JP5031652B2 - Automatic focus control device for surveying instrument - Google Patents

Description

  The present invention relates to an automatic focus control device for a surveying instrument that is mounted on a surveying instrument such as an electronic level equipped with a telescope that collimates a scale and can automatically focus the telescope on the scale.

  As an electronic level, a pattern image of a scale is converted into an electric signal by a photoelectric conversion unit, a peak of contrast is detected from the obtained electric signal, and focusing control is performed based on the detected value. For example, a telescope optical system including a focusing optical system for forming an image of a scale pattern, a photoelectric conversion unit that receives light from the telescope optical system and converts it into a pattern signal, and a pattern on the photoelectric conversion unit There is a focus drive unit for forming a focus and a focus control unit that detects the focus based on the output signal of the photoelectric conversion unit and controls the focus drive unit (see Patent Document 1).

  At this electronic level, when performing coarse measurement and fine measurement to detect the peak of contrast in the focus control unit, if the contrast value is above a certain value, coarse measurement is omitted and only fine measurement is performed. The time required for focusing is shortened.

JP 2001-91255 A (refer to pages 4 to 7, FIG. 1 and FIG. 5)

  In the prior art, when the contrast value is a certain value or more, the coarse measurement is omitted and only the fine measurement is performed. Therefore, when only the fine measurement is performed, the time required for focusing can be shortened. Depending on the surrounding environment and the like, when it takes time for the contrast value to reach a certain value or more, the time required for focusing increases accordingly.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide an automatic focus control device for a surveying instrument capable of reliably and quickly positioning a focusing lens at a focal point. is there.

  In order to achieve the above object, in the automatic focusing control device for a surveying instrument according to claim 1, a focusing screen disposed between the objective lens and the eyepiece, and an object image formed on the focusing screen. It is mounted on a surveying instrument equipped with a telescope having a collimating optical system in which focusing lenses for adjusting the in-focus state are arranged along the optical axis, and collimates a measuring scale in which a plurality of patterns are arranged at equal intervals. As an object, in an automatic focus control device of a surveying instrument that automatically focuses on the scale, the driving means for moving the focusing lens along the optical axis direction of the collimating optical system, and the collimating optical system Position detection means for detecting the position of the focusing lens, photoelectric conversion means for converting an object image formed on the focusing screen into an electrical signal, and the pitch of the scale pattern from the electrical signal output from the photoelectric conversion means Calculate From the telescope based on the pitch calculation means, the first distance calculation means for calculating the distance from the telescope to the scale based on the calculation result of the pitch calculation means, and the focus lens position detected by the position detection means According to the second distance calculation means for calculating the distance to the scale, drive control means for controlling the drive of the drive means to move the focusing lens over the movable range, and the output of the photoelectric conversion means Contrast value calculation means for calculating the contrast value of the object image from the electrical signal, and the drive control means is configured to move the focusing lens and the calculation result of the first distance calculation means in the process of moving the focusing lens. On the condition that the calculation results of the two distance calculation means match, the detection output of the position detection means and the calculation result of the contrast value calculation means are monitored in association with each other. To the driving means based on the results seen, it has a configuration in which the calculated value of the contrast value calculating means is by positioning the focusing lens to the in-focus lens position at which the maximum value or the maximum value.

  (Operation) In the process of moving the focusing lens along the optical axis direction of the collimating optical system, focusing is performed on the condition that the calculation result of the first distance calculation means matches the calculation result of the second distance calculation means. Assuming that the lens is substantially in focus, the detection output of the position detection means and the calculation result of the contrast value calculation means are monitored in association with each other, and the calculation value of the contrast value calculation means is determined for the drive means based on this monitoring result. Since the focus lens is positioned at the focus lens position when the maximum value or maximum value is shown, the contrast value is maximized after the focus lens is moved to the vicinity of the focus based on the distance from the telescope to the scale. The focusing lens can be positioned at the focusing lens position showing the value or the maximum value, and the focusing lens can be reliably and quickly positioned at the focusing point.

