Power-saving control method in laser measuring system and laser measuring system

A power-saving control method in a laser measuring system, which comprises a laser rotary irradiation device for forming a laser reference plane by projecting a laser beam in rotary irradiation and a photodetection device for carrying out position measurement by receiving the laser beam, comprising a step of detecting using status of the photodetection device by the photodetection device, a step of selecting steady operation or power-saving mode based on the detection of using status, a step of transmitting a power-saving mode transition instruction to the laser rotary irradiation device by the photodetection device when the power-saving mode is selected, a step of receiving the power-saving mode transition instruction by the laser rotary irradiation device, and a step of executing power-saving control.

BACKGROUND OF THE INVENTION

The present invention relates to a laser measuring system for forming a reference plane by projecting a laser beam in rotary irradiation from a laser rotary irradiation device, for receiving the laser beam by a photodetection device (light receiving device), and for measuring a position of operation or the like.

In the past, a laser rotary irradiation device has been known as a device for forming a reference plane to indicate a reference for operation in a wide range, and a photodetection device has been known as a device for receiving a laser beam and for measuring a position of the reference plane.

A laser rotary irradiation device forms a reference plane by projecting a laser beam with spot-like luminous flux in rotary irradiation. For instance, by projecting the laser beam in rotary irradiation within a horizontal plane, a horizontal reference plane can be formed. When the laser beam is projected in rotary irradiation within a vertical plane, a vertical reference plane can be formed. When the laser beam is projected in rotary irradiation within a tilted plane, a tilted reference plane can be formed.

A photodetection device has a photodetector for receiving and detecting a laser beam. Based on the laser beam detected by the photodetector, a horizontal reference position, a vertical reference position, etc. can be measured. A laser measuring system can be made up by combining the laser rotary irradiation device and the photodetection device. The laser measuring system using the reference plane formed by the laser beam is used for from the operation in wide range including civil engineering work to the operation in relatively limited space such as room interior finishing work, for example.

When civil engineering work is carried out, for instance, by using the laser measuring system as described above, ground-leveling work or the like is performed within a range of 100 m to 500 m in radius with the rotary laser beam at the center. In civil engineering work such as ground-leveling operation, the use of the reference plane is limited only to temporary use for level alignments, and the reference plane is not needed at all times. Also, in the case the work is temporarily suspended, the reference plane is not used as a matter of course.

However, in case the operation is performed for a wide range in space, when it is in a condition where the reference plane is not needed for the operation, it is troublesome and reduces working efficiency that power to the laser rotary irradiation device is turned on or off each time the condition may arise. In the situation as generally practiced up to now, if the laser rotary irradiation device is driven for once, the laser beam may be continuously projected in rotary irradiation for all day long. This is very wasteful if it is considered from the viewpoint of the efficiency in the use of the reference plane.

On the other hand, a battery is used as the power source for the laser rotary irradiation device, and there are limits in the power supply from the battery. This means that the time to use the laser measuring system may be limited. When the operation by using the laser measuring system is carried out for long time, the battery must be replaced periodically, and spare batteries are needed. Also, the operation must be interrupted during the exchange of batteries. In some cases, it is necessary to perform the setting of the reference plane again. This results in lower working efficiency.

Under the circumstances as described above, there have been strong demands to save the power when the laser measuring system is used.

JP-A-2000-356517 discloses an invention for power-saving control on the photodetection device.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a power-saving control method in a laser measuring system, by which it is possible to control the driving and to save power for the laser measuring system so that power consumption on the laser rotary irradiation device or on the photodetection device can be reduced when the level measurement by using a reference plane is not performed or when the operation by using a reference plane is not performed.

