US20010055110A1 - Indicator for an optical instrument - Google Patents

Indicator for an optical instrument Download PDF

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Publication number
US20010055110A1
US20010055110A1 US09/083,963 US8396398D US2001055110A1 US 20010055110 A1 US20010055110 A1 US 20010055110A1 US 8396398 D US8396398 D US 8396398D US 2001055110 A1 US2001055110 A1 US 2001055110A1
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Prior art keywords
lens group
focusing
object distance
detecting device
indicator
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US09/083,963
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US6317199B1 (en
Inventor
Shinichi Suzuki
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Pentax Corp
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Individual
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Assigned to ASAHI KOGAKU KOGYO KABUSHIKI KAISHA reassignment ASAHI KOGAKU KOGYO KABUSHIKI KAISHA ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: SUZUKI, SHINICHI
Publication of US20010055110A1 publication Critical patent/US20010055110A1/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C1/00—Measuring angles
    • G01C1/02—Theodolites
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B23/00—Telescopes, e.g. binoculars; Periscopes; Instruments for viewing the inside of hollow bodies; Viewfinders; Optical aiming or sighting devices
    • G02B23/02—Telescopes, e.g. binoculars; Periscopes; Instruments for viewing the inside of hollow bodies; Viewfinders; Optical aiming or sighting devices involving prisms or mirrors
    • G02B23/10—Telescopes, e.g. binoculars; Periscopes; Instruments for viewing the inside of hollow bodies; Viewfinders; Optical aiming or sighting devices involving prisms or mirrors reflecting into the field of view additional indications, e.g. from collimator

Definitions

  • the present invention relates to an indicator for an optical instrument, for example, an indicator applied to a surveying instrument such as an auto-level or a transit instrument having a telephotographic system.
  • a surveying instrument such as an auto-level or a transit instrument is basically provided with a collimating telescope, a level, and scales for measuring a rotative angle (an azimuth angle) or an elevational angle.
  • a typical auto-level collimating telescope is provided, in order from an object side, with an objective lens group, a focusing lens group, a horizontal compensation and erecting optical system, and an eyepiece lens group. The position of the focusing lens is adjusted according to the distance from the object, so that an image of the object may be formed on a reticle (focusing plate). The operator may thus observe the image superimposed on the reticle via the eyepiece.
  • Surveying instruments such as an auto-level, did not have a distance measuring apparatus that could indicate the distance to an object, for example to a staff.
  • the auto-level may preferably be located at the equal distance position from two measuring points, the auto-level has no function to measure the distance. Therefore in the prior art, the position of the auto-level has usually been decided according to experience and intuition of the operator. Accordingly, it would be convenient if the distance to the measuring point could be made known to the operator.
  • a collimating telescope of surveying instrument in which an automatic focusing apparatus is provided is well known. According to a conventional automatic focusing apparatus, even if accurate focusing is not carried out, as long as the defocus is little enough so that the operator may feel as though the image is focused, the focusing operation would be stopped. However, the measuring of the object distance with the existence of such a defocus may result in a large object distance error.
  • the distance of an object being viewed through a survey instrument having a collimating telescope is conventionally determined as being the distance from the objective lens group of the collimating telescope to the focusing plate, if the focal length of the objective lens group and the focusing lens group, and the distance between the objective lens group and the focusing lens group are known, the object d-stance can be readily determined. Namely, if the amount of movement of the focusing lens group from a reference position (for example, the position of a focusing lens group in infinity) is detected, the distance to the object can be obtained.
  • an indicator for an optical instrument including an observational optical system to observe an image formed by an objective optical system having a focusing lens group, composing of: a lens position detecting device to detect a position of the focusing lens group, a distance detecting device to obtain an object distance according to a position of the focusing lens group detected by the lens position detecting device, and an inside-visual-field display device to display an object distance in a visual field of the observational optical system detected by the distance detecting device.
  • an indicator for an optical instrument including an observational optical system to observe an image formed on a predetermined focal plane by an objective optical system having a focusing lens group, composing of: a split optical system positioned between the objective optical system and the observational optical system, a focusing detecting device to detect a defocus amount at a position equivalent to the focal plane by receiving light divided by the split optical system, a lens driving device to drive the focusing lens group according to a defocus amount detected by the focusing detecting device so that the defocus amount becomes a smallest value, a lens position detecting device to detect a position of the focusing lens group; an object distance detecting device to detect an object distance according to a position of the focusing lens group detected by the lens position detecting device and according to the defocus amount; and an inside-visual-field display device to display an object distance in a visual field of the observational optical system detected by the object distance detecting device.
  • FIG. 1 is a block diagram of main elements of an embodiment of an auto-level to which the present invention is applied;
  • FIG. 2 is a view of an embodiment of the visual field according to the present invention.
  • FIG. 3 is a block diagram of main elements of another aspect of an auto-level to which the present invention is applied;
  • FIG. 4 is a view showing a mechanism of obtaining an object distance according to the embodiment of the present invention.
