JP2003131123A - Af surveying instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an AF surveying instrument capable of satisfactorily securing the light quantity required for a collimation optical system, and having a bright viewing field at a surveying operation, and through which an object can be easily observed. SOLUTION: As for the AF surveying instrument provided with a collimation telescope 10 equipped with an objective lens 11, an AF detection unit 50 for detecting the focal state of the collimation telescope 10 and a control circuit 40, the machine is provided with a movable branching mirror assembly 101 which is supported so as to be moved to a branching position for guiding the AF luminous flux constituted of a part of the luminous flux transmitted through the objective lens 11 to the AF detection unit 50 and a retreat position where the assembly 101 does not interfere with the luminous flux transmitted through the objective lens 11, and the movable branching mirror assembly 101 is held in the branching position by the control circuit 40 at the AF operation time, and the assembly 101 is held in the retreat position at the time other than the AF operation time.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a surveying instrument having an AF function.

[0002]

2. Description of the Related Art The collimation telescope in surveying instruments such as total stations is being made into AF.
A phase-difference AF device (focus detection means) that is widely used as an AF device includes a pair of images formed by light beams passing through a pair of different pupil ranges set on an objective lens of a collimation telescope. The focus position is detected from the correlation (phase difference), and the collimation telescope is focused based on the detection result.

Generally, in an AF surveying instrument having a collimating telescope, a Porro prism is generally used as an erecting optical system for converting an inverted image formed by an objective lens into an erecting image. Is divided into the AF device direction and the eyepiece lens direction. In such a configuration in which the light flux from the objective lens is split, the amount of light incident on the eyepiece lens is reduced by the amount of light emitted toward the AF device, which causes a problem that the visual field becomes dark during observation. Especially at dusk,
It was difficult to collimate when the surroundings of the measurement object were dark.

[0004]

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide an AF surveying instrument which can secure a sufficient amount of light to the collimating optical system and which makes it easy to observe a bright visual field during a surveying operation.

[0005]

SUMMARY OF THE INVENTION An AF surveying instrument of the present invention transmits a collimation telescope for collimating an object to be measured, focus detection means for detecting a focus state of the collimation telescope, and an objective lens of the collimation telescope. A branching optical system that is movable to a branching position that guides the AF light flux, which is a part of the light flux, to the focus detection means, and a retracted position that does not interfere with the light flux that has passed through the objective lens, and the focus detection means in the operating state. A control means for holding the branching optical system at the branching position and for holding the branching optical system at the retracted position when in a non-operating state is provided.

According to the above arrangement, since the AF light flux is branched to the focus detecting means only when the focus detecting means is operating, it is possible to secure a sufficient amount of light incident on the eyepiece lens, and to perform a surveying operation. Sometimes it is possible to observe brightly through the eyepiece.

It is preferable that the branching optical system has a reflecting mirror which is located on the optical axis of the objective lens at the branching position and retracts from the optical path of the light beam transmitted through the objective lens at the retracted position. With this configuration, all the incident AF light fluxes can be guided to the focus detection unit at the branch position. Further, the size of the reflection mirror may be set to such a size that all of the AF light flux enters the focus detection means at the branch position.

Further, the branching optical system is configured to move to the branching position and the retracted position by a rotational movement about an axis located outside the optical axis of the objective lens, or
The objective lens may be configured to move to the branch position and the retracted position by a reciprocating linear motion in a direction orthogonal to the optical axis.

When the AF surveying instrument has an erecting optical system for forming an erecting image of an object image by the objective lens of the collimating telescope, if the branch optical system is arranged above the erecting optical system, This is preferable because the empty space around the upright optical system can be effectively used. In this case, the branching optical system positions the reflecting mirror in front of the entrance surface of the erecting optical system at the branching position and retracts the reflecting mirror from the front of the entrance surface of the erecting optical system in the retracted position.