To attain the above object, the present invention provides a power-saving control method in a laser measuring system, which comprises a laser rotary irradiation device for forming a laser reference plane by projecting a laser beam in rotary irradiation and a photodetection device for carrying out position measurement by receiving the laser beam, comprising a step of detecting using status of the photodetection device by the photodetection device, a step of selecting steady operation or power-saving mode based on the detection of using status, a step of transmitting a power-saving mode transition instruction to the laser rotary irradiation device by the photodetection device when the power-saving mode is selected, a step of receiving the power-saving mode transition instruction by the laser rotary irradiation device, and a step of executing power-saving control. Also, the present invention provides a power-saving control method in a laser measuring system as described above, wherein the using status of the photodetection device is judged by detecting at least one of laser beam photodetecting condition by the photodetection device, changes over time of tilting of the photodetection device, and vibration of the photodetection device. Further, the present invention provides a power-saving control method in a laser measuring system as described above, wherein the transition to the power-saving mode is judged based on the fact that non-using status of the photodetection device has continued for a predetermined time period. Also, the present invention provides a power-saving control method in a laser measuring system as described above, wherein the power-saving mode includes at least power-saving operation and shutdown of power supply of the laser rotary irradiation device. Further, the present invention provides a power-saving control method in a laser measuring system as described above, wherein the power-saving mode includes power-saving operations of the laser rotary irradiation device and the photodetection device and shutdowns of power supply to the laser rotary irradiation device and the photodetection device. Also, the present invention provides a power-saving control method in a laser measuring system as described above, wherein leveling operation of the laser rotary irradiation device is also maintained during the power-saving mode.

Further, the present invention provides a laser measuring system, which comprises a laser rotary irradiation device and a photodetection device, wherein the laser rotary irradiation device comprises a laser beam emitter, a rotator for projecting a laser beam in rotary irradiation, a first communication means for performing communication to and from the photodetection device, and a first control unit for controlling operation status of the laser rotary irradiation device including light emitting condition of the laser beam emitter and rotating condition of the rotator to steady operation and to power-saving mode, and wherein the photodetection device comprises a photodetector for detecting the laser beam, a second communication means for performing communication to and from the laser rotary irradiation device, a using status detecting means for detecting the using status of the photodetection device, and a second control unit for judging transition to power-saving mode based on the result of detection from the using status detecting means, wherein a power-saving mode transition instruction is transmitted to the laser rotary irradiation device via the second communication means and the first communication means, and the first control unit controls operating status of the laser rotary irradiation device to the power-saving mode based on the power-saving transition instruction. Also, the present invention provides the laser measuring system as described above, wherein the using status detecting means is at least one of a photodetector for detecting the photodetecting condition of the laser beam, a tilt sensor for detecting the tilting of the photodetection device and a vibration sensor for detecting the vibration of the photodetection device. Further, the present invention provides the laser measuring system as described above, wherein, in the power-saving mode, the light emitting condition of the laser beam of the laser rotary irradiation device is controlled to the decrease of emission light amount or to the stopping of the light emission. Also, the present invention provides the laser measuring system as described above, wherein, in the power-saving mode, the rotation status of the rotator of the laser rotary irradiation device is controlled to the decrease of rotation speed or to the stopping of rotation.

According to the present invention, in a power-saving control method in a laser measuring system, which comprises a laser rotary irradiation device for forming a laser reference plane by projecting a laser beam in rotary irradiation and a photodetection device for carrying out position measurement by receiving and detecting the laser beam, comprising a step of detecting using status of the photodetection device by the photodetection device, a step of selecting steady operation or power-saving mode based on the detection of using status, a step of transmitting a power-saving mode transition instruction to the laser rotary irradiation device by the photodetection device when power-saving mode is selected, a step of receiving the power-saving mode transition instruction by the laser rotary irradiation device, and a step of executing power-saving control. As a result, under the condition where the laser measuring system is not currently used, the power consumed by the laser rotary irradiation device can be reduced, and power consumption in the laser measuring system can be saved.

Also, according to the present invention, the power-saving mode includes at least power-saving operation and shutdown of power supply of the laser rotary irradiation device. This makes it possible to save power both on the laser rotary irradiation device and the photodetection device, and shutdown of power supply is helpful in preventing unintentional failure to turn off the power at the termination of operation.

Further, according to the present invention, there are provided a laser rotary irradiation device and a photodetection device, wherein the laser rotary irradiation device comprises a laser beam emitter, a rotator for projecting a laser beam in rotary irradiation, a first communication means for performing communication to and from the photodetection device, and a first control unit for controlling operation status of the laser rotary irradiation device including light emitting condition of the laser beam emitter and rotating condition of the rotator to steady operation and to power-saving mode, and wherein the photodetection device comprises a photodetector for detecting the laser beam, a second communication means for performing communication to and from the laser rotary irradiation device, a using status detecting means for detecting the using status of the photodetection device, and a second control unit for judging transition to power-saving mode based on the result of detection from the using status detecting means, wherein a power-saving mode transition instruction is transmitted to the laser rotary irradiation device via the second communication means and the first communication means, and the first control unit controls operation status of the laser rotary irradiation device to the power-saving mode based on the power-saving transition instruction. As a result, under the condition where the laser measuring system is not currently used, the power consumed by the laser rotary irradiation device can be reduced, and power consumption in the laser measuring system can be reduced. Also, transition to the power-saving mode can be carried out without the operation by an operation staff, and this is helpful in eliminating waste caused by unintentional failure in operation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Detailed description will be given below on the best mode aspect for carrying out the invention by referring to the attached drawings.