  In the automatic focus control apparatus for a surveying instrument according to claim 2, a focusing screen disposed between the objective lens and the eyepiece lens, and an in-focus state of an object image formed on the focusing screen are adjusted. Mounted on a surveying instrument equipped with a telescope having a collimating optical system in which focusing lenses are arranged along the optical axis, and a focus with a plurality of patterns arranged at equal intervals is used as a collimation target. In an automatic focusing control device of a surveying instrument that automatically adjusts, driving means for moving the focusing lens along the optical axis direction of the collimating optical system, and detecting the position of the focusing lens in the collimating optical system Position detection means, photoelectric conversion means for converting an object image formed on the focusing screen into an electric signal, pitch calculation means for calculating the pitch of the scale pattern from an electric signal output from the photoelectric conversion means, The pin The distance from the telescope to the standard based on the position of the focusing lens detected by the position detection unit and the first distance calculation unit for calculating the distance from the telescope to the standard based on the calculation result of the calculation unit In the process of calculating the second distance calculating means for calculating, and driving the driving means to move the focusing lens along the movable range, the calculation result of the first distance calculating means and the second A focus search range narrower than the movable range is set on condition that the calculation results of the distance calculation means match, and the drive of the drive means is controlled using the focus search range as the movement range of the focusing lens. A contrast value for calculating a contrast value of the object image from an electric signal output from the photoelectric conversion means in a process in which the driving control means and the focusing lens are moving within the focus search range And the drive control means monitors the detection output of the position detection means and the calculation result of the contrast value calculation means in association with each other, and based on the monitoring result, the drive control means The focusing lens is positioned at the focusing lens position when the calculated value of the value calculating means shows the maximum value or the maximum value.

  (Operation) In the process of moving the focusing lens over the movable range, the focusing lens is roughly aligned on the condition that the calculation result of the first distance calculation means and the calculation result of the second distance calculation means match. The focus search range narrower than the movable range is set as being in focus, and the detection output of the position detection means and the calculation result of the contrast value calculation means are calculated while the focusing lens is moving within the focus search range. Monitoring is performed in association with each other, and the focusing lens is positioned at the focusing lens position when the calculated value of the contrast value calculating means indicates the maximum value or the maximum value with respect to the driving means based on the monitoring result. After moving the focusing lens to the vicinity of the focal point based on the distance from the telescope to the scale, the focusing lens can be positioned at the focusing lens position where the contrast value shows the maximum value or the maximum value. It can be, it is possible to reliably and quickly position the focusing lens to the focal point.

  As apparent from the above description, according to the first aspect, the focusing lens can be reliably and quickly positioned at the focal point.

  According to the second aspect, the focusing lens can be reliably and quickly positioned at the focusing point.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view for explaining the relationship between an electronic level and a scale to which the present invention is applied, FIG. 2 is a block diagram of an automatic focus control device of a surveying instrument showing an embodiment of the present invention, and FIG. FIG. 4 is an output waveform diagram of the line sensor for explaining the process from when the telescope is focused to infinity until the focusing lens is positioned at the focal point. FIG. 4 is a position detection for detecting the position of the focusing lens. FIG. 5 is a characteristic diagram for explaining the relationship between the focusing lens position and the contrast value, and FIG. 6 is an operation of the automatic focus control apparatus according to the present invention. It is a flowchart for demonstrating.

  In FIG. 1, the electronic level 2 is configured as a surveying instrument that collimates the scale 1 with a telescope 20 and measures the height h of the collimation position. On the scale 1, a plurality of black marks 11 are displayed on the surface of a white background along the vertical direction (axial direction) of the scale 1, and the center position intervals are displayed at an equal pitch. The widths of the marks 11 in the vertical direction are not all the same, but a plurality of types of marks 11 are arranged on the scale 1 in a predetermined order.

  In other words, a plurality of patterns with the respective marks 11 are formed on the scale 1 as bar code patterns at equal intervals. The standard 1 is normally set in an upright state, but may be set in an inverted state in which the standard 1 is inverted in the vertical direction with respect to the ceiling surface C. In this case, the distance h from the ceiling surface C to the collimation position (hereinafter referred to as the collimation position height h as in the upright state) is measured at the electronic level 2.

  The measurement result of the electronic level 2 is displayed on the screen of the display unit 32 in FIG.

