JPH0926612A - Finder device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a finder device which does not cause parallax in both range-finding systems of a range finder and an automatic focusing unit, even if they are provided in the same device and increase a device scale as well. SOLUTION: A first image almost equivalent to an object photographed on a film is led to a finder visual field through an image receiving lens 10 and a second image for range-finding after passing through an objective lens 16 arranged at a fixed distance L from the image receiving lens 10 is led to the finder visual field by a total reflection mirror 20 and a half mirror 12. Then, the first and second images are synthesized as a double image, to execute range-finding from the degree of the coincidence of the first and second images. Further, each of luminous fluxes led by AF light receiving lenses 24 and 26 consisting of a pair of optical systems symmetrically arranged at a fixed distance Saf on both sides of the lens 10, in a direction where the axes of the lens 10 and the objective lens 16 are connected, is received by a sensor 34, to execute the range-finding from the deviation value between these images.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a range finder for guiding an image from two windows separated by a certain distance to the same field of view by using a mirror and the like, and a range finder for measuring a distance by overlapping the two images. The present invention relates to a finder device including an autofocus unit that measures a distance by using a means.

[0002]

2. Description of the Related Art A finder device such as a camera has a function of guiding an image substantially equivalent to an image formed on a film surface out of a subject image to a photographer's eye. Therefore, with this finder device, it is also possible to confirm the focus adjustment state of whether or not the subject is in focus.
Here, as a distance measuring method for performing focus adjustment, a method using a range finder that optically detects a distance and visually confirms it, and a method that uses an auto focus to electrically detect a distance are currently used. There is. 2. Description of the Related Art Conventionally, as a camera of a type in which a taking lens and a finder device are independent, a camera has been commercialized in which range information can be visually obtained by the range finder.

In this range finder, as shown in FIG. 4, a light flux from a subject that has passed through a finder objective lens 101 passes through a half mirror 102 and an eyepiece lens 103 and is guided to the eye. On the other hand, the protective glass 10 provided at a position separated from the finder objective lens 101 by a predetermined distance L.
The light flux of the subject that has passed 4 and the distance measuring field mask 105 is totally reflected by the reflection mirror 106, passes through the auxiliary objective lens 107, is reflected by the half mirror 102, and is reflected by the eyepiece lens 103.
Pass through and be guided by the eyes. With such a configuration, the image is doubled through the finder according to the principle of triangulation, which will be described later, so that the distance can be obtained by the degree of coincidence of the images.

FIG. 5 is a diagram showing the principle of triangulation used in an autofocus unit. In the figure, the light flux from the subject 110 placed at a distance X has a light receiving lens 111, 1 having an optical axis separated by a base line length Saf.
The light is received at 12, and an image is formed on the photoelectric conversion sensors 113 and 114 placed at the position of the focal length faf.

At this time, if the images formed on the sensor are formed at positions shifted by Z / 2 pixels from the optical axes of the light receiving lenses 111 and 112, the sensor pitch is P, and the distance X to the object is , X = (faf × Saf) / (Z × P) (1)

In recent years, the autofocus unit has been reduced in price, downsized, and improved in performance, so that it can be easily incorporated into a camera. Further, in order to simplify and downsize the camera operation, the above range finder is used. The number of manual focus adjustments is decreasing. However, the products that are commercialized by the user orientation tend to be divided into a dedicated machine equipped with an auto focus unit and a dedicated manual focus machine equipped with a range finder.

[0007]

However, it is difficult for the dedicated machine equipped with the conventional autofocus unit to utilize various intentions of the photographer for the distance measurement. That is, it cannot be close to manual operation. In addition, even if manual operation is possible, in practice, it is a reliable means to use the electric distance measurement information to judge whether or not the focus is accurately achieved. Confirmation is insufficient.