FIG. 1shows a case where the laser measuring system according to the present invention is applied in civil engineering work.

InFIG. 1, reference numeral1denotes a laser rotary irradiation device, and numeral2represents a photodetection device (a light receiving device).

The laser rotary irradiation device1is installed at a predetermined point, preferably at a known point, and at a known height via a tripod3. The photodetection device2is mounted at a position as required on a construction machine4such as a dozer. More concretely, the photodetection device2is fixedly mounted on a mounting pole7erected on an operation tool, e.g. a blade6, of the construction machine4. In this case, it is assumed that a distance from a reference position for photodetection (light receiving) of the photodetection device2to the position of a blade edge6aof the blade6is already known.

A laser beam13is projected by the laser rotary irradiation device1in rotary irradiation. The laser beam13is then detected by the photodetection device2. In this case, the height of the blade6is controlled and adjusted so that photodetecting position at the photodetection device2is maintained at a predetermined position, and ground-leveling operation can be carried out accurately as per the plane as planned.

FIG. 2shows an example of the laser rotary irradiation device1, which comprises a main unit11for containing a laser beam emitter, a projection optical system, a rotary driving mechanism, a leveling unit, etc., a power source accommodating unit12for accommodating power source such as battery, and a rotator14for deflecting the direction of the laser beam13to a horizontal direction and projecting the laser beam13in rotary irradiation. The main unit11further comprises an operation unit15and a first communication unit16such as a radio device.

FIG. 3shows an example of the photodetection device2. The photodetection device2is so designed that the photodetection device2is mounted on the mounting pole7, for instance. The photodetection device2comprises a photodetector18, a display unit19for indicating photodetecting condition, and a second communication unit20such as a radio device, which mutually communicates with the first communication unit16. Inside the photodetection device2, a control unit (to be described later) is provided. The control unit judges operation status of the construction machine4based on the result of photodetection by the photodetector18, and also judges the operation status of the construction machine4based on a tilt sensor as described later, and the control unit controls power-saving condition of the photodetection device2and power-saving condition of the laser rotary irradiation device1.

FIG. 4represents another example of the photodetection device2, which is designed as a portable unit. The photodetection device2comprises a photodetector18, a display unit19, an operation unit22and a communication unit (not shown). Similarly to the photodetection device2as shown inFIG. 3, there is provided inside the photodetection device2a control unit, which detects the level of photodetection light amount and determines light emitting condition of the laser rotary irradiation device1based on the result of detection.

Now, referring toFIG. 5, description will be given on approximate arrangement of the laser rotary irradiation device1.

The rotator14has a pentagonal prism25, which is a deflecting optical member which is rotatably supported, and the pentagonal prism25is rotated by a scanning motor26via a driving gear27and a rotary gear28. It is so designed that a rotation angle of the pentagonal prism25is detected by a rotary encoder29.

The laser beam13emitted from a laser beam emitter31enters the pentagonal prism25via a projection optical system30and is projected after being deflected in a horizontal direction by the pentagonal prism25.

Driving status such as driving, stopping and control of rotation speed of the scanning motor26are controlled by a control unit32. Light emitting condition such as light emission, turning-off of the light, increase or decrease of the light emission light amount, etc. of the laser beam emitter31are controlled by the control unit32.

The control unit32comprises a first arithmetic unit33, a first storage unit34, a light emission driving unit35, and a motor driving unit36. An angle detection signal from the rotary encoder29is inputted to the first arithmetic unit33, and the scanning motor26is controlled to rotate at a predetermined constant speed via the motor driving unit36according to the angle detection signal.