[0010]

1 to 6 show a first embodiment of an AF surveying instrument according to the present invention. The collimating telescope 10 is, as shown in FIG. 1, sequentially from the object side (front),
Objective lens 11, focus adjustment lens 18, Porro prism (upright optical system) 12, focusing screen 13, and eyepiece lens 14.
Is equipped with. At the center of the focusing screen 13, a cross hairline (collimation line) 15 that serves as a mark for collimation is drawn. The focus adjustment lens 18 is movable in the optical axis direction, and the position thereof is adjusted according to the distance of the measurement object 16 so that the image is correctly formed on the surface of the focusing screen 13 on the objective lens 11 side. The observer magnifies and observes the image on the focusing screen 13 through the eyepiece lens 14.

Behind the objective lens 11 of the collimation telescope 10, a transmitting / receiving mirror 21 which is a constituent element of the optical distance meter 20.
And the wavelength selection filter 22 that reflects the distance measuring light and transmits the visible light are sequentially arranged. The light transmitting / receiving mirror 21 is a parallel plane mirror positioned on the optical axis of the objective lens 11, and the surface on the objective lens 11 side constitutes the light transmitting mirror 21a and the surface on the wavelength selection filter 22 side constitutes the light receiving mirror 21b. There is.

Light emitting device (LD) 23 of lightwave rangefinder 20
Emits distance measuring light of a specific wavelength, and this distance measuring light enters the light transmitting mirror 21a via the collimator lens 24 and the fixed mirror 25. The distance measuring light that has entered the light transmitting mirror 21 a travels on the optical axis of the objective lens 11.

The wavelength selection filter 22 is used for the measurement object 16
The distance-measuring light reflected by the objective lens 11 is further reflected and returned to the light-receiving mirror 21b.
1b shows the reflected light from the incident end face 26 of the light receiving fiber 26.
It is incident on a. Reference numeral 27 denotes a holder for holding the light receiving fiber 26, which is fixed to the space behind the objective lens 11 together with the light transmitting / receiving mirror 21 by a fixing means (not shown).

On the distance measuring optical path between the light emitting element 23 and the fixed mirror 25, the switching mirror 28 and the ND filter 29 for light transmission are provided.
Are arranged. The switching mirror 28 switches the distance measuring light from the light emitting element 23 to the fixed mirror 25 or directly to the incident end face 26a of the light receiving fiber 26. The light-transmitting ND filter 29 is for adjusting the amount of distance-measuring light projected on the measurement object 16.

A condenser lens 32, a light receiving ND filter 33, and a bandpass filter 34 are arranged in this order between the light emitting element 26 and the emitting end face 26b of the light receiving fiber 26. The light receiving element 31 is connected to the control circuit 40 and outputs a photocurrent corresponding to the amount of received light. Control circuit 4
In addition to the light receiving element 31, an actuator 41 of the switching mirror 28 and a display 42 are connected to 0.

As is well known, the above-mentioned optical distance meter 20 is
The control circuit 40 drives the switching mirror 28 via the actuator 41 to apply the distance measuring light from the light emitting element 23 to the fixed mirror 25 and the incident end face 26 of the light receiving fiber 26.
and the state of being directly given to a. As described above, the distance measuring light applied to the fixed mirror 25 is projected onto the measuring object 16 via the light transmitting mirror 21a and the objective lens 11, and the reflected light is reflected by the objective lens 11, the wavelength selection filter 22, and the wavelength selecting filter 22. The light is incident on the incident end surface 26a of the light receiving fiber 26 via the light receiving mirror 21b. Then, the distance measuring light reflected by the measurement object 16 and incident on the incident end face 26a, and the switching mirror 2
The internal reference light directly given to the incident end face 26a via 8 is received by the light receiving element 31, and the control circuit 40 measures the phase difference between the transmitted light and the reflected light and the initial phase of the internal reference light, or measures the transmitted light. The time difference between the distance light and the reflected light is detected, and the measuring object 1
The distance up to 6 is calculated and displayed on the display 42. A distance measuring operation based on a phase difference or a time difference between the distance measuring light and the internal reference light is well known.

The control circuit 40 further includes a lens drive mechanism 43 for moving the focus adjustment lens 18, an AF start switch 44, a distance measurement start switch 45, and an AF detection unit 5.
0 is connected.

The AF detection unit 50 detects the focus state of the focus detection surface 51 which is optically equivalent to the focusing screen 13, that is, the defocus amount of the front focus, the rear focus, etc.
FIG. 2 shows its conceptual diagram. An object image formed by the objective lens 11 on the focus detection surface 51 is divided by a condenser lens 52 and a pair of separator lenses (imaging lenses) 53 arranged apart from each other by a base line length, and the divided pair of images is formed. Are re-imaged on the pair of CCD line sensors 54. The line sensor 54 has a large number of photoelectric conversion elements, and each photoelectric conversion element photoelectrically converts the received object image to integrate (accumulate) the photoelectrically converted charges, and the integrated charges are used as AF sensor data in the control circuit 40. Output to. The control circuit 40 performs a predetermined defocus calculation based on the pair of AF sensor data, and operates the lens driving unit 43 based on the calculated defocus amount to move the focus adjustment lens 18 to the in-focus position. Such defocus calculation is well known to those skilled in the art.

Considering the pair of images formed on each line sensor 54 as a reference, the AF detection unit 50 has a pair of different pupil ranges 11A and 11B on the objective lens 11.
The focus position is detected by the pair of images formed on the line sensor 54 by the light flux that has passed through. Pupil range 1
The shape of the pupil range of 1A and 11B depends on each separator lens 5
3 can be set by the masks 55 arranged in the vicinity of 3, respectively. The hatching in FIGS. 1 to 3 conceptually shows a portion (optical path) corresponding to the pair of pupil ranges 11A and 11B.

FIG. 3 shows this pupil range 1 on the objective lens 11.
The positional relationship between 1A and 11B and the positional relationship between the light transmitting / receiving mirror 21 of the lightwave distance meter 20 and the light receiving fiber 26 (holder 27) are shown. The positions, shapes, and directions of the pupil ranges 11A and 11B are determined by the condenser lens 52 of the AF detection unit 50, the separator lens 53, the mask 55, and a large number of photoelectric conversion elements of the line sensor 54 so as to satisfy the AF performance. ing.

The collimating telescope 10 described above includes the objective lens 1
A movable branch mirror assembly 101 having a reflection mirror 101a is provided as a branch optical system that guides the light flux from the first detection unit 50 to the AF detection unit 50. The movable branch mirror assembly 101 is rotated about an axis located outside the optical axis of the objective lens 11 to cause the objective lens 11 to move.
Of the objective lens 11 and the retracted position retracted to the outside of the optical axis of the objective lens 11.
It is held at the retracted position (except during the F operation) and is moved to the branch position during the AF operation. In FIG. 1, a state in which the movable branch mirror assembly 101 is in the branch position is indicated by a solid line, and a state in which the movable branch mirror assembly 101 is in the retracted position is indicated by a broken line.

With the movable branch mirror assembly 101 in the branch position, among the light fluxes from the objective lens 11, the light fluxes (AF) that have passed through the pupil ranges 11A and 11B in FIG.
The light flux) is reflected by the reflection mirror 101a and is guided to the AF detection unit 50 arranged on the reflection optical path. Of the light fluxes from the objective lens 11, the light fluxes other than the AF light flux (light fluxes not incident on the reflection mirror 101a) are incident on the Porro prism 12, and the Porro prism 12
It is reflected by the reflection surface of and is guided to the focusing screen 13. Further, when the movable branch mirror assembly 101 is in the retracted position, all of the light flux from the objective lens 11 is reflected.
01a without interference with Porro prism 12
Is reflected on the reflecting surface of the Porro prism 12, and is guided to the focusing screen 13.

The reflection mirror 101a is made of a material having a high reflectance, such as glass or metal. Further, the size (area) of the reflection mirror 101a is such that, at the branch position, at least all the AF light fluxes that have passed through the pupil ranges 11A and 11B in FIG. 3 can be incident on the AF detection unit 50.