  • FIG. 5 is a flow chart showing a partial operation (START) in an automatic focusing operation of an auto-level according to the present invention
  • FIG. 6 is a flow chart showing a partial operation (VDD LOOP) in the automatic focusing operation of the auto-level according to the present invention
  • FIG. 7 is a flow chart showing a partial operation (AF OPERATION) in the automatic focusing operation of the auto-level according to the present invention
  • FIG. 8 is a flow chart showing a partial operation (PULSE CALCULATION) in the automatic focusing operation of the auto-level according to the present invention
  • FIG. 9 is a flow chart showing a partial operation (DRIVE DIRECTION CHECK) in the automatic focusing operation of the auto-level according to the present invention.
  • FIG. 10 is a flow chart showing a distance indication operation of the auto-level according to the present invention.
  • FIG. 11 is a flow chart showing the other distance indication operation of the auto-level according to the present invention.
  • FIG. 1 shows an embodiment of an auto-level to which an automatic focusing apparatus according to the present invention is applied.
  • An auto-level 10 consists of a collimating objective lens group 11 of positive power and a focusing lens group 12 of negative power which serve as the objective optical system, an optical horizontal compensation system 13 , a spilt optical system (divided optical system) 16 , a first focusing plate 14 a and a second focusing plate 14 b to integrally serve as a focusing plate (reticle) 14 , and an eyepiece lens group 15 of positive power (observational optical system), in this order from the object side (left side of FIG. 1).
  • the optical horizontal compensation system 13 per se known, consists of a first compensation prism 13 a , a compensation mirror 13 b , and a second compensation prism 13 c , and has a symmetrical shape.
  • the optical horizontal compensation system 13 is hung from a shaft by a string or the like (not shown).
  • the angle defined between the compensation mirror 13 b and the first compensation prism 13 a is identical (in absolute-value) to the angle defined between the compensation mirror 13 b and the second compensation prism 13 c , but are opposite in direction.
  • the angle for example 30° varies depending on the length of the string, etc.
  • the optical horizontal compensation system 13 When the optical horizontal compensation system 13 is set so that the optical axes of the objective lens group 11 and the focusing lens group 12 are substantially parallel (inclined at, for example, about 10 to 15 minutes with respect to the horizontal axis), light incident upon the first compensation prism 13 a is deviated from the horizontal direction by the same amount, but the light reflected by and emitted from the first compensation prism 13 a , the compensation mirror 13 b and the second compensation mirror 13 c , is substantially collimated.
  • the focusing lens group 12 is provided with a rack 12 a secured thereto, which is engaged by a pinion 12 b .
  • a rotation of the pinion 12 b takes place to move the focusing lens group 12 in the optical axis direction, the image of an object 9 formed by the objective lens group 11 and the focusing lens group 12 is translated along the optical axis.
  • the operator views the object image formed on the focusing plate 14 together with the reticle etc., drawn on the focusing plate 14 , through the eyepiece 15 .
  • an indicator 17 provided under the focusing plate 14 .
  • the embodiment shown in FIG. 2 is the indicator 17 which indicates not only the distance information to the object 9 , but also whether or not the focusing is completed, and whether the current focusing state is in auto-mode (AF) or manual-mode (MF).
  • AF auto-mode
  • MF manual-mode
  • a beam splitter (half mirror) 16 is provided in the light path between the objective lens group 11 and the focusing plate 14 to split the light (or light path).
  • a focus detecting system (focus detector) 20 is provided in the split light path to detect the focus state (state of the formed image) at an equivalent surface 14 A which is optically equivalent to the focusing plate 14 .
  • the focusing lens 12 is driven by a lens driver (focusing lens group driving system) 30 in accordance with she output of the focus detector 20 .
  • the focus detector 20 includes an AF sensor 21 located in the vicinity of the equivalent surface 14 A, so that the defocus amount (defocus, front focus, rear focus) can be detected in accordance with the output of the AF sensor 21 , of which structure is known per se.
  • the AF sensor in the present embodiment is a phase matching type, in which the object image on the equivalent surface 14 A is split by a condenser lens and a pair of separator lenses (image forming lenses) spaced at a distance identical to the base length, and is re-formed on a pair of CCD line sensors.
  • the CCD line sensors are each provided with a number of photoelectric transducers which convert the object image received into electrical charges which are integrated (accumulated). The integrated charges are successively output as AF sensor data.
  • the AF sensor data is amplified by a preamplifier 22 before being supplied to the calculation/control circuit 23 .
  • the calculation/control circuit 23 calculates the defocus amount through a predetermined defocus calculation in accordance with the AF sensor data.
  • the displacement and direction of the movement of an AF motor 31 (the number of output pulses, referred to hereinafter as “AF pulses” of an encoder 33 ) necessary to move the focusing lens 12 until the defocus amount becomes zero is also calculated in accordance with the defocus amount.
