Abstract:
An electronic level for receiving a reflection light from a pattern marked on a leveling rod and for determining a height of sighting position and a distance to the leveling rod is disclosed. The electronic level comprises an electronic level main unit, a sighting optical system accommodated in the electronic level main unit and for sighting the leveling rod, a line sensor for receiving a part of reflection light, and a control arithmetic unit for calculating a height of sighting position and a distance to the leveling rod based on signals from the line sensor. The electronic level has a crude measurement mode and a precise measurement mode, wherein the crude measurement mode is initiated by the control arithmetic unit, and the measurement mode is changed over to the precise measurement mode by detecting the pattern based on a photodetection signal from said line sensor by measurement.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to an electronic level, for converting a pattern image of a leveling rod to an electric signal and for obtaining a sighting height and a distance to the leveling rod from the electric signal thus acquired. 
         [0002]    A level is a surveying instrument for measuring an elevation difference. In a conventional type level, an operator sights a leveling rod erected at a target point to be measured by using a telescope, and a numerical value indicated on the leveling rod is read by visual inspection. As a result, there has been a possibility that the operator may erroneously read the scale on the leveling rod. 
         [0003]    For the purpose of preventing an error in scale reading of the leveling rod, a new type of electronic level or leveling rod for electronic level has been developed, in which the leveling rod is sighted and a pattern printed is received by a photodetection element. Then, the result is converted to an electric signal, and a position is calculated and is displayed as a numerical value. However, in a pre-stage to determine an elevation difference automatically, the operator must sight the leveling rod for electronic level accurately using the electronic level by visual inspection. Also, the sighting operation must be performed each time the leveling rod for electronic level is moved. As a result, the sighting operation often leads to lower working efficiency. 
         [0004]    Further, in the case of a conventional type electronic level, an operator must change over the measurement mode manually from menu, depending on the measurement condition, thus, much time is required and working efficiency is low. 
         [0005]    The Japanese Patent Publication Laid-open 6-241791 discloses a leveling rod and an electronic level with function to detect the leveling rod, in which a light is emitted by a driving light emitting means, and the light is reflected by a reflection member of the leveling rod for electronic level. After a rotary driving means is driven and the electronic level is rotated, and after confirming that the reflection light has entered a photodetecting means, focusing operation of an objective lens unit is performed. Then, the reflection light is converted by photo-electric conversion, and a signal is taken by a calculation processing means, and the result of calculation such as an elevation difference and a horizontal distance, etc. are displayed on a display unit by the calculation processing means. 
       SUMMARY OF THE INVENTION 
       [0006]    It is an object of the present invention to provide an electronic level, by which it is possible to perform measurement easily even in a case where there is no sufficient working space or at a place where it is difficult to perform the sighting operation. 
         [0007]    To attain the object as described above, an electronic level according to the present invention comprises an electronic level for receiving a reflection light from a pattern marked on a leveling rod and for determining a height of a sighting position and a distance to the leveling rod, and the electronic level comprises an electronic level main unit, a sighting optical system accommodated in the electronic level main unit and for sighting the leveling rod, a line sensor for receiving a part of the reflection light, and a control arithmetic unit for calculating a height of sighting position and a distance to the leveling rod based on signals from the line sensor and for controlling measurement in a crude measurement mode and a precise measurement mode, wherein the crude measurement mode is initiated by the control arithmetic unit, and the crude measurement mode is changed over to the precise measurement mode by detecting the pattern based on a photodetection signal from the line sensor by measurement. 
         [0008]    Also, in the electronic level according to the present invention, the control arithmetic unit detects the leveling rod based on a photodetection signal from the line sensor in the crude measurement mode, and changes to the precise measurement mode by detecting the pattern, and in a case where the leveling rod cannot be detected by the photodetection signal, the precise measurement mode is changed to the crude measurement mode. 
         [0009]    Further, in the electronic level according to the present invention, the sighting optical system has an objective lens unit and an ocular lens unit, and the objective lens unit comprises an optical system with deeper depth of field. 