4 to 6 show a movable branch mirror assembly 101 and its driving mechanism. The movable branch mirror assembly 101 and its drive mechanism are arranged above the Porro prism 12 in FIG. 4 so that the empty space around the Porro prism 12 (see FIG. 1) can be effectively utilized. The movable branch mirror assembly 101 is
It is rotatably supported by a prism frame 103 holding a Porro prism 12. The prism frame 103 has a circular shape centered on the optical axis.

The movable branch mirror assembly 101 is a mirror fixing arm 10 to which the above-mentioned reflection mirror 101a is fixed.
1b and arm portions 101c on both sides orthogonal to the mirror fixing arm 101b. The end portion of the arm portion 101c has an axial pin 102 located outside the optical axis of the objective lens 11.
It is rotatably supported on both sides of the prism frame 103 via the, and the reflection mirror 101a is rotatable between a branch position located on the optical axis and a retracted position located outside the optical axis. That is, the reflection mirror 101a is located in front of the entrance surface of the Porro prism 12 at the branching position and above the Porro prism 12 retracted from the front of the entrance surface in the retracted position.

A pin 104 movably fitted in a cam groove 105a of a cam plate 105 is fixed to one arm portion 101c of the movable branch mirror assembly 101, and the cam plate 1
As shown in FIGS. 5 and 6, 05 is slidably fitted in the sliding groove 106a of the mirror frame 106. The mirror frame 106 is fixed to the prism frame 103. In addition, the pin 1 that penetrates the elongated hole 106b of the mirror frame 106 and fits into the cam groove 108a of the cam ring 108 on the cam plate 105.
07 is fixed, and the cam ring 108 is rotated by the motor 109.

When the cam ring 108 is rotated by the motor 109, the cam plate 105 moves along the sliding groove 106a of the mirror frame 106 via the pin 107. Then, the pin 104 interlocks with the movement of the cam plate 105.
The arm portion 101c of the movable branching mirror assembly 101 rotates about the shaft pin 102 as a center. Thereby, the reflection mirror 101a can move between the branch position and the retracted position. In the present embodiment, the rotation direction of the motor 109 that moves the movable branch mirror assembly 101 to the branch position is forward rotation, and the rotation direction of the motor 109 that moves the movable branch mirror assembly 101 to the retracted position is reverse rotation. The drive of the motor 109 is controlled by the control circuit 40.

The AF surveying instrument having the above construction is used as follows. First, the measuring object 16 is looked through a collimator (not shown) attached to the collimating telescope 10, and the optical axis of the collimating telescope 10 is approximately aligned with the measuring object 16. Next, the AF start switch 44 is turned on. Then, the control circuit 40 causes the motor 10
9 is normally rotated to move the movable branch mirror assembly 101 to the branch position to execute the AF operation described above. When the AF operation is completed, the motor 109 is rotated in the reverse direction to return the movable branch mirror assembly 101 to the retracted position. Indicator 4
2 is displayed to indicate that it is in focus. Subsequently, with the in-focus display being displayed on the display 42, the eyepiece lens 14
, And the cross hairline 15 of the focusing screen 13 is accurately aligned with the measuring object 16. Then, the distance measurement start switch 45 is turned on. Then, the control circuit 40 causes the lightwave rangefinder 2
The distance measurement operation described above is executed by 0, and the distance measurement result is displayed on the display 42.

In the above-described operation of the AF surveying instrument, the luminous flux from the objective lens 11 (AF luminous flux) is branched to the AF detection unit 50 only during the AF operation. It is possible to obtain a sufficient amount, and it is possible to observe brightly through the eyepiece lens 14 during the surveying operation.

FIGS. 7 to 10 show another embodiment of the movable branch mirror assembly, which is on the optical axis of the objective lens 11 and in front of the entrance surface of the Porro prism 12 due to the linear movement orthogonal to the optical axis of the objective lens 11. At the branch position (FIG. 7) located outside the optical axis of the objective lens 11 and the mirror frame 2
The movable branch mirror assembly 201 and its drive mechanism that can be moved to a retracted position (not shown) housed in 03 are shown. The movable branch mirror assembly 201 and its driving mechanism described below are arranged above the Porro prism 12 in FIG. 7 so that the empty space around the Porro prism 12 can be effectively used.

