous distance measurement is prevented by utilizing the result of the ratio calculation and the result of the light amount calculation by the distance measurement processing described below. .

FIG. 4 is a flowchart of the distance measuring process in the multipoint distance measuring apparatus. In steps S1 and S2,
A single ranging point that gives the shortest distance from the ranging points of the beam spots 15a, 15b, and 15c shown in FIG. 2 by performing the same processing as in steps S101 and S102 shown in FIG. Select In addition,
Whether the distance is close or not is determined based on the result of the ratio calculation by the ratio calculation circuit 20. In Step S3, Step S
It is determined whether the ranging point selected in step 2 is on the right side.

If it is determined in step S3 that the right distance measuring point has been selected, the beam spot 15a of the right distance measuring point suffers a spot loss shown in FIG. It may have been output. Incidentally, as shown in FIG. 12, if the beam spot 103L at the left ranging point has a spot missing, the beam spot is shifted to the opposite side to the dotted line shown in FIG. 3B. . The beam spot 103
Since the distance measurement data based on L gives distance measurement data on the farther side than the actual distance measurement, the distance measurement data based on the beam spot 103L is discarded in the closest distance selection processing in step S2.

The state in which the above-mentioned lack of the beam spot affects the closest selection depends on the arrangement structure of the light emitting and receiving unit of the camera. As shown in FIG.
In the camera in which the light receiving lens 3 is disposed on the right side of
That is, when the beam projected on the right side causes spot missing, the distance measuring point is selected as the closest distance, and the above-described erroneous distance measurement is likely to occur. However, in a camera in which the light receiving lens 3 is on the left side of the light projecting lens, contrary to the camera of FIG. 2, the beam projected on the left side is likely to cause erroneous distance measurement in a scene as shown in FIG. In a camera having such a structure, step S3 in FIG. 4 is a process of determining whether or not left selection is performed.

In the determination in step S3, the beam spot 1 on the light receiving lens side (right side) where erroneous distance measurement is likely to occur.
If it is determined that the right ranging point on 5a is selected as the point that gives the shortest distance, the process proceeds to step S4 to compare the light amount calculation results. That is, the reflected light amount of the right beam spot 15a is compared with the reflected light amount of the central beam spot 15c. If the former light amount is large, the process proceeds to step S5. If the latter light amount is large, step S6 is performed. Branch to each. As a technique for performing the light amount calculation simultaneously with the ratio calculation, there is Japanese Patent Application Laid-Open No. 4-48208 previously proposed by the present applicant.

When the subject is not actually located at the center as in the photographing screen 17 of FIG. 2 and the subject 16 is located at the distance measuring point position of the right beam spot 15a, the calculation result of the light quantity on the right becomes large. Step S4 as described above
Branch to step S5, and select the right side. That is, the main beam is emitted by the right beam spot 15a, for example, the light emission pulse MR shown in FIG. 13 is output. Then, in step S7, the distance is measured by the reflected light by the light emission pulse MR, and the focusing is performed.

Conversely, in the photographing scene as shown in FIG. 3B, the amount of reflected light from the missing beam on the spot 15a 'side is small as in the beam spot 103R shown in FIG. Step S4 to Step S6
After that, the main distance measurement is performed for the distance measurement point of the center beam spot 15b.

If it is determined in step S3 that the right distance measuring point has not been selected, that is, if a distance measuring point other than the one projected on the light receiving side has been selected, the direct measurement is performed. , Proceeding to step S7,
The main distance measurement process is performed using the closest distance measurement point selected in Step 2.

According to the multipoint distance measuring apparatus in the button mode of this embodiment, as described above, there is no side effect that the distance measuring point is erroneously measured as the point which gives the closest distance due to the lack of the beam spot, and the screen does not appear. It is possible to provide a multi-point distance measuring apparatus for a camera that can perform a correct distance measurement regardless of the position of a subject in the camera and can perform a highly accurate focusing.

The multi-point distance measuring apparatus of the above-described embodiment is further generalized to provide a modified multi-point distance measuring apparatus capable of supporting multi-point distance measurement capable of measuring more than three distance measuring points. Suggestions are possible.

FIG. 5 is a flowchart of the distance measuring process of the multipoint distance measuring apparatus according to this modification. FIG. 6 is an arrangement diagram of beam spots indicating distance measuring points on a photographing screen of a camera having the multipoint distance measuring apparatus of the present modification. In this modification, from the light projecting lens side to the light receiving lens side, the beam spots P1, P2, P3,.
The flow chart of FIG. 5 will be described on the assumption that the distance measurement points as P4 and P5 are arranged.

