JP5541799B2 - Autofocus surveying instrument - Google Patents

Description

  The present invention relates to an autofocus surveying instrument, and more specifically, an autofocus electronic that can quickly and accurately position a focusing lens at a focusing position regardless of expansion and contraction of a collimating telescope due to a temperature change. The level (electronic level).

  As shown in FIG. 3, the electronic level 2 is for measuring the height h by reading the barcode 11 using the scale 1 with the barcode 11 as a scale. In recent years, an autofocus electronic level has also appeared. As the autofocus electronic level, those disclosed in Patent Document 1 or 2 below are known. As an example of the autofocus electronic level, FIG. 1 shows a block diagram of what is disclosed in Patent Document 2 below.

  This electronic level includes the collimating telescope 20 and the electronic device unit 10. The collimating telescope 20 includes an objective lens 21a, a focusing lens 21b, an automatic horizontal correction mechanism 22, a beam splitter 23, a focusing screen 20a, and an eyepiece 20b.

  The electronic device unit 10 amplifies the output of the position sensor (CCD line sensor) 5 that detects the position of the focusing lens 21b, the CCD line sensor 24 that receives the light divided by the beam splitter 23, and the output of the CCD line sensor 24. An amplifier 25, an A / D converter 27 for A / D converting the output of the amplifier 25, a RAM 28 for storing the output of the A / D converter 27, a CCD drive circuit 29 for driving the CCD line sensor 24, A clock driver 26 that sends a clock signal to the A / D converter 27, the RAM 28, and the drive circuit 29, a stepping motor 41 that moves the focusing lens 21b, a motor drive circuit 4 that drives the stepping motor 41, and a motor drive circuit 4 And a microcomputer 3 for controlling the CCD drive circuit 29, a ROM 31 connected to the microcomputer 3, a display unit 32, an auto Focus and an (automatic focus) button 33.

  Autofocus is performed as follows. First, the focusing lens 21b is positioned closest to the eyepiece lens 20b so that the focusing lens 21b is focused at infinity. In this case, the focus 1 is not focused, and the output of the CCD line sensor 24 cannot find a waveform corresponding to the barcode 11 of the measure 1 as shown in FIG. Here, when the microcomputer 3 performs bandpass processing for extracting a specific frequency component, a waveform as shown in FIG. 4B is obtained. Further, the microcomputer 3 performs band pass filter processing on the output from the CCD line sensor 24 at a specific frequency determined by the pitch of the barcode 11 assuming that the scale is at infinity. Then, a signal having a waveform as shown in FIG. 4C is obtained, but since the maximum value M of this signal does not exceed the threshold value L, the focusing lens 21b is not at the focusing position, and the scale 1 It is determined that was not found.

  Accordingly, when the focusing lens 21b is moved to the objective lens 21a side in accordance with an instruction from the microcomputer 3, the frequency for performing the band-pass filter processing is changed according to the position of the focusing lens 21b. Signals S1, S2, and S3 having waveforms as shown in (a) are obtained. Further, when band-pass filter processing is performed at a specific frequency determined by the distance to the staff 1 and the pitch of the barcode 11 predicted when the focusing lens 21b is assumed to be in the in-focus position, FIG. As shown in FIG. 5, signals S11 and S31 having a waveform corresponding to the barcode 11 are obtained.

Furthermore, when a moving average process is performed in which the area A is moved while taking an average for the area A corresponding to the length of the scale 1, peaks S12 and S32 as shown in FIG. 5C are obtained. . Here, the maximum value M1 of the peak S12 exceeds the threshold value L, and the maximum value M3 of the peak S32 does not exceed the threshold value L. As shown, the area A centered on the maximum value M1 is determined as the standard area.

  Then, as shown in FIG. 5 (e), the period T of the signal S11 is obtained in the standard area A, and this period T corresponds to the pitch of the barcode 11, and the distance to the standard 1 by stadia surveying. Is calculated. If the distance to the scale 1 is obtained, the focusing lens 21b is moved so that the accurate focusing position of the focusing lens 21b matches the position of the focusing lens 21b detected by the position sensor 5. Thus, when the focusing lens 21b is positioned at the correct focusing position, the collimating telescope 20 is completely focused on the scale 1, and the barcode 11 attached to the scale 1 is output from the CCD line sensor 24. Can be read reliably.

