JPH1048509A - Range finder for camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized camera whose number of components is reduced by the improvement of a range finder having passive system AF (autofocusing) capable of rangefinding from short distance to long distance by the same accuracy without depending on the reflection intensity of range- finding light as a base and where focusing is surely made. SOLUTION: For the passive system AF, the attaching error of an optical system and the error of temperature character istic are restrained to the minimum by respectively reflecting light made incident on two lenses 1 and 2 only once, and also a device copes with light quantity unbalance on two sensors 4a and 4b corresponding to lenses based on a specified processing procedure, and the transmitted light of the optical system is effectively used, so that the small-sized range finder that does not have an object scene hard for range- finding is constituted. Also, a range finder accurately focusing is constituted by effectively using active system AF and light emitting devices 30-33.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera, and more particularly, to a technology of a distance measuring apparatus used for auto-focusing (automatic distance measuring: AF) of a camera.

[0002]

2. Description of the Related Art As a general distance measuring technique, "triangular distance measuring" is known, and a distance measuring method includes an "active method" in which light for distance measuring is projected from a light emitting element. In addition, two methods of a "passive method" using a correlation of a luminance distribution of an object viewed from two lens positions are known, and are adopted in many cameras.

The triangulation will be described with reference to the "active method" shown in FIG. 11 (A). Distance measuring light from a light source 20 is condensed and projected by a lens 21 and reflected on a subject O1, and the reflected signal light is reflected by the lens 21. Light position detecting element (PSD) via light receiving lens 21
When the light enters the light source 23, a signal current depending on the light position is output. Since this output includes light components other than the signal light,
This is removed by the stationary light removal circuit 23a, and the signal position detection circuit 23b determines the reflected signal light position from the extracted signal component. The incident position x of the reflected signal light is such that when the distance S between the principal points (base line length) of both lenses and the focal length f of the light receiving lens 2 are constant, the subject distance L is large according to the “principle of triangulation”. The smaller, the closer the distance,
This is a large value. As described above, the signal position detection circuit 23
If this x is detected by b, the subject distance is calculated, and the larger the value of x, the better the distance measurement accuracy.
As S or f is larger, more accurate distance measurement is possible.

On the other hand, the "passive type" shown in FIG. 11B does not have a light projecting element and a light position detecting element, but instead has a pair of sensors 4a for detecting an illumination state on a subject in a pattern. , 4b behind the light receiving lenses 1 and 2 respectively, the degree of shift of the light pattern generated on both sensors changes due to the parallax of the lenses, so that the distance measurement can be performed according to the same principle of the triangular distance measurement as described above. is there. Also in the case of the passive method, the greater the base line length and the focal length, the clearer the degree of displacement, so that more accurate distance measurement can be performed.

[0005]

However, in the case of AF employing any of the above methods, if the base line length is increased for higher accuracy, the size of the camera body becomes larger. Further, in the "passive system", it is difficult to form the sensors 4a and 4b as a sensor array with one chip. On the other hand, in order to reduce the size of the camera, the depth of the main body is strictly limited, and the f-number of the distance measuring device is apt to be limited. Also,
The conventional optical system that optically bends the optical path many times and measures the distance with a small sensor array becomes more complicated, the number of components increases, and the mounting error of the optical system and the temperature characteristics adversely affect AF. For that reason, the camera was vulnerable to environmental changes.

[0006] Further, these two types of AF have subjects peculiar to them, and are weak to a subject at a long distance where a signal is difficult to reach in an active type, and a low contrast subject in which a clear image cannot be obtained in a passive type. Also, distance measurement in dark scenes is not good. Furthermore, even with these two methods,
If there was no subject in the area to be measured, correct focusing could not be performed.

To cope with the above problems, Japanese Patent Publication No. 53-32
In Japanese Patent Application Laid-Open No. 699, there is also a proposal in which, after bending an AF optical system using a half mirror or the like, the transmitted light is observed and the distance is measured also as a finder. However, if only one light beam for triangulation is split in this way, the images formed on the two sensors become unbalanced (for example, the amount of light, etc.), so that accurate ranging was difficult. In addition,
Japanese Patent Publication No. 78603 discloses a combination of both types.

According to the present invention, regardless of the reflection intensity of the distance measuring light,
The objective is to provide a compact camera that can reduce the number of parts as much as possible and that does not fail in focusing by improving based on the “passive method” AF that can measure the distance with the same accuracy from short distance to long distance. .

