JP3340642B2 - Automatic focusing equipment for surveying equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic focusing apparatus having a telephoto optical system and suitable for surveying instruments such as an automatic level, a theodolite, and a transit.

[0002]

2. Description of the Related Art A surveying instrument such as an automatic level, transit, or theodolite basically includes a collimating telescope, a level, a scale for measuring a rotation angle, an elevation angle, and the like. Then, the surveying instrument is set horizontally, and the collimating point or the collimating object is collimated by the collimating telescope.

A collimating telescope of a general surveying instrument includes an objective lens, a focusing lens, and an eyepiece in order from the object side, and the focusing lens uses a reticle (reticle) to image the object according to an object distance. ) Is adjusted in position (focus adjustment) to form an image thereon. The user observes the image overlapped with the reticle through the eyepiece.

The collimating telescope of the surveying instrument has an object distance range of 1 m to ∞ which is much wider than that of a general telescope. When the focusing lens has a concave lens, the moving distance of the focusing lens is about 30 mm. . The focus adjustment lens is normally driven by a rotation operation of a rotation knob. However, if the amount of movement of the object image (that is, the amount of movement of the focus adjustment lens) is set to be smaller than the rotation angle of the rotation knob, the focus adjustment lens is smaller than the rotation angle It takes time to move the lens instead of moving the object image small. Conversely, if the amount of movement of the object image is larger than the rotation angle of the rotary knob, the amount of movement of the object image is too large compared to the rotation angle, making it difficult to stop the object image on the reticle. When the object is at a long distance, the object image moves back and forth greatly by slightly rotating the rotary knob. On the other hand, when the object is at a relatively short distance, the object image moves relative to the rotation amount of the rotary knob. The rotation amount of the rotation knob required to move the object image onto the reticle becomes too large. Furthermore, since it cannot be determined whether the collimated object is a front focus or a rear focus, the rotation knob may be rotated in a direction opposite to the focusing direction. In any case, conventional survey equipment
There is a problem that it takes a long time to adjust the focus.

Therefore, it is conceivable to mount a so-called passive type automatic focusing device on the surveying instrument. in this case,
The optical path of the collimating telephoto system is branched, and the object image formed at a position equivalent to the reticle in the branched optical path is re-imaged on the sensor, and defocus is detected based on the output of the sensor. Then, the focus is adjusted. However, surveying instruments often use a staff as a collimating object. In collapsing the staff, the size of the staff image on the imaging plate, that is, the size of the staff image on the sensor, decreases as the distance increases. Therefore, in the passive type autofocus device, the focus state (defocus) of the object around the staff with a large area is detected on the sensor, and there is a possibility that the staff is not focused.

[0006]

SUMMARY OF THE INVENTION The present invention has been made based on the above problem awareness of the conventional surveying instrument, and a surveying instrument which can surely focus on an object regardless of the size of the object and the distance to the object. An object of the present invention is to provide an automatic focusing device for an apparatus.

[0007]

SUMMARY OF THE INVENTION To achieve this object, the present invention provides focus detection means for detecting focus detection areas of different sizes symmetrical with respect to the center of the field of view of a telephoto optical system, and a reliability exceeding a certain value. And determining means for validating the narrowest focus detection area among the focus detection areas obtained by the above. According to this configuration, the narrowest focus detection area among the focus detection areas in which the reliability equal to or higher than a certain value is obtained is determined to be valid. Therefore, if the automatic focus adjustment is performed based on the focus detection area determined to be effective, it is possible to always focus on the object at the center of the visual field.

Further, the present invention provides a telephoto optical system, comprising: an objective lens group, a focusing lens group, a reticle having a reticle, and an eyepiece group for observing an object image formed on the reticle. A light beam splitting optical system disposed between the focusing lens group and the focusing screen, and as the light receiving unit,
A line sensor disposed in a divided optical path divided by the light beam dividing optical system and receiving a light beam in a horizontally long area around the reticle at an equivalent position to the focusing screen; Calculating means for performing the determination based on the output from the line sensor included in the detection area, and calculating a defocus amount based on the output of the line sensor included in the focus detection area determined to be valid by the determination means; Focus adjusting lens group driving means for moving the focus adjusting lens group based on the defocus amount calculated by the calculating means can be provided. According to this configuration, with the reticle as the center, automatic focus adjustment is performed for the narrowest area where an effective distance measurement result is obtained.For example, even when collimating a narrow staff, regardless of the distance to the staff. Focus on the staff.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of an automatic level to which an automatic focusing device according to the present invention is applied. The auto level 10 includes, from the object side, a positive collimating objective lens group 11,
The optical system includes a negative focusing lens group 12, a horizontal compensation optical system 13, a reticle (focal plane) 14, and a positive eyepiece lens group 15.

The horizontal compensating optical system 13 is a well-known one, and includes a first compensating prism 13a, a compensating mirror 13b and a second compensating mirror 13b.
It has a left-right symmetrical shape with a competing prism 13c, and is suspended from a shaft via a cord (not shown). Competition mirror 13b and first and second competition prisms 1
The angles with 3a and 13c are, for example, 30 [deg.] Having the same absolute value and opposite signs. This angle differs depending on factors such as the length of the cord. When the optical axes of the objective lens group 11 and the focus adjustment lens group 12 are set substantially horizontal (for example, in a state inclined from the horizontal by about 10 to 15 minutes), the horizontal compensation optical system 13 enters the first compensating prism 13a. Deviates from the horizontal by the same deviation amount, but the first competition prism 13a, the competition mirror 13b and the second competition prism 1
The luminous flux reflected and emitted at 3c is substantially horizontal.

