JPH08146287A - Distance measuring device - Google Patents

Abstract

PURPOSE: To provide a distance measuring device having no parallax between a photographing lens and a distance measuring device and capable of preventing a distance measuring optical path from being intercepted as the photographing lens is operated. CONSTITUTION: This distance measuring device provided for a photographing device is equipped with a distance measuring module 1 arranged out of the area of an effective luminous flux from a subject made incident on the photographing lens having a pair of image detection means, a pair of reflection means 4 which is arranged at a position where the effective luminous flux from the subject made incident on the photographing lens is not disturbed, and is axially symmetric with respect to the optical axis of the photographing lens, and an optical system crossing with a pair of reflection means, arranged on a plane nearly perpendicular to the optical axis of the photographing lens, at least having an optical element 2 arranged at a position where the effective luminous flux from the subject made incident on the photographing lens is not disturbed, and guiding the subject light from a pair of reflection means to a pair of image detection means through the optical element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring device attached to a photographing device for measuring the distance between a subject and the photographing device.

[0002]

2. Description of the Related Art In order to realize an autofocus function in a photographing device, it is widely used to attach a distance measuring device based on the principle of triangulation as a means for measuring the distance between a photographing lens and a subject. . Recently, a general-purpose distance measuring device in which a pair of lenses and a pair of image detectors are modularized and a signal processing circuit is incorporated in the distance measuring device is often used. In this distance measurement module, modularization makes the initial characteristics of the detectors at both ends of the baseline uniform, the temperatures of the detectors at both ends of the baseline become uniform, and the distance is calculated from the detector and control circuit as well as the detection result. Integration of processing circuits, etc. have been realized. Therefore, the distance measuring module having versatility is widely supplied and easily available. Due to the effect of mass production, such a general-purpose distance measuring module is more excellent in stable performance and cost reduction. Therefore, by using the distance measuring module as the distance measuring device, effects such as high performance, small size, homogeneity, and low price can be obtained as compared with those in which the distance measuring device is configured by combining the single parts.

In the actual distance calculation in this distance measuring module, a part of the image is cut out from a pair of image detectors arranged at both ends of the base line, a correlation is calculated for this pair of images, and the cut out part is sequentially shifted. The position of the combination having the highest correlation is obtained, the angle of the measurement object is calculated from both ends of the baseline from this position, and the distance is obtained by the principle of triangulation. At this time, the distance measurement of the object on the center line of the module is performed by always selecting symmetrically the cutout range of the image for which the correlation calculation is performed in the two image detectors.

[0004]

Therefore, the distance measuring device using this distance measuring module has the following drawbacks.

(1) Existence of parallax between photographing lens and distance measuring device FIG. 4 shows a sectional view of a main part of a photographing device incorporating a general distance measuring device. FIG. 4 is a sectional view of the lens shutter camera when viewed from above.

In FIG. 4, reference numeral 1 denotes a distance measuring module, and the ranges of two distance measuring light beams above and below the module are indicated by a chain double-dashed line. Then, the distance between the object and the distance measuring module in the portion common to the range of the two light fluxes for distance measurement shown by the hatched portion in FIG. 4 is measured. On the other hand, the lenses 8 arranged below the distance measuring module form a photographing lens, and the inside of the area of the effective light flux shown between two two-dot chain lines 21 sandwiching the center of the lens is the photographing area.

Although the photographing apparatus having such a structure has a simple structure, a parallax occurs between the photographing lens and the distance measuring device. For this reason, it is effective for lens shutter type still cameras that use a comparatively wide-angle lens, but it is not effective for shooting devices for TV cameras that use shooting lenses with long focal lengths such as telephoto lenses and lenses with a large zoom ratio. This is an inconvenience because it will have to measure objects outside the range.

(2) Enlargement of equipment In order to solve the above-mentioned drawbacks, as shown in FIG. 5, mirrors are arranged at symmetrical positions with respect to the optical axis of the taking lens so that they are located at the rear of the image plane of the taking apparatus. A structure in which a light beam from a subject is guided to a distance measuring module arranged on the optical axis of a photographing lens is disclosed in JP-A-60-125812, FIG.
9 can be easily thought of. However,
In the image capturing apparatus having the above configuration, the apparatus becomes large as can be seen from FIG.

(3) Obstruction of distance measurement by operation of the photographing lens When the photographer operates the focus ring 14 of the photographing lens, the hand cuts off the light beam for distance measurement, and the photograph is taken during photographing. This is particularly inconvenient for a television camera image capturing device that often operates a lens.