Steps S11 and S12 correspond to steps S1 and S2 of the flowchart shown in FIG.
This is the same processing as. In step S13, it is determined whether the closest point selected in step S12 is the far distance measuring point closest to the light receiving lens, that is, the point P1 having the smallest suffix number.

If the one point P1 is selected, there is no possibility of causing a side effect of the recent selection similarly to the case where the distance measuring point of the beam spot 103L shown in FIG. 12 is selected. , S16, and the main distance measurement is performed. However, if any other point is selected, there is a possibility of erroneous distance measurement due to missing spots.
It is determined whether or not the light amount at the closest point Pn selected in 12 is larger than the light amount at the point Pn-1 on the side of the light projecting lens (left side) adjacent thereto. That is, the validity of the selected point is confirmed by comparing the light amounts.

Then, the selected nearest point P
If the light amount of n is large, the process directly proceeds to step S16, and the main ranging based on the single selected closest ranging point Pn is executed. However, if the light quantity at the point Pn-1 is larger, the process proceeds to step S15, and this point Pn-1 is selected as a single closest ranging point. Thereafter, the process proceeds to step S16, and the main ranging is performed based on the selected closest ranging point Pn-1.

For example, when the multi-point distance measuring apparatus of the present modification measures the distance of a scene on the photographing screen 32 as shown in FIG. 7, spots are missing from the subject 33 at points P3 and P5. However, since the distance measuring point P4 that gives the closest distance is specified by the distance measuring process of FIG. 5, accurate focusing can be performed. The multi-point distance measuring apparatus according to the present modification can support not only three distance measuring points but also a multi-AF that employs an arbitrary number of points, and a camera with less erroneous distance measuring for various scenes. A distance measuring device can be provided.

Next, the pre-distance measurement or the main distance measurement is performed by switching the ∞determination level voltage Vc (see FIG. 2) for determining the subject distance as ∞distance equivalent, and the same effect can be obtained. A multipoint distance measuring apparatus according to a modification of the above will be described with reference to the flowchart of FIG. The configuration of this device is the same as that shown in the block diagram of the device of the embodiment of FIG.

Prior to the description of the sequential processing steps of the flowchart, the first and second levels indicating the strength of the ∞ judgment level in steps S21, S24, and S27 in the distance measurement processing of this modified example of FIG. That is, the high-level and low-level switching processing operation will be described. Note that this switching process is performed by switching the ∞ judgment level voltage Vc output from the level switching circuit 23 according to an instruction of the CPU 10 in FIG.

The above-mentioned (6) at the time of switching between the above-mentioned levels.
FIG. 9 shows the relationship between the ratio calculation value, which is the incident position data x obtained by the equation, and the distance measurement data represented by the reciprocal distance 1 / L. When the determination level is switched to the higher side, the distance measurement data is invalidated in a relatively large signal light current range, and the distance measurement data for the ratio operation value (x) in a relatively short range as shown by a dotted line in FIG. Falls to 0, ranging data is obtained only in a relatively short range, and ranging data 0, that is, a ranging value of ∞ is returned in other ranges. On the other hand, when the determination level is switched to the weak side, the distance measurement data for the ratio operation value (x) can be measured in a relatively long distance range as shown by the solid line in FIG.

In the multipoint distance measuring apparatus of the present modification, as shown in the flowchart of FIG. 8, first, in step S21, the ∞ judgment level is set to be strong, that is, set to be high.
At 22, a pre-ranging is performed. At this time, since the ∞ judgment level is high, if a spot is missing and the light amount decreases, the distance measurement data tends to be 0, that is, ∞ the distance measurement value. Therefore, only the distance measurement data of the distance measurement points with no missing spots is valid, and the correct distance measurement point can be selected.

In step S23, the output of the ranging data at all the ranging points is checked. If the ranging data are all 0, that is, if the ranging values of all the points cannot be obtained, for example, the subject is far away Alternatively, if all the beam spots are missing and no distance measurement data is obtained even after pre-distance measurement, the flow branches to step S24. In step S24, the ∞ determination level is switched to the weak side, and in step S25, the pre-ranging is performed again. Thereafter, the process proceeds to step S26. However, if there is a distance measurement point whose distance measurement data output is not 0 even at least one point, the process directly proceeds to step S26.