A signal transmitted from the first communication unit16or a signal received at the first communication unit16is inputted to or outputted from the first arithmetic unit33via an input/output control unit37. For instance, a signal transmitted from the photodetection device2is received at the first communication unit16and is inputted to the first arithmetic unit33via the input/output control unit37. The result of calculation at the first arithmetic unit33and an instruction to the photodetection device2, etc. are transmitted to the photodetection device2by the first communication unit16via the input/output control unit37.

The light emission driving unit35emits light and turns off light at the laser beam emitter31based on an instruction from the first arithmetic unit33. The light emission driving unit35has a function as an emission light amount adjusting means of the laser beam emitter31. Based on an instruction to increase or decrease the light amount from the first arithmetic unit33, the light emission driving unit35controls the emission light amount of the laser beam emitter31to the measuring status or to set to the sleeping status by decreasing the light amount.

Various types of programs and data are stored in the first storage unit34. These programs and data include: a control program to drive the scanning motor26at a constant speed or to increase or decrease the speed, a control program to control the light amount of the laser beam emitter31, a setting value necessary for the control, a data table, and further, as described later, a power-saving program for the laser rotary irradiation device to set the power-saving condition in the stages as required.

Referring toFIG. 6, description will be given now on the arrangement of the photodetection device2.

The photodetection device2comprises the photodetector18, a signal processing unit41, a level judging unit42, a second arithmetic unit43, and a second storage unit46, a second input/output control unit47, and a tilt sensor48for detecting the tilting of the photodetection device2.

When the photodetector18receives the laser beam13, a photodetection signal to correspond to the received light amount is outputted. The signal processing unit41performs the processing as necessary such as amplifying on the photodetection signal and determines a peak hold value and outputs the peak hold value to the level judging unit42.

The level judging unit42judges based on the peak hold value whether the received laser beam13is in the measuring status or in the sleeping status after decreasing the light amount. If the laser beam13is in the measuring status, it is judged whether the received light amount is on a photodetection level as necessary or not. The result of the judgment is outputted to the second arithmetic unit43.

In case the level judging unit42judges that the photodetecting condition is in the measuring status, it is judged whether the photodetecting level is adequate or not for the measurement. The result of judgment is inputted to the second arithmetic unit43via an A/D converter44.

Based on the signal from the level judging unit42, the second arithmetic unit43issues an instruction signal. The instruction signal is inputted to the signal processing unit41via a D/A converter45. Based on the instruction signal, gain is adjusted so that the photodetection signal from the photodetector18will be adequate.

When the photodetector18issues a photodetection signal, the second arithmetic unit43transmits an information to indicate that the photodetector18is in the photodetecting condition regardless of whether the photodetection signal is big or small to the first communication unit20via the second input/output control unit47either continuously or at a predetermined time interval.

The tilt sensor48detects whether the mounting pole7is tilted or not with respect to a vertical line, and a tilt detection signal is inputted to the second arithmetic unit43. Based on the tilt detection signal, the second arithmetic unit43calculates the tilting of the mounting pole7, and the level of the photodetecting position of the photodetection device2is corrected according to the result of calculation.

The second arithmetic unit43incorporates the tilt detection signal from the tilt sensor48at a predetermined time interval and calculates the changes over time of the tilt angle of the mounting pole7. In case the tilting of the mounting pole7changes over time, the second arithmetic unit43judges that the blade6is moving, i.e. the construction machine4is in operation.

The tilt sensor48fulfills a function as a means to detect the operation status of the construction machine4and also performs a function as an operation status detecting means for detecting whether the laser measuring system is in operation status or not.

Regarding the operation status of the construction machine4, the information is transmitted from the second communication unit20via the second input/output control unit47to the first communication unit16continuously or at a predetermined time interval.

Various types of programs and data are stored in the second storage unit46. These programs include: an adequate light amount calculation program, a gain adjustment program, and a power-saving program for the photodetection device. Also, the data include: data necessary for calculating the adequate light amount, data necessary for calculating adequate gain, data table for setting the matching of the length of the time without change with power-saving mode (sleeping mode) when the tilt angle is not changed over time.

In this case, the adequate light amount calculation program calculates adequate light amount of the laser beam13according to a photodetection signal from the photodetector18. The gain adjustment program calculates adequate amplification rate (gain) of the signal processing unit41with respect to the light amount of the laser beam13. The power-saving program judges a sleeping mode1, a sleeping mode2or a sleeping mode3respectively corresponding to stopping status, suspension status or operation termination status of the construction machine4when the changes over time of the tilting is not detected according to the tilt detection signal from the tilt sensor48within a predetermined time period of T1, T2or T3. Then, operation status of the device is set up to match the sleeping mode, and the device is controlled to each of the sleeping modes respectively.

