JP3117389B2 - Distance measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera distance measuring apparatus for automatically measuring a distance to a subject.

[0002]

2. Description of the Related Art As such a distance measuring device for a camera,
An active method of a triangulation type that has a distance measuring light source such as an LED and measures a distance to a subject in combination with a light receiving element is known.

Further, as another type of distance measuring device, there is no distance measuring light source, natural light reflected by a subject is received by two optical systems, and two optical images obtained by each optical system are obtained. There is known a triangulation-type passive method for measuring a distance to a subject based on the phase difference of the object.

[0004]

The distance measuring device of the active type measures the distance to the object by receiving the distance measuring light returning from the object as described above. When the external luminance is high, the light receiving element measures the distance to the object. In some cases, the reflected light of the distance light cannot be satisfactorily received, so that the distance measurement accuracy is reduced or the distance measurement cannot be performed depending on the external luminance. On the other hand, a passive distance measuring device, when the external luminance is low, naturally reduces the amount of natural light reflected from the subject, making it difficult to detect a phase difference, resulting in a decrease in distance measuring accuracy or a distance measuring device. In some cases, it becomes impossible.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a distance measuring apparatus which can always obtain a highly reliable distance measuring result.

[0006]

Accordingly, a distance measuring apparatus according to the present invention projects distance measuring light toward a subject and measures the distance to the subject based on the condensing position of the reflected light. Active type first distance measuring means, and passive light for receiving natural light reflected by a subject by two optical systems and measuring a distance to the subject based on two optical images obtained by the respective optical systems. A second distance measuring means, and a distance measuring value selecting means for selecting and outputting any one of the distance measuring results obtained from the first distance measuring means and the second distance measuring means. The distance measuring value selecting means calculates an average value of the distance measured by the first distance measuring means and the distance measured by the second distance measuring means, and outputs the calculated result as a distance measuring value. Prepare and configure.

The distance measuring apparatus according to a second aspect of the present invention further comprises a luminance detecting means for detecting the luminance of the external world, and the distance measuring value selecting means further comprises means for converting the external luminance detected by the luminance detecting means to a high level. Discriminating means for discriminating into three levels of intermediate level and low level; first means for selecting a distance measurement result of the first distance measuring section when the external luminance is determined to be low level; A second means for selecting the distance measurement result of the second distance measuring unit when the level is determined, and a third means for executing the arithmetic processing of the arithmetic means when the intermediate level is determined.

[0008]

Each distance measuring apparatus according to the present invention includes two types of distance measuring means, namely, an active type first distance measuring means and a passive type second distance measuring means, and performs distance measurement with both of them. .
At this time, in both the distance measurement methods, the distance measurement result may be slightly different due to a difference in the position (angle) at which the distance is measured.

Therefore, in the distance measuring apparatus according to the first aspect, if there is a certain difference between the distance measurement results of the two methods, an average value of the distance measurement results obtained by the two distance measurement methods is calculated by the calculating means. , And outputs the calculation result as a distance measurement value.

Further, in the distance measuring apparatus according to the second aspect, when the external luminance is determined to be low, the first means means
In this situation, the distance measurement value of the first distance measurement unit that can obtain a more reliable distance measurement result is selected. If the external luminance is determined to be at a high level, the second means selects a distance measurement value of the second distance measurement means that can obtain a more reliable distance measurement result in this situation. Furthermore, when the external luminance is determined to be at the intermediate level, the distance measurement value by both methods is:
It is not clear which of the distance measurement values is more reliable. For this reason, the averaging process by the calculating means is performed by the third means.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a schematic configuration of a distance measuring apparatus according to the present embodiment. The distance measuring device includes an active distance measuring unit A that performs a triangulation type active distance measuring, and
Similarly, a passive distance measuring section P for performing a triangulation-type passive distance measurement is provided, and a luminance detecting section L for detecting external luminance and a distance measurement value selection circuit 40 are also provided.

The active distance measuring section A has a light projecting section 11 composed of an LED or the like for projecting distance measuring light toward a subject, and a light receiving section 12 composed of a PSD or the like for receiving the reflected light. It has a distance measuring circuit 13 for calculating the distance to the subject based on the result of light projection and light reception (see FIG. 2).