JP 2001-12949 A JP 2006-234614 A

  In the electronic level disclosed in Patent Document 2, the distance to the staff 1 when the collimating telescope 20 is focused on (in focus) and the position detected by the position sensor (CCD line sensor) 5. There is a certain relationship with the focusing position of the focusing lens 21b. For example, the relationship between the distance to the scale 1 and the in-focus position of the focusing lens 21b detected by the position sensor 5 (indicated by the number of pixels from one end of the CCD line sensor) is as shown in FIG. Suppose there was.

  However, since the collimating telescope 20 expands and contracts depending on the temperature, the focusing position of the focusing lens 21b differs between the case where the temperature is changed from the normal temperature and the case where the distance to the scale 1 is the same.

  In an autofocus type surveying instrument, since the relational expression between the distance to the scale 1 and the focusing position of the focusing lens 21b detected by the position sensor 5 at room temperature is generally stored, the temperature has changed from room temperature. In this case, there is a problem that the focusing lens 21b cannot be accurately positioned at the in-focus position when the stored relational expression is used.

  The present invention has been made in view of the above problems, and even if the collimating telescope expands and contracts due to the air temperature, the focusing lens can be accurately positioned in a short time without correction by the temperature sensor. It is an object of the present invention to provide an autofocus type surveying instrument that can perform the above-mentioned.

A focusing lens, a position sensor for detecting the position of the focusing lens, a measuring object detecting means for finding a measuring object while moving the focusing lens from an initial position, and a distance calculation for calculating a distance to the measuring object An autofocus surveying instrument comprising : means for finely moving the focusing lens within a preset fine movement range after finding the measurement object by the measurement object detection means, and outputting the position sensor in the fine movement range A true focus position detecting means for determining the position of the focus lens when the maximum contrast is reached and determining the true focus position, and a focus lens calculated from the distance calculated by the distance calculation means A focus position correction amount calculating means for calculating a focus position correction amount from a difference between the in-focus position and the true focus position, and in the second and subsequent measurements, the initial position and the end of the fine movement range When the points are determined, the in-focus position correction amount obtained by the first measurement is added to each point.

In the invention according to claim 2, the focusing lens, a position sensor for detecting the position of the focusing lens, a measuring object detecting means for finding a measuring scale while moving the focusing lens from an initial position, and the measuring scale In an autofocus type level provided with a distance calculation means for calculating a distance to the object , the focus detection lens is finely moved within a fine movement range set in advance after the measuring object is detected by the measurement object detection means . From the distance calculated by the distance calculation means, the true focus position detection means for detecting the contrast of the output of the position sensor and determining the position of the focus lens when the maximum contrast is reached as the true focus position ; Focus position correction amount calculation means for calculating a focus position correction amount from the difference between the calculated focus position of the focus lens and the true focus position is provided, and the initial position is measured in the second and subsequent measurements. When the end point of the position and the fine movement range is determined, the in-focus position correction amount obtained by the first measurement is added to each.

  According to the first aspect of the present invention, the autofocus type surveying instrument is provided with the measuring object detecting means for finding the measuring object while moving the focusing lens from the initial position, and the distance calculating means for calculating the distance to the measuring object. A true in-focus position detecting means for finding a true in-focus position of the in-focus lens while finely moving the in-focus lens within a set fine movement range after finding the measurement object, and the distance calculating means A focus position correction amount calculating means for calculating a focus position correction amount from a difference between the focus position of the focus lens calculated from the distance calculated in step 1 and the true focus position, and the initial position and the fine movement range. The focus position correction amount is added when determining the end point of each lens.For continuous points, even if the focus position correction amount is not known at the first measurement, the focus position correction amount is determined at each measurement. To add The can so that the measured value does not depend on the change in ambient temperature, the focusing lens be expanded and shrunk collimating telescope is the temperature seen can be positioned exactly in-focus position in a short time.

  According to a second aspect of the present invention, there is provided an autofocus type leveling device comprising: a measuring object detecting unit that finds a standard while moving the focusing lens from an initial position; and a distance calculating unit that calculates a distance to the standard. Calculated from the distance calculated by the true focus position detection means for finding the true focus position of the focus lens while finely moving the focus lens within a set fine movement range after finding the A focus position correction amount calculating means for calculating a focus position correction amount from a difference between the focus position of the focused lens and the true focus position, and determining the initial position and the end point of the fine movement range. Since the in-focus position correction amount is added to each, the same effect as in the first aspect of the invention can be obtained.