Another means for detecting operation status of the construction machine4, e.g. a vibration sensor49may be provided on the photodetection device2. Under the condition that the vibration sensor49detects vibration, it may be judged that the construction machine4is in operation.

Description will be given below on operation of the laser measuring system.

Referring toFIG. 7, description will be given on a first embodiment.

In the first embodiment, the tilt sensor48is used as the means for detecting operation status of the construction machine4.

Power is supplied to the laser rotary irradiation device1, and also power is supplied to the photodetection device2, and operation of the laser measuring system is started.

The photodetector18of the photodetection device2receives the laser beam13. By receiving the laser beam13, the photodetection device2confirms that the laser measuring system has started the steady operation (Step01).

The tilt sensor48detects the tilting, and the result of the detection is outputted to the second arithmetic unit43(Step02).

The second arithmetic unit43incorporates the tilt detection signal from the tilt sensor48at a predetermined time interval, e.g. at a time interval of one second. The tilt detection signal is compared with the tilt detection signal previously incorporated, and it is calculated whether there is any change over time or not (Step03).

It is judged whether the change over time has occurred before the elapse of the time T1or not (Step04). When the change of the tilt angle is confirmed before the elapse of the time T1, it is judged that the operation of the construction machine4is currently continued, and the steady operations of the laser rotary irradiation device1and the photodetection device2are continued (Step05). The time T1is set to about 2 to 5 minutes, for instance. More concretely, the time T1is set from the operation unit22of the photodetection device2by giving full consideration on the condition at each individual operation site and on operation status.

When it is judged in Step04that there has been no change over time within the time T1, it is judged further whether the time T2has elapsed or not (Step06). The time T2is set to about 5 to 30 minutes. Similarly to the case of the time T1, by giving consideration on the conditions at each operation site and operation status, the time T2is set from the operation unit22of the photodetection device2.

In the case it is judged in Step06that the time T2has not elapsed, the sleeping mode1is selected. At the selection of the sleeping mode1, the power-saving program for the photodetection device is started. Then, power-saving control to match the sleeping mode1is performed by the second arithmetic unit43. For instance, power feeding to the photodetector18is stopped. The tilting sensor48and the second communication unit20are controlled so that operation will be continued.

In the power consumption of the photodetection device2, the power consumed by the photodetector18occupies about ⅚ of total power consumption by the photodetecion device2. Thus, significant power-saving effect can be attained.

As well as the photodetection device2is controlled in the sleeping mode1, a sleeping mode1selecting instruction is transmitted to the first communication unit16from the second communication unit20.

The sleeping mode1selecting instruction received at the first communication unit16is inputted to the first arithmetic unit33via the input/output control unit37. Based on the sleeping mode1selecting instruction, the power-saving program for the laser rotary irradiation device is started, and light emitting condition of the laser beam emitter31is changed to the sleeping mode1via the light emission driving unit35. As the sleeping mode of the laser beam emitter31, the decrease of the emission light amount of the laser beam emitter31or the stopping of the light emission is included for instance. The driving condition of the scanning motor26by the motor driving unit36is changed to the sleeping mode1. The change of the driving condition includes the decrease of the rotation speed of the scanning motor26or the stopping of the rotation or the like. As the power-saving control carried out in the sleeping mode1, turning-off of the light on the display unit, suspension of the display etc. are included, too.

The operation for the leveling of the laser rotary irradiation device1is maintained. This is for the purpose of omitting the processing of re-setting of the reference plane when the laser rotary irradiation device is restored from the sleeping mode1to the steady operation. The steady operation for the first communication unit16is maintained so that the information and the instruction can be given to and taken from the photodetection device2(Step07).

In the laser rotary irradiation device1, the power needed for the light emission of the laser beam is in the range of about 30% to 40% of the total power consumption, and the power needed for the driving of the motor is in the range of 30% to 40%. By controlling the laser rotary irradiation device1to the sleeping mode1, high power-saving effect can be attained.

Even in the sleeping mode1, the tilt angle is detected by the tilt sensor48. When there has been any change in the tilt angle, the laser measuring system is restored to the steady operation (Step08).