In step S26, a distance measuring point which gives the closest data is selected from the distance measuring data obtained by the pre-ranging. That is, the closest point is selected from the multi AF points. Then, the ∞ determination level is set to the low side in step S27, and the main distance measurement is executed in step S28.

In the multi-point distance measuring apparatus of this modification, the above-described distance measuring process is executed. Therefore, at the distance measuring point where spot chipping occurs at the time of pre-ranging, the amount of incident light is reduced. Becomes easier to be treated as a distance measurement value and is removed as the closest distance data, so that erroneous distance measurement is reduced and more accurate focusing can be performed.

Next, a description will be given of a multipoint distance measuring apparatus according to still another modification in which distance measurement is performed by switching the judgment level in the same manner as in the modification, with reference to the flowchart of FIG. Note that the configuration of the device is the same as the block configuration diagram of the device of the embodiment of FIG.

In the distance measuring process of this modification, the determination level is switched between strong and weak in steps S31 and S33, and two steps are performed in steps S32 and S34.
Perform pre-distance measurement twice. Thereafter, in step S35, a distance measuring point having no change in the ratio data, which is the ratio operation value (x) shown in the equation (6), is selected. When the determination level is changed as described above, it is considered that the distance measurement point where the ratio data changes is considered to have already been reduced in the light amount due to the lack of the spot. A ranging point to which a beam that has not been projected is selected. Subsequently, step S3
At 6, the main ranging based on the selected ranging point is executed.

According to the multipoint distance measuring apparatus of this modification, by changing the ∞ judgment level, a point where the ratio data does not change is regarded as a point having no spot missing, and is selected as a distance measuring point. Correct focusing is possible.

(Supplementary Note) Based on the embodiment of the present invention described above, a camera multipoint distance measuring apparatus having the following configuration can be proposed. That is, (1) a light projecting means for projecting a light beam for distance measurement in a plurality of directions in a photographing screen, and receiving light reflected from an object by the plurality of light beams for distance measurement, and the incident position and incident intensity thereof. And light receiving means for outputting an incident position signal and an incident intensity signal, respectively, based on respective outputs of the light receiving means when projecting the distance-measuring light beam in each direction in the photographing screen, Determining means for determining the distance to the object, wherein the determining means first compares the incident position signals, and then compares the incident intensity signals. Point ranging device. According to the multi-point distance measuring device of the camera, it is possible to measure a distance to a plurality of points on a subject with respect to a shooting screen, and to compare the incident position signals and the incident intensity signals to an object. Since the distance is determined, correct distance measurement can be performed regardless of where the subject is located in the screen.

(2) Light projecting means for projecting a light beam for distance measurement in a plurality of directions within a photographing screen, and receiving light reflected from an object by the plurality of light beams for distance measurement, and detecting the incident position and incidence of the light. Light receiving means that determines the intensity and outputs an incident position signal and an incident intensity signal, respectively, receives the output of the light receiving means, compares the incident intensity signal with a predetermined reference value, and when the incident light intensity is low Determining means for invalidating the incident position signal; and selecting means for controlling the light emitting means and selecting one of the plurality of directions while sequentially switching the predetermined reference value. A multi-point distance measuring device for cameras. According to the multi-point distance measuring device of the camera, it is possible to measure a distance to a plurality of points on a subject with respect to a shooting screen, and by invalidating the incident position signal having a low incident intensity, the distance to the object can be reduced. Since the distance is determined, correct distance measurement can be performed regardless of where the subject is located in the screen.

(3) Light projecting means for projecting a light beam for distance measurement to an object existing in a predetermined direction, and receiving light reflected from the object by the light emission, and a light receiving position and light receiving position. A light receiving means for outputting a signal related to the light amount, a comparing means for receiving the output of the light receiving means and comparing the received light amount information with a predetermined value, and an output for receiving the light receiving means; Calculating means for calculating the distance to the object;
And the calculating means includes:
Controlling the light emitting means to project a light beam and monitoring the output of the comparing means to determine whether or not distance measurement in a predetermined direction is effective. apparatus. According to the multi-point distance measuring device of the camera, the output of the comparing means is monitored to determine whether or not distance measurement in a predetermined direction is valid, and the distance to the object is determined. The correct distance measurement can be performed wherever the subject is located.

[0060]

As described above, the multi-point distance measuring apparatus according to the first aspect of the present invention can measure a distance to a plurality of points on a subject, and can perform a single distance measurement by pre-ranging. Since a distance point is selected and distance measurement is performed for the distance measurement point, correct distance measurement can be performed regardless of where the subject is located on the screen.

