JPH08338719A - Survey machine with auto focus function - Google Patents

Abstract

PURPOSE: To provide a survey machine which is hardly affected by disturbance light even if object distance changes during auto-focusing. CONSTITUTION: The survey machine is provided with focused state detection systems 21 and 48 for detecting the focused state of a collimation object B by receiving light from a light path with a line sensor via a branch optical member 18 being provided in the light path between an objective lens 11 and a reticle 14 and a means 9 for driving a focusing adjustment lens 12 in the direction of a light axis. Also, it is provided with a lens position detection means 40 for detecting the position of the focusing adjustment lens driven by the drive means 9 and a control means 47 for changing the usage region of a group of light reception elements of the line sensor according to the lens position of the focusing adjustment lens 12 detected by the lens position detection means 40 and controlling the drive means based on a reception light signal from the group of light reception elements in the changed usage region.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art The auto level basically comprises a collimating telescope and a horizontal compensation optical system. When the collimation telescope is set almost horizontally and the reference position is collimated, even if the optical axis of the collimation telescope is not completely located in the horizontal plane,
The horizontal adaptive optics makes the collimation line horizontal. When the collimation telescope is rotated about a vertical axis orthogonal to the optical axis and another collimation point is collimated, the collimation point is located in the horizontal plane including the reference position.

In such an auto level, a focus adjusting lens is provided for observing a clear object image regardless of the distance of a collimating object such as a surveying staff. That is, the collimating telescope is composed of an objective lens, a focus adjustment lens and an eyepiece lens in this order from the object side.
The position of the object image is adjusted according to the object distance so that the object image is formed on the reticle, and the image on the reticle is observed through the eyepiece lens.

If the object distance range of the collimating telescope is set to 0.2 m to ∞ and the focus adjusting lens is a concave lens, the moving distance of the focus adjusting lens is about 30 mm.
The focus adjustment lens is usually driven by rotating the rotary knob, but if the amount of movement of the object image (that is, the amount of movement of the focus adjustment lens) is set small relative to the rotation angle of the rotation knob, it will be compared to the rotation angle. Although the residence time of the image on the reticle is long, it takes time to move the lens. Conversely, if the amount of movement of the object image is increased relative to the rotation angle of the rotary knob, the image retention time on the reticle will be shorter than the rotation angle, and sometimes the object image will pass the reticle. Take time for. Also, when the object is at a long distance, the focus can be adjusted by simply rotating the rotary knob, but when the object is at a relatively short distance, the object image can be easily obtained by rotating the rotary knob. The phenomenon of not moving up occurs. Further, since it is not possible to determine whether the collimation object is front-focused or rear-focused, the rotary knob may be rotated in the direction opposite to the focusing direction. In any case, the conventional auto level has a problem that it takes a long time to adjust the focus.

Therefore, the applicant of the present invention arranged a branching optical system in the optical path between the objective lens and the reticle by arranging a branching optical element for branching the optical path, and in the branching optical system, a conjugate surface with the reticle was formed. And a focus detection system for detecting the focus state on the conjugate plane, and an output of this focus detection system is used to propose an inner-focus telescope capable of shortening the time required for focus adjustment. (See Jpn. Pat. Appln. No. 6-328786 (unpublished)).

The inner focus telescope proposed by the applicant of the present invention can automatically drive the focusing lens based on the signal from the focus detection system to focus the object.
CC that the focus detection system has as the object distance increases
The ratio of the object to be collimated and the background, which is received by the detection area having a constant width of D, changes. For example, if the object distance becomes long, the ratio of the object to be collimated in the field of view of the telescope becomes small and the ratio of the background becomes large, so that many signals related to the background are detected by the CCD of the focus detection system. Such a situation is not preferable in measuring the object distance by the focus detection system, because the influence of ambient light becomes large.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a surveying instrument which is less likely to be affected by ambient light even when the object distance changes during autofocusing, based on the above-mentioned awareness of the problems regarding surveying instruments such as auto level.

