JP2002296035A - Laser surveying instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser surveying instrument equipped with a convenient and economical autofocus mechanism capable of using a conventional target without changing the structure of the laser surveying instrument itself. SOLUTION: This laser surveying instrument is equipped with a pentaprism 42A for emitting a visible laser beam L2, a main motor 48A for driving/rotating the pentaprism, a focusing lens 6A for changing the condensing distance of the beam L2, and a light receiver 86A for receiving reflected laser beams L4 reflected from a multitude of microprisms mounted on a target 60A, wherein a microcomputer 100A is provided for controlling the position of the lens 6A so as to maximize the number of pulses generated when the receiver 86A receives the reflected laser beams L4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser surveying instrument (level) that scans a laser beam in a horizontal plane or the like and performs a reference plane such as a horizontal plane or a vertical plane when performing construction or the like indoors and outdoors. Planar).

[0002]

2. Description of the Related Art As shown in FIG.
00C emits the laser beam L from the rotating unit 10C, and scans the laser beam L at a predetermined scan width θ and scan speed v with reference to the direction of the target 60A installed on the wall surface 8 or the like. This indicates a reference plane such as a horizontal plane or a vertical plane. Target 60A
As shown in FIG. 3, a rectangular target body 60b attached with a large number of microprisms 60c is often used. The microprism 60c reflects reflected light in the direction in which the incident light comes, regardless of the incident angle of the incident light.

[0003] By the way, the level planar 300C includes:
The laser beam L is simply emitted as a parallel light beam having a diameter of about 10 mm, and the laser beam L can be focused on the target 60A in order to improve visibility and accurately indicate the reference plane. There is another type in which the focusing distance of the laser beam L (hereinafter referred to as the focusing distance) can be changed. In many cases, the set value of the focusing distance of the laser beam L is manually changed.

[0004] However, manually changing the focusing distance of the laser beam L is troublesome for the operator and degrades the work efficiency. For this reason, recently, as disclosed in Japanese Patent Application Laid-Open No. 2000-161961,
Some devices have been provided with an autofocus mechanism so that the laser beam L can be automatically focused on the target 60A.

FIG. 7 shows a block diagram of an optical system of the level planar disclosed in the above publication and a control system for controlling the optical system.

When the output of the oscillator 102 is inputted through an LD (laser diode) driving circuit 104, the level planar emits a light emitting unit 3 such as a laser diode for emitting a visible light laser, and a laser emitted from the light emitting unit 3. A collimator lens 2 that converts the light into a laser beam 0 of a parallel light beam;
Tilt angle correction system 1 for correcting the tilt angle of laser beam 0
A reflecting mirror 4 for reflecting the laser beam passing through the tilt angle correction system 1 vertically upward, a beam expander 6 for changing the focusing distance of the laser beam 0 reflected by the reflecting mirror 4,
It has a perforated mirror 7 for transmitting the laser beam 0 and reflecting the laser beam reflected from the target 60 in a right angle direction, and a pentaprism 42 for reflecting the incident laser beam 0 in a right angle direction. Tilt angle correction system 1
Means that the pentaprism 42
This is for always keeping the laser beam 0 incident to the vertical direction, and is composed of a sealing glass 1d and an oil path 1c having a reflecting surface 1b. Prisms 30 and 32 that change the polarization plane of the laser light emitted from the light emitting unit 3 are provided in the tilt correction system 1.

The beam expander 6 includes a pair of lenses 36 and 38 having different focal lengths.
Can be moved up and down by a focus driving motor 200. And one lens 38
By moving the laser beam, the focusing distance of the laser beam 0 can be changed according to the distance to the wall surface, whereby the laser beam 0 is focused on the target 60 installed on the wall surface and the laser beam is focused. The illuminance at the irradiation point of the beam 0 is increased to improve the visibility, and the reference plane can be displayed with high accuracy.

The pentaprism 42 is fixed on a rotary support 40, and a gear 46 is formed on the rotary support 40, and the gear 46 meshes with an output gear 50 of a main motor 48. Along the central axis of the rotary support 40,
A through hole for passing the laser beam 0 is provided.