  • the number of AF purses is set in an AF pulse counter 23 a incorporated in the calculation/control circuit 23 .
  • the calculation/control circuit 23 drives the AF motor 31 through an AF motor drive circuit 25 , in accordance with the rotational direction of the AF motor 31 , in order to be decrement the AF pulse counter 23 a by detecting the output from the encoder 33 .
  • the rotation of the AF motor 31 is transmitted to the pinion 12 b through a clutch-incorporated reduction mechanism 32 to move the rack 12 a (namely, the focusing lens group 12 ).
  • the calculation/control circuit 23 also controls the driving speed and stopping of the AF motor 31 based on the amount counted by the AF pulse counter 23 a . Namely, when the counted amount is larger than a predetermined amount, the driving speed becomes high, and when the counted amount is smaller than the predetermined amount, the driving speed becomes low to allow braking, etc.
  • the calculation/control circuit 23 detects the defocus amount (i.e. detects focusing) against the object 9 by device of the focus detector 20 and the lens driver 30 , in order to move the focusing lens group 12 in the optical axis direction. Accordingly, when the absolute amount of defocus is smaller than the predetermined amount, the lens driver 30 stops at that point, being determined as in-focus. Thus the focusing is essentially completed with respect to the object 9 .
  • the focusing lens group 12 (rack 12 a ) is provided with a movement detector 19 to detect the moving amount of the focusing lens group 12 from an infinity focal position.
  • the distance to the object 9 in a focused state is uniformly defined according to the focal lengths of the objective lens group 11 and the focusing lens group 12 , the distance between the objective lens group 11 and the focusing plate 14 , and the distance between the objective lens group 11 and the focusing lens group 12 . Accordingly, when the moving amount of the focusing lens group 12 is detected by the movement detector 19 , the distance to the object 9 may be obtained.
  • the calculation/control circuit 23 obtains the object distance based on the amount of movement of the focusing lens group 12 detected by the movement detector 19 , and indicates the obtained object distance on the indicator 17 .
  • the movement detector 19 may include, for example, a code-plate/brush mechanism known per se, to detect the absolute position of the focusing lens group 12 .
  • the movement detector 19 may also include, for example, an optical encoder which detects the relative position of the focusing lens group 12 , namely the moving amount from the reference position (infinity focal position).
  • the focus detector 20 is provided with an AF start switch 27 to start the automatic focusing operation, a focusing operation knob 34 to change modes of focusing, and an AF switch 29 which detects the AF mode (that is, the mode which is not the manual focus mode).
  • the pinion 12 b is driven in either a manual focus mode by the focusing operation knob 34 , or in an autofocus mode, in which the automatic focusing operation is carried out in accordance with the focus detector 20 and the lens driver 30 .
  • the auto-level 10 is constructed such that the focusing mode is switched between the autofocus mode, in which the focusing lens group 12 is driven in accordance with the output of the focus detector 20 , and the manual focus mode, in which the focusing lens group 12 is driven manually regardless of the output of the focus detector 20 .
  • the focusing operation knob 34 which constitutes a mode switching device between the manual focus mode and the autofocus mode
  • the manual mode is obtained
  • an autofocus mode is obtained.
  • the clutch-incorporated reduction mechanism 32 disconnects the AF motor 31 from the reduction mechanism 32
  • the clutch-incorporated reduction mechanism 32 clutches the AF motor 31 with the reduction mechanism 32 .
  • the clutch-incorporated reduction mechanism 32 may either be constructed so as to maintain connection with the focusing operation knob 34 at all times regardless of position (mode) of the focusing operation knob 34 , or be constructed so as to disconnect from the focusing operation knob 34 when switched to the autofocus mode.
  • the calculation/control circuit 23 detects whether the focusing operation knob 34 is switched to the autofocus mode when the AF switch 29 is turned OFF.
  • FIG. 3 shows another aspect according to the embodiment of the present invention, wherein the auto-level 10 according to the embodiment of FIG. 1 has an indication projector 172 above the beam splitter 16 , instead of the indicator 17 , to project the indication data such as distance information.
  • the indication light projected from the indication projector 172 is incident on the beam splitter 16 through a projection lens 173 .
  • the light is then reflected toward the focusing plate 14 at a surface of the beam splitter 16 on which the split light is reflected, so that the light may be incident on the lower portion of the focusing plate 14 .
  • the projection lens 173 is adjusted to be focused on the focusing plate 14 , the lower portion of the focusing plate 14 indicates, the object distance, whether AF or MF, and whether focused or not focused, as shown in FIG. 2.
  • the projection of the distance information by the indication projector 172 is controlled by the calculation/control circuit 23 .
  • the lens system is an inner focus lens which forms an image on a focusing surface P at a fixed position, by a fixed objective lens group L 1 and a movable focusing lens group L 2 , likewise the case of the collimating telescope as shown in FIG. 1.