The passive distance measuring section P has a right light receiving section 21 and a left light receiving section 22 for receiving reflected light of natural light from a subject by two optical systems (see FIG. 2), and further through these. (Optical position detecting device: not shown) for receiving two optical images obtained by the above-mentioned operation, and a distance measuring circuit 23 for calculating the distance to the subject based on the results.

The luminance detecting section L utilizes the configuration of the AE section (automatic exposure section) in FIG. 3, and is based on a light receiving section 31 composed of a light receiving element for exposure control, for example, CdS, and the light receiving result. It is composed of a photometric calculation circuit 32 for calculating the external luminance.

The distance measurement value selection circuit 40 includes a
Is a circuit that selects and outputs one of the distance measurement values measured by each of the distance measurement units A and P based on the external luminance obtained in step S1. FIG. 2 shows an external view of a camera provided with the distance measuring apparatus according to the present embodiment, and FIG. 3 shows an outline of an internal mechanism thereof. The distance measurement calculation circuits 13 and 23, the light measurement calculation circuit 32, the distance measurement value selection circuit 40, and the like illustrated in FIG. 1 are configured in the CPU illustrated in FIG.

Here, the operation of the distance measuring apparatus will be described with reference to FIG.

First, when the camera is pointed at the subject and a release switch (not shown) is turned on (# 100), the power supply voltage is read and the voltage value is checked (# 100).
102, # 104). Here, if the read voltage value is less than the threshold value ("NO" in # 104), the photographing process becomes impossible, so that the user is notified by a display, a warning sound, or the like. Shifts to a predetermined NG treatment (# 1
06).

If the read voltage value has cleared the threshold value ("Yes" in # 104), the photometric processing for detecting the external luminance is performed by the luminance detecting section L (#).
108). In addition, the active ranging unit A performs the active ranging, and the passive ranging unit P performs the passive ranging (# 110, # 11).
2). Note that the distance measurement results in the respective distance measurement units A and P are given to the distance measurement value selection circuit 40 via the distance measurement calculation circuits 13 and 23.

Next, in the distance measurement value selection circuit 40, it is determined whether or not the external luminance obtained by the luminance detector L is a high luminance level equal to or higher than Lv14 (# 114). In the case where the external luminance is high, in the active method, the light receiving unit 12 cannot receive the reflected light of the distance measurement light satisfactorily, and the distance measurement accuracy may be reduced. On the other hand, in the passive method, since the amount of natural light reflected by the subject increases, the reliability of the distance measurement value is high. Therefore, when the external luminance obtained by the luminance detection unit L is equal to or higher than Lv14 (“No” in # 114), the distance measurement value selection circuit 40 selects the distance measurement value (passive data) of the passive distance measurement unit P. And output as distance measurement data (# 11
6). Then, for example, a photographing lens is set based on the set distance measurement data (# 118), the subsequent photographing processing is executed based on the distance measurement value output from the distance measurement value selection circuit 40. (# 120).

On the other hand, when the external luminance is lower than Lv14 ("Yes" in # 114), it is further determined whether or not the external luminance is lower than Lv3 (# 122). When the external luminance is low, the passive system has a small amount of reflected natural light and lacks reliability.
In this case, the reflected light of the distance measurement light is detected favorably, so that the reliability of the distance measurement value is high. Therefore, when the external luminance obtained by the luminance detection unit L is equal to or lower than Lv3 (“N” in # 122).
o "), the ranging value selection circuit 40 selects and outputs the ranging value of the active ranging unit A (# 124). Subsequent photographing processing is executed based on the distance measurement value output from the distance measurement value selection circuit 40 (# 118, # 120).

When the external luminance is a high luminance level equal to or higher than Lv14 or a low luminance level equal to or lower than Lv3, the distance measurement value selection circuit 40 immediately selects one of the distance measurement values as described above. select.

When the luminance level is an intermediate luminance level of 3 <Lv <14 (“Yes” in # 122), the distance value obtained by the active distance measuring section A and the distance value obtained by the passive distance measuring section P are obtained. An average value with the obtained distance measurement value is calculated and obtained, and the calculation result obtained here is output as detected distance measurement data (# 126). It is desirable that the distance measurement results obtained by the two distance measurement methods be the same, but the distance measurement results are different due to different distance measurement positions (angles) as shown in FIG. In some cases. Under the situation where the above-described determination conditions are satisfied, it is difficult to determine which method of the distance measurement result is more accurate. Therefore, in such a case, an average value of the distance measurement value of the active distance measurement unit A and the distance measurement value of the passive distance measurement unit P is obtained, and the obtained distance measurement result is obtained.