[0010]

According to a first aspect of the present invention, there is provided a distance measuring device provided for a photographing device, comprising a pair of image detecting means. Distance measuring module disposed outside the effective light flux area from the subject incident on the photographing lens, and an axis with respect to the optical axis of the photographing lens disposed at a position that does not interfere with the effective light flux from the subject incident on the photographing lens. A pair of symmetrical reflecting means and a pair of reflecting means are arranged in a plane that intersects with the pair of reflecting means and is substantially perpendicular to the optical axis of the photographing lens, and at a position that does not interfere with the effective light flux from the subject incident on the photographing lens. And an optical system for guiding each subject light from the pair of reflecting means to the pair of image detecting means via the optical element.

The distance measuring device having the above structure has the following functions.

(1) There is no parallax between the taking lens and the distance measuring device.

(2) Since the distance measuring device can be arranged on the front surface of the lens, the distance measuring optical path is not interrupted by the operation of the taking lens.

Therefore, the following effects are obtained.

(1) Even when a lens having a long focal length is used, the distance measuring range is within the photographing range.

(2) The lens can be operated during the distance measurement.

According to a second aspect of the present invention, as described in claim 2, in claim 1, the distance measuring device is integrated with a detachable accessory on the front surface of the taking lens. .

The distance measuring device having the above structure has the following functions.

(1) It is possible to realize a photographing device with a distance measuring device which is approximately the same size as a photographing device equipped with an accessory without a conventional distance measuring device.

(2) The distance measuring device can be attached to and detached from the photographing device together with the accessory which can be attached to and detached from the front surface of the photographing lens.

Therefore, it is possible to reduce the size of the device and attach or detach the distance measuring device depending on whether the distance measuring device is necessary or unnecessary.

According to a third invention of the present application, as described in claim 3, in claim 1 or 2, the pair of reflecting means or the optical path forming member such as an optical element has a photographing lens viewed from the front. In this state, it is arranged at a position overlapping the photographing lens.

With the above-mentioned structure, each member of the distance measuring device can be arranged near the effective light flux of the photographing lens, and the size of the device can be reduced.

According to a fourth invention of the present application, as described in claim 4, in claim 1, 2 or 3, the distance measuring module uses a correlation operation to calculate an image shift amount of the pair of image detecting means. The feature is that the distance is obtained by the triangulation method.

With this configuration, there is an effect that a highly accurate, compact, lightweight and inexpensive distance measuring module can be realized.

Therefore, there is an effect that the distance measuring device has a large degree of freedom in design, is highly accurate, is small and lightweight, and is inexpensive.

[0027]

【Example】

<First Embodiment> FIG. 1 is a view best showing the features of the present invention, and is a view of a photographing apparatus to which a distance measuring apparatus of the present embodiment is attached, as seen from the subject side.

In FIG. 1, light rays from the subject are left and right 1
The light is reflected by the mirrors 4, 3 and 2 prepared for each pair, and an image is formed on the image detector provided inside the distance measurement module 1 through the lens 1a provided for the distance measurement module 1 as a pair.

The distance measuring module 1 includes a pair of left and right lenses 1a and an image detector, and an electric circuit for processing the images detected by the two image detectors and calculating the distance. Since the angle formed by each image detector and the subject can be calculated from the position of the subject image on the image detector, the line segment connecting the image detectors is used as the base line, and the distance between the subject and distance measurement module The distance can be calculated and this calculation is done in an electrical circuit inside the distance measuring module. Note that the actual distance calculation in this distance measurement module is performed by cutting out a part of the image from a pair of image detectors arranged at both ends of the baseline, obtaining the correlation for this pair of images, and comparing the positions of the highest correlation with the ends of the baseline. The angle of the object to be measured is calculated from, and the distance is obtained by the principle of triangulation. At this time, the distances of the objects on the center line of the module are measured by always selecting symmetrically the two image detectors to select the cut-out range of the image on which the correlation calculation is performed.

FIG. 2 is a cross-sectional view of the photographing device with the distance measuring device of the present invention cut along the optical axis of the photographing lens, and corresponds to a view of FIG. 1 from the right side.

A two-dot chain line 21 in FIG. 2 indicates a range of an effective light beam of the photographing device, that is, an effective light beam, and the effective light beam passes through a range sandwiched between the two two-dot chain lines 21. It can be seen from this figure that the mirror 2 is provided outside this effective ray. Similarly, when viewed from the upper side of FIG. 1 or FIG. 2, the mirrors 3 and 4 are arranged outside the effective luminous flux (not shown). Generally, the image pickup screen is a horizontally long rectangle, and therefore the effective portion of the first surface of the taking lens is also substantially rectangular. Therefore, like the mirror 2 in FIG. Even if the member of the distance measuring device is constructed so as to overlap the photographing lens, it can be prevented from being reflected in the photographing device if it is outside the effective luminous flux of the photographing lens.
By arranging the members in this way, it is possible to further reduce the size.