         [0010]    Also, the electronic level according to the present invention further comprises an operation unit for carrying out setting and a displaying unit for displaying the measurement result, wherein the operation unit, the display unit, and the ocular lens unit are disposed on an upper surface of the electronic level main unit. 
         [0011]    Also, the electronic level according to the present invention further comprises an operation unit for carrying out setting and a display unit for displaying the measurement result, wherein the operation unit, the display unit, the ocular lens unit are disposed on a rear surface portion of the electronic level main unit, and the rear surface portion is rotatable so as to be directed in upward direction. 
         [0012]    Further, the electronic level according to the present invention further comprises a laser emitting mechanism for emitting a guide laser beam in parallel to an optical axis of the sighting optical system. 
         [0013]    According to the present invention, an electronic level comprises a first optical system including an objective lens, a luminous flux selecting member for selectively allowing a part of luminous fluxes to pass through via the first optical system, an optical member where a interference membrane is formed with the luminous fluxes selecting member arranged at object side focal position or approximately at object side focal position, and selecting a wavelength region of the luminous fluxes passing through the luminous fluxes selecting member depending on a position of the luminous fluxes selecting member, a second optical system for guiding the luminous fluxes to the optical member, and an image pickup element for receiving the light in the wavelength region selected by the optical member. As a result, it is possible to easily acquire an optical spectrum of a specific wavelength in a predetermined wavelength region, and to change the specific wavelength in an easy manner, and to simplify the structure with the reduction of the cost. 
         [0014]    Also, according to the present invention, in the electronic level, the control arithmetic unit detects the leveling rod based on a photodetection signal from the line sensor in the crude measurement mode, changes to the precise measurement mode by detecting the pattern, and in a case where the leveling rod cannot be detected by the photodetection signal, the precise measurement mode is changed to the crude measurement mode. As a result, there is no need to manually change the measurement mode each time the measurement is performed, and the working load can be reduced. 
         [0015]    Further, according to the present invention, in the electronic level, the sighting optical system has an objective lens unit and an ocular lens unit, and the objective lens unit has an optical system with deeper depth of field. As a result, focusing operation can be omitted or can be simplified, and further, the working load can be reduced and the working time can be shortened. 
         [0016]    Also, according to the present invention, the electronic level further comprises an operation unit for carrying out setting and a display unit for displaying the measurement result, wherein the operation unit, the display unit, and the ocular lens unit are disposed on an upper surface of the electronic level main unit. As a result, there is no need to confirm the setting and to verify the measurement result from behind the electronic level main unit, and the measurement can be easily performed in a narrow place without sufficient working space. 
         [0017]    Further, according to the present invention, the electronic level further comprises an operation unit for carrying out the setting and a display unit for displaying the measurement result, wherein the operation unit, the display unit, and the ocular lens unit are disposed on a rear surface portion of the electronic level main unit, and the rear surface portion can be rotated so as to be faced in upward direction. As a result, there is no need to confirm the setting and the measurement result from behind the electronic level main unit, and the measurement can be easily performed in a narrow place without sufficient working space. 
         [0018]    Also, according to the present invention, the electronic level further comprises a laser emitting mechanism for emitting a guide laser beam in parallel to an optical axis of the sighting optical system. As a result, an operator can easily perform the working procedure by directing the objective lens unit in a direction toward the leveling rod. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  is a perspective view of an electronic level according to a first embodiment of the present invention; 
           [0020]      FIG. 2  is a perspective view of the electronic level according to the first embodiment of the present invention; 
           [0021]      FIG. 3  is a perspective view to explain measurement of a leveling rod by the electronic level; 
           [0022]      FIG. 4  is a drawing to explain an example of a pattern marked on the leveling rod; 
           [0023]      FIG. 5  is an approximate block diagram to show an optical system of the electronic level; 
           [0024]      FIG. 6  is a flowchart to explain measurement by the electronic level according to the first embodiment of the present invention; 
           [0025]      FIG. 7  is a perspective view of an electronic level according to a second embodiment of the present invention; and 
           [0026]      FIG. 8  is an approximate block diagram to show an optical system of the electronic level. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0027]    Description will be given below on embodiments of the present invention by referring to the attached drawings. 