When the distance measurement value is obtained by this calculation, the calculation result is output from the distance measurement value selection circuit 40, and the subsequent photographing processing is executed based on the distance measurement value. (# 118, # 120).

As described above, the distance measuring apparatus according to the present embodiment
Among the distance measurement values obtained by the active distance measurement unit A and the passive distance measurement unit P, a more reliable distance measurement value is selected as an appropriate distance measurement value. Furthermore, if it is not possible to determine which of the two types of distance measurement results is more effective, the distance measurement results obtained by both methods are averaged, and this value is used as the distance measurement value. Distance accuracy is obtained.

In the above-described embodiment, an example in which the external luminance is detected by the luminance detecting unit L has been described.
As shown in the figure, each of the light receiving units 21 and 22 of the passive distance measuring unit P
It is also possible to determine the external luminance by the photometric / ranging arithmetic circuit 24 based on the light receiving result of (1).

In the flowchart shown in FIG.
Although the example in which the active distance measurement is performed first has been described, the passive distance measurement may be performed first, or the active distance measurement and the passive distance measurement may be performed simultaneously.

[0027]

As described above, in the distance measuring apparatus according to the first aspect, it is possible to determine which of the active and passive distance measuring results is more effective. When there is no distance measurement value, the distance measurement value obtained by averaging the distance measurement value obtained by the first distance measurement means and the distance measurement value obtained by the second distance measurement means is calculated by the calculation means. Can be improved.

Further, in the distance measuring apparatus according to the second aspect, when the external luminance is determined to be a low level or a high level,
By the first and second means, a distance measurement result that can be determined to be more reliable under each situation can be selected. When the external luminance is determined to be at an intermediate level, the distance measurement value by both methods is Because we can't determine which is more accurate,
Since the average value of both the distance measurement values is obtained by the third means, it is possible to always obtain a highly accurate distance measurement result under any photographing conditions.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically illustrating a configuration of a distance measuring apparatus according to an embodiment.

FIG. 2 is a front view showing a camera provided with the distance measuring device according to the embodiment.

FIG. 3 is a block diagram schematically showing a configuration inside a camera.

FIG. 4 is a flowchart illustrating an operation of the distance measuring apparatus according to the embodiment.

FIG. 5 is a block diagram showing another embodiment of the distance measuring apparatus.

[Explanation of symbols]

A: active distance measuring section (first distance measuring means), P: passive distance measuring section (second distance measuring means), L: luminance detecting section, 40: distance measuring value selection circuit.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-5-119250 (JP, A) JP-A-4-307507 (JP, A) JP-A-63-100411 (JP, A) JP-A-3-100 212631 (JP, A) JP-A-3-46507 (JP, A) JP-A-1-195431 (JP, A) JP-A-60-60616 (JP, A) JP-A-62-56912 (JP, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) G02B ^7/ 28-7/40

Claims (2)

(57) [Claims] An active type first distance measuring means for projecting distance measuring light toward a subject and measuring a distance to the subject based on a condensing position of the reflected light; Passive type second distance measuring means for receiving natural light with two optical systems and measuring the distance to the subject based on two optical images obtained by the respective optical systems; Means for selecting and outputting one of the distance measurement results from the distance measurement results obtained from the first and second distance measurement means. The distance value selection means comprises: A distance measuring apparatus comprising a calculating means for calculating an average value of a distance measured by the distance measuring means and a distance measured by the second distance measuring means, and outputting a result of the calculation as a distance measured value. 2. The distance measuring apparatus further comprises a luminance detecting means for detecting the luminance of the external world, and the distance measuring value selecting means further outputs the external luminance detected by the luminance detecting means to a high level and an intermediate level. Discriminating means for discriminating into three levels of low level; and first means for selecting a distance measurement result of the first distance measuring section when the external luminance is determined to be the low level by the discriminating means; When the external luminance is determined to be the high level by the determining means, second means for selecting a distance measurement result of the second distance measuring section; and determining the external luminance to the intermediate level by the determining means. 3. The distance measuring apparatus according to claim 1, further comprising: third means for executing the arithmetic processing of said arithmetic means when the operation is performed.