The distance measuring module 1, the mirror 2,
All 3 and 4 can be fixed inside the lens hood.

Incidentally, the lens hood is a thing attached to a photographing device, which generally has a function of preventing a light beam other than an effective light beam of the photographing device from entering, in particular, a light beam which adversely affects the equipment. Further, the lens hood is often attachable / detachable to / from the photographing device in order to deal with the case where it is unnecessary.

Inside the lens hood 5, a distance measuring module and an electric element attached to the distance measuring module are fixed, and a board 7 which constitutes an electric circuit by ensuring proper conduction between the distance measuring module and each electric element is built in. And processing the measured distance signal.

A contact 12a is connected to the substrate 7, and is connected to a switch 13 and a lens driving motor 15 provided in the photographing device via a contact 12b on the photographing device side. The lens driving motor 15 rotates the feed screw 16 to move the rack 17 meshing with the feed screw in the direction along the optical axis. This allows the rack 17
The lens 22 coupled to the lens moves along the optical axis, and the focus position of the optical system of the photographing apparatus changes. With this configuration, the focus position of the photographing device is automatically adjusted according to the distance to the subject measured by the distance measuring device, and the autofocus function is realized. The switch 13 also controls the functions of the distance measuring device and the photographing device, such as whether or not to perform the distance measurement and the autofocus operation. The focus ring 14 is connected to one or more of the lenses 8 by a mechanism (not shown), and the focus ring 14 is rotated about the optical axis of the taking lens to change the focal position of the taking lens, thereby an object intended for taking a picture. Is for adjusting so that the image of is formed on the CCD element.

On the other hand, the light rays that have passed through the taking lens are distributed by the color separation optical system 9 according to the wavelength, and the CCD element 1
After being converted into an electric signal by 0, it becomes an image signal by the processing circuit 11.

The lens hood 5 and the photographing device are fixed by pressing the contact member 20 against the photographing device with the screw 19 at the fitting portion of the lens hood 5 and the photographing device, and rotating the screw 19. As a result, it is removable. Further, the fitting portion and the contact point 12b on the side of the photographing device are cylindrical with the optical axis of the photographing lens as the center, and the angular relationship between the distance measuring device and the photographing device with the optical axis of the photographing device as the center. It is optional.

In FIGS. 1 and 2, the alternate long and short dash line drawn in the approximate center of the distance measuring light beam indicates the center of the distance measuring light beam when the object to be measured is at infinity.

In this embodiment, the lens hood is given as an example of an accessory that can be attached to and detached from the front surface of the taking lens, but other accessories such as an optical filter and an optical system for camera shake correction may be used. Especially suitable for integrating the lens hood and accessories that have a function of preventing the incidence of light rays other than the effective light rays of the imaging device, which is the function of the lens hood, in particular light rays that adversely affect the equipment, with the distance measuring device. Often shaped.

Further, in this embodiment, the switch 13 is mentioned as an object for controlling the functions of the distance measuring device and the photographing device, but a variable resistor or the like may be suitable in some cases.

The following are examples of the effects unique to this embodiment and the structure that brings them.

(1) The front surface of the taking lens is detachably attached, and the coupling surface of the accessory and the taking device, which has a built-in distance measuring device, has a cylindrical shape about the optical axis of the taking lens.
This configuration has an effect that the angular relationship between the distance measuring device and the photographing lens optical axis of the photographing device becomes free. Therefore, there is an effect that the base line of the distance measuring device can be selected in an optimum direction according to the property of the subject, and highly accurate distance measurement can be performed.

(2) It has a structure in which an accessory having a built-in distance measuring device and a photographing device are attached to the front surface of the photographing lens by a detachable electric contact. This configuration
It has an effect that the mechanical connection and the electrical connection of the distance measuring device and the photographing device are simultaneously performed. Therefore, there is an effect that the connection procedure between the distance measuring device and the photographing device is simplified.

(3) At least one of the hood side and the photographic device side of the accessory which has a distance measuring device detachably attached to the front surface of the photographic lens and the electric contact of the photographic device is centered on the optical axis of the photographic lens. And has a configuration having a shape of a cylinder or a part thereof. This configuration has the effect that the electrical continuity between the contacts is maintained even if the angular relationship between the distance measuring device and the image taking lens optical axis of the image taking device changes. Therefore, there is an effect that the operation of selecting the base line of the distance measuring device in the optimum direction according to the property of the subject is simplified.

(4) The distance measuring module is directly fixed to the substrate. This structure has an effect that the fixing member and the wiring member of the distance measuring module can also serve as the substrate. Therefore, there are effects of downsizing, weight reduction, and cost reduction of the device.