  • Marks G 1 and G 2 respectively correspond to principal points of the objective lens group L 1 and the focusing lens group L 2 .
  • f1 is the focal length of the objective lens group L 1
  • f2 is the focal length of the focusing lens group L 2
  • L is the distance from the principal point G 1 (of the objective lens group L 1 ) to the focusing surface p
  • a is the distance from the principal point G 1 to the object 9 (hereinafter “object distance”)
  • b is the distance from the principal point G 1 to an image point I 1 of the object 9 formed by the objective lens group L 1
  • d is the distance between the principal points G 1 and G 2
  • a′ is the distance from the principal point G 2 (of the focusing lens group) to the focal point f1 of the objective lens group L 1
  • b′ is the distance from the principal point G 2 to the focusing surface p.
  • the focal lengths f1 and f2 and the distance L from the principal point G 1 to the focusing surface p are invariable values so long as the image optical system is an inner focus type, and the lens distance d+ ⁇ d is a variable number according to the object distance a.
  • the distance d′ between the principal points G 1 and G 2 can be obtained as follows:
  • the focal lengths f1 and f2 the distances L from the principal point G 1 to the focusing surface p, and the distance d between the lenses, are fixed. Therefore, when the moving amount of the lens ⁇ d is measured, it is possible to obtain the object distance “a” by applying the formulas (3) through (8).
  • the above formulas relate to the operation to obtain the object distance for an inner focus telephotographic optical system.
  • the object distance “a” may be obtained by:
  • the above formulas are the examples to obtain the object distance “a” by calculation. However, it is also possible to obtain the distance by reading the object distance data corresponding to table data.
  • the table data is recorded in a memory (EEPROM 26 ) by calculating the relation between the object distance “a” and the moving amount ⁇ d of the focusing lens group L 2 in advance through calculation of every predetermined step of the focusing lens group L 2 When the moving amount of focusing lens group L 2 is detected, the object distance data can be read corresponding to the table data.
  • the object distance is indicated on the indicator 17 or by the indication projector 172 by detecting the moving amount of the focusing lens group 12 at predetermined intervals when the AF start switch 27 is turned ON, regardless of the automatic focusing operation mode (AF mode) or the manual focusing operation mode (MF mode).
  • AF mode automatic focusing operation mode
  • MF mode manual focusing operation mode
  • step S 101 When the battery (not illustrated) is loaded, an internal RAM and input/output ports, are firstly initialized at step S 101 to subsequently enter the power-down operation at step S 103 . Thereafter, no operation at steps S 101 and S 103 are performed unless the battery is unloaded and is then reloaded.
  • the power-down operation corresponds to a stand-by operation in which the power source is OFF (except to calculation/control circuit 23 and the movement detector 19 ) while the AF start switch 27 is OFF to wait for the operation of the AF start switch 27 . If the AF start switch 27 is turned ON, the power source is turned ON to perform the AF operation (automatic focusing operation).
  • flags for the AF operation are reset at step S 105 .
  • flags to be reset there are several kinds of flags to be reset, including a focusing flag which represents that a focused state is obtained, an AFNG flag which represents that the automatic focusing operation cannot be carried out, a re-integration flag which represents that the integration operation is performed after the focused state has been obtained, and a search/overlap flag which is adapted to discriminate that the integral operation is performed during movement of the focusing lens 12 .
  • step S 107 If the reset operation for the AF operation is completed, a check is made to determine whether the AF start switch 27 is turned ON (step S 107 ). Since the AF start switch 27 is OFF at the initial position in which no operation by the operator occurs, the “OFF” data is written in the AF start switch memory (steps S 107 , NO; S 109 ). Thereafter, a check is made to determine whether the power source is ON at step S 113 . Since the power source is OFF at the initial position in which no power is supplied to each circuit (step S 113 : NO), the control is returned to step S 105 and the operations at steps S 107 , S 109 and S 113 are repeated.
  • step S 111 If the AF start switch 27 is turned ON at step S 107 , the control proceeds to step S 111 to check whether the AF start switch memory is ON. When the AF start switch memory is OFF (the AF start switch memory is OFF at the first time), the control proceeds to step S 119 to write “ON” data in the AF start switch memory, and to start a power hold timer (steps S 111 , NO; S 119 ). Thereafter, if the AF switch 29 is turned ON (in the AF mode), the power source is turned ON to supply power to the circuits in order to perform the VDD loop operation (steps S 121 ; S 123 , YES; S 125 ). If the AF switch 29 is OFF, which corresponds to the manual focusing mode, the control is returned to step S 101 (S 123 , NO; S 113 ).
  • the power source is turned ON by turning the AF start switch 27 ON, thereby the power is supplied to each circuit until the time of the power hold timer is up.
  • the distance is displayed on the indicator 17 or by the indication projector 172 .
  • the automatic focusing operation is carried out to obtain a focused state while detecting the state of the AF start switch 27 , and if the focused state cannot be obtained, the control is returned to step S 113 .