         [0028]    First, by referring to  FIG. 1  to  FIG. 3 , description will be given on an electronic level  1  and a leveling rod  2  for electronic level in a first embodiment. 
         [0029]    The electronic level  1  primarily comprises an electronic level main unit  3 , a sighting device (sighter)  4  to sight a target point, a base unit  5  to support the electronic level main unit  3  and to perform leveling, an ocular lens unit  6  for sighting the leveling rod  2  for electronic level at the target point, a focusing knob  7  for performing sighting the target point, a direction adjusting knob  8  for adjusting the sighting direction, an objective lens unit  9  of a telescope where a reflection light from the leveling rod  2  for the electronic level enters, an operation unit  11  where a power switch and a menu button and the like to change over a measurement mode are disposed, a display unit  12  where the present measurement mode, measurement results and the like are displayed. 
         [0030]    The operation unit  11  is so arranged that the operation unit  11  can change over various types of modes such as a high-speed continuous measurement mode (a crude measurement mode) to search and capture a pattern of the leveling rod  2  for electronic level by continuously carrying out the crude measurement, a precise single measurement mode for carrying out a precise measurement only once after the pattern is captured, a precise continuous measurement mode (the precise measurement mode) for continuously carrying out the precise measurement, and a precise average mode to display an average value of the precise measurement carried out as many as required as a measurement value on the display unit  12  via the menu button. 
         [0031]    In the present embodiment, an optical system with deeper depth of field is used on the objective lens unit  9 , a focusing operation is not required by using a fixed focal point or operation can be easily performed by using a mechanism, which can set a stage depending on a distance. 
         [0032]    On the leveling rod  2  for electronic level, a predetermined pattern (e.g. a bar code  13 ) is printed or marked (hereinafter described as “marking”) on a straight base, and several types of patterns of the bar code  13  are used as patterns of the bar code to be marked on the base. The leveling rod  2  for electronic level may be designed as convex type where the bar code  13  is marked on a band-like base, which can be wound up. 
         [0033]    For instance, on the bar code  13 , as shown in  FIG. 4 , a first pattern A, a second pattern B and a third pattern R are repeatedly arranged with an equal distance (p). That is, one block is constituted of three types of patterns and each block is continuously formed. If it is defined that a block arranged at the lowest position is  0  block, and if these are marked as R( 0 ), A( 0 ) and B( 0 ) respectively, these are repeatedly arranged as R( 1 ), A( 1 ), B( 1 ), R( 2 ), A( 2 ), B( 2 ), . . . . Because all patterns are repeatedly arranged at equal distance (p), by regarding a signal corresponding to the distance as a reference signal, sighting height can be acquired according to the reference signal. 
         [0034]    Now, referring to  FIG. 5 , description will be given below on an approximate arrangement of the electronic level  1  according to the present invention. 
         [0035]    The electronic level  1  has a sighting optical system  14 , a line sensor  15 , and a control arithmetic unit  16 . Further, the sighting optical system  14  has the objective lens unit  9  including a focusing lens  9   a,  an automatic correcting unit  17 , which is an automatic compensation mechanism for an optical axis, a beam splitter  18 , and the ocular lens unit  6 . 
         [0036]    The beam splitter  18  splits a reflection light from the leveling rod  2  for electronic level entering the sighting optical system  14 . One of the light thus split enters the ocular lens unit  6 , and the other is received by the line sensor  15 . 
         [0037]    The control arithmetic unit  16  performs A/D conversion on the reflection light received by the line sensor  15 , and reads the signal after A/D conversion and controls an uptake of the signal. The control arithmetic unit  16  processes the signal thus taken up, reads a pattern of the bar code  13 , and calculates a height of sighting position and a distance to the leveling rod  2  for electronic level according to the size of the image of the pattern. Also, the control arithmetic unit  16  has a storage unit  19  such as ROM. At the storage unit  19 , parameters, data such as constant, operation expression and various types of programs such as a program for performing measurement, a program for changing over the measurement mode, etc. are stored. 