The multi-point distance measuring apparatus according to the second aspect of the present invention has the same effect as the multi-point distance measuring apparatus according to the first aspect, but also compares the incident light amount information with each other and measures the one with the larger light amount. Since it is selected as a distance point, there is also an effect that correct distance measurement can be performed.

Further, the multi-point distance measuring apparatus according to the third aspect of the present invention performs pre-ranging and re-ranging in addition to the effect of the multi-point distance measuring apparatus according to the first aspect, so that more accurate distance measurement is possible. It also has the effect that distance can be measured.

[Brief description of the drawings]

FIG. 1 is a main block configuration diagram of a multipoint distance measuring apparatus according to the present invention.

FIG. 2 is a main block configuration diagram of a camera incorporating a multipoint distance measuring apparatus according to an embodiment of the present invention.

3 shows an optical path diagram of distance measuring light in triangulation in the multipoint distance measuring apparatus of FIG. 2, FIG. 3A shows a state where a beam spot is located at the center of a subject, and FIG. )
This shows a state where the beam spot for the subject is missing.

FIG. 4 is a flowchart of a distance measuring process in the multipoint distance measuring apparatus of FIG. 2;

FIG. 5 is a flowchart of a distance measuring process in a multi-point distance measuring apparatus which is a modification of the multi-point distance measuring apparatus of FIG. 2;

FIG. 6 is a diagram showing an arrangement of beam spots in the multipoint distance measuring apparatus of FIG. 5;

FIG. 7 is a view showing a photographing screen in which a beam spot has a spot missing in the distance measuring process in the multipoint distance measuring apparatus of FIG. 5;

FIG. 8 is a flowchart of a distance measuring process in a multipoint distance measuring apparatus which is another modified example of the multipoint distance measuring apparatus of FIG. 2;

FIG. 9 is a diagram showing a relationship between a light amount calculation value and distance measurement data when the ∞ determination level is switched in the multipoint distance measuring apparatus of FIG. 8;

FIG. 10 is a flowchart of a distance measuring process in a multi-point distance measuring apparatus as still another modification of the multi-point distance measuring apparatus of FIG. 2;

FIG. 11 is a flowchart of a distance measuring process in a conventional multipoint distance measuring apparatus.

FIG. 12 is a diagram showing a photographing screen used for explaining a distance measuring process in a conventional multipoint distance measuring apparatus or the multipoint distance measuring apparatus of the present invention.

FIG. 13 is a time chart of a distance measuring light emission pulse in a distance measuring process in a conventional multipoint distance measuring apparatus.

[Description of Signs] 15a, 15b, 15c... Beam spot (distance measuring point) 1a, 1b, 1c... IRED (light projecting means) 4a, 4b, 4c... PSD (light receiving means) 10. Means 51 51 Projecting means 52 Light receiving means 58 Calculation control means (Control means) ip ... All signal light current (Incident light intensity information) x ... Incident position data x (Incident position information) Vc ... ... Judgment level voltage (infinity judgment level) P1, P2, P3, P4, P5... Beam spot (distance measurement point)

Claims (3)

[Claims] 1. A light projecting means for sequentially projecting a light beam toward a plurality of distance measuring points arranged on a subject within a shooting angle of view, and receiving reflected light from the subject by the light projection, and information on an incident position of the reflected light. And light receiving means for outputting incident light intensity information; and sequentially controlling light emission by the light emitting means, and selecting one of the plurality of distance measuring points in response to an output from the light receiving means. And control means for calculating the distance to the subject at the distance measuring point. The control means first performs pre-ranging for sequentially projecting light for all the distance measuring points. A single ranging point is selected based on the output of the light receiving means at that time, and the subject distance is determined by re-ranging the selected single ranging point. Multi-point distance measuring device. 2. The control unit further sets a distance measurement point indicating the closest subject distance as a result of the pre-distance measurement as a temporary reference position, and sets incident light amount information at distance measurement points adjacent to this point to each other. 2. The multi-point distance measuring apparatus for a camera according to claim 1, wherein a distance measuring point having a larger amount of incident light is selected by comparing the distance measuring points. 3. The control means further performs the pre-ranging with the infinity determination level as a first level, selects a ranging point according to the result, and sets the infinity determination level to the first infinity determination level. As a second level lower than the level of
2. The multi-point distance measuring apparatus for a camera according to claim 1, wherein the distance is measured again.