A rack 12a is fixed to the focusing lens group 12 as lens moving means, and a pinion 12b meshes with the rack 12a. By rotating the pinion 12b to move the focusing lens group 12 along the optical axis, the position of the image of the object 9 formed by the objective lens group 11 and the focusing lens group 12 is parallelized along the optical axis. Can be moved. The worker
The object image formed on the reticle 14 is observed by the eyepiece 15 together with the reticle and the like drawn on the reticle 14.

A branching optical element (half mirror) 18 for branching the optical path is arranged in an optical path from the objective lens group 11 to the focusing screen 14, and a focus state (equivalent surface 14A of the focusing screen 14 on the equivalent surface 14A) in the branching optical path. A focus detection system 20 for detecting an imaging state is provided, and a focus adjustment lens group drive system 30 for driving the focus adjustment lens group 12 based on the output of the focus detection system 20 is provided.

A focus detection system 20 for detecting a focus state of the equivalent surface 14A has an AF sensor 21 disposed near the equivalent surface 14A, and detects an amount of defocus based on an output of the AF sensor 21. is there. AF of the present embodiment
The sensor 21 is of a phase difference method. As shown in FIG. 2, the object image on the equivalent surface 14A is formed by a condenser lens 21a and a pair of separator lenses (imaging lenses) 21b arranged apart from each other by a base line length. The image is divided and re-imaged on the pair of CCD line sensors 21c. The incident position of the object image on the pair of line sensors 21c is determined when the image of the object 9 is accurately formed on the equivalent surface 14A (in focus) or when the image is formed ahead of the equivalent surface 14A ( When an image is formed behind the equivalent surface 14A (front pin) and when the image is formed behind (the rear pin)
And the shift amount (defocus amount) from the in-focus position can also be determined based on the image formation position of the object image on the pair of line sensors 21c.

The CCD line sensor 21c has a large number of photoelectric conversion elements (light receiving elements) as shown in FIG. 3 as a reference portion. Each photoelectric conversion element photoelectrically converts a received object image and performs photoelectric conversion. The converted charges are integrated (accumulated), and the integrated charges are sequentially output as AF sensor data (image data).

In the line sensor 21c, the collimating axis (vertical line v) of the reticle is located at the center (design center) with respect to the reticle provided on the reticle 14, and the horizontal line is parallel to the horizontal line h. It is arranged to be located at the center. Therefore, when collimating the measurement staff (staff) 9 vertically set on the ground surface, the image of the staff 9 is orthogonal to the line sensor 21c (see FIGS. 5 to 8). According to this arrangement, since the longitudinal direction of the survey staff 9 does not coincide with the direction in which the line sensor 21c extends, the contour of the survey staff 9 (both sides).
And automatic focus adjustment becomes possible.

The auto level 10 is composed of four focus detection areas Z1 symmetrical with respect to the entire focus detection area Z and the center (vertical line v) of the CCD line sensor 21c used for automatic focus adjustment. , Z2, Z3, Z4. Note that the focus detection area is not a mechanically or optically partitioned area, but a CCD line sensor 2.
It refers to the range of pixels that have output AF sensor data used for calculation of focus detection among the AF sensor data output from 1c.

A monitor sensor 21d is provided adjacent to the CCD line sensor 21c to control the integration time according to the brightness of the object image. This monitor sensor 21d includes three monitor sensors M1, M2, M3.
It has. The AF sensor 21 is a monitor sensor M
The outputs of 1, M2, and M3 are detected to control the integration time of the CCD line sensor 21d, that is, the end of integration. The operation / control circuit 23 is provided with a monitor M
1, M2 and M3 can be selected.

The AF sensor data output from the pair of CCD line sensors 21c is amplified by a preamplifier 22 and input to a calculation / control circuit 23. The calculation / control circuit 23 calculates a defocus amount by a defocus calculation based on the pair of AF sensor data. In the present embodiment, the defocus amount is set to 0 based on the defocus amount.
The driving direction and the driving amount (the number of output pulses (hereinafter referred to as “AF pulses”) of the encoder 33) of the AF motor 31 required to move the focus adjustment lens group 12 to the position are calculated.

The arithmetic and control circuit 23 drives the AF motor 31 via the AF motor drive circuit 25 based on the calculated rotation direction and the number of AF pulses of the AF motor 31.
The rotation of the AF motor 31 is transmitted to the pinion 12b via the clutch built-in deceleration mechanism 32, and the focus adjustment lens group 1
2 (see FIG. 1).

The rotation of the AF motor 31 is controlled by an encoder 33
The arithmetic / control circuit 23 detects and counts the pulses output by the control unit, and performs speed control and stop control based on the count value and the number of pulses previously calculated. The focus detection system 20 and the focus adjustment lens group drive system 30
As a result, the focusing lens group 12 is driven along the optical axis in accordance with the object distance, and is automatically focused.