         [0038]    The automatic correcting unit  17  has a pair of erect prisms  21   a  and  21   b  and a mirror surface member  22 , which is suspended in such manner that a reflection surface of the mirror surface member  22  is kept at horizontal position. Therefore, even when an optical axis of the sighting optical system  14  is tilted, by the gravity keeping a reflected light reflected on the horizontal mirror surface member  22 , the optical axis of the reflection light projected from the erect prism  21   b  is maintained in horizontal direction. 
         [0039]    Next, referring to the flowchart shown in  FIG. 6 , description will be given on a measurement using the electronic level  1 . 
         [0040]    By pressing a power switch of the operation unit  11 , a power is turned on. At the electronic level  1  in the present embodiment, when the power is turned on and an initiation of the measurement is inputted, a high-speed continuous measurement mode for automatically repeating a crude measurement is executed, and a searching of the bar code  13  is started in the high-speed continuous measurement mode. 
         [0041]    As a pre-stage to start the measurement processing, initial stage setting is performed such as a time interval for executing the crude measurement in the high-speed continuous measurement mode, a time interval to perform a precise measurement in a precise continuous measurement mode, how many times the precise measurement is to be performed, an exposure time of a shutter, and the like. For instance, setting is made in such manner that the precise measurement is performed at a rate of 10 times compared with the case of the crude measurement and the precise measurement is carried out at such time interval that the precise measurement is carried out more than 7 times and the measurement results are obtained. 
         [0042]    (Step 01) After the initial setting has been completed, the electronic level main unit  3  is rotated by an operator via the base unit  5  under the condition where the crude measurement is performed. Or, the electronic level  1  is taken up and the objective lens unit  9  is directed toward the leveling rod  2  for electronic level. 
         [0043]    In the crude measurement, the high-speed continuous measurement is carried out at a predetermined time interval, e.g. at an interval of 0.1 second. In a process where the crude measurement is performed, the control arithmetic unit  16  monitors a signal from the line sensor  15  and judges whether or not the leveling rod  2  for electronic level has entered within a visual field of the sighting optical system  14 . That is, the leveling rod  2  for electronic level is searched electronically according to a signal from the line sensor  15 . The operator rotates the electronic level main unit  3 , and a reflection light from the leveling rod  2  for electronic level is projected to the line sensor  15 . When the control arithmetic unit  16  confirms the presence of the leveling rod  2  for electronic level based on a photodetection signal from the line sensor  15 , a first data, which is a data within capturing range including information such as a light amount of the reflection light, is acquired by processing the photodetection signal. 
         [0044]    (Step 02) When the first data is acquired, the control arithmetic unit  16  judges whether the photodetection light amount of the first data thus acquired is adequate or not. Here, it is supposed that the electronic level main unit  3  is continuously rotated. 
         [0045]    (Step 03) In Step 02, when the light amount in the first data is judged to be adequate, the control arithmetic unit  16  judges whether the bar code  13  is present in the first data (i.e. within capturing range) or not. In a case where the bar code  13  is present in the first data even if slightly, the presence of the bar code  13  is displayed on the display unit  12 . Or, by notifying via alarm, it is notified to the operator that the bar code  13  is present in the first data. The operator performs fine adjustment of horizontal angle of the electronic level main unit  3  by using the direction adjusting knob  8  or the like. 
         [0046]    (Step 04) In Step 02, when the photodetection light amount of the first data is judged to be not adequate, the control arithmetic unit  16  calculates exposure time of a shutter based on the result of the judgment. After the result of calculation has been reflected in the setting, acquisition of the first data is carried out in Step 01 again, and the photodetection light amount is judged again in Step 02. 
         [0047]    (Step 05) In Step 03, when the bar code  13  is detected in the first data, it is judged by the control arithmetic unit  16  as to whether the bar code  13  is present throughout the first data or not, that is, whether the bar code  13  is present within an effective code range W (within the range where the precise measurement can be performed). 
         [0048]    In Step 03, when the bar code  13  is judged to be not present in the first data, the operator continues adjustment of horizontal angle of the electronic level main unit  3 , and the control arithmetic unit  16  carries out a series of procedures of Step 01 to Step 03 again. 