[0008]

SUMMARY OF THE INVENTION The present invention for achieving the above object comprises a collimation objective lens in order from the object side; and an object image formed on a reticle that forms a collimation optical system with this collimation objective lens. In a surveying instrument equipped with a focus adjustment lens for adjusting a focus state; and an eyepiece lens for observing an image on the reticle, there is provided a measuring device including a branch optical member provided in an optical path between the objective lens and the reticle. A focus state detection system that receives the light from the optical path with a line sensor to detect the focus state of the collimation object; a drive unit that drives the focus adjustment lens in the optical axis direction; and a drive unit that is moved by this drive unit. Lens position detecting means for detecting the position of the focus adjusting lens; changing the use area of the light receiving element group of the line sensor according to the lens position of the focus adjusting lens detected by the lens position detecting means, It is characterized by comprising; control means and for controlling said drive means based on a photodetection signal from the light receiving element group in use region obtained by reduction.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to illustrated embodiments. 9 and 10 show an embodiment of an auto level (surveyor) to which the present invention is applied, and FIG. 1 schematically shows an optical system and an auto focus control system in this auto level. This auto level 10 incorporates a TTL AF system, and its collimating telescope has a positive collimating objective lens 1 in order from the surveying staff (object) B located on the left side of FIG.
1, a negative focusing lens 12, a well-known horizontal adaptive optical system 1
3, branch optical element (half mirror) 18, reticle plate 1
4 and a positive eyepiece lens 15. The present collimating telescope having these components has a magnification set to, for example, 24 times, and the lens barrel member 1 fixed on the rotary table 17.
It is supported by 9. The rotary table 17 is rotatable about a vertical axis 17X which is orthogonal to the optical axes of the objective lens 11 and the focus adjustment lens 12 and which should be set vertically, and can see an object at an arbitrary distance in the same horizontal plane. Can be applied.

The auto level 10 also has a focus adjustment lens drive system 9 for driving the focus adjustment lens 12 in the optical axis direction to adjust the focus state of the surveying staff B (focus adjustment). The focus adjustment lens drive system 9 includes a lens drive motor 42 such as a stepping motor and the motor 42.
The deceleration mechanism 41 with a built-in clutch for transmitting the rotation of the screw shaft 43 to the screw shaft 43, the nut 44 fixed to the focus adjusting lens 12 and screwed into the screw shaft 43, and the focus adjusting lens 1 based on the rotation speed of the screw shaft 43.
It has an encoder (lens position detecting means) 40 which outputs the position information of No. 2 as a pulse signal of a predetermined bit.

The branch optical element 18 branches the optical path from the objective lens 11 to the reticle plate 14, and the conjugate optical system 14C of the reticle plate 14 is provided in the branch optical system formed as a result. The reflected light from the diverging optical element 18 is received by the focus detection sensor unit (focus state detection system) 21, and the focused state on the conjugate plane 14C is received by the focus detection sensor unit 21 according to the received reflected light. Based on the signal, the focus state detection unit (focus state detection system) 48 of the AF control unit 49 detects.

The focus detection sensor section 21 has a conjugate plane 14
The light receiving signals output from the pair of line sensors 21c placed in the vicinity of C are output to the focus state detection unit 48,
Various specific configurations are known. FIG. 2 shows the principle of the example, in which the condenser lens 2 is provided behind the conjugate plane 14C.
1a, a pair of separator lenses 21b, and a pair of line sensors 21c such as CCDs located behind each separator lens 21b. On each line sensor 21c, for example, an object image seen in the AF detection area (distance measurement zone) Z shown in FIG. 3 is formed. The line sensor 21c is preferably provided in a positional relationship orthogonal to the surveying staff B when collimating the surveying staff (staff) B standing upright on the ground surface. According to this, since the surveying staff B and the line sensor 21c do not coincide in direction, the AF function can be surely obtained.

The incident position of the object image on the pair of line sensors 21c is imaged in front of the conjugate surface 14C when the image of the object B is accurately imaged on the conjugate surface 14C (focusing). When the image is formed behind (the front focus) and behind the conjugate plane 14C (the rear focus),
Moreover, the amount of deviation from the in-focus position is also determined by the pair of line sensors 2
It can be determined by the image forming position of the object image on 1c. That is, the focus state detection unit 48 that receives the outputs of the pair of line sensors 21c amplifies this output by a preamplifier (not shown) and then calculates it by a calculation circuit (not shown), thereby achieving focus, The out-of-focus state, the front focus, the rear focus, and the defocus amount are detected, and the detection data are output to the CPU (control means) 47.