  As shown in FIG. 2, the telescope 20 includes an objective lens 21a, a focusing lens 21b, an automatic compensation mechanism (compensator) 22, a beam splitter 23, a focusing screen 20a, and an eyepiece 20b as a collimating optical system. The focusing lens 21b, the automatic compensation mechanism 22, the beam splitter 23, and the focusing screen 20a are arranged on the optical axis connecting the objective lens 21a and the eyepiece lens 20b. The automatic compensation mechanism 22 includes a mechanism that automatically corrects the horizontal direction (collimation plane) even if the collimation axis at the electronic level is tilted.

  When the collimation target such as the scale 1 is collimated by the telescope 20 having the collimation optical system, the optical signal received by this collimation is the objective lens 21a, the focusing lens 21b, the automatic tilt compensation mechanism 22, and the beam splitter 23. Then, an image is formed as an object image on the focusing screen 20a.

  In order to adjust the in-focus state of the object image formed on the focusing screen 20a, for example, in-focus / in-focus according to the distance from the scale 1, a focusing lens 21b is provided. The lens 21b is arranged so as to reciprocate along the optical axis of the collimating optical system so that it can move over a predetermined range along the optical axis of the collimating optical system. In order to move the focusing lens 21b along the optical axis of the collimating optical system, a stepping motor 41 is connected to the focusing lens 21b via a mechanism (not shown) such as a rack and pinion. .

  This stepping motor 41 is mechanically connected to the focusing lens 21b as driving means for driving the focusing lens 21b, and moves the focusing lens 21b to light of the collimating optical system in response to a pulse signal from the driving circuit 4. It is designed to reciprocate along the axis. The drive circuit 4 amplifies the pulse signal generated by the microcomputer 3 and outputs it to the stepping motor 41.

  At this time, the microcomputer 3 generates a pulse signal for rotating the stepping motor 41 forward and backward, counts the number of steps of the stepping motor 41 based on the generated pulse signal, and views the focusing lens 21b from the counted value. The position detecting means is configured to detect a position in the quasi-optical system.

  Specifically, the microcomputer 3 drives the stepping motor 41 to move the focusing lens 21b once to the end of the movable range to the end on the eyepiece 20b side, and the telescope 20 is moved to an infinite position at that position. When the in-focus state is obtained, the step number of the stepping motor 41 at that time is stored as 0 point, and then each time a pulse signal for moving the focusing lens 21b in the positive direction away from the eyepiece lens 20b is generated, Each time the number is increased and a pulse signal for moving the focusing lens 21b in the reverse direction is generated, the number of steps is decreased, and the focusing lens is calculated from the count value of the number of steps (the total number of steps based on 0 point). The position in the collimating optical system 21b is detected.

  A line sensor 24 is disposed in the vicinity of the telescope 20 at a position conjugate with the focusing screen 20a. The line sensor 24 constitutes an image optical system together with the objective lens 21a, the focusing lens 21b, the automatic compensation mechanism 22, and the beam splitter 23. The optical signal branched by the beam splitter 23 is received by the light receiving surface, and the light receiving surface. The object image formed above (an object image corresponding to an object image formed on the focusing screen 20a) is configured as a photoelectric conversion unit that converts the object image into an electric signal according to the brightness.

  The line sensor 24 is configured by using, for example, a CCD (charge coupled device), and an electric signal generated by the output of the line sensor 24 is amplified by an amplifier 25 and then supplied to an A / D (analog / digital) converter 27. It is designed to be entered.

  The A / D converter 27 samples and holds the input signal in synchronization with the clock signal from the clock driver 26, converts the held analog signal into a digital signal, and outputs the digital signal to the RAM 28. Digital signals obtained by the conversion operation of the A / D converter 27 are sequentially recorded as digital data in designated areas of the RAM 28, and the recorded data is transferred to the microcomputer 3.

  The microcomputer (CPU) 3 calculates the pitch of the mark 11 on the measure 1 from the electric signal output from the line sensor 24, and calculates the distance from the telescope 20 to the measure 1 based on the calculated pitch. And the position of the focusing lens 21b in the collimating optical system (focusing lens position) obtained from the number of steps of the stepping motor 41, and the distance from the telescope 20 to the scale 1 and focusing. It has a function as a second distance calculating means for calculating a distance from the telescope 20 to the staff 1 based on a reference value (data stored in the ROM 31) of a quadratic function set in advance with respect to the relationship with the lens position. .

  When calculating the distance from the telescope 20 to the scale 1 based on the pitch of the marks 11 on the scale 1 using the microcomputer 3, first, the distance to the eyepiece 20b side of the movable range of the focusing lens 21b is adjusted. The focusing lens 21b is moved to bring the telescope 20 into focus at an infinite position. At this time, the image projected onto the line sensor 24 is not clear enough to specify the scale 1, and is mixed throughout. The output signal of the line sensor 24 has a flat waveform as shown in FIG. It has become.

  Prior to moving the focusing lens 21b toward the objective lens 21a from the state where the telescope 20 is focused at infinity, the microcomputer 3 corresponds to the peak from the peak of the output signal of the line sensor 24. The level range α is set as a threshold value, and the focusing lens 21b is moved to the objective lens 21a side until the output signal (level) of the line sensor 24 becomes α or more.

  In this process, as shown in FIG. 3B, when the output signal (peak-to-peak level) of the line sensor 24 is greater than or equal to α, the length of a certain portion of the signal components within α. In addition to obtaining β, a center line CL that is the center position of β is obtained. When there are a plurality of signal components within α, the position of the center line CL is obtained for each location, the interval between the center lines CL is averaged, and the average value is obtained.

  This average value corresponds to an equal interval pitch of the marks 11 on the scale 1 in the image on the line sensor 24. The average value corresponding to the equidistant pitch of the marks 11 indicates a small value when the distance from the telescope 20 to the measure 1 is long, and conversely indicates a large value when the distance from the telescope 20 to the measure 1 is short. For this reason, the distance from the telescope 20 to the staff 1 can be obtained based on the average value of the distance between the center lines CL, which corresponds to the equally spaced pitch of the marks 11 on the staff 1.

  When the telescope 20 is automatically focused on the scale 1, the output signal of the line sensor 24 has a waveform as shown in FIG.

  Further, when the microcomputer 3 is used to detect the position of the focusing lens 21b in the collimating optical system, as shown in FIG. 4, a light emitting diode 50 is disposed above the focusing lens 21b, and the light emitting diode 50 is disposed. The line sensor 51 is arranged along the movable range of the focusing lens 21b, and the output of the line sensor 51 is input to the microcomputer 3 via the A / D converter 52 with a built-in amplifier. The position of the focusing lens 21b in the collimating optical system can be detected by detecting the position of the line sensor 51 that has received the light from the light emitting diode 50. As the line sensor 51, a sensor having the same function as the line sensor 24 can be used.

  When the position detecting means of the focusing lens 21b is used, it is not necessary to store the zero point and perform the operation for the position detection performed by the position detection by counting the number of steps of the stepping motor 41 described above.

  Further, the microcomputer 3 calculates the distance and the second distance calculated by the first distance calculating means in the process of moving the focusing lens 21b toward the objective lens 21a from the state where the telescope 20 is focused on the position at infinity. On the condition that the distances calculated by the means coincide with each other, assuming that the focusing lens 21b is substantially in focus, the driving of the stepping motor 41 is temporarily stopped, and a focusing search range as a moving range of the focusing lens 21b is set. After setting and stopping the driving of the stepping motor 41, the stepping motor 41 is driven again, and the function as a drive control means for moving the focusing lens 21b over the in-focus search range is provided. During this time, the contrast value of the object image is sequentially calculated from the electrical signal output from the line sensor 24, and the peak (maximum value) is calculated from each calculated value. It is configured to include a function as a contrast value calculating means for detecting.

  Further, when the microcomputer 3 moves the focusing lens 21b over the in-focus search range, the microcomputer 3 monitors the detection output (focusing lens position) of the position detection unit and the calculation result of the contrast value calculation unit, and the contrast value. When the peak of the contrast value is detected, the focus lens position when the peak of the contrast value is detected is stored, and the focus control lens 21b is positioned at the focus lens position when the peak of the contrast value is detected. A mechanism as a means is provided.

  When the microcomputer 3 is used to calculate the contrast value of the object image from the output signal of the line sensor 24, as shown in FIG. 5, the microcomputer 3 detects when the focusing lens 21b moves within the focus search range. The output signals of the line sensor 24 are sequentially sampled and differentiated, and the differential values are set as contrast values C1, C2, C3, C4, C5, C6,..., And focusing lens positions L1, L2, L3, L4, L5 , L6,... At this time, since the output signal of the line sensor 24 is an AC signal that changes in brightness, the greater the differential value of the output signal of the line sensor 24, the greater the contrast value.

  The microcomputer 3 stores the contrast values C1, C2, C3, C4, C5, C6,... And the focusing lens positions L1, L2, L3, L4, L5, L6,. The relationship between C1, C2, C3, C4, C5, C6,... And the focusing lens positions L1, L2, L3, L4, L5, L6,. Conversion to f (x), the maximum contrast value or the maximum value is calculated as the contrast value peak CP based on the in-focus determination approximate curve f (x), and the focusing lens corresponding to the contrast value peak CP The position LP is calculated as the in-focus lens position LP.

  Next, the specific operation of the present embodiment will be described based on the flowchart of FIG. First, when the autofocus button 33 is operated, the microcomputer 3 starts autofocus processing, a command accompanying this processing is given to the drive circuit 4, and pulse signals are sequentially output from the drive circuit 4 to the stepping motor 41. . When the stepping motor 41 rotates in response to this pulse signal, the focusing lens 21b temporarily moves to the end on the eyepiece 20b side within the movable range of the focusing lens 21b and stops (S1). At this time, the telescope 20 is in a focused state at an infinite position, and the microcomputer 3 stores the number of steps of the stepping motor 41 as 0 points. If the focusing lens position detection means shown in FIG. 4 is used, the process of S1 can be omitted. In the next process of S2, it is not always necessary to move the focusing lens 21b from ∞ to near. What is necessary is just to determine a moving direction according to a focusing lens position.

  Next, the microcomputer 3 drives the drive circuit 4 to sequentially move the focusing lens 21b to the objective lens 21a side at a predetermined speed (S2). At this time, the microcomputer 3 counts the pulse signal output from the drive circuit 4, monitors the number of steps of the stepping motor 41 from this count value, and corresponds to the peak from the peak of the output signal of the line sensor 24. The level range α is set as a threshold value, and the focusing lens 21b is moved to the objective lens 21a side until the output signal (level) of the line sensor 24 becomes α or more.

  In this process, when the output signal (peak-to-peak level) of the line sensor 24 is greater than or equal to α, the microcomputer 3 uses the mark 11 on the scale 1 based on the average value of the signal components within α. Are calculated, and the distance (pitch calculation distance) from the telescope 20 to the staff 1 is obtained based on the calculated value (S3). Further, the microcomputer 3 calculates the focusing lens position of the focusing lens 21b from the number of steps of the stepping motor 41, and obtains the distance from the telescope 20 to the standard 1 based on this calculated value (S4).

  Next, the microcomputer 3 determines whether or not the distance (pitch calculation distance) obtained from the equidistant pitch of the marks 11 on the scale 1 matches the distance obtained from the focusing lens position of the focusing lens 21b. (S5) If the distance between the two does not match, the process returns to step S3 and the processes of steps S3 to S5 are repeated. If the distance between the two matches, the focusing lens 21b is assumed to be at the approximate focus position. The movement of the focusing lens 21b is temporarily stopped (S6).

  That is, considering that errors in the distance calculation due to individual differences in the optical system or errors in the calculation related to the focusing lens position due to temperature change are taken into account, the equal intervals of the marks 11 on the scale 1 are equal. If the distance obtained from the pitch (pitch calculation distance) and the distance obtained from the focusing lens position of the focusing lens 21b only coincide with each other, the focusing lens 21b is not necessarily at the focusing position.

  Therefore, in order to position the focusing lens 21b at the correct focal point, the microcomputer 3 determines the distance (pitch calculation distance) obtained from the equidistant pitch of the marks 11 on the scale 1 and the focusing lens of the focusing lens 21b. On the condition that the distances obtained from the positions coincide with each other, the in-focus search range is set as the moving range of the in-focus lens 21b for searching the in-focus (S7), and one of the set in-focus search ranges The focusing lens 21b is moved to the end (S8), the focusing lens 21b is moved from one end to the other end, and a search for searching for the focal point is started (S9).

  Next, the microcomputer 3 sequentially samples and differentiates the output signal of the line sensor 24 in order to acquire contrast data at the start of the search, and differentiates each differential value with contrast values C1, C2, C3, C4, C5, Are stored in correspondence with the in-focus lens positions L1, L2, L3, L4, L5, L6,... (S10), and the stored contrast values C1, C2, C3, C4, C5, C6,. .. And the focusing lens positions L1, L2, L3, L4, L5, L6,... Are converted into an in-focus determination approximate curve f (x), and the in-focus determination approximate curve f (x) is used as a basis. In the process of calculating the maximum value or maximum value of the contrast value, it is determined whether the maximum value or maximum value of the contrast value has been obtained by calculation, that is, whether or not a contrast peak has been detected. S11).

  At this time, if the maximum value or the maximum value of the contrast value cannot be obtained by the calculation, the microcomputer 3 repeats the calculation until the maximum value or the maximum value of the contrast value is obtained by the calculation, and the maximum value or the maximum value of the contrast value is obtained. When obtained by calculation, the calculated value is set as the contrast value peak CP, the focusing lens position LP corresponding to the contrast value peak CP is set as the focusing lens position LP, and the focusing lens 21b is set as the focusing lens. The focus lens 21b is moved to the position LP to position the focus lens 21b at the focus lens position LP of the focal point (S12), and the processing in this routine is terminated.

According to this embodiment, while moving the focusing lens 21b along the optical axis of the collimation optical system, the object image accompanying collimation of the telescope 20 is converted into an electrical signal by the line sensor 24 and input to the microcomputer 3. When this occurs, the microcomputer 3 processes the signal to obtain the distance from the telescope 20 to the measure 1 based on the equidistant pitch of the marks 11 on the measure 1, and based on the focus lens position of the focus lens 21b. When the distance from the telescope 20 to the scale 1 is obtained, and the distance between the two coincides, it is determined that the focusing lens 21b is substantially in focus (near the focus), and then the movement of the focus lens 21b is temporarily stopped to achieve the focus In the process of setting the search range and moving the focus lens 21b within the focus search range, the contrast signal is obtained by sequentially differentiating the output signal of the line sensor 24 and associating it with the focus lens position. Together with The relationship with the lens position is converted into an in-focus determination approximate curve f (x), the peak of the contrast value is obtained based on the in-focus determination approximate curve f (x), and the in-focus lens position corresponding to the peak is determined as the in-focus position. Since the focusing lens 21b is positioned, an error occurs in the distance calculation due to an individual difference in the optical system, or an error occurs in the distance calculation due to a change in ambient temperature or an individual difference in the optical system. In addition, the focusing lens 21b can be reliably and quickly positioned at the focal point.
When the microcomputer 3 is used to determine the distance from the telescope 20 to the staff 1, the electrical signal output from the line sensor 24 is an AC signal corresponding to the brightness of the pattern on the staff 1 (AC signal corresponding to the luminance). Is output as an AC signal whose frequency changes depending on the position of the focusing lens 21b, and the distance from the telescope 20 to the scale 1 can be obtained by analyzing the frequency of the AC signal. it can.

  When the microcomputer 3 is used as the drive control means, the calculation of the first distance calculation means is performed in the process of moving the focusing lens 21b toward the objective lens 21a from the state where the telescope 20 is in focus at infinity. On the condition that the difference between the distance calculated by the second distance calculating means and the distance calculated by the second distance calculating means is within the allowable range, the driving of the stepping motor 41 is temporarily stopped and the in-focus state is determined assuming that the focusing lens 21b is substantially in focus After setting the in-focus search range as the movement range of the lens 21b and temporarily stopping the driving of the stepping motor 41, the stepping motor 41 is driven again to move the in-focus lens 21b over the in-focus search range. It can also be configured as follows.