  • step S 210 the state of the AF switch 29 is input again (step S 210 ), and the control will be able to proceed provided that the AF switch 29 is ON. If the AF switch 29 is OFF, which corresponds to the manual focus mode, the control is returned to the power-down operation (steps S 201 ; S 203 , NO; S 113 ). The following discussion will be given on the assumption that the AF switch 29 is ON.
  • the AF switch 29 is ON, the AF operation is performed to detect the defocus amount and accordingly move the focusing lens group 12 to a focal position (steps S 203 , YES; S 205 ). While the AF start switch 27 is maintained ON, a check is made to determine whether the AF start switch memory is ON at step S 211 .
  • step S 119 Since the AF start switch memory has been ON at step S 119 , the focusing flag and the AFNG flag are checked (steps S 207 , YES; S 211 , YES; S 215 ; S 217 ) Since the focusing flag and the AFNG flag are both cleared if no focused state nor the impossibility of the focusing operation are detected during the AF operation, the control is returned to step S 201 (steps S 215 , NO; S 217 , NO; S 210 ).
  • the focusing lens group 12 has been moved to the focal position during the AF operation at step S 205 , and when the focusing flag is set to “1”, the control is returned to the power-down operation (steps S 215 , YES; S 113 ). If focusing cannot be effected for some reason, for example, when the aiming object moves or is too dark or is too low in contrast, the AFNG flag is set to “1” to return the control to the power-down operation at step S 101 (steps S 217 : YES, S 113 ).
  • step S 207 When the AF start switch 27 is turned OFF during the VDD loop operation, the control proceeds from step S 207 to step S 209 to write “OFF” in the AF start switch memory. The control then proceeds to step S 215 by jumping step S 211 (steps S 207 : YES, S 209 , S 215 ).
  • step S 203 when the AF switch 29 is turned OFF during the VDD loop operation, that is, when the focusing operation knob 34 is switched to the manual focus position, the control is returned from step S 203 to step S 101 to end the AF operation S 203 , NO; S 113 ).
  • step S 113 When the control is returned to the power-down operation (step S 113 ), a check is made to determine whether the power source is turned ON at step S 113 . When the power source is OFF, the control is returned to the step S 105 . When the power source is ON and the power hold state is maintained,the control is returned to step S 107 (steps S 113 , YES; S 115 , YES; S 107 ). When the power hold state is released, the control is returned to step S 105 by executing the power-down operation (steps S 115 , NO; S 117 ; S 105 ). The term “maintaining” of the power hold means that the power hold timer has not lapsed.
  • step S 205 The AF operation at step S 205 will be described below in detail with reference to the flow charts shown in FIGS. 7 through 9.
  • the overlap flag, the search flag and the reintegration flag are checked (steps S 301 , S 303 , S 305 ). Since all the flags have been cleared at step S 105 at the first step, the AF sensor executes the integration and the integration result is input as AF sensor data to calculate the defocus amount (steps S 301 , NO; S 303 , NO; S 305 , NO; S 307 ).
  • a correlation ratio of the data of a pair of AF sensors is obtained, so that the direction of defocus (front focus or rear focus) and the defocus amount can be obtained in accordance with the correlation ratio.
  • the focus check operation is performed. If a focused state is obtained, the focus flag is set to “1”. If a focused state is not obtained, i.e., an out-of-focus state, the focus flag is set to “0”(steps S 309 , YES; S 321 ). In the illustrated embodiment, when the defocus amount is within a predetermined limit or allowance, it is considered that a focused state is obtained. If the focused state is obtained at step S 323 , the control is returned to the VDD loop operation to perform the operations at step S 207 and steps subsequent thereto (step S 323 , YES). In the case of an out-of-focus state, the control proceeds to the pulse calculation operation (step S 323 , NO).
  • the number of AF pulses are calculated based on the effective defocus amount.
  • the amount of drive of the AF motor 31 (the number of AF pulses supplied from the encode 33 ) necessary to move the focusing lens group 12 until the defocus amount is zero is attained.
  • step S 331 When the control enters the AF pulse calculation operation, the drive direction of the AF motor 31 and the number of AF pulses are calculated in accordance with the defocus amount (step S 331 ).
  • the obtained AF pulse number is set in the AF pulse counter 23 a and the AF motor 31 is DC-driven and the pulse checking is carried out (steps S 333 , S 335 ).
  • the value of the AF pulse counter 23 a is decreased by one every tire one AF pulse is output from the encoder 33 .
  • the drive speed of the AF motor 31 is controlled in accordance with the value of the AF pulse counter 23 a. Namely, when the counted number is larger than the overlap-integration-prohibition-pulse-number, the AF motor 31 is driven at a high speed to move the focusing lens 12 toward the focal position within a short space of time and the overlap integration is also effected. When the counted number is smaller than the overlap-integration-prohibition-pulse-number, although the AF motor 31 is still driven at high speed, the overlap integration is prohibited.