In the case it is judged that the time T2has elapsed in Step06, it is judged further whether the time T3has elapsed or not (Step09). In this case, the time T3is set as one hour, for instance. Similarly to the case of the time T1, the time T3is set from the operation unit22of the photodetection device2by giving full consideration on the condition at each operation site and on operation status. The time T3is regarded as a reference for judging the termination of operation.

In the case it is judged that the time T2has elapsed, and further that the time T3has not elapsed yet, the sleeping mode2is selected. In the sleeping mode2, the operations of circuits, sensors, etc. other than the tilt sensor48and the second communication unit20are controlled in the suspension status.

When the photodetection device2is controlled in the sleeping mode2, a sleeping mode2selecting instruction is transmitted to the first communication unit16from the second communication unit20.

The laser rotary irradiation device1is controlled in the sleeping mode2based on the sleeping mode2selecting instruction as received according to the power-saving program for the laser rotary irradiation device1. In the condition of the sleeping mode2, the functions of the component members other than the first communication unit16are turned to the suspension status so that the communication can be made with the photodetection device2(Step10).

Even in the status of the sleeping mode2, the detection of tilting by the tilt sensor48is continued. If there is any change in the tilt angle, an operation restoration instruction is issued from the second communication unit20to the first communication unit16, and the steady operation is resumed (Step11).

In the case it is judged that the time T3has elapsed in Step09, the second arithmetic unit43issues a shutdown instruction to the laser rotary irradiation device1according to the power-saving program for the photodetection device. Upon receipt of the shutdown instruction, the laser rotary irradiation device1turns off the power source of the laser rotary irradiation device1according to the power-saving program for the laser rotary irradiation device. At the same time, the photodetection device2turns off the power source of the photodetection device2according to the power-saving program for the photodetection device (Step12).

FIG. 8shows a second embodiment of the invention.

In the second embodiment, the photodetector18is used as the means for detecting operation status of the construction machine4. In the following description, the descriptions for the time T1, the time T2, the time T3, and each of the sleeping modes are the same as those described in the first embodiment, and detailed description is not given here.

When civil engineering work is carried out by using the laser measuring system as described above, the level is detected by receiving and detecting the laser beam13at the photodetection device2. Therefore, if it is watched carefully whether light has been detected or not by the photodetection device2, it is possible to detect whether the laser measuring system is in use or not.

The power source of the laser rotary irradiation device is turned on, the power source of the photodetection device2is turned on, and operation of the laser measuring system is started.

The photodetector18of the photodetection device2receives the laser beam13. By the receiving of the laser beam13, the photodetection device2confirms that the steady operation of the laser measuring system has been started (Step21).

The second arithmetic unit43checks at a predetermined time interval, e.g. at a time interval of one second whether there has been a photodetection signal or not from the photodetector18. It is judged whether the photodetection signal has been received or not before the time T1has elapsed (Step22). When the photodetection signal is confirmed before the elapse of the time T1, it is judged that the operation of the construction machine4is currently continued, and the steady operations of the laser rotary irradiation device1and the photodetection device2are continued (Step23).

When it is judged in Step22that there has been no photodetection signal within the time T1, it is judged further whether the time T2has elapsed or not (Step24).

When it is judged in Step24that the time T2has not elapsed yet, the sleeping mode1is selected. At the selection of the sleeping mode1, the power-saving program for the photodetection device is started, and the photodetection device2performs the power-saving control to match the sleeping mode1. A sleeping mode1selecting instruction is transmitted from the second communication unit20to the first communication unit16, and the laser rotary irradiation device1performs power-saving control according to the power-saving program for the laser rotary irradiation device1(Step25).

In the case the laser beam13is detected by the photodetector18under the condition of the sleeping mode1, the laser measuring system is restored to the steady operation (Step26).

In the case it is judged in Step24that the time T2has elapsed, it is judged further whether the time T3has elapsed or not (Step27).

In the case it is judged that the time T2has elapsed, and it is judged further that the time T3has not elapsed, the sleeping mode2is selected. In the sleeping mode2, the component members (circuits, sensor, etc.) other than the photodetector18and the second communication unit20are controlled and adjusted to the suspension status.

As well as the photodetection device2is controlled in the sleeping mode2, a sleeping mode2selecting instruction is transmitted to the first communication unit16from the second communication unit20.

In the laser rotary irradiation device1, based on the received sleeping mode2selecting instruction and according to the power-saving program for the laser rotary irradiation device, the laser rotary irradiation device1is controlled and adjusted in the sleeping mode2(Step28).

Similarly to the case of the sleeping mode1, even in the status of the sleeping mode2, the photodetecting operation of the laser beam13by the photodetector18is continued. When the laser beam is detected by the photodetector18, the steady operation is started again (Step29).

When it is judged in Step27that the time T3has elapsed, the photodetection device2is shut down according to the power-saving program for the photodetection device, and the laser rotary irradiation device1is also shut down according to the power-saving program for laser rotary irradiation device (Step30).

FIG. 9represents a third embodiment of the invention.

In the third embodiment, the vibration sensor49is used as the means for detecting the operation status of the construction machine4. In the following, the descriptions on the time T1, the time T2, the time T3and each of the sleeping modes are the same as those described in the first embodiment, and detailed description is not given here.

In case civil engineering work is carried out by using the laser measuring system, vibration of the mounting pole7is detected by the vibration sensor49. Therefore, if it is carefully watched whether there is vibration or not by the vibration sensor49, it is possible to detect that the laser measuring system is currently in use or not.

The power source of the laser rotary irradiation device1is turned on, and the power source of the photodetection device2is also turned on. Then, the operation of the laser measuring system is started.

When vibration is detected by the vibration sensor49, the photodetection device2confirms that the laser measuring system has started the steady operation (Step41).

The second arithmetic unit43confirms, at a predetermined time interval, e.g. at a time interval of one second, whether a vibration detection signal has been issued from the vibration sensor49or not. It is judged whether the vibration detection signal has been issued or not before the elapse of the time T1(Step42). If the vibration detection signal is confirmed before the elapse of the time T1, it is judged that the operation by the construction machine4is being continued, and the steady operations of the laser rotary irradiation device1and the photodetection deice2are continued (Step43).

In the case it is judged in Step42that the vibration detection signal has not been issued within the time T1, it is judged further whether the time T2has elapsed or not (Step44).

In the case it is judged in Step44that the time T2has not elapsed yet, the sleeping mode1is selected. At the selection of the sleeping mode1, the power-saving program for the photodetection device is started, and the photodetection device2performs the power-saving control to match the sleeping mode1. A sleeping mode1selecting instruction is transmitted to the first communication unit16from the second communication unit20, and the laser rotary irradiation device1performs power-saving control according to the power-saving program for the laser rotary irradiation device (Step45).

When vibration is detected by the vibration sensor49in the sleeping mode1, the laser measuring system is restored to the steady operation (Step45).

In the case it is judged in Step44that the time T2has elapsed, it is judged further whether the time T3has elapsed or not (Step47).

In the case it is judged that the time T2has elapsed and further that the time T3has not elapsed yet, the sleeping mode2is selected (Step48). In the sleeping mode2, operations of the component members (such as circuits and sensors like the photodetector18, etc.) other than the vibration sensor49and the second communication unit20are controlled in the suspension status. Then, a sleeping mode2selecting instruction from the photodetection device2is transmitted to the first communication unit16from the second communication unit20.

The laser rotary irradiation device1is also controlled to the sleeping mode2based on the received sleeping mode2selecting instruction.

When the vibration is detected by the vibration sensor49during the sleeping mode2, the steady operation is resumed (Step49).

In the case it is judged in Step47that the time T3has elapsed in the status with no detection of vibration, the photodetection device2is shut down according to the power-saving program for the photodetection device, and the laser rotary irradiation device1is shut down according to the power-saving program for the laser rotary irradiation device (Step50).

In the first embodiment, the second embodiment and the third embodiment, description has been given on the cases where the tilt sensor48, the vibration sensor49, and the photodetector18are individually used as the means for detecting the operation status of the construction machine4, while it may be so designed that three of these detection means or any arbitrary two of these are combined together and are used as the means for detecting the operation status. By such combination, the accuracy to detect the suspension status and the termination status of the laser measuring system can be improved, and this contributes to the prevention of erroneous operation in the transition to the sleeping mode.

In the above, description has been given on two aspects of the sleeping mode, while one aspect or three aspects or more may be provided for the sleeping mode.

According to the present invention, wasteful power consumption can be avoided without requiring the intervention of operation staff when the laser measuring system is not currently in use, and this is helpful in achieving successful power-saving effect.