         [0049]    (Step 06) In Step 05, when the bar code  13  is judged to be present within the effective code range, the measurement mode is automatically changed over to the precise continuous measurement mode from the high-speed continuous measurement mode by the control arithmetic unit  16 . Further, the control arithmetic unit  16  notifies the operator that the bar code  13  is present within the effective code range by displaying it on the display unit  12  or notifies by means of an alarm different from the alarm of Step 03. The operator recognizes that the bar code  13  is present within the effective code range, and fine adjustment of horizontal angle of the electronic level main unit  3  is stopped. When the measurement mode is changed over by the control arithmetic unit  16 , searching of the bar code  13  to continuously execute the crude measurement is stopped, and the precise measurement is performed under the condition that the line sensor  15  holds the bar code  13 . By processing the signal outputted from the line sensor  15  to the control arithmetic unit  16  in the precise measurement as in the case of the crude measurement, a second data is acquired, which is data including information such as a light amount of the reflection light. 
         [0050]    In Step 05, when the bar code  13  is judged to be not present within the effective code range, a series of procedures of Step 01 to Step 04 are carried out again. The operator performs fine adjustment of horizontal angle of the electronic level  1  until the bar code  13  is detected within the effective code range. 
         [0051]    (Step 07) In Step 06, when the second data has been acquired, it is judged by the control arithmetic unit  16  as to whether the photodetection light amount of the second data acquired is adequate or not. 
         [0052]    (Step 08) In Step 07, when the light amount of the second data acquired is judged to be adequate, the control arithmetic unit  16  reads a pattern of the bar code  13  and a height of sighting position is calculated, and a distance to the leveling rod  2  for electronic level is calculated from the size of the pattern image of the bar code  13 . 
         [0053]    In Step 07, when the photodetection light amount of the second data is judged to be not adequate, the control arithmetic unit  16  calculates exposure time of a shutter according to the light amount of the second data acquired in Step 06. After the result of calculation is reflected in the setting, the first data is acquired again in Step 01, and a series of the procedures in Step 02 to Step 06 is carried out again. 
         [0054]    (Step 09) In Step 08, when the pattern of the bar code  13  is read, it is then judged whether the measurement result has been normal or not by the control arithmetic unit  16 . 
         [0055]    (Step 10) In Step 09, when the measurement result is judged to has been normal, it is judged by the control arithmetic unit  16  as to whether the precise measurement has been performed as many times as required in the initial setting. 
         [0056]    In Step 09, the case where a distance or a height is judged to has not been measured correctly is as follows, for instance: a case where after the bar code  13  is detected within the effective code range in Step 05 and the measurement mode is changed over to the precise continuous measurement mode, by the fact that horizontal angle of the electronic level main unit  3  is displaced, the electronic level main unit  3  overruns and the bar code  13  goes beyond the effective code range. When the measurement result is judged to be not normal, the control arithmetic unit  16  changes over again the measurement mode from the precise continuous measurement mode to the high-speed continuous measurement mode, and the first data is acquired again in Step 01, and a series of the procedures of Step 02 to Step 08 is carried out again. 
         [0057]    (Step 11) In Step 10, when the precise measurement is judged to has been performed as many times as required, an average value of the measurement result of the precise measurement performed as many times as required is calculated by the control arithmetic unit  16 , and the average value is displayed on the display unit  12  as the measured value. 
         [0058]    In Step 10, when the precise measurement is judged to has not been performed as many times as required, a series of the procedures of Step 06 to Step 09 is repeatedly carried out until the number of the precise measurement performed reaches a required number. 
         [0059]    In the case of the electronic level  1  in the present embodiment, a measurement is continued until completion of the measurement is selected in the operation. After the measured value is displayed on the display unit  12 , acquisition of the second data is carried out again in Step 06, and each procedure is repeatedly performed until the completion of the measurement is selected by the operation. 