By the way, like this auto level 10,
In a surveying instrument that performs autofocus based on forming an object image on the line sensor 21c, a surveying staff B
Is near (for example, 5 m), as shown in FIG. 3, a surveying staff B in the telescope field of view F of the collimating telescope
Since the ratio to the background is large, the distance measurement error due to the influence of ambient light is very small. In the figure, a shows the dimension on the conjugate plane 14C when the width of the surveying staff B is 70 mm (3.3 mm in the case of the embodiment), and b shows the AF detection area Z by the line sensor 21c (actually, The area Z itself is not displayed, and the distance measuring zone mark zm (FIG. 8) corresponding to the area Z is not displayed.
Is displayed) and h is a hairline (thickness 0.003 mm).

However, the object distance of the surveying staff B is
As the length gradually increases from 5m to 10m, 20m, 30m, 50m, the width of the surveying staff B in the telescope field of view F becomes c (1.6
mm), d (0.8 mm), e (0.6 mm), g (0.3 mm), and the width of AF detection area Z by line sensor 21c is constant. In, the ratio of the background is gradually increasing.

This is shown in the following table using actual dimensions. That is, the magnification of the collimating telescope including the collimating objective lens 11 and the focus adjusting lens 12 is 24 times, the diameter of the telescope field frame on the reticle plate (focus surface) 14 is about 6 mm, and the light receiving area of the line sensor 21c. (AF detection area Z) is about 4 mm
Fixed to, the combined focal length of the collimating objective lens 11 and the focus adjustment lens 12 is about 240 mm, and the width of the surveying staff B is 70 mm.
As an example, the image size of the surveying staff B on the reticle plate 14 when the surveying staff B is set at the following object distance from the auto level 10 and the ratio to the telescope field of view F and the line sensor 21c are shown below.

Distance (m) Image size (mm) Image size / Field of view range (%) Image size / Sensor detection area (%) 3 5.5 93 138 5 3.3 56 56 82 10 1.65 28 41 20 0.83 14 21 30 30 0.55 9 14 50 0.33 6 8

As shown in this table, the line sensor 2
If the width of the AF detection area Z of 1c is fixed,
When the object distance is 10 m or more, the ratio of the surveying staff B in the AF detection area Z becomes extremely small. Therefore, it is understood that as the object distance increases, the ratio of the background other than the surveying staff B in the telescope field of view F increases. Therefore, in such a case, an error may occur in the measurement of the object distance due to the influence of ambient light or the like. In addition,
Since the apparent image size when the surveying staff B imaged on the reticle plate 14 is viewed through the eyepiece lens 15, the apparent size of the image is defined by the clear visual distance / focal length of the eyepiece lens. Focal length for example
If it is 9.6 (mm), then 250 (mm) /9.6 (mm) = 26. That is, the surveying staff B is observed by the observer at 26 times the image size on the reticle plate 14.

In order to solve the above problems, the auto level 10 of the present invention is characterized by having a function of changing the width of the AF detection area Z of the line sensor 21c in accordance with the change of the object distance. The specific configuration will be described below.

That is, in order to realize this function, the auto level 10 has the AF controller 49, the CPU 47, and
The motor driver 45 and the encoder pulse detector 46
And the focusing state detection unit 48 and the RAM 50.

The CPU 47, based on the defocus amount data received from the in-focus state detecting section 48, focuses the lens image in the direction of focusing the object image on the conjugate plane 14C.
A drive signal is output to the lens drive motor 42 via the motor driver 45 in order to drive the. The rotation of the lens drive motor 42 is converted into pulse data via the encoder 40 as an encoder pulse detection unit (object distance detection means).
It is output to 46. This encoder pulse detector 46
Feeds back the position of the focus adjustment lens 12 to the CPU 47 as a signal indicating the object distance based on this pulse data.

Further, the RAM 50 has a large number of positions of the light-receiving element group, that is, the positions of the light-receiving element groups for obtaining the light-receiving signal of the line sensor 21c, which are different according to the object distance detected by the encoder pulse detecting unit 46, that is, the number of the line sensor 21c. Among the light receiving element groups, the position of the element group that should obtain the light receiving signal when the object distance is detected is stored as table data. Therefore, in the auto level 10, the CPU 47 reads the position of the light receiving element group to be used from the RAM 50 according to the object distance of the focus adjustment lens 12 detected by the encoder pulse detection unit 46, and determines the use range of the AF detection area Z. , First area Z ₁ , second area Z ₂ , third area Z
₃ , the fourth area Z ₄ is changed so as to become gradually narrower. The CPU 47 also changes the distance measuring zone mark zm in the telescope field of view F in accordance with the change in the AF detection area Z so that the pair of zone marks i, j, k, and n become narrower in this order.