It is a block diagram of the present invention and a conventional autofocus electronic level. It is a flowchart explaining one Example of the measurement procedure of the said electronic level. It is a figure explaining an electronic level and a staff. It is a figure explaining the output from a CCD line sensor immediately after starting an autofocus by the conventional autofocus type electronic level. It is a figure explaining the output from a CCD line sensor when the distance calculation to a staff is attained with the conventional autofocus type electronic level. It is a figure explaining the relationship between the distance to a scale and the focusing position of a focusing lens.

  First, the principle of the present invention will be described. In the autofocus surveying instrument, for example, as shown in FIG. 6, when the collimating telescope is focused on a measurement object 30 m ahead at room temperature, the position of the focusing lens measured by the CCD line sensor which is a position sensor Is the 1000th pixel (pixel). In addition, when the temperature changes from room temperature, when the object to be measured is 30 meters ahead, the position of the focusing lens is the 980th pixel. In this case, the position of the focusing lens may be added by a focus position correction amount of −20 pixels compared to the case of normal temperature. The focus position correction amount is assumed to be constant regardless of the distance. Then, if the relational expression between the distance to the object to be measured at normal temperature and the position of the focusing lens is known, the distance to the object to be measured is obtained even when the temperature changes from room temperature. By adding only the in-focus position correction amount obtained in advance for the position of the focusing lens, automatic focusing can always be performed.

  Therefore, in the first measurement, the time when the lens is completely focused is detected by detecting the contrast, and the position of the focusing lens at this time is determined as the true focusing position. Further, the distance to the measurement object when the measurement object is accurately focused is obtained, and the in-focus position of the focusing lens is calculated from the relational expression between the distance to the measurement object and the position of the focusing lens. Then, the difference between the in-focus position calculated from the distance and the true in-focus position is calculated, and this difference is stored as the in-focus position correction amount. In the second and subsequent measurements, by using the focusing position correction amount, the focusing lens can be quickly and accurately moved to the focusing position for autofocusing.

  An embodiment of the electronic level according to the present invention will be described below with reference to FIGS. This electronic level includes a microcomputer 3 having a built-in measurement program capable of autofocusing that allows the focusing lens 21b to be quickly and accurately positioned at the in-focus position even if the collimating telescope 20 expands and contracts due to the air temperature. The rest is the same as the conventional autofocus electronic level shown in FIG.

  A measurement procedure performed by the measurement program performed by the electronic level microcomputer 3 will be described in detail based on the flowchart shown in FIG.

  As shown in FIG. 3, when the worker sets the electronic level 2 and the staff 1 to the set positions and turns on the power switch, the measurement program starts. First, the process proceeds to step S1 and waits for the measurement start button for electronic level 2 to be pressed. When the operator collimates the staff 1 and presses the measurement start button, the process proceeds to step S2 where the position of the focusing lens 21b is determined and the lens position range for performing the band-pass filter processing (maximum contrast to be described later is detected). For example, the range in which the focusing lens 21b is moved, for example, a range of ± 1 mm with respect to the position of the focusing lens 21b) is determined. In the case of the first measurement, the focusing position correction amount is set to 0, and the focusing lens 21b is positioned closest to the eyepiece lens 20b. At this time, the focusing lens 21b is in focus at infinity. Further, in the second and subsequent measurements, an in-focus position correction amount described later is added.

  Next, the process proceeds to step S3, where the output from the CCD line sensor 24 is determined by the distance to the staff 1 and the pitch of the barcode 11 which are predicted on the assumption that the focusing lens 21b is at the in-focus position. Perform bandpass filtering at a specific frequency. Then, the process proceeds to step S4 to check whether or not the staff 1 is found from the output of the CCD line sensor 24. The determination as to whether or not the staff 1 has been found is made in the same manner as the electronic level disclosed in Patent Document 2. When the scale 1 is not found, the process proceeds to step S5, the focusing lens 21b is moved to the objective lens 21a side by the lens position range determined in step S2, and the process returns to step S3. Then, steps S3 to S5 are repeated until the staff 1 is found.

  When the staff 1 is found in step S4, the process proceeds to step S6, and the focusing lens 21b is moved to the end point of the lens position range determined in step S2. Also in this case, the focus position correction amount described later is added in the second and subsequent measurements. In the case of the first measurement, the focus position correction amount is set to zero. Further, a temperature sensor is provided, and a change in the relationship between the distance to the measurement point when the temperature changes from room temperature and the in-focus position of the focusing lens (see FIG. 6) is stored. The in-focus position correction amount may be determined.