  • the AF motor 31 is driven under PWM (Pulse Width Modulation) at low speed to prevent the focusing lens group 12 from moving beyond the focal position.
  • PWM Pulse Width Modulation
  • step S 341 the value of the AF pulse counter 23 a is compared with the overlap-integration-prohibition-pulse-number. If the counter value is larger than the overlap-integration-prohibition-pulse-number, the control proceeds to step S 343 in which the overlap flag is set to “1”. Thereafter, the overlap integration begins, and the AF sensor data is input from the AF sensor 21 to perform the amount-of-defocus calculation (steps S 341 , NO; S 343 ; S 345 ). If an effective calculation result is obtained, the control proceeds to the drive direction check operation (step S 347 : YES), and if no effective calculation result is obtained, the control is returned (step S 347 , NO).
  • the AF pulse number is calculated and set in the counter, based on the AF sensor data obtained by the integration during driving of the AF motor 31 . If the drive direction changes, the AF motor 31 is braked and stopped. In the illustrated embodiment, the AF motor 31 is braked by the short-circuiting of the AF motor 31 at opposite electrodes thereof.
  • step S 361 When the control enters the drive direction check operation, the overlap flag is set to “1”, and the search flag is set to “0” (step S 361 ). Thereafter, the previous and present drive directions of the focusing lens group 12 are compared in accordance with the calculation result (step S 363 ). When the directions are identical with each other, the AF pulse number is calculated at an intermediate point of the integration, so that the calculated value is set by the counter (steps S 363 , YES; S 365 ). Subsequently, the control is returned. If the drive direction changes, the AF motor 31 is braked and stopped. Consequently, the overlap flag is set to “0” and the re-integration flag is set to “1”. Thereafter, the control is returned to the VDD loop operation (steps S 363 , NO; S 367 ; S 369 ; S 371 ).
  • step S 207 When the control is returned to the VDD loop operation, the operations at step S 207 and steps subsequent thereto are carried out, and the control enters the AF operation again. If no change in the drive direction occurs, the control proceeds to the pulse check operation from step S 301 since the overlap flag is set to “1”. The operations from step S 341 to step S 347 and the operations of the drive direction check operation from step S 361 to step S 365 are carried out and the control is returned to step S 205 for the pulse check operation. These operations are repeated until the counter value is smaller than the overlap-integration-prohibition-pulse-number.
  • step S 349 stop the AF motor 31 upon completion of driving of the AF motor corresponding to the calculated AF pulse number.
  • control does not proceed until the AF pulse number is smaller than the constant speed control start pulse number. If the AF pulse number is smaller than the constant speed control start pulse number, the AF motor 31 is driven at a low speed in accordance with the remaining AF pulse number. When the AF pulse number is zero, the AF motor 31 is stopped (steps S 349 , YES; S 351 ; S 353 , NO).
  • the overlap flag is set to “0”, and the re-integrat ion flag is set to “1” (steps S 353 , YES; S 355 ). Thereafter, the control is returned to the VDD loop operation.
  • step S 205 of the VDD loop operation the control then enters the re-integration operation at step S 305 , since the overlap flag and the search flag are set to “0” and the re-integration flag is set to “1”. The same is true when the drive direction changes at step S 363 .
  • the defocus amount is calculated and whether or not the telescope is focused is checked in accordance with the defocus amount thus obtained. If a focused state is obtained, the focusing flag is set to “1”, and if a focused state is not obtained, the AF pulse is calculated again to move the focusing lens group 12 .
  • step S 215 If the control is returned to the VDD loop operation when the focusing flag is set to “1”, the control proceeds to the power-down operation from step S 215 . Thus, the AF operation ends and the control waits for the operation of the AF start switch 27 .
  • the integration starts, the AF sensor data is input, and the defocus amount is calculated at step S 307 (steps S 301 , NO; S 303 , NO; S 305 , NO; S 307 ). If it is impossible to calculate the effective defocus amount for some reason, for example, when the object contrast is too low, the control proceeds to the search integration operation from step S 309 (steps S 309 , NO; S 311 ).
  • the integration and the defocus calculation are carried out to obtain an effective defocus amount while driving the AF motor 31 from a close focal position to an infinity focal position. If no effective defocus amount is obtained even by the search integration operation, the AFNG flag is set to “1” and the control is returned and enters the power-down operation at step S 217 .
  • the control enters the search integration operation (search operation)
  • the AF motor 31 is firstly search-driven (in the direction of the close focal position) and the search flag is set to “1” to commence the integration by the AF sensor 21 .
  • the integral value is input as the AF sensor data to calculate the defocus amount by defocus calculation (steps S 311 , S 313 , S 315 ). If the effective defocus amount is obtained, the control proceeds to the drive direction checking operation (step S 317 , YES). If no effective defocus amount is obtained, the control is returned to the VDD loop operation to perform the operations at step S 207 and steps subsequent thereto (steps S 317 , NO; S 319 ).