(5) A switch or a variable resistor for controlling the distance measuring module is fixed to the photographing device. This configuration has an effect that the control of the distance measuring module can be performed from the photographing device. For this reason, it is possible to arrange the control means of the distance measuring module in the vicinity of the operation unit such as the focus ring and the zoom ring that the photographer frequently operates, and it is possible to quickly switch between auto focus and manual focus. There is an effect.

<Second Embodiment> FIG. 3 is a view best showing the features of the second embodiment of the present invention. As in FIG. 1, the distance measuring apparatus of the present invention is attached to the photographing apparatus from the object side. It is the figure seen.

In this embodiment, the reflection image of the mirror 4 is changed to the mirror 2
It is intended to lead directly to. This embodiment is the first
Compared with the embodiment described above, the following points are different.

(1) The number of mirrors is small.

(2) The distance measuring light beam intersects the photographing light beam.

(3) The image of the object to be measured formed on the distance measuring module is horizontally reversed as compared with the case where the distance measuring module is used alone.

(4) Corresponding to (3) above, when the distance measuring module is used alone, an object at infinity is located at a position substantially the same as the position where the image of the object at the measurement limit on the near side is formed. The angles of the mirrors 2 and 4 are arranged so that an image is formed.

(5) Corresponding to the above (3), a means (not shown) for performing conversion for exchanging the distance measurement value output from the distance measuring module between the close side and the infinite side by the means of (4). Hold.

The effects unique to this embodiment and the structure which brings them are the following in addition to those common to the first embodiment.

(1) It has a structure with fewer mirrors than the first embodiment, and this structure has the effect of simplifying the optical system. Therefore, there is an effect that a smaller and lighter device can be obtained, and the deterioration of the image due to the mirror is reduced to improve the measurement accuracy.

[0056]

According to the first aspect of the present invention, the distance measuring range is within the photographing range even when a lens having a long focal length is used. Further, the lens can be operated during the distance measurement.

According to the first aspect of the invention, it is possible to reduce the size of the device and attach or detach the distance measuring device depending on whether the distance measuring device is necessary or unnecessary.

According to the third aspect of the present invention, each member of the distance measuring device can be arranged near the effective light flux of the photographing lens, and the size of the device can be reduced.

According to the invention described in claim 4, there is an effect that the distance measuring device has a great degree of freedom in designing, is highly accurate, is small and lightweight, and is inexpensive.

[Brief description of drawings]

FIG. 1 is a front view of a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the essential parts of the first embodiment of the present invention.

FIG. 3 is a front view of the second embodiment of the present invention.

FIG. 4 is a sectional view of a main part of a first conventional example.

FIG. 5 is a sectional view of a main part of a second conventional example.

[Explanation of symbols]

1 ... Distance measuring module 1a ... Lens 1b ... Image detector 2 ... Mirror 3 ... Mirror 4 ... Mirror 5 ... Lens hood 6 ... Photographing lens 7 ... Substrate 8 ... Photographing lens 9 ... Color separation optical system 10 ... CCD 11 ... Processing circuit 12 ... Electrical contact 12a ... Distance measuring device side electrical contact 12b ... Imaging device side electrical contact 13 ... Distance measuring device control switch 14 ... Focus ring 15 ... Motor 16 ... Feed screw 17 ... Rack 18 ... Imaging surface 19 ... Knob 20 ... Pressing bracket 21 ... Outside of luminous flux for photography 22 ... Focus position adjusting lens

Claims (4)

[Claims] 1. A distance measuring device provided for a photographing device, the distance measuring module being arranged outside an effective light flux region from a subject incident on a photographing lens having a pair of image detecting means, and the photographing lens. A pair of reflecting means that is axisymmetric with respect to the optical axis of the taking lens disposed at a position that does not interfere with the effective light flux from the subject that is incident on the object, and that intersects with the pair of reflecting means and that is substantially perpendicular to the optical axis of the taking lens. Each object light from the pair of reflecting means is arranged in a plane and has at least an optical element arranged at a position that does not interfere with an effective light flux from the object incident on the photographing lens. And an optical system that guides each to the pair of image detecting means. 2. The distance measuring device according to claim 1, wherein the distance measuring device is integrated with a detachable accessory on the front surface of the taking lens. 3. The optical path forming member such as a pair of reflecting means or an optical element according to claim 1 or 2, wherein the optical path forming member such as a pair of reflecting means or an optical element is arranged at a position overlapping the taking lens when the taking lens is viewed from the front. Distance measuring device. 4. The distance measuring device according to claim 1, 2 or 3, wherein the distance measuring module obtains the amount of deviation of the images of the pair of image detecting means by a correlation calculation and obtains the distance by a triangulation method. .