Therefore, if there is a finder device having both the auto focus unit and the range finder, the above-mentioned problems can be solved. However, if the range finder as shown in FIG. 4 and the auto focus unit as shown in FIG. 5 are combined to form a finder device, the finder device becomes large. Further, since the distance measuring system is provided separately, parallax occurs in the distance measuring system of the range finder and the auto focus unit.

Therefore, the present invention has been made to solve the above problems, and even if the range finder and the auto focus unit are provided in the same device, parallax does not occur in both distance measuring systems. It is an object of the present invention to provide a finder device that does not increase in size itself.

[0010]

In order to achieve the above object, the finder device of the present invention is a first finder for guiding a first image, which is almost equivalent to a subject appearing on a film, to a finder field.
An optical unit, a second optical unit disposed at a position separated from the first optical unit by a first predetermined distance and for guiding a second image for distance measurement to the viewfinder field, the first image and the second image. Image combining means for combining the images as a double image, and a second predetermined distance on both sides of the first optical means along a direction connecting the optical axes of the first optical means and the second optical means. It is characterized in that it is provided with third optical means composed of a pair of symmetrically arranged optical systems, and photoelectric conversion means for receiving and photoelectrically converting the light beams guided by the third optical means.

Furthermore, the finder device of the present invention is
An optical path of the third optical means is bent at least once in an optical axis direction of the first optical means and the second optical means and a direction orthogonal to a direction connecting the optical axes of the first and second optical means.

Furthermore, the finder device of the present invention is
The finder optical system including the first optical unit and the second optical unit has a baseline length set to be longer than half the baseline length of the pair of optical systems of the third optical unit. To do.

That is, in the viewfinder device of the present invention, the first image which is almost equivalent to the subject on the film is the first image.
The optical means guides the second image for distance measurement to the viewfinder field by the second optical means arranged at a position separated from the first optical means by the first predetermined distance. Then, the first image and the second image are combined as a double image by the image combining means, and distance measurement is performed from the degree of coincidence. Further, a third optical system including a pair of optical systems symmetrically arranged at a second predetermined distance on both sides of the first optical unit along a direction connecting the optical axes of the first optical unit and the second optical unit. The light beams guided by the means are received by the photoelectric conversion means and are photoelectrically converted, and distance measurement is performed from the amount of deviation of the images.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. First, the finder device according to the first embodiment of the present invention will be described. In the first embodiment, an Albada type optical system is used.
In this albada type, the lens on the most object side among the objective lenses, that is, the lens size of the first surface is large, but an optical system for inverting the image is not necessary and can be configured relatively easily. . 1A and 1B are views showing the configuration of the finder device according to the first embodiment, wherein FIG. 1A is a bottom view and FIG. 1B is a front view.

The range finder in this finder device has a light receiving lens 10, a half mirror 12, and an eyepiece lens 1 on the optical axis of the finder from the side receiving the light flux of the object.
4 are arranged in this order, and the objective lens 16 and the distance measuring field stop 18 are arranged at a position separated from the finder optical axis by the base line length L.
Is arranged. These objective lens 16 and distance measuring field stop 1
A total reflection mirror 20 whose reflection angle can be changed is arranged on the eyepiece lens 14 side on the optical axis of 8, and an auxiliary objective lens 22 is arranged between the total reflection mirror 20 and the half mirror 12.

Further, in the autofocus unit in this finder device, the pair of autofocus light-receiving lenses 24 and 26 are arranged so as to be orthogonal to the finder optical axis and symmetrical about both sides with respect to the finder optical axis.
These are the autofocus light-receiving lenses 2 arranged at af
Prisms 28 and 30 are arranged on the optical axis sides of the eyepiece lenses 4 and 26, respectively. These prisms 28, 3
A total reflection mirror 32 is arranged between 0, and a sensor 34 is arranged below the total reflection mirror 32 with respect to the front surface of the finder device.