It is a perspective view for demonstrating the relationship between an electronic level and a scale when this invention is applied to an electronic level. It is a block block diagram of the automatic focus control apparatus of the surveying instrument which shows one Example of this invention. It is an output waveform diagram of the line sensor for explaining the process from when the telescope is focused at infinity until the focusing lens is positioned at the focal point. It is a principal block block diagram which shows the other Example of the position detection means to detect the position of a focusing lens. It is a characteristic view for demonstrating the relationship between a focusing lens position and contrast value. It is a flowchart for demonstrating an effect | action of the automatic focus control apparatus which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Standard 2 Electronic level 3 Microcomputer 4 Drive circuit 20 Telescope 20a Focus plate 20b Eyepiece lens 21a Objective lens 21b Focus lens 22 Automatic compensation mechanism 23 Beam splitter 24 Line sensor 41 Stepping motor

Claims (2)

Collimating optics in which a focusing plate arranged between an objective lens and an eyepiece lens and a focusing lens for adjusting a focusing state of an object image formed on the focusing plate are arranged along an optical axis In an automatic focus control device of a surveying instrument that is mounted on a surveying instrument equipped with a telescope having a system and automatically focuses a focus on the measuring scale with a measuring scale in which a plurality of patterns are arranged at equal intervals as a collimation target,
Driving means for moving the focusing lens along the optical axis direction of the collimating optical system, position detecting means for detecting the position of the focusing lens in the collimating optical system, and imaging on the focusing screen Photoelectric conversion means for converting an object image to be converted into an electric signal, pitch calculation means for calculating the pitch of the scale pattern from the electric signal output from the photoelectric conversion means, and the telescope based on the calculation result of the pitch calculation means A first distance calculating means for calculating a distance from the standard to the staff, a second distance calculating means for calculating a distance from the telescope to the standard based on a focus lens position detected by the position detecting means, and the drive Drive control means for controlling the drive of the means to move the focusing lens over the movable range, and the contrast value of the object image is calculated from an electrical signal output from the photoelectric conversion means. A contrast value calculating means for,
The drive control means is configured so that, in the process of moving the focusing lens, the calculation result of the first distance calculation means and the calculation result of the second distance calculation means coincide with each other. The detection output and the calculation result of the contrast value calculation means are monitored in association with each other, and based on this monitoring result, the result when the calculation value of the contrast value calculation means shows the maximum value or the maximum value for the drive means. An automatic focus control device for a surveying instrument in which the focusing lens is positioned at a focusing lens position. Collimating optics in which a focusing plate arranged between an objective lens and an eyepiece lens and a focusing lens for adjusting a focusing state of an object image formed on the focusing plate are arranged along an optical axis In an automatic focus control device of a surveying instrument that is mounted on a surveying instrument equipped with a telescope having a system and automatically focuses a focus on the measuring scale with a measuring scale in which a plurality of patterns are arranged at equal intervals as a collimation target,
Driving means for moving the focusing lens along the optical axis direction of the collimating optical system, position detecting means for detecting the position of the focusing lens in the collimating optical system, and imaging on the focusing screen Photoelectric conversion means for converting an object image to be converted into an electric signal, pitch calculation means for calculating the pitch of the scale pattern from the electric signal output from the photoelectric conversion means, and the telescope based on the calculation result of the pitch calculation means A first distance calculating means for calculating a distance from the standard to the staff, a second distance calculating means for calculating a distance from the telescope to the standard based on a focus lens position detected by the position detecting means, and the drive In the process of controlling the driving of the means and moving the focusing lens along the movable range, the calculation result of the first distance calculation means and the calculation result of the second distance calculation means match. A focusing control range that is narrower than the movable range, and a driving control unit that controls the driving of the driving unit using the focusing range as the moving range of the focusing lens, and the focusing lens includes: Contrast value calculation means for calculating the contrast value of the object image from the electrical signal output from the photoelectric conversion means in the process of moving within the in-focus search range,
The drive control unit monitors the detection output of the position detection unit and the calculation result of the contrast value calculation unit in association with each other, and based on this monitoring result, the calculation value of the contrast value calculation unit for the drive unit An automatic focus control device for a surveying instrument in which the focusing lens is positioned at the focusing lens position when the maximum value or the maximum value.

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