  • the AF motor search-driving operation refers to an operation in which the AF motor 31 is first driven in the direction of the close focal position and when the focusing lens 12 reaches and stops at a movement extremity on the close distance side, the AF motor 31 is driven in the reverse direction, i.e., in the direction of the infinity focal position.
  • the AF motor 31 is stopped. If an effective calculation result is obtained during the search driving, the AF motor is driven in accordance with the effective value of the defocus amount.
  • the control enters the operation at step S 205 of the VDD loop operation, the overlap flag is cleared. Since the search flag is set to “1”, the control enters the search integration operation at step S 303 and the search integration operations at step S 313 and steps subsequent thereto are carried out. If no effective calculation result is obtained when the focusing lens group 12 reaches the infinity focal position, the control enters the AFNG operation, in which the AFNG flag is set to “1”. Thereafter, the control is returned to the VDD loop operation and enters the power-down operation at step S 217 (steps S 317 , NO; S 319 , YES; S 391 ).
  • step S 381 the control proceeds to the AFNG operation from step S 385 .
  • the AFNG flag is set to “1” in the AFNG operation and thereafter, the control is returned to the VDD loop operation and enters the power-down operation at step S 217 (S 385 , NO; S 391 ).
  • the interrupt operation whereby the calculation/control circuit 23 interrupts at regular intervals via a hard timer during executing the above operations, will now be described with reference to FIG. 10.
  • the moving amount data from the reference position of the focusing lens group 12 detected by the movement detector 19 (counter value) are input at step S 401 .
  • the amount-of-movement data is represented by ⁇ d.
  • the object distance “a” is obtained by calculation based on the amount-of-movement data (step S 403 ).
  • the obtained object distance is displayed on the indicator 17 (step S 405 ).
  • the state of the AF switch 29 is input at step S 407 . If the AF switch 29 is OFF, namely the present state is not the AF mode, the manual focus mode as well as the out-of-focus state are displayed (steps S 407 ; S 409 , NO; S 411 ; S 413 ). Then the control is returned. If the AF switch 29 is ON, namely the present state is the AF mode, the AF mode is displayed (steps S 407 ; S 409 , YES; S 415 ). Thereafter, the focusing flag is checked. If the focusing flag has been set to “1”, the focused state is displayed (steps S 417 , YES; S 419 ). Conversely, if the focusing flag has been set to “0”, the out-of-focus state is displayed (steps S 417 , NO; S 421 ).
  • the above interrupt operation may display the object distance currently focused, on the display 17 a in the visual field of the indicator 17 , both in the autofocus mode and the manual focus mode.
  • an amount-of-defocus to be considered as being focused in the automatic focusing operation is set within a predetermined amount, and the object distance may be obtained with reference to the amount-of-defocus.
  • FIG. 11 shows the second embodiment of the present invention, which is illustrated by a flow chart of the distance indication operation. This distance indication is actuated according to the forced interruption at regular intervals by a timer, similar to the distance indication operation shown in FIG. 10.
  • the number of calculations is firstly cleared at step S 501 .
  • the number of calculations relates to a counter which counts and controls the number of calculations of the defocus amount.
  • the lens position counter value is then input from the movement detector 19 , and the AF sensor data is also input to calculate the defocus amount (steps S 503 , S 505 ).
  • step S 507 , YES; S 508 ; S 509 , NO; S 505 the control is returned to step 505 (steps S 507 , YES; S 508 ; S 509 , NO; S 505 )
  • the calculations of the defocus amount are repeated several times to improve accuracy of calculation of the defocus amount.
  • the control proceeds to step S 515 (steps S 509 , YES; S 511 ; S 513 ; S 515 ). If the telescope is in an out-of-focus state, the control jumps from step 507 to step 515 (steps S 507 , NO; S 515 ).
  • the object distance “a” is calculated at step 515 based on the lens position counter value and the lens position amended data.
  • the calculated object distance “a” is then displayed in a visual field of the indicator 17 or by the indication projector 172 (step 517 ).
  • the focusing flag is checked.
  • the focused state the focused state is displayed (steps S 519 , YES; S 521 ), and in the out-of-focus state, the out-of-focus state is displayed (steps S 519 , NO; S 523 ).
  • the state of the AF switch 29 is input at step 525 .
  • the AF mode AF switch 29 is ON
  • the AF mode is displayed and the control is returned (steps S 527 , YES; S 529 ).
  • the manual focus mode namely not in the AF mode (AF switch 29 is OFF)
  • the MF mode is displayed (steps S 527 , NO; S 531 ).
  • step S 533 , YES; S 535 If the defocus amount is not effective, the control is returned by jumping step 535 (step 533 , NO).
  • the object distance is displayed by not only using the position of the focusing lens group 12 , but also using the defocus amount detected by the AF sensor 21 , thus an accurate object distance may be detected and displayed.