The movable branch mirror assembly 201 has a reflection mirror 201a and a mirror fixing portion 201b to which the reflection mirror 201a is fixed, and this mirror fixing portion 201b.
Are movably supported by the mirror frame 203 via the balls 202. That is, an accommodation hole 201b1 for accommodating the ball 202 is formed in the mirror fixing portion 201b, and a guide groove 203a for accommodating the ball 202 in a movable state is formed in the mirror frame 203. Ball 2
02 is the leaf spring 2 inserted in the bottom of the accommodation hole 201b1.
It is urged by 04 in the direction to be fitted in the guide groove 203a. Therefore, the mirror fixing portion 201b is movable only in the linear direction orthogonal to the optical axis.

A support pin 205 is fixed to the mirror fixing portion 201b at substantially the center of one end in the longitudinal direction, and the support pin 205 is formed in a cam groove formed on the peripheral surface of the cam ring 206. It is slidably fitted to 206a. The cam ring 206 has a cam ring body portion 206b having the cam groove 206a and a gear portion 206c connected to one end portion of the cam ring body portion 206, and is rotatable with respect to the mirror frame 203 via a pair of pins 207. Supported by. The gear unit 206c has a motor 20 fixed to the mirror frame 203.
The gear 209 driven by 8 is meshed. When the motor 208 reciprocates, the gear 209 and the gear unit 20
The cam ring main body 206b rotates via 6c, and the supporting pin 205 is pressed by this rotational force, and the mirror fixing portion 2
01b reciprocates linearly. Thereby, the reflection mirror 2
01a can move between the branch position and the retracted position. The motor 208 is the same as in the first embodiment.
The drive is controlled by the control circuit 40.

In this embodiment, the movable branch mirror assembly 201 can be moved to the branch position and the retracted position by the linear movement of the objective lens 11 in the direction orthogonal to the optical axis. Therefore, as in the first embodiment, a sufficient amount of light incident on the eyepiece lens 11 can be obtained, and bright observation can be performed through the eyepiece lens 14 during the surveying operation. Further, in this configuration, there is an advantage that the vibration when the movable branch mirror assembly 201 is stopped has little influence on the change in the imaging position of the AF detection unit 50.

In each of the above embodiments, the movable branch mirror assembly 101 (201) is held at the branch position where the light beam from the objective lens 11 is branched to the AF detection unit 50 during the AF operation, and the objective is kept except during the AF operation. Since the light flux from the lens 11 is held at the retracted position where it does not interfere, performance of the collimation telescope 10 such as brightness and resolving power does not deteriorate during the surveying operation, and accurate surveying work can be performed. Further, in this embodiment, the movable branch mirror assembly 101 (2
01) is in the branch position, all the light beams from the objective lens 11 other than the AF light beams that have passed through the pupil ranges 11A and 11B are incident on the eyepiece lens 14, so that the object to be measured from the eyepiece lens 14 also during the AF operation. It is possible to observe the object 16.

Further, in this embodiment, the reflection mirror 101a.
Since (201a) is made movable, the reflection mirror 101a
The reflectance of (201a) can be made high (about 100%). Thereby, the pair of pupil ranges 11A and 11A
All the AF luminous fluxes that have passed through B are detected by the AF detection unit 50.
Is guided to the above-mentioned AF by the semi-transmissive surface of the branch optical system.
The pair of pupil ranges can be set smaller than in the conventional case in which the use light beam is branched. In other words, the size of the reflecting mirror can be reduced according to the pair of pupil ranges, and the collimating telescope 10 can be downsized. Further, in the non-prism type AF range finder, it becomes easy to arrange the optical components of the range finder system. Note that, for the purpose of high-speed AF, the pair of pupil ranges 11A and 11B may be set to be slightly wider than that of the present embodiment.

Although the AF detection unit 50 of the phase difference detection method is used in this embodiment, it goes without saying that another AF method such as the contrast method may be used.

The above is the case where the present invention is applied to a surveying instrument having an optical distance meter, but it may be applied to another surveying instrument such as a level (standard).

[0038]

According to the present invention, it is possible to obtain an AF surveying instrument which can secure a sufficient amount of light to the collimating optical system and which is easy to observe with a bright visual field during a surveying operation.

[Brief description of drawings]

FIG. 1 is a system connection diagram showing a first embodiment of an AF surveying instrument according to the present invention.

FIG. 2 is a view taken in the direction of arrow I in FIG. 1, showing focus detection means (AF
It is a conceptual diagram of a detection unit, a phase difference type focus detection means).

FIG. 3 is a diagram showing a positional relationship between a pair of pupil ranges on an objective lens of a focus detection unit and a light-transmitting / receiving mirror and a light-receiving fiber as seen from a line II-II in FIG.

FIG. 4 is a view on arrow III in FIG.

5 is a view on arrow IV in FIG. 4. FIG.

6 is a view on arrow V in FIG.

FIG. 7 is a front view showing another embodiment of the branching mirror assembly.

FIG. 8 is a view on arrow VI in FIG. 7.

9 is a view on arrow VII of FIG. 7. FIG.

FIG. 10 is a view on arrow VIII in FIG. 7.

[Explanation of symbols]

10 Collimation telescope 11 Objective lens 11A 11B pupil range 12 Porro prism (upright optical system) 13 Focus plate 14 eyepiece 15 Cross hairline (collimation line) 16 Object to be measured 18 Focusing lens 20 Lightwave rangefinder 21 Transmit / receive mirror 22 Wavelength selection filter 23 Light emitting element 24 Collimator lens 25 fixed mirror 26 Receiving fiber 27 holder 28 Switching mirror 29 ND filter for light transmission 31 Light receiving element 32 condenser lens 33 ND filter for receiving light 34 bandpass filter 40 control circuit 41 actuator 42 indicator 43 Lens drive mechanism 44 AF start switch 45 Distance measurement start switch 50 AF detection unit (focus detection means) 51 Focus detection surface 52 Condensing lens 53 Separator lens 54 line sensor 55 mask 101 201 Movable branch mirror assembly 101a 201a Reflective mirror 101b Mirror fixed arm 101c arm 102 axis pin 103 Prism frame 104 107 207 pin 105 cam plate 105a cam groove 106 203 Mirror frame 106a sliding groove 106b slot 108 206 Cam ring 108a 206a Cam groove 109 208 Motor 201b Mirror fixed part 202 ball 204 leaf spring 205 Support pin 206b Cam ring body 206c Gear part 209 gears

Claims (6)

[Claims] 1. An AF comprising a collimation telescope for collimating an object to be measured, focus detection means for detecting a focus state of the collimation telescope, and a part of a light beam transmitted through an objective lens of the collimation telescope. A branching position for guiding the light flux to the focus detection means,
A branching optical system that is movable to a retracted position that does not interfere with the light beam that has passed through the objective lens; An AF surveying instrument, comprising: a control unit that holds the system in a retracted position. 2. The AF surveying instrument according to claim 1, wherein the branching optical system is located on the optical axis of the objective lens at the branching position, and retracts from the optical path of the light flux passing through the objective lens at the retracted position. A with a reflective mirror
F surveying instrument. 3. The AF surveying instrument according to claim 1 or 2, wherein the size of the reflecting mirror is such that all of the AF light flux is incident on the focus detecting means at a branch position. 4. The AF surveying instrument according to claim 1, wherein the branching optical system is branched by a rotational movement about an axis located outside the optical axis of the objective lens. AF surveying instrument that moves to the position and the retracted position. 5. The AF surveying instrument according to claim 1, wherein the branching optical system is reciprocated linearly in a direction orthogonal to the optical axis of the objective lens, and the branching position and the retracted position are set. AF surveying instrument moving to. 6. The AF surveying instrument according to claim 2, further comprising an erecting optical system that forms an erecting image of an object image by the objective lens, and the branching optical system comprises the erecting optical system. Is disposed above the optical system, and the reflection mirror is positioned in front of the entrance surface of the erecting optical system at the branch position,
An AF surveying instrument that retracts the reflection mirror from the front of the entrance surface of the erecting optical system at the retracted position.