In the range finder of the finder device constructed as described above, the light beam on the shift side of the double image passes through the objective lens 16 and the distance measuring field stop 18, and is reflected by the total reflection mirror 20. The light passes through the auxiliary objective lens 22, is reflected by the half mirror 12, and is guided to the eye through the eyepiece lens 14.

The total reflection mirror 20 is driven in the rotational direction in conjunction with the extension of a photographic lens (not shown), and reflects an image received at a position having a parallax of the finder optical axis and the base line length L to the half mirror 12. . Therefore, the observer performs distance measurement by viewing the double image of the subject through the eyepiece lens 14 at a position corresponding to the distance measurement range.

The autofocus unit of this finder device measures the distance by a so-called phase difference method called a passive type. In this autofocus unit, the baseline length Sa is sandwiched across the finder optical axis.
A pair of autofocus light receiving lenses 24 and 26 arranged at positions separated by f receive the light flux from the subject. Subsequently, the respective luminous fluxes are directed to the lower side of the apparatus by the prisms 28 and 30 in the direction orthogonal to the direction connecting the optical axes of the autofocus light receiving lenses 24 and 26, that is, the lower side of the apparatus orthogonal to the finder optical axis (see FIG. It is bent to the lower side in b), and further to the device center side orthogonal to the finder optical axis, and reaches the prism 32.

The light flux reaching the prism 32 is reflected by the prism 32 toward the lower side of the device orthogonal to the optical axis of the finder, that is, the lower side in FIG. 2B, and the light receiving surface formed on the sensor 34. Be led to. Then, the finder device measures the distance by the light flux guided onto the sensor 34.

Since the distance measuring sensor 34 is arranged in the lower portion of the finder device as described above, the range finder and the auto focus unit are not increased without increasing the thickness of the finder device in the finder optical axis direction more than necessary. Can be configured in the same device.

FIG. 2 is a view showing the fields of view of the two distance measuring systems of the range finder and the autofocus unit in the finder device of the first embodiment. In the figure, the range finding system of the range finder performs trigonometric range finding using the total reflection mirror 42 with the optical axis connecting the subject 40 and the half mirror 41 as a reference.

On the other hand, the distance measuring system of the autofocus unit comprises a subject 40 and a light receiving sensor 43 for autofocus.
Triangular distance measurement is performed using 44. In the distance measuring system of the autofocus unit, the reference optical axis is the center of the autofocus base line length, that is, the optical axis connecting the subject 40 and the half mirror 41, and the reference optical axis in the rangefinder distance measuring system. Match the axis.

Therefore, according to the first embodiment, parallax does not occur between the range finder and the autofocus unit. By the way, since the accuracy of the distance measuring system of the autofocus unit is proportional to the product of the base line length Saf and the focal length, when the distance measuring accuracy is kept constant, it is necessary to lengthen the focal length when the base line length Saf is short. is there. At this time, the brightness of the light receiving surface on the sensor 34 is determined by the F numbers of the autofocus light receiving lenses 24 and 26. Therefore, in the case of the above condition in which the focal length needs to be long, it is necessary to make the apertures of the autofocus light receiving lenses 24 and 26 large, and there is a limit in shortening the base line length Saf in relation to accuracy. Become.

In the case of the first embodiment, the diameters of the autofocus light receiving lenses 24, 26 are set at the positions where the autofocus light receiving lenses 24, 26 are arranged on both sides of the light receiving lens 10 on the first surface of the finder device. The size of the light receiving lens 10 is substantially the same as the size of the light receiving lens 10 in the short piece direction (radius).

Now, the ranging accuracy of the range finder and the autofocus unit will be described. If the focal length of the taking lens (not shown) is fTL, the distance between the subject and the taking lens principal point is X, the F number of the taking lens is F, and the film surface confusion circle diameter is d, the depth of field of the taking lens is Depth of field = − (F × d × X ² ) / fTL ² (2)

On the other hand, according to the principle of range finding of the range finder, the condition that the range finding error of the range finder is smaller than the depth of field is that the range finder base line length is L, the magnification is M, and the eye resolution is γ. Then, it is necessary to satisfy the relationship of F> (fTL ² × γ) / (L × M × d) (3).