  • the defocus direction and the defocus amount are displayed, it is possible to confirm whether the accurate focused state is obtained, and in the case of an out-of-focus state, it is possible to confirm whether the present state is front focus or rear focus, as well as the amount of error thereof.
  • the display is not limited to be positioned in the visual field, and may be positioned outside the optical instrument.
  • the above embodiments are applied to an auto-level, the present invention can be equally applied to other surveying instruments, such as a transit or a total station, as well as a telescopic optical system such as a telescope or a binocular telescope, etc.
  • the object distance is indicated in the visual field of observation, by obtaining the object distance from the position of the focusing lens group, in regard to the optical instrument in which the focusing is carried out by moving the focusing lens group.
  • the operator can easily confirm the object distance during observing the object.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Astronomy & Astrophysics (AREA)
  • Optics & Photonics (AREA)
  • Automatic Focus Adjustment (AREA)
  • Telescopes (AREA)
  • Measurement Of Optical Distance (AREA)
  • Lens Barrels (AREA)
US09/083,963 1997-05-23 1998-05-26 Indicator for an optical instrument Granted US20010055110A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP9133844A JPH10325718A (ja) 1997-05-23 1997-05-23 光学機器の表示装置
JP9-133844 1997-05-23

Publications (1)

Publication Number Publication Date
US20010055110A1 true US20010055110A1 (en) 2001-12-27

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US09/083,963 Expired - Fee Related US6317199B1 (en) 1997-05-23 1998-05-26 Indicator for an optical instrument
US09/083,963 Granted US20010055110A1 (en) 1997-05-23 1998-05-26 Indicator for an optical instrument

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JP (1) JPH10325718A (ja)
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RU2491586C1 (ru) * 2012-01-23 2013-08-27 Российская Федерация, от имени которой выступает Министерство промышленности и торговли РФ Автоколлимационное углоизмерительное устройство

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JP3873272B2 (ja) * 2001-11-09 2007-01-24 フジノン株式会社 被写体距離表示装置
US20040046938A1 (en) * 2002-09-05 2004-03-11 Gary Gero Automatic and manual lens focusing system with visual matching for motion picture camera
DE10317483A1 (de) 2003-04-16 2004-11-04 Steiner-Optik Gmbh Abbildende optische Vorrichtung, insbesondere Fernglas oder Fernrohr
WO2004104667A1 (en) * 2003-05-22 2004-12-02 Koninklijke Philips Electronics N.V. Distance measurement in motor-driven focusing systems
US6903811B2 (en) * 2003-08-11 2005-06-07 Kamakura Koki Co., Ltd. Rangefinder binoculars
JP3951984B2 (ja) * 2003-08-22 2007-08-01 日本電気株式会社 画像投影方法、及び画像投影装置
JP4996043B2 (ja) * 2004-06-15 2012-08-08 株式会社トプコン 光波距離測定方法及び光波距離測定装置
CN100437187C (zh) * 2004-06-30 2008-11-26 皇家飞利浦电子股份有限公司 测量设备
JP2013221831A (ja) * 2012-04-16 2013-10-28 Topcon Corp 電子レベル
CN108141522A (zh) * 2015-11-30 2018-06-08 深圳市大疆创新科技有限公司 成像系统和方法
JP6983517B2 (ja) * 2017-03-02 2021-12-17 株式会社トプコン 測量機

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JPS58217911A (ja) * 1982-06-14 1983-12-19 Hoya Corp 距離表示付双眼鏡
US5231441A (en) * 1988-12-23 1993-07-27 Ricoh Company, Ltd. Focusing device for driving focusing lens group according to a position of zoom lens group
US5258802A (en) * 1989-04-30 1993-11-02 Minolta Camera Kabushiki Kaisha Camera system which compensates for defocusing during operation
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JPH0752626A (ja) 1993-08-10 1995-02-28 Mitsubishi Motors Corp 車両の懸架装置
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US20090185279A1 (en) * 2005-05-23 2009-07-23 Hisashi Goto Image Pickup apparatus
US7787188B2 (en) * 2005-05-23 2010-08-31 Olympus Imaging Corp. Image pickup apparatus
US20130057720A1 (en) * 2010-03-15 2013-03-07 Nikon Corporation Electronic device
RU2491586C1 (ru) * 2012-01-23 2013-08-27 Российская Федерация, от имени которой выступает Министерство промышленности и торговли РФ Автоколлимационное углоизмерительное устройство
RU2491586C9 (ru) * 2012-01-23 2013-11-10 Российская Федерация, от имени которой выступает Министерство промышленности и торговли РФ Автоколлимационное углоизмерительное устройство

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US6317199B1 (en) 2001-11-13
DE19823076B4 (de) 2008-06-12
JPH10325718A (ja) 1998-12-08
DE19823076A1 (de) 1998-11-26

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