These first, second, third and fourth areas Z
The specific positions of the light receiving element groups of ₁ , Z ₂ , Z ₃ and Z ₄ are
The position of the focus adjustment lens 12, the object distance to be detected, and the image size of the surveyed object are obtained by optical calculation, and are determined based on these numerical values. That is, when the object distance is L, for example, 100% of the light receiving element group of the line sensor 21c is used when 0m <L ≦ 10m, and 50% of the entire light receiving element group from the center to the left and right when 10m <L <30m. Use, 30m ≦
When L <50m, 30% of the entire light receiving element group is used from the center to the left and right, and when 50m ≦ L, 20% of the entire light receiving element group is used from the center to the left and right.
Can be set to use%. By setting in this way, the light receiving signal from the light receiving element group in the vicinity of the center where the object to be surveyed is located in the AF detection area Z is used, and the light receiving element group which causes an error such as the background of the peripheral portion is used. The signal of can be cut. CPU47
Is the RAM 50 according to the object distance of the focus adjustment lens 12.
A drive signal for controlling the focus adjustment lens 12 is obtained based on the received light signals from the light receiving element group corresponding to the positions read from the above.

Incidentally, there are the following restrictions on the setting of the numerical values for the AF detection area Z. That is, when the collimation telescope is aimed at the surveying staff B, blurring occurs because the direction is normally adjusted with the naked eye, and the surveying staff B can only be roughly aligned within the distance measuring zone mark zm. In that case, there is also a mounting error of the sight. Therefore, if the range of the light receiving element to be used is narrowed in inverse proportion to the object distance L, it may be difficult to put the surveying staff B in the AF detection area Z. That is, the AF detection area Z
Is equal to the width of the surveying staff B, it is difficult to put the surveying staff B in the area Z, and therefore it is required that both ends project to some extent from the AF detection area Z. As described above, there is a limit to narrowing the AF detection area Z (about 15 'to 30' in the telescope viewing angle).
Is the limit).

The zone marks i, j, k, n of the distance measuring zone mark zm are selected on the transparent display plate arranged in the optical path of the collimation telescope, for example, selected first, second, third, and third.
The fourth regions Z ₁ , Z ₂ , Z ₃ , and Z ₄ can be configured to be turned on. It is also possible to draw with paint or the like on a cover glass or the like (not shown) used for the collimation telescope.

Therefore, the auto-level 10 having the above-described structure is arranged so that the object light from the vertically oriented surveying staff B is passed through the collimating objective lens 11, the focusing lens 12, the horizontal compensation optical system 13 and the branch optical element 18 to form a conjugate plane. It can be imaged on 14C. In this case, even if the optical axis of the collimation telescope is not completely located in the horizontal plane, the horizontal compensating optical system 13 makes the collimation line horizontal with an accuracy that practically does not cause any problem. When the vertical axis 17X orthogonal to the axis is rotated to collimate another collimation point, the collimation point is located in the horizontal plane including the reference position. Surveyor
In this state, the eyepiece lens 15 is looked into and the object image formed on the reticle plate 14 is observed.

At this time, when the object light branched by the branch optical element 18 enters the focus detection sensor section 21 through the conjugate plane 14C, the focus state detection section is detected based on the light reception signal received by the line sensor 21c. 48 calculates a defocus amount relating to the image of the object B to obtain a focused state, that is, a focused state, a non-focused state,
Detects front pin and rear pin. And this detection data is C
When input to the PU 47, the CPU 47 outputs a lens drive signal to the focus adjustment lens drive system 9 via the motor driver 45, rotationally drives the lens drive motor 42, and adjusts the focus via the screw shaft 43 and the nut 44. The lens 12 is driven in the optical axis direction. At this time, the encoder pulse detector 46 feeds back the position of the focus adjustment lens 12 to the CPU 47 as an object distance signal based on the pulse data from the encoder 40.
7 is a pair of line sensors 21c according to the object distance signal.
The use area of the light receiving element group is changed, and the lens drive motor 42 is driven based on the light receiving signal from the light receiving element group in the changed use area to stop the focus adjustment lens 12 at an appropriate position.

In this case, when the object distance of the surveying staff B is 5 m (see FIG. 3) or 10 m (see FIG. 4), C
The first area Z ₁ is selected and set in the AF detection area Z by the PU 47, and the pair of zone marks i as the distance measurement zone marks zm are lit in the telescope field of view F. When the object distance is 20 m (see FIG. 5), the second area Z ₂ is selectively set in the AF detection area Z, and the distance measuring zone mark zm is turned on in the telescope field of view F as a pair of zone marks j. It Furthermore, when the object distance is 30 m (see Fig. 6),
The third area Z ₃ is selectively set in the AF detection area Z, and a pair of zone marks k are lit in the telescope field of view F as distance measuring zone marks zm. Further, when the object distance is 50 m (see FIG. 7), the fourth area Z ₄ is selectively set in the AF detection area Z, and the pair of zone marks n as the distance measuring zone marks zm are lit in the telescope field of view F. It

As described above, according to the auto level 10 of the present invention, the number of effective pixels can be electrically changed according to the change of the object distance, and the width of the AF detection area Z of the line sensor 21c can be changed large or small. Therefore, the influence of ambient light incident on the line sensor 21c can be reduced as much as possible at any object distance, and the error in measuring the object distance during autofocus can be reduced.

Although the use area (position) of the AF detection area Z is selected corresponding to each of the object distances divided stepwise in the above embodiment, the present invention is not limited to this. That is, the object distance can be regarded as a continuous change, and the AF detection area Z can be continuously changed according to the continuously changing object distance, that is, both can be configured as a linear relationship.

[0031]

As described above, according to the present invention, the position of the light receiving element group of the line sensor can be changed according to the change of the object distance, so that even if the object distance is changed during autofocusing, the disturbance light is changed. It is possible to provide a surveying instrument that is less likely to be affected by.

[Brief description of drawings]

FIG. 1 is a diagram showing an auto-level collimating telescope and an auto-focus control system according to the present invention.

FIG. 2 is a diagram showing a principle of a focus detection system in the autofocus control system.

FIG. 3 is a diagram showing a surveying staff visually recognized within a field of view of a telescope at an object distance of 5 m.

FIG. 4 is a view showing a surveying staff visually recognized within a field of view of a telescope at an object distance of 10 m.

FIG. 5 is a diagram showing a surveying staff visually recognized within a field of view of a telescope at an object distance of 20 m.

FIG. 6 is a diagram showing a surveying staff visually recognized within a field of view of a telescope at an object distance of 30 m.

FIG. 7 is a diagram showing a surveying staff visually recognized within a field of view of a telescope at an object distance of 50 m.

FIG. 8 is a diagram showing distance measurement zone marks displayed in the field of view of the telescope.

FIG. 9 is a front view showing an automatic level according to the present embodiment.

FIG. 10 is a plan view showing the same auto level.

[Explanation of symbols]

9 Focus Adjustment Lens Drive System (Drive Means) 10 Auto Level (Surveyor) 11 Collimation Objective Lens 12 Focus Adjustment Lens 14 Reticle Plate 14C Conjugate Surface 15 Eyepiece 18 Branch Optical Element (Branch Optical Member) 21 Focus Detection Sensor Section ( Focus state detection system) 21c Line sensor 40 Encoder (lens position detection means) 46 Encoder pulse detection section (object distance detection means) 47 CPU (control means) 48 Focus state detection section (focus state detection system) 50 RAM B Surveying staff (collimation object) i j k n Zone mark Z AF detection area Zm Distance measurement zone mark Z ₁ 1st area Z ₂ 2nd area Z ₃ 3rd area Z ₄ 4th area

Claims (2)

[Claims] 1. A collimating objective lens in order from the object side; a focus adjusting lens which forms a collimating optical system by the collimating objective lens and which adjusts a focused state of an object image formed on a reticle; In a surveying instrument equipped with an eyepiece for observing an image on the reticle, a line sensor receives light from the optical path through a branch optical member provided in an optical path between the objective lens and the reticle. Focus state detection system for detecting the focus state of the collimation object; drive means for driving the focus adjustment lens in the optical axis direction; lens position for detecting the position of the focus adjustment lens moved by the drive means A detecting means; the use area of the light receiving element group of the line sensor is changed according to the lens position of the focus adjustment lens detected by the lens position detecting means, and the light receiving element group in the changed use area is Surveying instrument having an autofocus function, characterized by comprising; and control means for controlling said drive means based on a photodetection signal. 2. The object distance detecting means according to claim 1, further comprising an object distance detecting means for detecting a distance of a collimating object from a position of the focus adjustment lens detected by the lens position detecting means, wherein the control means is a line sensor. The use area of the light receiving element group,
A surveying instrument having an autofocus function for narrowing the collimating object distance as the distance increases.