The focus detection system 20 includes, as switches, an AF start switch 27 for starting automatic focus adjustment processing, a mode switch 28 for changing a mode relating to focus adjustment, and an AF switch.
An AF switch 29 for detecting the mode (not the manual focus mode) and an offset dial 35 are provided. AF start switch 27
This is a push button switch that is turned on when pressed by a user or the like, and is automatically reset (off) when the pressing force is removed. AF
The switch 29 is a switch that is turned on when the focus operation knob 16 is depressed to enter the automatic focus adjustment mode in conjunction with the movement of the focus operation knob 16 in the axial direction.

The pinion 12b can be driven by one of manual focus adjustment by the focus operation knob 16 and automatic focus adjustment by the focus detection system 20 and the focus adjustment lens group drive system 30. In other words, the auto level 10 includes an auto focus mode (automatic focus adjustment) in which the focus adjustment lens group 12 is driven by the output of the focus detection system 20 and the focus operation knob 16 that is manually rotated without being driven by the output of the focus detection system 20 The mode can be switched to a manual mode (manual focus adjustment) in which the focus adjustment lens group 12 is moved.

As means for switching between the auto focus mode and the manual mode, for example, when the manual focus operation knob 16 is moved in one of the axial directions, the mode is switched to the manual mode, and when the knob 16 is moved to the other, the auto focus (AF) is performed. ) Mode. Further, the arithmetic / control circuit 23 knows that the focus operation knob 16 has been switched to the auto focus mode by the fact that the AF switch 29 is on.

In a surveying instrument which performs autofocusing based on an object image formed on the line sensor 21c as in the auto level 10, if the survey staff 9 is at a short distance (for example, 5 m), FIG. Since the ratio of the surveying staff 9 to the background in the collimating field of view F of the collimating telescope is large as shown in FIG. In the figure, a is a dimension on the conjugate plane 14A when the survey staff 9 has a width of 70 mm (3.3 mm in this embodiment).
, B indicates the width dimension (4 mm) of the maximum focus detection area Z by the line sensor 21c (actually, the entire area Z itself is not displayed, but the corresponding distance measurement zone mark is displayed), h indicates a horizontal hairline, and v indicates a vertical hairline (thickness 0.003 mm).

However, as the object distance of the survey staff 9 gradually increases from 5 m to 10 m, 20 m, 30 m, 50 m, as shown in FIGS. The width is c (1.7 mm) and d (0.8
mm), e (0.6 mm) and g (0.3 mm). On the other hand, at this time, since the width dimension of the maximum focus detection area Z by the line sensor 21c is constant, the ratio of the background in the collimated visual field F gradually increases.

The magnification of the collimating telescope comprising the collimating objective lens group 11 and the focusing lens group 12 is set to 24 times,
4, the diameter of the finder field frame is about 6 mm, the receivable area (maximum focus detection area Z) of the line sensor 21c is about 4 mm, the combined focal length of the collimating objective lens 11 and the focusing lens group 12 is about 240 mm, The width of the staff 9 for surveying is 70 mm
The image size of the survey staff 9 on the reticle plate 14 when the survey staff 9 is set at the following object distance from the auto level 10 and the ratio of the survey staff 9 to the collimated visual field F and the line sensor 21c are shown below. , 10, 20, 30, 50m
The visual field at the time of is shown in FIGS.

Distance (m) Image Size (mm) Image Size / Field of View (%) Image Size / Detection Area (%) 3 3.5 93 138 5 3.3 56 82 10 1.65 28 41 20 0.83 14 21 30 0.55 9 14 50 0.33 6 8

As shown in this table, the line sensor 2
When the width dimension of the maximum focus detection area Z of 1c is fixed, when the object distance is 10 m or more, the ratio of the survey staff 9 occupying the maximum focus detection area Z becomes very small. Therefore,
It is understood that as the object distance increases, the ratio of the background other than the survey staff 9 in the collimated visual field F increases. Therefore, in such a case, there is a possibility that the image of the staff 9 is blurred due to the influence of the background and the distance measurement and focusing are performed on the background, or the focusing is impossible.

In order to solve this problem, the auto level 10 of the present invention uses a plurality of focus detection areas centered on the collimation axis (in this embodiment, the entire focus detection area Z, the central focus detection area). Areas Z1 to Z4) are set,
First, the contrast is detected in the maximum focus detection area Z, and when an effective contrast is obtained, the contrast is detected from the narrowest central focus detection area Z1. If an effective contrast is not obtained, the focus detection areas to be used until an effective contrast is obtained are set as focus detection areas Z2, Z3,.
Select in the order of Z4. Then, a defocus amount is calculated using the AF sensor data of the focus detection area where an effective contrast is obtained, and the focus adjustment lens group 12 is moved based on the defocus amount. Central focus detection area Z
If no effective contrast is obtained from any of 1 to Z4, the focus is adjusted using the AF data of the maximum focus detection area Z.

By selecting the focus detection area in this manner, focus detection is enabled by the AF detection area corresponding to the width of the collimated object, and erroneous distance measurement such as focusing on the background of the collimated object is eliminated. .

The automatic focus adjustment processing of the automatic level 10 will be described in more detail with reference to the flowcharts shown in FIGS. This processing is executed by the arithmetic and control circuit 23 in a state where a battery (not shown) is attached to the automatic level 10.

In the present embodiment, the AF start switch 27
Is turned on, the focus adjustment process is continued until the focus adjustment process ends, even if the AF start switch 27 is turned off thereafter.

When a battery (not shown) is mounted, the process starts. First, step (hereinafter abbreviated as "S") 10
In step 1, the internal RAM, each input / output port, etc. are initialized, and then the process proceeds to power down processing. Thereafter, S101 is not executed unless the battery is removed and remounted.

The power-down process is a so-called standby process. As long as the AF start switch 27 is not turned on, the power of each circuit except the arithmetic / control circuit 23 is turned off and the AF start switch 27 is operated. When the AF start switch 27 is turned on, the power supply (power) of each circuit is turned on to execute the AF processing (focus adjustment processing).

In the power down processing, first, a flag relating to the AF operation (focus adjustment processing) is cleared (set to 0), and the operation ends (S111). In the present embodiment, as the flag, a focusing flag for identifying that focusing has been performed, an AFNG flag for identifying that automatic focusing has not been performed, a reintegration flag for identifying that the integration process has been performed once, and A search and overlap flag for identifying the integration process while moving the focus adjustment lens group 12, a defocus OK flag for identifying that a valid defocus amount has been obtained, and an AF focus detection area are selected. It has an area select flag for identifying that the operation has been performed.

When the reset process related to the AF operation is completed, it is checked whether the AF start switch 27 is on (S113). Since it is off in the initial state where the user does not operate, the AF start switch memory is turned off (OF
F is written) (S113, S115). Then, it is checked whether or not the power is on. In an initial state, power is not supplied to each circuit.
3, the process of S113, S115, and S119 is repeated.

When the AF start switch 27 is turned on, the following processing is executed. Since the AF start switch 27 has been turned on, the process advances from S113 to S117 to check whether the AF start switch memory is ON. Since the first time is OFF, the process advances to S123 to turn on the AF start switch memory ( ON is written) (S123).
Then, the state of the AF switch 29 is input. When the AF switch 29 is off, the process returns to the power down process because the manual focus adjustment mode is set (S125, S11).
1). When the AF switch 29 is on, that is, in the automatic focus adjustment mode, the power is turned on and VDD is turned on.
Proceed to loop processing (S125).

When returning to the power-down processing, the AF start switch memory is ON, so that the AF start switch 27
Are turned on, S113, S117, S119
The process then proceeds to S121 to turn off the power, and waits for the AF start switch 27 to turn off and on. When the AF start switch 27 is off, the processing from S113 to S115
To OFF, write OFF in the AF start switch memory, and
The process advances from step 119 to S121 to turn off the power and wait for the AF start switch 27 to turn on.

The VDD loop process is a process of executing a focus adjustment process and detecting the state of the AF start switch 27 to perform focusing or returning to the power down process if it is determined that focusing is impossible. When the VDD loop processing starts, the state of the AF switch 29 is input again, and the processing proceeds under the condition that the AF switch 29 is turned on.
1, S203), and terminates the AF operation. Hereinafter, the description will be made assuming that the AF switch 29 is on.

When the AF switch 29 is on,
An AF process (focus adjustment process) for detecting the defocus and moving the focus adjustment lens group 12 to the in-focus position is executed (S
205), it is periodically checked whether the AF start switch 27 is turned on during the processing (S207). 1
In the second check, since the normal AF start switch 27 remains ON, it is checked whether the AF start switch memory is ON. However, since it is ON in S123,
The focus flag and the AFNG flag are checked (S21).
1, S213, S215). In the middle of the AF process, if it is not possible to determine whether the focus is achieved or the AF is not possible, since both the focus flag and the AFNG flag are in a clear state, S201
Return to

Steps S201, S203, S205, S207, and S2 are performed until the in-focus state and the in-focus flag are set to 1 or the in-focus state is set to 1 in the AFNG flag.
11, the processing of S213 and S215 is repeated. If the AF start switch 27 is turned off during this process, the process proceeds from S207 to S209 to write OFF in the AF start switch memory, and then returns to S201 from the focus flag and AFNG flag check processes (S213, S215). repeat.

Normally, the focus adjustment lens group 12 is moved to the in-focus position by the AF processing in S205, so that the focusing flag is set to 1 and the processing returns from S213 to the power-down processing (S213), and the AF operation ends. Yes (S11
1). If focusing cannot be performed for some reason, such as when the collimating object is not stationary, too dark, or the contrast is too low, the AFNG flag is set to 1 and the process returns to the power process (S215). ), The AF operation ends (S111).

Returning to the power down process, when the AF start switch 27 is ON, the AF start switch memory is ON, so that S113, S117, S119 to S1
21 and the power is turned off.
If is OFF, the process proceeds from S113 to S115 to write OFF in the AF start switch memory, and S119
Then, the process goes to S121 to turn off the power, and waits for the AF start switch 27 to be turned on.

In any case, when the process returns to the power down process, the power is turned off and the power supply to peripheral circuits other than the arithmetic / control circuit 23 is cut off.

If the AF start switch 27 is turned off and then turned on again during the VDD loop processing, S20
From S7, the process proceeds to S211. At first, since the AF start switch memory is OFF, the process proceeds from S211 to S217, writes ON in the AF start switch memory, and returns to S201.
The processing of S201 to S207, S211 to S215, and S201 is executed.

As described above, once the AF start switch 27 is turned on, the focus adjustment processing is repeated until focusing or until it is detected that focusing is impossible, so that the user is troublesome in the focus adjustment processing. Not perform surveying work.

When the AF switch 29 is turned off during the VDD loop processing, that is, when the focus operation knob 16 is moved to the manual focus position, the process returns from S203 to the power down processing, and the AF processing ends.

Next, the details of the AF processing in S205 will be described with reference to the flowcharts shown in FIGS. When the AF process is started, the overlap flag, the search flag, and the re-integration flag are checked (S301, S303, S305). Is started, the integration result is input as AF sensor data, and a defocus calculation is executed (S307). In the defocus calculation, as is well known, a correlation is obtained from a pair of AF sensor data, and a defocus direction (front focus or rear focus) and a defocus amount are calculated from the correlation.

Then, it is checked whether the operation result is valid. If the collimating object has too low contrast, if it has a repetitive pattern, if the brightness is too low,
The calculation result may be invalid. Normally, a valid operation result is obtained, so a case where the operation result is valid will be described first.

When the calculation result is valid, a focusing check process is performed. If the focusing is performed, the focusing flag is set to 1;
If out of focus, the focus flag is set to 0 (S32)
1). In this embodiment, the in-focus state is determined when the defocus amount is equal to or less than a predetermined amount. VD if focused
Returning to the D loop processing, the processing after S207 is executed, and when out of focus, the processing proceeds to the pulse calculation processing (S32).
3).

In the pulse calculation process, the number of AF pulses, that is, the defocus amount is 0 based on the effective defocus amount.
This is a process of calculating the drive amount (the number of AF pulses output by the encoder 33) of the AF motor 31 required to move the focus adjustment lens group 12 to a position where.

In the pulse calculation process, the driving direction of the AF motor 31 and the number of AF pulses are calculated from the defocus amount (S331). This AF pulse number is set in the AF pulse counter 23a, the AF motor 31 is DC-activated, and a pulse check process is executed (S333, S33).
5). The value of the AF pulse counter 23a is
3 is decremented by 1 each time one AF pulse is output.

The pulse check process is a process for controlling the driving speed of the AF motor 31 according to the value of the AF pulse counter 23a. That is, when the number of pulses is larger than the overlap integral prohibition pulse number, the AF motor 31 is driven at a high speed to bring the focus adjustment lens group 12 closer to the focus position in a shorter time, and the overlap integral is also executed. If it becomes less than the predetermined value, the overlap integration is stopped while driving at high speed. If the number of pulses becomes less than the constant speed control start pulse number, the counter value is reduced to 0 while performing low-speed PWM control of the AF motor 31 to prevent overshoot. This is the processing for stopping the AF motor 31 when it has come.

In the pulse check process, the value of the AF pulse counter 23a is compared with the number of overlap integral inhibition pulses (S341).
Proceeding to 43, sets 1 in the overlap flag.
The overlap integration is started and the AF sensor 21 is started.
The AF sensor data is input from the controller and defocus calculation is executed (S345). Then, when a valid operation result is obtained, the process proceeds to the driving direction check process, and when a valid operation result is not obtained, the process returns (S347).

The driving direction check processing is performed by the AF motor 31.
The number of AF pulses is calculated based on the AF sensor data obtained by integration during driving, and is set in a counter.
When the driving direction has changed, the AF motor 31 is braked and stopped. The brake of the present embodiment is a process of short-circuiting both poles of the AF motor 31 to stop the rotation.

When the driving direction check process starts, the overlap flag is set to 1 and the search flag is set to 0, and the previous and current driving directions of the focusing lens group 12 are compared from the calculation results. (S361, S363).
In the case of the same direction, the number of AF pulses at the integration intermediate point is calculated, the calculated value is set in the AF pulse counter 23a, and the process returns (S363, S365). When the driving direction changes, the AF motor 31 is braked and stopped, the overlap flag is set to 0, the reintegration flag is set to 1, and the process returns to the VDD loop processing (S363, S367, S369). , S371).

When returning to the VDD loop processing, S20
Step 7 and subsequent steps are executed, and the AF processing is started again. If the driving direction has not changed, the overlap flag is set to 1
Is set, the pulse check process starts from S301, and returns to the VDD loop process via S341 to S347 and the drive direction check process from S361 to S365 until the counter value becomes smaller than the overlap prohibition pulse number. , The process of returning to the pulse check process is repeated.

During the above processing, normally, the number of AF pulses for driving to the in-focus position decreases to become smaller than the number of overlap integration prohibition pulses, and the flow proceeds from S341 to S349 in the pulse check processing.

The processing from S349 to S355 is processing for terminating driving for the calculated number of AF pulses and stopping the AF motor 31. In S349, the control waits until the number of AF pulses becomes less than the number of constant speed control start pulses, and when it becomes less, the AF motor 31 according to the remaining number of AF pulses.
Is controlled so that the AF motor 31 is stopped when the number of AF pulses is 0 (S349, S351, S35).
3). Then, when the AF motor 31 is stopped, the overlap flag is set to 0, the reintegration flag is set to 1, and the process returns to the VDD loop processing (S353,
S355).

Returning to the VDD loop processing, the next time S205 is entered, the overlap flag and the search flag are set to 0, and the reintegration flag is set to 1. Enter the integration process.
The same applies when the driving direction changes in S363.

In the reintegration process, a defocus amount is obtained to check whether or not the subject is in focus. If the subject is in focus, the focusing flag is set to 1; This is a process of calculating the number and driving the focusing lens 12. Here, the focus flag is set to 1,
When the process returns to the VDD loop process, the process exits from S213 to the power down process, ends the AF process, and enters a standby state waiting for the AF start switch 27 to be turned on.

The above is the processing when focusing is performed normally. However, when focusing is difficult and when focusing is impossible, the process exits the VDD loop processing in the state where focusing is impossible and returns to the power down processing. , The AF operation ends.

The AF processing when focusing is difficult and when focusing is impossible will be described. When the AF process is started, the first time, the integration start of S307, the input of the AF sensor data, and the defocus calculation process are executed (S301, S303,
S305). If the effective defocus amount cannot be obtained because the contrast of the object is too low or the like, the process enters the search integration process from S309.

The search integration process is a process of performing integration and defocus calculations while driving the AF motor 31 from a close-range in-focus position to an infinity-focus position so that an effective defocus amount is obtained. If an effective defocus amount is not obtained by this search integration process,
The AFNG flag is set to 1 and the process returns to S215
To return to the power down process.

In the search integration process (search process),
First, the AF motor 31 is driven for search (first, driven in the short-distance focusing direction), and 1 is set in the search flag.
The integration is started by the AF sensor 21, and when the integration is completed, the integrated value is taken in as AF sensor data, and a defocus amount is obtained by a defocus calculation (S311,
S313, S315). Here, if an effective defocus amount is obtained, the process goes to the drive direction check (S317). If not, the process returns to the VDD loop process and executes the processes from S207 (S317, S31).
9).

The AF motor search drive means the AF motor 3
1 is first driven in the direction of the short-distance in-focus position, and when the focus adjustment lens group 12 reaches the short-distance side moving end point and stops, AF
When the motor 31 is reversed in the direction of the infinity in-focus position and the focus adjustment lens group 12 reaches the infinity side moving end point and stops,
This is a process of stopping the AF motor 31. If an effective calculation result is obtained during the search drive, the operation returns to the drive based on the defocus.

When the processing returns to the VDD loop processing and enters S205 again, the overlap flag is cleared and the searching flag is set to 1. Therefore, the search integration processing is started from S303, and the search integration processing from S313 is executed. Execute. If a valid calculation result is not obtained even when the focusing lens group 12 reaches the infinity in-focus position, AFNG processing is started, the AFNG flag is set to 1, and the processing returns to the VDD loop processing. Exit from S215 to power down processing (S317, S319, S39)
1).

The above is a process in the case where a valid operation result is not obtained from the beginning. However, a valid operation result is obtained once, and after the lens is driven instead of focusing, the valid operation result is obtained in the reintegration process. Is not obtained, the AF from S385 is performed.
NG processing is started, AFNG flag is set to 1 and VD
The process returns to the D loop process, and exits from S215 to the power down process (S385, S391).

Next, S307, S315, S345,
Details of the defocus calculation processing executed in S383 will be described with reference to FIG. In the present embodiment,
The degree of contrast is used as reliability. That is, in this defocus calculation processing, first, a contrast is detected in the maximum focus detection area Z, and when a contrast equal to or more than a predetermined value is obtained, the contrast is detected from the narrowest focus detection area Z1. If an effective contrast cannot be obtained, the contrast is checked in the order of the focus detection areas Z2, Z3, and Z4 until an effective contrast is obtained. The defocus amount is calculated using the AF data of the focus detection area (the narrowest area) where an effective contrast is obtained, and the focusing lens group 12 is moved based on the defocus amount. Select focus detection area Z1
If an effective contrast cannot be obtained from any of .about.Z4, the focus is adjusted using the AF data of the maximum focus detection area Z.

In the defocus calculation process, first, a contrast calculation is performed based on the AF data from the maximum focus detection area Z (S401). The contrast calculation uses, for example, the sum of the absolute values of the differences between the integrated values of adjacent pixels (photoelectric conversion elements) in the area to be used in the reference line sensor.

[Formula 1] In Expression 1, s is the bit number of the first pixel in the focus detection area, and N is the bit number of the last pixel in the focus detection area. That is, if the sum of the differences between the integral values is larger than a predetermined value, it is determined that there is sufficient contrast, and
If it is smaller than the predetermined value, it is determined that there is no contrast. When it is determined that there is no contrast, 0 is set for each of the defocus OK flag and the area select flag, and the process returns (S403, S453).

The defocus OK flag is a flag for identifying whether a valid defocus is obtained, and the area select flag is a flag for identifying whether or not to select a focus detection area.

If the contrast is equal to or more than the predetermined value, it is checked whether the area select flag is 1 (whether the focus detection area is selected). However, since the area is not selected at first, the maximum focus detection is performed. Area Z
A correlation operation is performed by using the AF data from, and a phase difference is calculated (S403, S405, S407). If the phase difference cannot be calculated, the process returns after performing the flag clearing process of S453 (S409). The phase difference cannot be calculated when a matching point between the images formed in the pair of focus detection areas Z cannot be detected, such as when the image formed in the focus detection area Z is in a large blur state.

When an effective phase difference is obtained, it is checked whether or not the phase difference is less than a predetermined value (whether or not the focus shift is small). While the focus detection area is large, the focus detection area is not selected, the process proceeds to the interpolation calculation processing, and the defocus amount is calculated using the maximum detection area Z (S411, S413),
The defocus OK flag is set to 1 (S41
7). Then, while the phase shift is equal to or more than the predetermined value, S40
1 to S411 and S413 to S417 are repeated.

If the phase shift is less than the predetermined value, the process proceeds to S4
The process advances from S11 to S423 to execute an area select check process. The area select check process performs a contrast check in order from the narrowest focus detection area Z1,
First, a focus detection area in which a contrast higher than a predetermined value is obtained, that is, a narrowest focus detection area in which a contrast higher than a predetermined value is obtained is selected. When the contrast equal to or more than the predetermined value is not obtained, the focus detection area is not selected.

Upon returning from the area selection check processing, it is checked whether a focus detection area has been selected. If no focus detection area has been selected, the flow advances to step S413. When selected, the data save flag is set to 1, and the correlation calculation data (phase difference calculation data) of the maximum focus detection area (all areas) is once saved to a predetermined address of the RAM (S427, S429).

A phase difference is calculated by performing a correlation operation on the selected focus detection area (S435). If an effective phase difference cannot be obtained, it is checked whether data is saved, and the data is saved. Therefore, the operation data of all the areas is read from the RAM, all the areas are validated, and the data save flag and the area select flag are set to 0 before proceeding to the interpolation calculation processing (S437, S437).
439, S441, S443, S413).

When a valid phase difference is obtained, 0 is set in the data save flag (S437, S438), and S4
The process proceeds to the interpolation calculation process of No. 13.

If any one of the focus detection areas Z1 to Z4 is selected and the area selection flag is set to 1, and then the defocus calculation processing is started, S4
The process proceeds from S05 to S431 to execute an area select check process. If the focus detection area has not been selected, S407 is used to use the maximum focus detection area Z.
(S433, S407), and if selected, the process proceeds to S435 to perform a correlation operation on the selected region and calculate a phase difference (S433, S435).

The process proceeds from S431 and S433 to S435 to calculate the phase difference of the select area. If a valid phase difference is obtained, the data save flag is set to 0 and the process proceeds to the interpolation calculation (S438 and S413). When a large phase difference was not obtained, the entire area calculation data was not saved.
Proceeding from S439 to S445, the defocus OK flag is set to 0, the area select flag is set to 0, and the process returns (S451).

The AF sensor of the narrowest focus detection area among the focus detection areas in which the contrast equal to or more than the predetermined value is obtained on condition that the contrast equal to or more than the predetermined value is obtained in the entire area by the above defocus calculation processing. A defocus amount is calculated based on the data.

The area selection processing in S423 and S431 will be described in more detail with reference to FIG. The area selection processing selects the narrowest focus detection area among the focus detection areas Z1 to Z4 having a contrast equal to or more than the second predetermined value from the areas Z1 to Z4, and performs focus adjustment on the focus detection area. Processing. Focus detection areas Z1 to Z in which a contrast equal to or greater than a second predetermined value is obtained
When there is no 4, focus adjustment is performed using the maximum focus detection area Z.

In this process, the minimum number of bits used, that is, the number of pixels (photoelectric conversion elements, light receiving means) corresponding to the minimum focus detection area is set (S501). Then, the start position of the select area is set (S50).
3). That is, the bit number of the pixel at the center of the focus detection area used for focus detection, and the bit numbers S and N at both left and right ends with this bit number as the center are set. In the present embodiment, the center shift can be further adjusted.
When the center shift adjustment is performed, the center bit number is shifted.

The contrast calculation is executed based on the AF sensor data of the selected focus detection area based on the formula 1, and the calculation result is stored in the RAM (S505).

The calculated contrast is the O at the time of selection.
It is checked whether the level is equal to or higher than the K level (second predetermined value) (S507), and if it is, the area select flag is set to 1 and the routine returns (S513).

In any case, when returning, the defocus amount is calculated based on the AF sensor data of the selected focus detection area, and the focus adjustment lens group 12 is moved.

If it is determined in the contrast check in S507 that the contrast is lower than the OK level at the time of selection, since accurate defocus is not required in that area, focus detection area enlarging processing from S515 is performed. S5
In step 15, it is checked whether the selection has been completed, that is, whether the contrast of the focus detection area Z4 has been checked, and if the contrast of the focus detection areas Z1 to Z3 has been checked, the next step is performed. Is set, that is, the focus detection area to be used is enlarged by one step, and the process returns to S503 (S515, S517, S503). If the contrast in the focus detection area is equal to or more than the OK level at the time of selection, the process goes from S507 to S513, and if less than the OK level at the time of selection, the process returns from S507 to S515.

If the contrast does not reach the OK level at the time of selection even when the used area is expanded to the focus detection area Z4, the area selection flag is set to 0 and the routine returns (S515, S519). In this case, defocus is calculated using the all-focus detection area Z.

S307, S315, S345, S383
FIG. 16 shows the integration start process executed in FIG.
This will be described in more detail with reference to FIG. When the integration start process starts, first, all monitor sensors are enabled (S60).
3) Start integration (S611).

When the integration is started, the integration is terminated and CCD data (AF sensor data) is input when the output of the monitor sensor falls below the AGC level or when the maximum integration time has elapsed, whichever is earlier. The focus calculation processing is executed (S611, S613, S615, S61
7, S619), and returns.

In the illustrated embodiment, C is used as the focus detection means.
Although a CD line sensor is used, a MOS type line sensor can be used. As described above, in the present embodiment, the present invention is applied to one of the auto levels, but the present invention is not limited to this, and can be applied to other surveying instruments such as transit, and furthermore, telescopes, telescope optical systems such as binoculars Also applicable to

[0091]

As is clear from the above description, the present invention
Focus detection is performed on focus detection areas of different sizes symmetrical about the center of the field of view of the telephoto optical system, and focus processing is performed on the narrowest focus detection area among the focus detection areas that can obtain a certain level of reliability or more. Is performed, focusing is ensured on the object located at the center of the field of view.

[Brief description of the drawings]

FIG. 1 is a diagram showing a main configuration of an embodiment of an automatic level to which the present invention is applied.

FIG. 2 is a diagram showing an outline of an embodiment of the auto-level AF sensor.

FIG. 3 is a diagram showing an outline of a reference CCD sensor of the AF sensor.

FIG. 4 is a diagram showing a relationship between a survey staff and a ranging focus detection area visually recognized in a visual field at an object distance of 5 m.

FIG. 5 is a diagram illustrating a relationship between a survey staff and a focus detection area that are visually recognized in a visual field at an object distance of 10 m.

FIG. 6 is a diagram showing a relationship between a survey staff and a ranging focus detection area visually recognized in a visual field at an object distance of 20 m.

FIG. 7 is a diagram illustrating the relationship between a survey staff and a focus detection area that are visually recognized in a visual field at an object distance of 30 m.

FIG. 8 is a diagram showing a relationship between a survey staff and a ranging focus detection area visually recognized in a visual field at an object distance of 50 m.

FIG. 9 is a diagram showing a part of a flowchart relating to automatic focus adjustment processing of the automatic level.

FIG. 10 is a diagram showing a part of a flowchart relating to the automatic focus adjustment processing of the automatic level.

FIG. 11 is a diagram showing a part of a flowchart relating to automatic focus adjustment processing of the automatic level.

FIG. 12 is a diagram showing a part of a flowchart relating to the automatic focus adjustment processing of the automatic level.

FIG. 13 is a diagram showing a part of a flowchart relating to the automatic focus adjustment processing of the automatic level.

FIG. 14 is a view showing a flowchart relating to defocus calculation processing in the automatic focus adjustment processing at the auto level.

FIG. 15 is a view showing a flowchart relating to a focus detection area selection check process in the automatic focus adjustment process of the auto level.

FIG. 16 is a view showing a flowchart relating to integration start processing in the automatic level automatic focus adjustment processing.

[Explanation of symbols]

 Reference Signs 9 auto staff 12 auto level 12 focus adjustment lens group 20 focus detection system (focus detection means) 21 AF sensor 21c CCD line sensor (light receiving means) 23 calculation / control circuit (judgment means, control means) 27 AF start switch 29 AF switch 30 Focusing lens group drive system 31 AF motor

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields investigated (Int. Cl. ⁷ , DB name) G01C 5/00-5/02 G01C 1/02 G01C 15/00 103 G02B 7/11 G03B 3/00

Claims (7)

(57) [Claims] 1. Focus detection means for performing focus detection on focus detection areas of different sizes symmetrical with respect to the center of the field of view of a telephoto optical system as a center, and a focus detection area in which a reliability equal to or higher than a certain value is obtained. An automatic focusing device, comprising: a determination unit that enables a narrowest focus detection area. 2. The focus detecting means includes a plurality of light receiving means for receiving an object image formed by the telephoto optical system, and is included in a focus detection area symmetrical left and right from the center of the field of view of the telephoto optical system. A focus state is detected based on an output from the light receiving unit, and the determination unit obtains reliability of an output from the light receiving unit included in a focus detection area having a different size during automatic focus adjustment, and a fixed reliability is obtained. 2. The automatic focusing apparatus according to claim 1, wherein the narrowest focus detection area among the focus detection areas from which the degree is obtained is made effective. 3. The telephoto optical system includes an objective lens group, a focusing lens group, a reticle having a reticle, an eyepiece lens group for observing an object image formed on the reticle, and the focusing lens. A light beam splitting optical system disposed between the group and the focusing screen, wherein the light receiving unit is disposed in a split optical path split by the light beam splitting optical system, in a horizontal direction around the reticle. A line sensor for receiving a light beam corresponding to a light beam incident on an extending region, wherein the determination unit performs the determination based on an output from a line sensor included in a different focus detection region. 3. The automatic focusing device of the surveying instrument according to 1 or 2. 4. A focus detecting device comprising: a calculating means for calculating a defocus amount based on an output of the line sensor included in a focus detecting area determined to be valid by the determining means; and a defocus amount calculated by the calculating means. 4. The automatic focusing apparatus according to claim 3, further comprising a focusing lens group driving unit that moves the focusing lens group based on a focus amount. 5. The focus detecting means calculates a contrast of an image received based on an output of the line sensor,
4. The automatic focusing device of a surveying instrument according to claim 3, wherein the determination unit determines that the reliability is present when the contrast is equal to or more than a predetermined value. 6. The automatic surveying instrument according to claim 4, wherein when there is no focus detection area determined to be valid by said determination means, calculation is performed using the maximum focus detection area. Focusing device. 7. The focus detecting means divides a light beam in a divided light path into two and forms an image of each of the divided light beams on a pair of line sensors, based on an output of the pair of line sensors.
4. The automatic focusing device of a surveying instrument according to claim 3, wherein the focusing device is a phase-difference-type focus detection unit that detects a phase difference between images formed on a pair of line sensors and obtains a defocus amount.