[0009]

SUMMARY OF THE INVENTION Accordingly, the present invention minimizes the mounting error of the optical system and the error of the temperature characteristic by bending the light incident on the two light receiving lenses of the "passive type" AF only once. The present invention provides a small-sized AF camera that does not have a subject that is difficult to handle, while also taking measures against light amount imbalance on both sensors and effectively using light transmitted through the optical system.

[0010] Further, the so-called "active AF" is effectively used in combination with the AF to enable more accurate focusing.
Provide a camera. Specifically, [1] a plurality of lenses having parallax, and a plurality of light receiving element rows placed at respective focal positions of the plurality of lenses, and a light amount distribution incident on each light receiving element row A distance measuring device that measures a distance to a subject based on the plurality of lenses and the plurality of light receiving element rows, and an optical path dividing unit that divides incident light beams of the plurality of lenses is arranged. A distance measuring device for a camera is provided, wherein a plurality of optical paths obtained by the optical path dividing means are also used as optical paths for purposes other than distance measurement.

[2] The optical path for applications other than distance measurement is at least a finder optical path for a finder field of view, a light receiving optical path of a photometric sensor for photometry, a light emitting optical path of a light emitting means for emitting light to a subject, Alternatively, there is provided the distance measuring device for a camera according to [1], which is a light receiving optical path of a remote control light beam from a remote control device.

[3] A plurality of lenses having parallax, and a plurality of light receiving element rows arranged at respective focal positions of the plurality of lenses, and a subject is detected based on a light amount distribution incident on each of the light receiving element rows. The first to measure the distance to
A distance measuring unit, an optical path dividing unit disposed between the plurality of lenses of the first distance measuring unit and the plurality of light receiving element rows, and dividing an incident light beam, and an optical path obtained by the optical path dividing unit. Projection means for projecting a light beam for distance measurement toward the subject, and light receiving means for receiving reflected light from the subject due to the projection, and further comprising: A second distance measuring means for measuring a distance to the first distance measuring means and a control means for selectively operating either the first distance measuring means or the second distance measuring means in accordance with predetermined distance measuring conditions. A distance measuring device for a camera, comprising:

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to a plurality of embodiments. (First Embodiment) FIG. 1 shows a basic structure of a distance measuring apparatus according to a first embodiment of the camera of the present invention.

The passive-type apparatus includes lenses 1 and 2 for condensing reflected light from a subject incident on a camera, and a light condensed by these lenses arranged on a sensor array 4.
And a half mirror 3 for guiding the two sensors 4a and 4b. The sensor array 4 is an IC clear mold package including a sensor data readout circuit (not shown). This package is mounted on a substrate 5 on which this IC is mounted, and these sensors 4a,
4b, based on the base line length and focal length of the two lenses 1 and 2 and the distance to the subject (subject distance) in accordance with “Principle of passive triangulation” (see FIG. 11B). (CP)
U) 10 are implemented.

The arithmetic means 10 is constituted by a one-chip microcomputer or the like, and performs "focusing" by appropriately controlling a photographing lens (not shown) with respect to a subject distance obtained by a series of distance measuring operations. The light transmitted through the half mirror 3 from the two lenses 1 and 2 is a prism optical system 7 for the finder and a photometric element 6 for controlling the exposure of the camera.
It is led to. Although the viewfinder optical system 7 such as the viewfinder prism is shown in a columnar shape in FIG. 1, the optical path is not limited to the shape, and the optical path is folded using a predetermined mirror or the like so as not to become longer in the thickness direction of the camera. Is set to

(Function and Effect 1) Basically, these lenses 1 and 2 have the same optical characteristics, and the half mirror 3 shares the same one for both lenses. The subject image on 4b does not become unbalanced, and the focal length of the lenses 1 and 2 can be increased without increasing the thickness direction of the camera, so that a highly accurate distance measuring device can be provided.

Also, since the photographer 9 can observe the subject through the eyepiece 8, the subject can be correctly focused on the target aimed by the photographer, and there is no parallax between the distance measuring device and the photometric means. Accurate exposure control can be performed for a correct subject.

(Second Embodiment) As a modification of the configuration of the first embodiment, a configuration as shown in FIG. 2 is also possible. That is, in the distance measuring apparatus for a camera according to the second embodiment, the lenses 1 and 2 are formed of “prism-shaped” lenses, and the lenses 1 and 2 are formed with the function of forming images on the sensors 4 a and 4 b via the holding member 11. Viewfinder optical system 7 and photometric sensor 6
It has a structure that also has the function of guiding light to each side.

FIG. 3A shows a cross section along the optical axis on the lens 1 side. The prism lens 1 having the half mirror surface 1a is disposed on the holding member 11, and the sensor IC package 4 is held. It is attached below the member 11.
The half mirror surface has a function of reflection and transmission, and light incident from the front and reflected vertically downward by the mirror surface 1a is guided to the sensor IC, and the obtained signal is used for exposure control.