Similarly, according to the principle of distance measurement of the autofocus unit, the condition that the distance measurement error of the autofocus unit is smaller than the depth of field is that the sensor pitch of the autofocus unit is P and the baseline length of the autofocus unit is. Saf, the focal length of the autofocus light receiving lens is faf, and the interpolation capability during autofocus detection processing is h (<1), F> (fTL ² × P × h) / (d × Saf × faf) (4) ) Must be met.

If the distance detection capability of the autofocus device is greater than the range detection capability of the range finder,
As a result of driving the taking lens according to the distance measurement detection result of the autofocus device, the problem that the image in the range finder is displaced does not occur. The conditions at this time are (3) above.
From the formula and the formula (4), γ / (L × M) ≧ (P × h) / (Saf × faf) (5) Therefore, by setting each dimension in the first embodiment to a value that satisfies the above expression (5), even if the distance is measured by the autofocus device and the photographing lens is driven to adjust the focus, It is possible to prevent such a defect that the image of the image is displaced.

Next, a finder device according to a second embodiment of the present invention will be described. 3A and 3B are views showing the configuration of the finder device according to the second embodiment, wherein FIG. 3A is a bottom view and FIG. 3B is a front view.

Regarding the configuration of the second embodiment,
Only the autofocus unit is different, and the other structures such as the structure of the range finder are the same as those of the first embodiment, and therefore the description thereof will be omitted here.

As shown in the figure, the autofocus unit in this finder device is integrally constructed as one unit and performs distance measurement by a so-called phase difference method called a passive type.

In this autofocus unit, a pair of autofocus light-receiving lenses 5 arranged at positions separated by the base line length Saf with the finder optical axis interposed therebetween.
The light flux from the subject is received at 0 and 52. Subsequently, the respective light fluxes are directed to the lower side of the apparatus by the prisms 54 and 56 in the direction orthogonal to the direction connecting the optical axes of the autofocus light-receiving lenses 50 and 52, that is, the lower side of the apparatus orthogonal to the optical axis of the finder (see FIG. bent downward in b)),
Further, it is bent toward the center of the apparatus orthogonal to the finder optical axis, further bent toward the light receiving lens 10 side in parallel with the finder optical axis, and guided to the light receiving surface formed on the sensor 58. Then, the finder device measures the distance by the light flux guided to the sensor 58.

Therefore, in the second embodiment, the distance measuring system unit for autofocus can be made thin, and the finder device itself can be made compact.

As described above, according to the above embodiment, it is possible to provide a small and compact finder device in which the range finder and the autofocus unit are efficiently arranged. Also, by arranging the optical system of the autofocus unit symmetrically on both sides of the finder optical axis that is the reference of the range finder,
The parallax of the ranging system of both the range finder and the auto focus unit can be virtually eliminated.

Further, of the two distance measuring systems of the range finder and the auto focus unit, the optical path of the distance measuring system of the auto focus unit is orthogonal to the optical axis direction of the optical system of the range finder and the direction connecting both optical axes. Since the two distance measuring systems can be arranged without interfering with each other's optical path by being configured to be bent at least once in the direction, an efficient viewfinder in which visual distance measurement and electrical distance measurement can be used together A device can be provided.

Furthermore, since the range finding ability of the range finder is designed to be higher than the range finding ability of the auto focus unit, when auto focus is executed, the image in the range finder becomes double due to lack of accuracy. It is possible to eliminate the problem of being visible and provide a comfortable shooting environment.