         [0060]    As described above, in the present embodiment, when the power is turned on and the initiation of the measurement is inputted, the crude measurement is started automatically. When the operator simply directs the electronic level main unit  3  toward the leveling rod  2  for electronic level and rotates the electronic level main unit  3  in a horizontal direction, the bar code  13  marked on the leveling rod  2  for electronic level is detected by the electronic level main unit  3 , and the measurement mode is automatically changed over and the precise measurement is carried out. Therefore, there is no need that the operator manually sets up the measurement mode via the menu button of the operation unit  11  for the purpose of performing the precise measurement. This contributes to the reduction of the working load and to shorten the working time. 
         [0061]    Also, it is so arranged that the operator turns the objective lens unit  9  in a direction toward the leveling rod  2  for electronic level, and by simply rotating, the bar code  13  can be detected automatically and the precise measurement is performed. Thus, there is no need for the operator to perform precise sighting operation, and this reduces the working load and shortens the working time. 
         [0062]    Because the precise measurement can be performed automatically without the sighting operation by the operator, the measurement can be performed easily in such place where there is no additional space for working and the operator hardly goes into because of the presence of interior fittings and tools, piping, etc. in the building, and this contributes to the improvement of conveniences in the operation of the electronic level  1 . 
         [0063]    Because the objective lens unit  9  is changed from a conventional optical system to an optical system with deeper depth of field, there is no need to provide auto-focusing function. This makes it possible to reduce the cost and to omit or shorten the procedure of focusing operation and the working load can be further reduced and the working time can be further shortened. 
         [0064]    Further, in the present embodiment, by simply turning the power on and to input the initiation of the measurement, the crude measurement is automatically started, and the precise measurement can also be automatically started by detection of the bar code  13 . As a result, there is no need to substantially change the mechanical arrangement or circuit arrangement as in the case of conventional type electronic level, and this contributes to the attainment of the procedure at lower cost. 
         [0065]    Because the sighting procedure by the operator is not required in the present embodiment, the sighting device  4  for performing sighting may not be used. 
         [0066]    Because the width of the leveling rod  2  for electronic level is increased, the bar code  13  can be detected in an easier manner by the electronic level  1 , and this contributes to further improvement of working convenience. 
         [0067]    Next, by referring to  FIG. 7  and  FIG. 8 , description will be given on a second embodiment of the present invention. In  FIG. 7  and  FIG. 8 , the same component as in  FIG. 1  or  FIG. 5  is referred by the same symbol, and detailed description is not given here. 
         [0068]    In the case of a electronic level  1  in the second embodiment, an operation unit  11  and a display unit  12  are provided on an upper surface of the electronic level main unit  3  and a part of the reflection light reflected from the leveling rod  2  for electronic level (see  FIG. 2 ) is reflected in upward direction by a beam splitter  18 , and the light enters an ocular lens unit  6 . 
         [0069]    In the second embodiment, the electronic level  1  can be operated from above and the measurement result can be confirmed from above. Therefore, there is no need for the operator to perform operation via the operation unit  11 , and also, there is no need to confirm the display unit  12  from behind the electronic level  1 . This makes it possible to carry out the measurement at such place where there is no space wide enough. This contributes to further improvement of conveniences in the operation of the electronic level  1 . 
         [0070]    In the second embodiment, the ocular lens unit  6 , the operation unit  11 , and the display unit  12  are provided on an upper surface of the electronic level main unit  3 , while it may be so arranged that the ocular lens unit  6 , the operation unit  11  and the display unit  12  are disposed on a rear surface portion of the electronic level main unit  3  similarly to the case of the first embodiment and the rear surface portion is rotatably mounted with respect to the electronic level main unit  3  so that the rear surface portion is faced in upward direction by rotating the rear surface portion. 
         [0071]    Also, it may be so arranged that a laser emitting mechanism for emitting a guide laser beam in forward direction is added on the electronic level  1  and the sighting direction can be confirmed by visual inspection, and also, it may be so arranged that the operator can direct the electronic level  1  in a direction toward the leveling rod  2  of the electronic level more easily. 
         [0072]    Further, it may also be so arranged that a display device is separately furnished or that the display unit  12  is removably installed, and the acquired data can be transmitted to the display device or the display unit  12  via cable or radio communication so that the operator can confirm the display device or the display unit  12  while taking easier posture.