In step S7, the contrast of the output of the CCD line sensor 24 is detected. The contrast is determined from the differential value in the vicinity of the light / dark boundary with respect to the output of the CCD line sensor 24. In step S8, it is determined whether the maximum contrast has been detected. When the maximum contrast is not detected, the process proceeds to step S9, the focusing lens 21b is finely moved toward the objective lens 21a, and the process returns to step S9. Thereafter, steps S7 to S9 are repeated until the maximum contrast is detected. When the maximum contrast is detected in step S8, the process proceeds to step S10, and the position of the focusing lens 21b when the maximum contrast is reached is the true focus. While determining as a position, the focusing lens 21b is moved to a true focusing position. Next, it progresses to step S11 and performs height and distance measurement similarly to the conventional one. Next, the process proceeds to step S12, and the difference between the focusing lens 21b position obtained from the relational expression between the measured distance to the measured object and the focusing lens 21b position and the true focusing position determined in step S10 is calculated. Thus, this difference is stored as a focus position correction amount. Next, the process returns to step S1, returns to step S1, and waits until the measurement start button is pressed again.

  Then, when another measurement scale 1 is collimated and the measurement start button is pressed, the second and subsequent measurements take into account the focus position correction amount calculated in step S12. Even if it expands and contracts, it is possible to quickly find the standard and to focus the collimating telescope 20 on the standard 1.

As is apparent from the above description, according to the present embodiment, the object detection means (S2 to S5) for finding the measure 1 while moving the focusing lens 21b from the initial position, and the distance to the measure 1 are calculated. In an autofocus level equipped with a distance calculation means (S11), after finding the scale 1, the true position of the focusing lens 21b is found while finely moving the focusing lens 21b within the set fine movement range. In-focus position detection means (S6 to S10), and a focus position correction amount is calculated from the difference between the focus position of the focus lens calculated from the distance calculated by the distance calculation means and the true focus position. A position correction amount calculation unit (S12), and when the initial position and the end point of the fine movement range are determined, the focusing position correction amount is added and the focusing lens 21b is positioned, thereby collimating. Even if the telescope 20 expands and contracts depending on the temperature, the focusing lens 21b can be accurately positioned in a short time. However, the present invention is not limited to the above embodiment, and various modifications are possible. is there. For example, although the above-described embodiment is an electronic level, the present invention can be applied to other surveying instruments capable of measuring distances. Moreover, in the said Example, although distance calculation is performed by stadia surveying, you may obtain | require distance by appropriate means, such as a light wave distance meter.

1 Standard 2 Electronic level 11 Barcode 20 Collimating telescope 21b Focusing lens

Claims (2)

A focusing lens, a position sensor for detecting the position of the focusing lens, a measuring object detecting means for finding a measuring object while moving the focusing lens from an initial position, and a distance calculation for calculating a distance to the measuring object In an autofocus surveying instrument equipped with means,
After the object to be detected is detected by the object to be detected, the focusing lens is finely moved within a preset fine movement range, and the contrast of the output of the position sensor in the fine movement range is detected, and the maximum contrast is obtained. the true focus position detecting means for determining the position of the focusing lens and the true focus position, the focus position and said true focus position of the focusing lens which is calculated from the distance calculated by said distance calculation means A focus position correction amount calculating means for calculating a focus position correction amount from the difference;
An autofocus surveying instrument characterized by adding the in-focus position correction amount obtained by the first measurement to determine the initial position and the end point of the fine movement range in the second and subsequent measurements .
A focusing lens; a position sensor that detects a position of the focusing lens; a measurement object detection unit that finds a standard while moving the focusing lens from an initial position; and a distance calculation unit that calculates a distance to the standard. In the autofocus level with
After the measuring object is detected by the measurement object detection means, the focusing lens is finely moved within a preset fine movement range, and the contrast of the output of the position sensor in the fine movement range is detected. the difference between the true focus position detecting means for determining the position of the focus lens and the true focus position, a focus position and said true focus position of the focusing lens which is calculated from the distance calculated by said distance calculation means An in-focus position correction amount calculating means for calculating an in-focus position correction amount from
An autofocus type level characterized by adding the in-focus position correction amount obtained by the first measurement to determine the initial position and the end point of the fine movement range in the second and subsequent measurements .

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