The laser beam 0 emitted from the level planar is reflected by a target 60 mounted on a wall or the like, reverses the optical path that has come, is reflected by a perforated mirror 7 in a right angle direction, and is condensed by a condenser lens 82. Then, the light enters a light receiver 86 such as a photodiode via a pinhole plate 84. When the light receiver 86 receives the reflected laser beam 00 from the target 60, the light receiver 86 generates a light receiving signal pulse, which is sent to a control system 100 including a microcomputer or the like. The control system 100 also receives a rotation angle signal from an encoder 44 that detects the rotation angle of the rotation support base 40.

Therefore, the control system 100 scans the laser beam 0 with a predetermined scan width based on the direction of the target 60 based on the pulse from the light receiver 86 and the rotation angle signal from the encoder 44. Control system 1
Reference numeral 00 denotes a program that constitutes an autofocus mechanism that automatically focuses the laser beam 0 on the target 60 based on the reflected laser beam 00 from the target 60.

The principle of the auto focus mechanism will be described. As shown in FIG. 8, the target 60 has two reflection zones 62 and 64 spaced from each other. When the target 60 facing the level planar is scanned with the laser beam 0 as shown by a broken line s in FIG.
When the light receiver 86 receives the reflected laser beam 00,
Detect two adjacent pulses. At the time of detection of these two pulses, the rotation angle signal sent from the encoder 44 is read, and the angle difference is obtained, so that the two reflection zones 62 and 64 are viewed from the level planar 300 as shown in FIG. Obtain the viewing angle θ. Then, the distance d between the two reflection zones 62 and 64 is known, and θ
Is very small, the distance R to the target 60 is
R = d / tan θ = d / θ. The auto-focus mechanism controls the position of the focus lens 38 according to the distance R, and focuses the laser beam 0 on the target 60.

Further, since the target 60 has the two reflection zones 62 and 64, the reflected laser beam 00 from the target 60 can be determined only when two adjacent pulses are detected. is there.

[0013]

However, as shown by the broken line in FIG. 9, when the target 60 is not directly opposed to the level planar 300C, the viewing angle θ 'is such that the target 60 is directly opposed to the level planar 300C. Is smaller than the visual angle θ at that time. Therefore, the control system 10
Since there is a problem that the laser beam 0 is not condensed on the target 60 because the target 0 is erroneous when the target 60 is farther than the actual one. In addition, since a special target 60 must be used, it is inconvenient and uneconomical.

Therefore, in order to solve the above-mentioned problems, a laser surveying instrument equipped with a convenient and economical autofocus mechanism can be used without changing the structure of the laser surveying instrument itself, and can use a conventional target. Offer machine.

[0015]

According to a first aspect of the present invention, there is provided a rotating unit for emitting a visible laser beam, and a focusing distance changing unit for changing a focusing distance of the laser beam. And a light receiver for receiving the reflected laser beam reflected by the target, wherein the laser beam is collected so that the number of pulses generated when the light receiver receives the reflected laser beam is maximized. A control system for controlling the optical distance changing means is provided.

According to a second aspect of the present invention, in the first aspect of the present invention, the control system includes a pulse generated when the rotating unit is normally rotated and the light receiver receives the reflected laser beam. Only when the number is plural, the operation shifts to the scanning operation to control the focusing distance changing means.

In the invention according to claim 3, claim 1 or 2
In the invention according to the invention, a plurality of distance setting steps are predetermined in advance from the minimum distance to the maximum distance with respect to the focusing distance, and the control system changes the distance setting step by one step while changing the pulse number. Is characterized by finding a distance setting step in which is maximized.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an optical system of a laser surveying instrument (level planar) of this embodiment and a control system for controlling the optical system. The target 60A is the same as the conventional target shown in FIG.

The laser surveying instrument 300A of the present embodiment is disposed on an optical path of an upper light emitting body 3A such as a laser diode that emits a laser light L1 vertically upward and a laser light L1 emitted from the upper light emitting body 3A. A focus lens 6A,
A beam splitter 7A that transmits the laser light L1 and reflects the laser light reflected from the target 60A in a perpendicular direction, and an objective lens 41 that condenses the laser light L1 transmitted through the beam splitter 7A to form a laser beam L2.
A, a wedge glass 43A, 43A 'for correcting the displacement of the laser beam L2, and a λ / 4 plate 45 for converting the laser beam L2 transmitted through the wedge glass 43A, 43A' into circularly polarized light.
A, and a pentaprism 42A that transmits part of the laser beam L2 transmitted through the λ / 4 plate 45A in the vertical direction and reflects the rest in the horizontal direction.

As shown in FIG. 2, one side of the focus lens 6A is in contact with the spring 58A, and the projection 56A provided on the other side is a focus motor (stepping motor) 2A.
Triangular member 54A fixed to the tip of the output shaft 52A of 00A
It is in contact with the slope. The triangular member 54A is slidably attached to the guide member 57A, and the output shaft 52A of the focus motor 200A moves in the axial direction. Here, the output shaft 5 of the focus motor 200A
When 2A moves in the axial direction, the triangular member 54A slides along the guide member 57A, and the slope of the triangular member 54A presses the convex portion 56A of the focus lens 6A,
The focus lens 6A is moved against the reaction force of the spring 58A, thereby changing the focusing distance. Convex part 5
6A, the guide member 57A, and the triangular member 54A are provided with holes or the like so as not to block the laser beam L1 of the upper light emitting body 3A.

The guide member 57A is provided with a position sensor (not shown) for detecting the position of the triangular member 54A, and a signal from this position sensor is input to the limiter 59A. When the limiter 59A detects that the triangular member 54A has reached the restricting position based on a signal from the position sensor, it sends a restricting signal to the microcomputer 100A to restrict further movement of the triangular member 54A. That is, when the triangular member 54A comes to a position where the focus motor 200A, which is the stepping motor, is reversed by a predetermined pulse from the reference position, the limiter 59A regulates the further reverse rotation. The emitted laser beam L2 is a parallel ray or a divergent ray. When the triangular member 54A comes to a position where the focus motor 200A is rotated forward by a predetermined pulse from the reference position, the limiter 59A regulates further forward rotation.
The focusing distance of the laser beam L2 emitted from the laser surveying instrument 300 is minimized.

In this embodiment, the focusing distance changing means is constituted by the focus lens 6A and the focus motor 200A. However, the focusing distance changing means changes the focusing distance such as the objective lens 41A and a device for moving the objective lens 41A. Anything that can be used may be used.

The pentaprism 42A includes a main motor 4
The pentaprism 42A, the main motor 48A, and the encoder 44A are fixed on a rotation support 40A that is driven to rotate at 8A, and constitute a rotating unit that rotates the emission direction of the laser beam L2. Along the central axis of the main motor 48A and the rotary support 40A, the laser beam L2
A through-hole (not shown) is provided at the center of the shaft to allow the passage of the air. The laser beam L2 is 2 inside the pentaprism 42A.
Is reflected in the horizontal direction and is emitted in the horizontal direction.
Since A is horizontally rotated by the main motor 48A, the emitted laser beam L2 forms a plane. A part of the laser beam L2 is a laser beam L3 emitted vertically.
Then, the light passes through the pentaprism 42A and the prism 49A and is emitted upward as it is. Laser surveying instrument 300
The laser beams L2 and L3 emitted from A are maintained in a horizontal plane and a vertical line by an inclination sensor 78A and a leveling device (not shown).

On the other hand, the lower luminous body 6 such as a laser diode
The laser light L5 emitted from the light-collecting optical system 67A
Is emitted downward from the laser surveying instrument 300A, and a vertical line is set. Both light emitters 3A and 65A are connected to a power supply device 105A to which a battery is attached.

The laser beam L2 emitted from the laser surveying instrument 300A is applied to a target 6 mounted on a wall or the like.
When reflected at 0A, it travels backward in the optical path that has just come, is reflected by the pentaprism 42A, and is further reflected at right angles by the beam splitter 7A to become a reflected laser beam L4. Receiver 86
A. The light reception signal of the light receiver 86A is amplified by an amplifier 87A, shaped into a pulse wave by a waveform shaper 88A, and then controlled by a microcomputer (control system).
100A.

The microcomputer 100A has an encoder 44A for detecting the rotation angle of the pentaprism 42A.
An output signal pulse from is also input.
Then, the microcomputer 100A includes the light receiver 86
A and the output signal pulse from the encoder 44A.
A drive pulse is sent to 8A to control the rotation speed and direction of the main motor 48A.

Further, the microcomputer 100A includes:
The rotation speed of the main motor 48A is calculated from the number of pulses per second sent from the encoder 44A, and when the rotation speed falls below a predetermined value, the laser surveying instrument 300A
Is set to a stop mode (a state in which the laser beam L2 is stopped and only one point is irradiated), or when the inclination sensor 78A detects an inclination equal to or more than a predetermined value, first, the laser beam L2 emitted from the laser surveying instrument 300A.
Is blinked (except when the stop mode is set), then the main motor 48A is stopped, a command signal is sent to the focus motor 200A, and the laser beam L2 emitted from the laser surveying instrument 300A is turned into a parallel light beam. Alternatively, the focus lens 6A is moved so as to be divergent light. Therefore, even if the laser beam L2 hits the eyes of the worker, the energy of the laser beam L2 does not concentrate on one point, so that it is safe. In addition, laser surveying instrument 3
Since the laser beam L2 emitted from 00A is stopped in a blinking state, it is possible to reliably inform the operator of the abnormality.

Further, the microcomputer 100A
Also has an auto-focus mechanism that automatically focuses the laser beam L2 emitted from the laser surveying instrument 300A on the target 60A by using a light receiving signal from the light receiver 86A. First, the principle of the autofocus mechanism of the present embodiment will be described. As shown in FIG. 3, a target 60A on which a number of microprisms 60c are mounted is scanned with a laser beam L2 as indicated by a dashed line r, and a reflected laser beam L4 reflected by the target 60A is received by a light receiver 86A. Suppose you did. When the laser beam L2 is not converged on the target 60A and is a thick light beam g, a light receiving signal as shown in FIG. 4A is generated from the light receiver 86A, and the light receiving signal is shaped into a waveform. Vessel 88A
When a pulse whose waveform is shaped by comparing it with a reference value such as a broken line and determining 0 or 1 is generated, a single pulse is generated as shown in FIG.

The laser beam L2 is focused on the target 60A, and the size of the microprism 60c (several mm in diameter)
(B) and (c) of FIG. 4 as the light fluxes h and i (diameter of about 1 mm) become smaller.
(E) and (f) in the same figure when the received light signal is pulsed by the waveform shaper 88A.
A plurality of adjacent pulses are generated as shown in FIG.

Then, the laser beam L2 is applied to the target 6
When the light beam is most narrowed on 0A and becomes a thin light beam, that is, when the light beam is most concentrated on the target 60A, the light receiving device 8
The number of pulses generated by 6A is maximized. Accordingly, the microcomputer 100A finds the time when the number of pulses sent from the light receiver 86A becomes maximum while gradually changing the focusing distance of the laser beam L2, and at this time, the laser beam L2 is focused on the target 60A. It is determined that the light is completely collected. When the number of pulses is maximized, the laser beam L2 is
Since the light is most condensed on 0A, the present invention can perform the autofocus more reliably than the conventional autofocus according to the distance to the target.

Incidentally, the microcomputer 100A
Stores eight distance setting stages for the focusing distance in advance as shown in Table 1 below. In Table 1, the scan width θ and the scan speed v are determined so that the visibility becomes the best depending on the distance to the target, in addition to the focusing distance at each distance setting stage. Scan width θ and scan speed v
Is reduced when the target 60A is far, and conversely,
When the target 60A is close, the size is increased. The functions of this embodiment include a stop mode and a scan mode.
When the distance setting step is determined by the auto focus mechanism in the scan mode, referring to Table 1,
The scan width θ and the scan speed v are automatically set, and the rotation direction and the rotation speed of the main motor 48A are also controlled according to the set scan speed v and scan width θ. For this reason, since the operator does not need to set the scan width θ and the scan speed v, the work efficiency can be improved.

The laser surveying instrument 300A has a key (not shown) for manually raising and lowering the focusing distance step on the operation panel 76A and a plurality of LEDs (not shown) for displaying the approximate focusing distance. Diodes) a, b,
c and d are provided. Table 1 also specifies which of these LEDs should be turned on. Therefore, the worker can know the approximate focusing distance from the emitted LED, and can easily change the focusing distance manually.

The number of distance setting steps may be more or less than eight. However, considering the accuracy of focusing the laser beam L2 and the burden on the microcomputer 100A, the number of steps is about eight. Is most desirable.

[0034]

[Table 1]

Referring to FIG. 5, the laser beam L emitted from the laser surveying instrument 300A in the scan mode
A processing procedure performed by the autofocus mechanism incorporated in the microcomputer 100A to change the focusing distance of No. 2 will be described.

In the scan mode, first, the auto-focus mechanism is started, the process proceeds to step S1, and after setting the focusing distance of the laser beam L2 to the longest distance of 30 m in the distance setting step 8, the laser beam L2 is moved in a certain direction. Rotate constantly. The reason why the focusing distance is set to be the longest first is to make the laser beam L2 into a substantially parallel light beam and reliably capture the target 60A. If the focusing distance is initially set to be the shortest, the laser beam L2 may be diverged too much at the position of the target 60A and the reflected laser beam L4 may not be detected depending on the distance to the target 60A. is there. The position of the focus lens 6A where the laser beam L2 becomes a parallel light beam is set in advance by adjustment.

Next, the process proceeds to step S2, where the target 60
A reflected laser beam L4 from A is detected. When the photodetector 86A detects the reflected laser beam L4, step S3
To the distance setting stage 1 of 3 m where the focusing distance is the shortest while keeping the steady rotation. If the reflected laser beam L4 cannot be detected, the process returns to step S1 without changing the distance setting stage. At this time, an operator operates the laser surveying instrument 300A or the target 60A so that the target 60A can be detected.
It is necessary to adjust the position of A.

After step S3, the process proceeds to step S4. When the reflected laser beam L4 is received, the light receiving device 86
It is detected whether the light receiving signal sent from A is a plurality of adjacent pulses. The pulse from the light receiver 86A is shown in FIG.
In the case of a single pulse as shown in FIG.
Does not converge on the target 60A, the process proceeds to step S5, the distance setting stage is increased by one, and the process returns to step S4 again while maintaining the steady rotation. When the light receiving signal from the light receiver 86A is a plurality of adjacent pulses as shown in FIGS. 4 (e) and 4 (f), it can be confirmed that the signal is the reflected laser beam L4 from the target 60A.
The process proceeds to a scanning operation in which the emitted laser beam L2 is reciprocated at a predetermined scan width.

After the scanning operation is started, in order to stabilize the scanning speed, after performing a predetermined number of scans for stabilization,
Proceed to step S7. Of course, the scan cycle may be actually measured, and after this cycle becomes substantially constant, it may be determined that the scan speed has become stable, and the process may proceed to step S7. In step S7, every time the target 60A is scanned with the laser beam L2, the number of pulses of the light receiving signal sent from the light receiver 86A is read, and after scanning the target 60A a predetermined number of times, the average number of pulses is acquired.

After obtaining the average number of pulses, step S8
To increase the distance setting stage by one, and furthermore, to step S9
Then, similarly to step S7, the average number of pulses is acquired after scanning the target 60A a predetermined number of times. Then, the process proceeds to step S10, and it is determined whether or not the number of pulses acquired in step S10 is smaller than the number of pulses acquired in step S7. For example, when the number of pulses obtained in step S7 is five as shown in FIG. 4F, and when the number of pulses obtained in step S10 is reduced as shown in FIG. At the distance setting stage one step lower than the distance setting stage selected in step S10, it is known that the laser beam L2 is in the narrowest state on the target 60A, so the process proceeds to step S13. Then, the distance setting stage is lowered by one, and the focusing distance setting operation is completed.

In step S10, for example, while the number of pulses obtained in step S7 is three as shown in FIG. 4 (e), the number of pulses obtained in step S10 is not (e) in FIG. When the distance is the same or increased as in (f), the laser beam L2 is narrowed down on the target 60A at the distance setting stage selected in step S10 more than at the lower distance setting stage. Since it is found that the distance is set or narrowed down, the process proceeds to step S11, and the distance setting step is increased by one.
Subsequently, the process proceeds to step S12. In step S12, the existence of a stage in which the distance setting stage has been increased by one in Table 1 is checked. If the stage exists, the process returns to step S7,
If there is no such step (step 9 in the present embodiment), the process proceeds to step S13, the distance setting step is decreased by one, and the focusing distance setting operation is completed.

According to this embodiment, the conventional target 60
A can be used as it is and the microcomputer 100
Only by improving the software of A, the laser surveying instrument 30
The structure of OA is not changed, so it is convenient and economical. As is clear from the flowchart of FIG. 5, the target 6 is received only when the reflected laser beam L4 is received by the light receiver 86A and a plurality of pulses are detected.
If it is confirmed that the reflection is from 0A, then step S
Since the process proceeds to step 6, the laser beam L2 can be accurately focused on the target 60A without setting the focusing distance for the wrong reflector.

[0043]

As is apparent from the above description, according to the first aspect of the present invention, even when the target 60A is tilted with respect to the laser surveying instrument, it is generated when the light receiver receives the reflected laser beam. An autofocus mechanism can be obtained only by improving the software of the control system such as controlling the focusing distance changing means so that the number of pulses to be maximized, and when the number of pulses is maximized, be sure to Since the laser beam is most focused on the target, the present invention can reliably perform autofocus even when the target is tilted, as compared with a conventional device that performs autofocus according to the distance to the target.

According to the second aspect of the present invention, further, when the reflected laser beam is received by the light receiver, the reflection from the target is confirmed only when a plurality of pulses are detected, and the operation shifts to the scanning operation. Therefore, the laser beam can be accurately focused on the target without setting the focusing distance for the wrong reflector.

According to the third aspect of the present invention, the number of pulses generated when the light receiver receives the reflected laser beam is maximized while increasing the predetermined distance setting step by step. Since the autofocus is performed by finding the distance setting stage, there is an advantage that the software incorporated in the control system is simple.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a laser surveying instrument (level planar) according to a preferred embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a focusing distance changing unit in the laser surveying instrument.

FIG. 3 is a diagram showing a conventional target used with the laser surveying instrument.

FIG. 4 is a diagram illustrating a light receiving signal generated by a light receiver of the laser surveying instrument.

FIG. 5 is a flowchart showing a processing procedure performed by an autofocus mechanism incorporated in a microcomputer of the laser surveying instrument.

FIG. 6 is a diagram showing an overview of a conventional level planar.

FIG. 7 is a diagram showing an example of a conventional level planar.

FIG. 8 is a diagram showing a target used with the level planar shown in FIG. 7;

FIG. 9 is a diagram showing the principle of the autofocus mechanism of the level planar shown in FIG.

[Description of Signs] 300A Laser surveying instrument (level planar) 60A Target 6A Focus lens (condensing distance changing means) 200A Focus motor (condensing distance changing means) 42A Penta prism (rotating section) 48A Main motor (rotating section) 84A Light receiver 100A Microcomputer (control system)

Claims (3)

[Claims] A rotating unit that emits a visible laser beam;
In a laser surveying instrument comprising a focusing distance changing means for changing a focusing distance of the laser beam and a light receiving device for receiving a reflected laser beam reflected by a target, the light receiving device receives the reflected laser beam. A laser surveying instrument comprising a control system for controlling the focusing distance changing means so that the number of pulses generated when the laser beam is measured is maximized. 2. The control system according to claim 1, wherein when the rotating unit is rotated in a steady state, the scanning operation is performed only when the number of pulses generated when the light receiving device receives the reflected laser beam is plural. The laser surveying instrument according to claim 1, wherein the laser surveying device controls the focusing distance changing unit. 3. A plurality of distance setting steps are previously determined for the focusing distance from a minimum distance to a maximum distance, and the control system changes the distance setting step by one step while changing the pulse number. 3. The laser surveying instrument according to claim 1, wherein a distance setting step in which is maximized is found. 4.