On the other hand, the transmitted light that has traveled straight is guided to a finder optical system 7 behind the half mirror, and provides a subject image to the photographer's eye 9 via an eyepiece 8. FIG. 3B shows a cross section along the optical axis on the lens 2 side, and shows a half mirror surface 2a.
The light reflected by is guided to the distance measuring sensor 4b, and the transmitted light is guided to the photometric sensor 6. The holding member 11 is also fixed between the lens 2 and the array 4 of the IC package.

The light receiving surface of the photometric sensor 6 shown is divided into two parts,
As shown in the block diagram of FIG. 4, one of them is provided as an exposure control sensor 6a, and the other is provided as a remote control signal receiving sensor 6b for operating the camera body from a remote place. Configure the camera system.

That is, according to FIG. 4, the sensor array 4 composed of the distance measuring sensors 4a and 4b is connected to sensor data readout circuits 14a and 14b, respectively, and these circuits are arranged in accordance with the brightness of a subject image. A capacitor for integrating the photocurrent to be output and an A / D converter for A / D converting the integrated voltage
It is composed of a D converter and the like. Further, based on the data thus obtained, a shift amount based on the “lens parallax” of the subject images on the two sensors is calculated by the correlation operation circuit 13. These are configured on the same semiconductor chip in the IC package 4 shown in FIG.

On the other hand, the above-mentioned exposure photometric element 6a outputs a photocurrent corresponding to the brightness of the subject, and the AE circuit 12 connected thereto outputs an A / D-converted photocurrent and the CPU 10
Input as digital data. The output of the remote control light-receiving element 6b is input to a remote control circuit 15, which amplifies only a signal of a predetermined frequency generated by a remote control transmitter (not shown), and transmits this signal pattern to the CPU 10. The input is made to make the CPU 10 recognize that the remote control signal has entered.

Incidentally, the photographer can operate the remote controller in addition to the remote control operation.
Release SW17 linked to release button (not shown)
The photographing instruction can also be given by the operation of. Based on the distance measurement result, photometry result, and remote control signal reception result obtained by such a configuration, the CPU 10
The focus position and exposure control of the photographing lens are determined by predetermined arithmetic processing, and each part of the camera performs an appropriate photographing operation. For example, at the time of focusing, an actuator that drives a lens such as a motor or a focusing unit 18 composed of a mechanical mechanism is controlled.
9 to perform appropriate exposure control. At this time, variations in the characteristics of the photometric element itself, variations in the sensitivity of the sensor arrays 4a and 4b, and errors in the ranging characteristics of the AF means (means including the focusing means 18) based on the degree of perfection and mounting errors of the optical system are reduced. Since the inspection data is inspected beforehand during the manufacture of the camera and the correction data for the error is stored in an electrically writable memory (for example, EEPROM) 16, the CPU 10 refers to the correction data in this memory at the time of photographing. However, it is also possible to perform optimal ranging control.

Next, the operation of the CPU 10 for controlling each section of the camera having the above-described configuration will be described with reference to the flowchart shown in FIG. First, it is detected whether or not the release SW of the camera or the remote control transmitter has been operated (S1, S2). When any one of these is operated, the data is read from the EEPROM 16 (S3),
Photometry is performed according to the amount of light incident on the sensor 6a (S
4). An operation of integrating the photocurrent of each sensor of the sensor arrays 4a and 4b is performed (S5), and the operation is read out via the data reading means (S6), and the correlation calculating means 13 determines the amount of image shift based on the result. It is detected (S7). Note that the CPU 10 may have this shift amount detection function in a predetermined routine.

Based on the amount of deviation obtained in the above steps, the CPU 10 performs a predetermined distance calculation for focusing (S8), and performs focusing control of the photographing lens using the focusing means 18 (S9). . Further, exposure control is performed based on the photometry result (S10).

(Function and Effect 2) As described above, in this embodiment, since there is no “parallax” between the distance measuring device and the finder, the target object can be correctly focused, and
Since the optical system is shared, the number of parts can be reduced, so that a smaller camera can be provided.

(Third Embodiment) FIG. 6 shows a distance measuring apparatus for a camera according to a third embodiment of the present invention, which employs a pair of prism lenses 1 and 2 as illustrated in FIG.
However, the light transmitted through the half mirror surface is not guided to a finder or a photometric element, but is used for the “active type” AF shown in FIG. In the present embodiment, the “active AF” is effectively combined with the “passive AF” to reduce a subject pattern that is difficult to focus. In the active AF shown in FIG. 11A, it is necessary to obtain the position of the reflected signal light regardless of the brightness of the subject, so that the photocurrent component due to the steady light incident on the light position detecting element is removed. It has the function to do. Therefore, good distance measurement is possible even for a subject pattern having a high brightness and a low contrast, which is difficult for the passive method.

An infrared light emitting diode (I) supplied with current by driver means 21 controlled by CPU 10 in FIG.
When the (RED) 20 emits light, the distance measuring light is projected toward the subject by the condensing action of the lens 1. Then, the reflected signal light from the subject is guided by the lens 2 to the light position detecting element (PSD) 22. The active AFIC 23 connected to this element and calculating the output signal current supplies the incident signal light position signal to the CPU 10, so that the
U10 can calculate the distance to the subject from the position signal according to the above-mentioned "principle of triangulation". On the other hand, the light reflected by the light receiving lens reflecting surface is incident on a passive distance measuring sensor.

Therefore, according to the third embodiment, it is possible to design a device utilizing both the advantages of the passive type and the active type distance measuring device. In such a configuration, the CPU
Reference numeral 10 determines a distance for focusing in accordance with a control procedure based on a flowchart as shown in FIG.

In step S20, first, the "passive AF" of the IC 4 is operated, and the distance between the images relative to the respective sensors is calculated based on the "principle of triangulation" shown in FIG. Find Lp. At the same time, the contrast of the image is detected, and for example, a contrast value Cp based on a difference between the maximum light amount and the minimum light amount incident on each sensor array at that time.
Is calculated (S20).

If the value Cp is small, clear images cannot be compared, and the result of distance measurement at that time is considered to have low reliability.
Therefore, the contrast value Cp is compared with a predetermined value Cp0 (threshold value) (S21). If Cp is smaller than this threshold value, the flow branches to step S23, the driver 21 is operated to cause the IRED 20 to emit light, and the light enters the PSD 22. The active AF operation is performed according to the position of the reflected signal light (S23). The obtained result is set as LA, focusing is performed on this distance (S24), and a shooting sequence is performed (S25).

On the other hand, if it is determined in step S21 that the contrast is higher than the threshold, focus control is performed in accordance with the distance measurement result Lp of "passive AF" (S22), and a shooting sequence is similarly performed (S2).
5).

(Function and Effect 3) As described above, in the third embodiment, it is possible to provide a distance measuring apparatus that overcomes the weak point of “passive AF” that “a low contrast object cannot be measured”. Further, in this embodiment, since the light emission of the “active AF” is performed using one of the light receiving lenses of the passive AF, an error based on “parallax” or the like does not occur in the distance measurement point.

Other than the low contrast, "passive A
F "also overcomes the drawback of" active AF "in which a distance measurement error occurs due to a decrease in the amount of reflected signal such as a subject at a long distance. Since the lenses 1 and 2 have the same optical characteristics as in the second embodiment, the two sensors 4
Since the subject image on the sensor array 4 on which the sensors a and 4b are arranged does not become unbalanced, and since these sensors 4a and 4b are shared by two passive / active systems,
The number of camera parts can be reduced. Further, the distance from the lenses 1 and 2 to the sensor array 4 can be increased without increasing the thickness direction of the camera, so that a highly accurate distance measuring device can be provided.

(Third Embodiment) Next, a description will be given of an embodiment in which a strobe device having the structure shown in FIG. 6 described above and used as a so-called "exposure assist" built in a camera is effectively used for distance measurement. . Xenon tube 31 as light source
Is connected to the light emitting means 33 controlled by the CPU 10. When a high trigger voltage is applied to the light emitting means 33, the xenon tube 31 discharges the energy stored in the charging circuit 32 instantaneously and emits strobe light.

FIG. 8 is a flowchart showing the emission timing of the auxiliary light of the strobe. That is, in the distance measuring process, first, the brightness BV of the subject is measured and compared with a predetermined brightness Bv0 (threshold) (S30). If the result of the comparison is that the brightness is smaller than the predetermined brightness BV0, the process proceeds to step S
The flow branches to 31, and the xenon tube 31 emits light for distance measurement (S31). The light of the xenon tube is projected over a wide range by the reflector 30, and a shadow is added to a subject in a dark scene. Therefore, according to the contrast obtained in this manner, the "passive type" distance measurement becomes easy. However, even in this case, a clear contrast value Cp may not be obtained.
To determine this, Cp is compared with a threshold value Cp0 (S32). If the contrast is not higher than the predetermined value, the process branches to step S35, in which the IRED 20 emits light, the PSD 22 receives the reflected signal, and the "active method" distance measurement is performed (S35). Then, the obtained distance is set as LA and the focus is adjusted there (S36).
A shooting sequence is performed (S38).

On the other hand, if the brightness Bv is brighter than the predetermined value Bv0 in step S30, the "passive method" is used based on the relative image position difference on the sensor array 4 without auxiliary illumination.
(S33). At this time, if the contrast is equal to or more than a predetermined value, the obtained distance is set as LP and the focus is adjusted there (S37), and the photographing sequence is performed (S3).
8).

However, if the subject does not have a predetermined contrast, it is difficult to perform a correct distance measurement. Therefore, the flow branches to step S35 to perform the same distance measurement as described above. (Function and Effect 3 ′) As described above, according to the present embodiment, correct focusing can be performed regardless of the brightness of the subject and the presence or absence of contrast. In other words, a distant subject is not good at active AF, but a person in a distant and bright place can measure the distance by a passive method using contours and shadows. For example, when the subject is a landscape, reflected light during active distance measurement is extremely small. As described above, according to the present embodiment, it is possible to focus on most subjects.

(Third Embodiment) Further, as an example of a subject for which it is difficult to focus the camera, there is a scene as shown in Fig. 12. Particularly in the case of the active AF, the scene shown in Fig. 12 is used.
In such a scene, it is necessary to project the distance measuring light in the direction in order to properly focus on the object O2 existing (off center) other than at the center of the screen. In general, when a desired light emitting direction is switched by moving an IRED or the like, accurate distance measurement cannot be performed due to a position error or the like. Therefore, there is a technique of providing a large number of light emitting elements and sequentially emitting light, but the number of light emitting elements can be increased. As a result, the number of drivers also increases, resulting in cost and space problems.

Therefore, in the sensor adopting the passive system as shown in FIG. 11B, it is desired to measure the distance not to the object O1 on the optical axis of the lens 1 but to the object O2 at a laterally shifted position. In this case, it is only necessary to arrange the sensors up to a position distant from the optical axis. Although the number of sensors slightly increases, so-called “multi-point ranging” can be relatively easily performed. That is, if the sensor 4b can detect not the image on the sensor on the optical axis of the lens 1 but the image on the sensor 4b that coincides with the image on the sensor at the shifted position, the principle of triangulation is based on the relative positional shift amount. Thus, the distance measurement of the object O2 becomes possible. The flowchart shown in FIG. 9 is an improved operation procedure that also takes such characteristics into consideration and further measures the distance to a dark place, which is a further weak point of the passive AF, and a low-contrast subject with high luminance. .

The basic configuration of the apparatus according to this embodiment is the same as that shown in FIG. 6. The sensitivity of the sensor array 4 is extended to the "infrared" range, and the IRED 20 is used as the "auxiliary light" at the time of passive distance measurement. It has been improved so that it can be used as well.

That is, in a dark scene, since there is no clear change in the luminance distribution of the object, light is emitted from the camera side to enable passive distance measurement. However, even in a low-contrast subject in a bright scene, the distance measurement cannot be performed correctly because the amount of the auxiliary light is smaller than that of sunlight or the like. Therefore, an active AF technique that removes a stationary light component that constantly illuminates the subject, such as sunlight, and extracts only a reflected signal light of distance measuring light (light of the IRED 20) projected from the camera side is also used. Thus, it also supports a scene as shown in FIG. 12 (that is, a case where the subject person is off-center).

The signal light extraction technique includes, for example, a method of projecting distance measuring light in a state where a stationary photocurrent is sampled and held, and using a change component at that time as a distance measuring signal, or a method of modulating a distance measuring signal. A method of projecting a signal and amplifying only a signal of a specific frequency by a band-pass filter or the like is adopted.

According to the flowchart of FIG. 9, first, it is determined whether or not the brightness of the passive AF can be measured without auxiliary light (S40). If the brightness is sufficiently bright, FIG. In the passive triangulation method described in the above, three ranging points corresponding to the left, right, and center in the screen in the following steps (p1, p2, p3 in FIG. 12)
, And the contrast value of each ranging point is detected (S41 to S43).

If this contrast value is small, the reliability of the distance measurement result at that point pn (n = 1, 2, 3,) is low. To obtain the main subject distance Lp. In this embodiment, assuming that "the main subject should be closest", Lp is determined by closest selection from the obtained distance measurement results (S44, S45).

If the contrast is low at any of the distance measuring points, the IRED 20 is caused to emit light (S46).
The PSD 22 receives the reflected signal light, and performs the “active method” distance measurement. In this method, since the distance can be measured by removing the stationary light and extracting only the signal light as described above, correct distance measurement can be performed even on such a high-brightness, low-contrast subject. Therefore, in such a scene, the result of the active AF is prioritized, and the distance L obtained as a result is obtained.
Focusing is performed on A (S47).

On the other hand, as a result of the determination in step S40, in the case of a dark scene, the process branches to step S50, where IR
After the ED 20 is projected and used as auxiliary light, "passive AF" is performed (S50). In this case, since the IRED 20 cannot irradiate an extremely wide range, the distance measurement range is set to only the irradiation area. At this time, the contrast is checked at the same time (S51). If the result is a low contrast, "active AF" is performed in step S46. If the contrast is sufficient, focusing is performed on the distance obtained at this time (S52), and the shooting sequence is started (S5).
3).

(Effect 3 ″) According to this embodiment, an effect almost equivalent to the above-mentioned (Effect 3 ′) can be obtained.

(Fourth Embodiment) A distance measuring device for a camera according to a fourth embodiment of the present invention is a system capable of storing the outputs of all sensor arrays at one time or taking in the CPU. The processing procedure of the flowchart as shown in FIG. 10 is possible.

Assuming that the basic configuration is substantially the same as the configuration shown in FIG. 6 described above, a flash device with a built-in camera which is usually used as an exposure assist is similar to the configuration shown in FIG.
It is effectively used as an auxiliary light source for F. However, the IRED 20 originally for active AF is also used for passive AF.
Used for business. To explain these uses properly,
Strobe light that can illuminate a wide area with a large amount of light illuminates the screen uniformly, so despite having inherent contrast,
This is effective for subjects whose distance cannot be measured due to low brightness. The subject does not need to be in the center of the screen due to the wide illumination angle of the strobe and the range in which the sensor array can measure multiple points.

However, in general, the strobe light is emitted by the discharge of the charged energy, so it emits light only for a moment and is uniform, so that no contrast can be given to a subject having no contrast. That point,
The light of the IRED for the active AF has a good light-collecting property and can emit light for a long time even in a narrow range. Therefore, when the luminance is low, for example, even if the subject is at a long distance, if the light is emitted for a long time, a clear contrast can be given to the subject without contrast by the integration effect. This is more effective for a subject at a short distance. Also, the auxiliary light by the IRED, which is effective for creating such a contrast, is not expected to be effective in a bright scene because it is drowned out by the light of the environment. In this case, the stationary light removing effect of the active AF is effective. .

Therefore, an improved processing procedure based on the above-described reason is exemplified in the flowchart of FIG.
First, the brightness of the subject is determined (S60), and the outputs of the respective sensors 4a and 4b are input to the CPU 10 and the CPU 1
0 stores it as an image output, but if it is determined to be "low luminance", the contrast of the object is enhanced by irradiating strobe auxiliary light during image detection (S70). Next, the CPU is used to store the low brightness state.
10 sets the low luminance flag to H (= 1) (S71).

On the other hand, if the subject luminance is determined to be "high luminance", the auxiliary light irradiation is useless and the image signal is detected without the auxiliary light (S61). Then, the low-brightness flag is set to L
(= 0) is set (S62).

As described above, the subject distance is detected from the deviation of the subject image signal obtained through the two lenses by the "principle of triangulation" shown in FIG. 11B.
The reference sensor position is set in the following steps (S63 to S63).
65) to switch the direction of distance measurement. As a result, distance measurement of three points in the screen of L (left), C (center), and R (right) becomes possible. However, since the image signal with low contrast is not suitable for distance measurement, it is removed (S6).
6) The closest distance measurement result is obtained from reliable ones (S83), the result is focused, and exposure is performed (S84).

It is determined whether or not all the sensors show low contrast (S67). In that case, some countermeasure is required. For example, in this case, based on the determination result of the low luminance flag obtained earlier. (S80) If the brightness is low,
The auxiliary light source is formed by irradiating the IRED 20 which is superior in the light condensing property of the strobe light and can form a contrast on the object (S
81). At the time of this irradiation, since the light of the IRED 20 is incident only on the sensor for the center of the screen, the CPU 10 preferentially takes in the image signal of the center of the screen and performs a predetermined distance calculation based on the value obtained as a result. .

The auxiliary light of the IRED 20 is also drowned out by surrounding light when the luminance is high, so that the low luminance flag is set to L
In the case of (= 0), the active-type distance measurement capable of measuring the distance by removing the stationary light is performed by the light emission of the IRED 20 and the light reception by the PSD 22. The principle of ranging at this time is also shown in FIG.
This is performed in the same manner as described in 1 (A).

(Effect 4) As described above, in the fourth embodiment, even in a dark scene where the subject does not exist at the center of the screen, it is possible to correctly focus by the strobe light that irradiates a wide range. In addition, since the IRED is used even for a subject having no clear contrast, distance measurement is possible, and a high-luminance, low-contrast subject, which has been weak in the conventional passive AF, can be measured with the “active AF”. Correct focus can be achieved in the scene.

Although the present invention has been described based on a plurality of examples, the present invention includes the following inventions. [1] A plurality of lenses having parallax, and a plurality of light receiving element arrays located at respective focal positions of the plurality of lenses, and a subject is detected based on a light amount distribution incident on each light receiving element array. A distance measuring device for measuring a distance between the plurality of lenses and the plurality of light receiving element rows, wherein an optical path dividing means for dividing incident light beams of the plurality of lenses is disposed, A distance measuring device for a camera, wherein a plurality of optical paths obtained by the above method are used also as optical paths for purposes other than distance measurement.

[2] The optical path for applications other than the distance measurement is at least a finder optical path for a finder field of view, a light receiving optical path of a photometric sensor for photometry, a light emitting optical path of a light emitting unit for emitting light to a subject, or [1] is a light receiving optical path of a remote control light beam from a remote control device.
A distance measuring device for a camera according to item 1.

[3] A plurality of lenses having parallax, and a plurality of light receiving element rows arranged at respective focal positions of the plurality of lenses are provided, based on a light amount distribution incident on each light receiving element row. First distance measuring means for measuring a distance to a subject, and an optical path dividing means arranged between a plurality of lenses of the first distance measuring means and the plurality of light receiving element rows to divide incident light rays; A projection unit for projecting a light beam for distance measurement toward the subject via an optical path obtained by the optical path splitting unit; and a light receiving unit for receiving light reflected from the subject by the projection. A second distance measuring means for measuring a distance to the subject based on an optical path length of the light; and either the first distance measuring means or the second distance measuring means selected according to predetermined distance measuring conditions. Control means for automatically operating A distance measuring device for a camera.

In addition, the following inventions are also included. (1) Light from a subject is received by first and second lenses provided at different positions, and a light receiving element array for detecting the light distribution of each transmitted light, and transmission by the first and second lenses In a distance measuring apparatus for a camera that detects a distance to the subject based on a relative position of a light distribution of light,
A distance measuring device for a camera, comprising a division optical system for dividing an optical path between a second lens and the light receiving element row.

(2) Part of the light passing through one of the first and second lenses enters the finder optical system of the camera, and part of the light passing through the other lens controls the exposure of the camera. The distance measuring device for a camera according to (1), which is incident on a photometric sensor for the camera.

(3) It further comprises light projecting means for projecting a light beam for distance measurement to the object, and a part of the light passing through one of the first and second lenses is used as the light receiving element array. The distance measuring device for a camera according to (1), wherein the light is incident on a sensor provided separately from the sensor for receiving reflected light from the subject due to the distance measuring light beam.

(4) Projecting means for projecting a light beam for distance measurement onto a subject, and receiving reflected light from the subject,
A light position detecting means for detecting an incident position of the reflected light, a plurality of sensor arrays for detecting the image of the subject via a plurality of optical paths having parallax, and detecting a relative position difference between the respective subject images; Calculation control means for calculating the distance to the subject based on the output of the light position detection means or the relative position difference between the subject images on the plurality of sensor arrays, and A camera which activates the light emitting means is also a distance measuring device.

(5) The camera distance measuring apparatus according to (4), wherein when the brightness of the subject is high and the contrast is low, the output of the light position detecting element is preferentially used.

(6) In a camera having a built-in strobe device, a light emitting element for projecting a light beam for distance measurement to a subject and a first light receiving element for distance measurement for measuring a plurality of points in a photographing screen. And a second light receiving element for measuring a distance at one point in the screen, wherein the strobe device emits light when the first light receiving element is used, and the light emission when the second light receiving element is used. A ranging device for a camera, wherein the device is controlled so as to operate the device.

[0068]

As described above, since the two lenses have the same optical characteristics and the half mirror uses the same half mirror, the subject images on the two sensors are unbalanced. In addition, the focal length of the lens can be increased without increasing the thickness direction of the camera, and the AF performance can be improved.

Therefore, according to the present invention, the light incident on the two lenses of the "passive type" AF is bent only once, thereby minimizing the mounting error of the optical system and the error of the temperature characteristic. It is possible to provide a small-sized AF camera that does not have an objectionable subject by taking into account the light amount imbalance on the sensor and effectively using the transmitted light of the optical system.

The "active AF" and "passive A"
An effective combination with "F" can provide a camera with more accurate focusing. Therefore, according to the above-described present invention, a component based on a “passive type” AF capable of measuring a distance from a short distance to a long distance with the same accuracy irrespective of the reflection intensity of the light for distance measurement and its improvement, The number of points can be reduced, and a compact camera free from focusing failure can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a distance measuring device for a camera according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a distance measuring device for a camera according to a second embodiment of the present invention.

FIG. 3A is a cross-sectional view along one optical axis of a distance measuring apparatus according to a second embodiment, and FIG. 3B is a cross-sectional view along another optical axis of the distance measuring apparatus according to the second embodiment; FIG.

FIG. 4 is a block diagram of a main part related to a camera distance measuring apparatus according to the present invention.

FIG. 5 is a flowchart illustrating a procedure of a distance measuring sequence of the camera according to the second embodiment of the present invention.

FIG. 6 is a perspective view showing a distance measuring device for a camera according to a third embodiment of the present invention.

FIG. 7 is a flowchart illustrating a basic procedure of distance measurement according to a third embodiment;

FIG. 8 is a flowchart illustrating a detailed processing procedure of distance measurement according to the third embodiment;

FIG. 9 is a flowchart showing a detailed processing procedure of distance measurement according to the third embodiment;

FIG. 10 is a flowchart illustrating a detailed processing procedure of distance measurement according to a fourth embodiment;

11A is an explanatory diagram showing the principle of active triangulation; FIG. 11B is an explanatory diagram showing the principle of passive triangulation; FIG.

FIG. 12 is an explanatory diagram showing positions of a plurality of photometry points in a certain shooting scene.

[Explanation of symbols]

 1, 2, ... lens (prism lens), 3: half mirror, 4: sensor array (IC package), 5: substrate, 6: photometric element (photometric sensor), 7: finder optical system, 8: eyepiece, 10: CPU (calculation means), 11: holding member, 12: AE circuit, 13: correlation calculation circuit, 14a, 14b: data readout circuit, 15: remote control circuit, 16: EEPROM, 17: release SW, 18: focus adjustment means, 19: shutter means, 20: infrared light emitting diode (IRED), 21: driver means, 22: light position detection element (PSD), 23: active AFIC, 30: reflector, 31: xenon tube, 32: charging circuit, 33 ... Light emitting means. O1, O2: subject, p1, p2, p3: photometric point. S1 to S10: the ranging sequence of the second embodiment; S20 to S25: the ranging sequence of the third embodiment; S30 to S38: the ranging sequence of the third 'embodiment; S40 to S53: the third embodiment. Distance measuring sequence, S60 to S84: Distance measuring sequence according to the fourth embodiment.

Claims (3)

[Claims] 1. A method according to claim 1, further comprising: a plurality of lenses having parallax; and a plurality of light receiving element rows disposed at respective focal positions of the plurality of lenses, based on a light amount distribution incident on each light receiving element row. What is claimed is: 1. A distance measuring apparatus for measuring a distance to a subject, comprising: an optical path dividing unit disposed between the plurality of lenses and the plurality of light receiving element rows, for dividing incident light beams of the plurality of lenses; A distance measuring device for a camera, wherein a plurality of optical paths obtained by the dividing means are also used as optical paths for purposes other than distance measurement. 2. An optical path for an application other than the distance measurement, at least a finder optical path for a finder visual field, a light receiving optical path of a photometric sensor for photometry, a light emitting optical path of a light emitting unit for emitting light to a subject, or 2. A light receiving path of a remote control light beam from a remote control device.
A distance measuring device for a camera according to item 1. 3. An object comprising: a plurality of lenses having parallax; and a plurality of light receiving element arrays disposed at respective focal positions of the plurality of lenses, based on a light amount distribution incident on each of the light receiving element arrays. A first distance measuring unit that measures a distance to the optical path dividing unit; an optical path dividing unit that is arranged between a plurality of lenses of the first distance measuring unit and the plurality of light receiving element arrays and divides an incident light beam; A projecting unit for projecting a light beam for distance measurement toward the subject via an optical path obtained by the optical path dividing unit; and a light receiving unit for receiving light reflected from the subject by the projection. A second distance measuring unit for measuring a distance to the subject based on an optical path length of the light; and selecting one of the first distance measuring unit and the second distance measuring unit according to predetermined distance measuring conditions. Control means for automatically operating A distance measuring device for a camera.