According to the embodiment of the present invention as described in detail above, the following constitution can be obtained. (1) First optical means for guiding a first image, which is almost equivalent to a subject imaged on the film, to the viewfinder field, and a first predetermined distance apart from the first optical means for distance measurement Second optical means for guiding the second image of the first image to the viewfinder field, image combining means for combining the first image and the second image as a double image, the first optical means and the second optical means. And a light beam guided by the third optical means, the third optical means including a pair of optical systems symmetrically arranged on both sides of the first optical means with a second predetermined distance therebetween along a direction connecting the optical axes of And a photoelectric conversion unit that receives and photoelectrically converts the respective light. (2) The optical path of the third optical means is bent at least once in the optical axis direction of the first optical means and the second optical means and in the direction orthogonal to the direction connecting the optical axes of both. The finder device according to (1) above. (3) The base line length of the finder optical system including the first optical unit and the second optical unit is set to be longer than half the base line length of the pair of optical systems of the third optical unit. The finder device according to (1) above. (4) The finder device according to (1), wherein the photoelectric conversion means is composed of a pair of photoelectric conversion elements. (5) The finder device according to (4), wherein the pair of photoelectric conversion elements are arranged on the same plane. (6) M is the finder magnification in the first optical means, L is the first predetermined distance that is the baseline length of the first optical means and the second optical means, and L is the second predetermined distance that is the baseline length of the third optical means. Let Saf, the focal length of the third optical means be faf, the light receiving sensor pitch of the photoelectric conversion means be P, the interpolation coefficient be K, and the eye resolution be γ: γ / (M × L) ≧ (P × K) / The finder device according to (1) above, which satisfies the condition of (Saf × faf).

[0039]

As described above, according to the present invention, even if the range finder and the autofocus unit are provided in the same device, parallax does not occur in both distance measuring systems, and the device itself is enlarged. It is possible to provide a finder device that does not do so.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a finder device according to a first embodiment.

FIG. 2 is a diagram showing fields of view of two distance measuring systems of a range finder and an auto focus unit in the finder device of the first embodiment.

FIG. 3 is a diagram showing a configuration of a finder device according to a second embodiment.

FIG. 4 is a diagram showing a configuration of a conventional range finder.

FIG. 5 is a diagram for explaining the principle of triangulation used in an autofocus unit.

[Explanation of symbols]

10 ... Light receiving lens 10, 12 ... Half mirror, 14 ... Eyepiece lens, 16 ... Objective lens, 18 ... Distance measuring field stop, 2
0 ... Total reflection mirror, 22 ... Auxiliary objective lens, 24, 26
... auto-focus receiving lens, 28, 30 ... prism, 32 ... total reflection mirror, 34 ... sensor, 40 ... subject, 41 ... half mirror, 42 ... total reflection mirror, 43,
44 ... Light receiving sensor, 50, 52 ... Autofocus light receiving lens, 54, 56 ... Prism, 58 ... Sensor.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kiyoshi Tosaka 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside Olympus Optical Co., Ltd. (72) Yoshie Kobayashi 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd.

Claims (3)

[Claims] 1. A first device which is almost equivalent to a subject on a film.
First optical means for guiding an image to the viewfinder field, and second optical means arranged at a position separated from the first optical means by a first predetermined distance for guiding a second image for distance measurement to the viewfinder field. Means, an image synthesizing means for synthesizing the first image and the second image as a double image, and the first optical means along a direction connecting the optical axes of the first optical means and the second optical means. A third optical means composed of a pair of optical systems symmetrically arranged on both sides of the second predetermined distance, and photoelectric conversion means for receiving and photoelectrically converting the light beams guided by the third optical means. A finder device provided with. 2. The optical path of the third optical means is bent at least once in the optical axis direction of the first optical means and the second optical means and in the direction orthogonal to the direction connecting the optical axes of the first and second optical means. The finder device according to claim 1. 3. A finder optical system consisting of the first optical means and the second optical means is set to have a baseline length longer than half the baseline length of the pair of optical systems of the third optical means. The finder device according to claim 1, wherein: