JPH09304681A - Automatic focusing device for telescopic optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the operability of focusing by connecting a motor driving means to a lens moving means, only when automatic focusing is performed and disconnecting the motor driving means, when the automatic focusing is not performed. SOLUTION: The lens moving means (rack) 12a is fixed on a focusing lens 12 and a pinion 12b is engaged with the rack 12a. The pinion 12b can be driven by either of manual focusing by a focusing operation knob 16 and the automatic focusing by a focus detecting system 20 and a focusing lens driving system 30. In other words, an electromagnetic clutch is in a disconnected state, until an AF starting switch 27 is turned on and the motor driving means (AF motor) 31 is disconnected from the pinion 12b, so that the manual focusing operation knob 16 is manually operated to rotate, for enabling focusing. When the AF starting switch 27 is turned on, the electromagnetic clutch is turned on and the AF motor 31 is connected to the pinion 12b, to execute the automatic focusing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an autofocus device equipped with a telescopic optical system, which is suitable for surveying instruments such as auto level, theodolite, and transit.

[0002]

2. Description of the Related Art Surveying devices such as auto level, transit, and theodolite basically have a collimating telescope and a level for measuring a level, a rotation angle, and a depression / elevation angle. The surveying instrument is set horizontally and the collimation telescope is used to collimate the collimation point or object.

In this type of surveying instrument, a focus adjusting device is provided for observing a clear object image regardless of the distance of the collimated object. That is, in order to observe the collimation object in a clear state, the operator has to operate the focus adjustment device while observing the collimation object through the collimation telescope. Therefore, an autofocus device has been desired. But,
In some cases, such as when the autofocus device cannot focus, the user may want to manually adjust the focus or may have to manually adjust the focus.

[0004]

SUMMARY OF THE INVENTION The present invention has been made on the basis of the awareness of the problems of the conventional surveying instrument, and provides an automatic focusing device for a telephoto optical system which is capable of automatic focusing and manual focusing and has good operability. The purpose is to provide.

[0005]

SUMMARY OF THE INVENTION According to the present invention, which achieves this object, a telescopic optical system for moving a focus adjusting lens along an optical axis to perform focus adjustment; focus detecting means for detecting the focus state through the telescopic optical system; Lens moving means for moving the focus adjusting lens; Motor driving means for driving the lens moving means; Clutch means for connecting and disconnecting the motor driving means and the lens moving means; Automatically driving the focus detecting means and the motor driving means A control means for adjusting the focus; the control means is characterized in that the clutch means is engaged when the automatic focus adjustment is executed, and the clutch means is disconnected while the automatic focus adjustment is not executed. According to this configuration, since the lens moving means and the motor driving means are separated by the clutch means while the automatic focus adjustment is not performed, it is possible to manually drive the lens moving means.

In the present invention, a manual drive means for driving the lens moving means by an external operation force is provided, and the control means, when the automatic focus adjustment is not executed, the operation force of the manual drive means is the motor. The clutch means can be disengaged so as not to be transmitted to the drive means.
Further, the present invention is provided with automatic focus start operation means, and the control means can execute automatic focus adjustment by connecting the clutch when the automatic focus start operation means is operated. According to this configuration, when the automatic focus start operation means is operated without performing the switching operation between the automatic focus adjustment and the manual focus adjustment, the automatic focus adjustment is executed, and the manual drive is performed while the automatic focus adjustment processing is not executed. Focusing can be performed by means.

According to an eighth aspect of the present invention, there is provided a telephoto optical system for moving the focus adjustment lens along the optical axis to adjust the focus; focus detecting means for detecting the focus state through the telescopic optical system; Lens moving means for moving the adjusting lens;
Manual driving means for driving the lens moving means by an external operation force; motor driving means for driving the lens moving means; clutch means for connecting and disconnecting the motor driving means and the lens moving means; the focus detecting means and the motor driving means A control means for driving and automatically adjusting the focus; the control means always disconnects the clutch means, connects the clutch means when executing the automatic focus adjustment, and focuses the focus adjustment lens. When moving to the position, the clutch means is disengaged, and when the focus adjusting lens cannot be moved to the focus position, the focus adjusting lens is moved to a predetermined position and then the clutch means is disengaged. Have. According to this configuration, when focusing cannot be performed by the automatic focus adjustment process, the clutch is disengaged after the focus adjustment lens moves to a predetermined position, so that the user can easily perform subsequent focus adjustment manually. Become. The predetermined position is a position where the focus is on a frequently used distance, or
The position can be adjusted to a distance preset by the user.

[0008]

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 auto level to which an automatic focus adjusting device of the present invention is applied, and FIG. 2 is a plan view of the auto level 10. The auto level 10 includes, from the object side, a positive collimation objective lens 11, a negative focusing lens 12, a horizontal compensation optical system 13, and a focusing screen (focal plane) 1.
4 and a positive eyepiece lens 15.

The horizontal adaptive optical system 13 is a well-known one, and includes a first compensating prism 13a, a competing 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. In this horizontal compensation optical system 13, when the optical axes of the objective lens 11 and the focus adjustment lens 12 are set to be substantially horizontal (for example, a state in which the optical axes are inclined from the horizontal for about 10 to 15 minutes), the incident light flux to the first compensating prism 13a is the same. Although it deviates from the horizontal by the amount of deviation, the first competition prism 13
a, the competition mirror 13b, and the second competition prism 13c
The luminous flux reflected and emitted by is substantially horizontal.

A rack 12a is fixed to the focus adjusting lens 12 as a lens moving means.
The pinion 12b meshes with 2a. By rotating the pinion 12b to move the focus adjustment lens 12 along the optical axis, the position of the image of the object 9 formed by the objective lens 11 and the focus adjustment lens 12 is moved in parallel along the optical axis. You can The operator uses the focusing screen 1
The object image formed on the image plane 4 is observed by the eyepiece lens 15 together with the collimation line drawn on the focusing screen 14.

A branching optical element (half mirror) 18 for branching the optical path is arranged in the optical path from the objective lens 11 to the focusing screen 14, and the focusing state (conclusion) on the equivalent surface 14A of the focusing screen 14 is set in the branching optical path. A focus detection system 20 for detecting the image state) is provided, and a focus adjustment lens drive system 30 for driving the focus adjustment lens 12 based on the output of the focus detection system 20 is provided. Main parts of the focus detection system 20 and the focus adjustment lens drive system 30 are housed in the bottom plate part 17.

A focus detection system 20 for detecting the focus state of the equivalent surface 14A has an AF sensor 21 arranged near the equivalent surface 14A. It detects a front focus, a rear focus, and defocus, and various specific configurations are known. The AF sensor 21 of the present embodiment is of a phase difference method type, and has an equivalent surface 1
The object image of 4A is divided by a condenser lens and a pair of separator lenses (imaging lenses) arranged apart from each other by a base line length, and re-imaged on a pair of CCD line sensors. C
The CD line sensor has a large number of photoelectric conversion elements, each photoelectric conversion element photoelectrically converts the received object image to integrate (accumulate) the photoelectrically converted charges, and outputs the integrated charges as AF sensor data. It is amplified by the preamplifier 22 and input to the arithmetic / control circuit 23. The calculation / control circuit 23 calculates the defocus amount by the defocus calculation based on the pair of AF sensor data. Further, in the present embodiment, based on the defocus amount, the driving direction and the driving amount of the AF motor 31 (encoder 3) necessary to move the focus adjustment lens 12 to the position where the defocus amount becomes zero.
The number of output pulses of 3 (hereinafter referred to as “AF pulse”) is calculated. The number of AF pulses is set in the AF pulse counter 23a incorporated in the arithmetic / control circuit 23.

The calculation / 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 performed by the deceleration mechanism 32 with a built-in electromagnetic clutch that incorporates the electromagnetic clutch 50.
And the focus adjustment lens 12 is moved (see FIG. 3). The electromagnetic clutch 50 includes the electromagnetic clutch drive circuit 26.
The energization is controlled by the arithmetic / control circuit 23 via the. The rotation of the AF motor 31 is detected and counted by the arithmetic / control circuit 23 (AF pulse counter 23a) by the pulse output from the encoder 33, and speed control is performed based on the count value and the number of pulses previously calculated. Performs stop control, etc. With the focus detection system 20 and the focus adjustment lens drive system 30, the focus adjustment lens 12 is driven along the optical axis according to the object distance and is automatically focused.

The focus detection system 20 includes, as switches, an AF start switch 27 for starting the automatic focus adjustment process and an AF switch 29 for detecting that the electromagnetic clutch 50 is connected (in the AF mode). There is. A
The F detection switch 29 is connected to the electromagnetic clutch 50 to
It turns on when the F motor 31 is connected to the pinion 12b,
When the electromagnetic clutch 50 is disconnected and the AF motor 31 is disconnected from the pinion 12b and the focus operation knob 16, the electromagnetic clutch 50 is turned off.

The pinion 12b can be driven by either manual focus adjustment by the focus operation knob 16 or automatic focus adjustment by the focus detection system 20 and the focus adjustment lens drive system 30. That is, the auto level 10 is the output of the focus detection system 20 and the focus adjustment lens 1
Autofocus mode to drive 2 (autofocus adjustment)
And a manual mode (manual focus adjustment) in which the focus operation knob 16 is manually driven to rotate to move the focus adjustment lens 12 without depending on the output of the focus detection system 20.

In this embodiment, an electromagnetic clutch 50 is provided as means for switching between the auto focus mode and the manual mode. This electromagnetic clutch 50
It always switches to manual focus and switches to auto focus only during auto focus processing.

FIG. 3 is a sectional view of the main part of the peripheral mechanism of the focus operation knob 16, and FIGS. 4 and 5 show the electromagnetic clutch 50.
The principal part sectional drawing of is shown.

The rotation of the AF motor 31 is controlled by the pinion 41,
Through the reduction gears 42, 43, 44, the electromagnetic clutch 50
Is transmitted to the drive shaft 52 of. The rotation of the output shaft 55 of the electromagnetic clutch 50 is rotated by the gears 45 and 46 through the pinion 12b.
Is transmitted to the shaft 47 of. That is, the rotation of the AF motor 31 is performed by the pinion 41, the reduction gears 42, 43, 44, and the electromagnetic clutch 50 that constitute the electromagnetic clutch built-in reduction mechanism 32.
(Drive shaft 52, output shaft 55), transmitted to the pinion shaft 47 and the pinion 12b via the gears 45 and 46, transmitted to the rack 12a and the focus adjustment lens 12 via the pinion 12b, and the focus adjustment lens 12 to the optical axis. Move back and forth along.

The structure of the electromagnetic clutch 50 will be described in more detail with reference to FIGS. 4 and 5. The drive shaft 52 is a bearing 5 fixed to one open end of a cylindrical casing 51.
3 is rotatably supported with the thrust movement restricted. A coil 54 having the bobbin as the core and the drive shaft 52 as the core is fitted in the bearing 53. An output shaft 55 is rotatably supported by a bearing 56 fixed to the other open end of the casing 51 in a state where the thrust movement is restricted.

A D-shaped shaft portion 55a having a D-shaped cross section is formed at the end of the output shaft 55 inside the casing, and an armature 57 is fitted on the D-shaped shaft portion 55a so as to be freely thrustable. . And the armature 57 and the drive shaft 5
A spring 58 is fitted between the two ends of the casing. The spring 58 constantly urges the armature 57 in a direction away from the end of the drive shaft 52. A cylindrical rotor portion 52a is formed at the end of the drive shaft 52, and a cylindrical portion 57a having an end surface that is attracted to the end surface of the rotor portion 52a is formed at the armature 57. And
The spring 58 is housed in the rotor portion 52a and the tubular portion 57a.

When no current is flowing through the coil 54,
The armature 57 causes the drive shaft 5 to move by the urging force of the spring 58.
It is separated from 2 (see FIG. 4). Therefore, even if the drive shaft 52 rotates, the output shaft 55 does not rotate, and conversely, even if the output shaft 55 rotates, the drive shaft 52 does not rotate. This state is manual focus.

When a current flows through the coil 54, the magnetic force of the end face of the tubular portion 57a generated by this causes the armature 57 to adsorb against the biasing force of the spring 58 (FIG. 5).
reference). Therefore, when the drive shaft 52 rotates, the output shaft 55 rotates integrally via the armature 57 attracted to the drive shaft 52. By this connection, autofocus for moving the focus adjustment lens 12 by the AF motor 31 becomes possible. Interlocking drive shaft 52 and armature 57
Acts as a sliding friction mechanism that slips when overloaded. When the current to the coil 54 is cut off, the magnetic force disappears and the armature 57 is separated from the drive shaft 52 by the urging force of the spring 58 (see FIG. 4). The AF switch 59 detects that the armature 57 is attracted to the rotor 52a, that is, that the electromagnetic clutch 50 is engaged.

In another embodiment, one or both of the drive shaft 52 and the armature 57 are made of permanent magnets. Normally, the biasing force of the spring 58 exceeds the attraction force of the drive shaft 52 and the armature 57, and the armature 57 is separated from the drive shaft 52. However, when the coil 54 is energized in the forward direction, the drive shaft 52 and the armature 57 are separated. 57
The attraction force of the armature 5 exceeds the biasing force of the spring 58 and the armature 5
7 is adsorbed on the drive shaft 52, and the adsorbed state is maintained even if the power supply to the coil 54 is cut off in this adsorbed state. Further, when the coil 54 is energized in the reverse direction in this attracted state, the attracting force between the drive shaft 52 and the armature 57 becomes weaker than the biasing force of the spring 58, and the armature 57 is separated from the drive shaft 52 by the biasing force of the spring 58. Configure According to this configuration, the energization time to the coil 54 can be shortened, so that the power saving effect can be obtained.

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

In this embodiment, the AF start switch 27
When is turned on, even if the AF start switch 27 is turned off thereafter, the focus adjustment processing is continued until the focus adjustment processing is completed.

When the battery is installed, this focus adjustment processing starts, and first, step (hereinafter abbreviated as "S") 10
In 1, the internal RAM, each input / output port, etc. are initialized, and then the power-down processing is started. After that, the process of S101 is not executed unless the battery is reattached.

The power-down process is a so-called standby process, and while the AF start switch 27 is not turned on, the power of each circuit except the arithmetic / control circuit 23 is turned off to perform AF.
Wait for the start switch 27 to be operated, and when the AF start switch 27 is turned on, the power supply for each circuit
To turn on the focus adjustment process.

In the power-down process, first, the flag related to the AF operation (focus adjustment process) is cleared (set to 0) and the AF operation is ended (S111). In this embodiment, as a flag, a focus flag for identifying that focus has been achieved,
An AFNG flag for identifying that automatic focus adjustment was not possible, a reintegration flag for identifying integration processing after focusing once, and a search for identifying integration processing while moving the focus adjustment lens 12. It has medium and overlapping medium flags.

When the reset process relating to the AF operation is completed, the electromagnetic clutch 50 is deenergized (S112),
It is checked whether the AF start switch 27 is on (S113). Since it is off in the initial state when the user does not operate it, the AF start switch memory is turned off (OFF
Is written) (S113, S115). Then, it is checked whether or not the power is on. In the initial state, since the power is off in which power is not supplied to each circuit, S113
Then, the processing of S113, S115, and S119 is repeated.

The electromagnetic clutch 50 disconnects the AF motor 25 from the focus adjusting lens 12 by the process of cutting off the energization of the electromagnetic clutch 50 in S112. That is, the present embodiment is normally in the manual focus state in which the focus can be adjusted by rotating the manual focus operation knob 16.

When the AF start switch 27 is turned on, the following processing is executed. Since the AF start switch 27 is turned on, the process proceeds from S113 to S117 to check whether the AF start switch memory is ON. However, since it is OFF for the first time, the process proceeds to S123 to turn on the AF start switch memory ( Write ON) (S123).
Then, the state of the AF switch 29 is input, but since the electromagnetic clutch 50 is normally in the disengaged state, the AF switch 29
Is off (S125). Therefore, the electromagnetic clutch 50 is energized to wait for the AF switch 29 to be turned on (S131, S133, S125, S127, S13).
1). When the electromagnetic clutch 50 is energized, the armature 57 is attracted to the rotor 52a and is brought into a connected state.
The AF switch 29 turns on. When the AF switch 29 is turned on, the power is turned on to supply power to each circuit to VDD.
The process proceeds to loop processing (S127, S129). If the AF switch 29 is not turned on within the predetermined time, it means that something is wrong, and the process returns to the power down process (S133).

When returning to the power-down processing, the AF start switch memory is ON, so the AF start switch 27
When is on, S113, S117, S119
From S121, the power is turned off, and the AF start switch 27 is turned off and waits for it to be turned on. When the AF start switch 27 is off, S113 to S115
Go to, write OFF to AF start switch memory, and
The process proceeds from S119 to S121 to turn off the power and wait for the AF start switch 27 to turn on. When the power is turned off, the power supply to the electromagnetic clutch 50 is also cut off, so that the electromagnetic clutch 50 is disconnected.

The VDD loop processing is processing for executing focus adjustment processing, detecting the state of the AF start switch 27, and returning to power-down processing when it is determined that focusing is possible or focusing is impossible. When entering the VDD loop process, the state of the AF switch 29 is input again and the process proceeds on the condition that it is on. However, when it is off, the focus is manual focus, so the process returns to the power-down process (S20).
1, S203). Hereinafter, the description will be made assuming that the AF switch 29 is on.

When the AF switch 29 is on,
AF processing (focus adjustment processing) for detecting defocus and moving the focus adjustment lens 12 to the in-focus position is executed (S2).
05), it is periodically checked whether or not the AF start switch 27 is turned on during a predetermined period (S207). In the first check, since the AF start switch 27 is normally on, it is checked whether the AF start switch memory is ON. However, since it is turned on in S123, the focus flag and the AFNG flag are checked ( S21
1, S213, S215). If neither in-focus nor in-focus can be determined during the AF process, both the in-focus flag and the AFNG flag are in the clear state, and S201
Return to

While the AF start switch 27 is on, the focus is set and the focus flag is set to 1 or the AFNG flag is set to 1 because the focus cannot be achieved in S201.
S203, S205, S207, S211, S213,
The process of S215 is repeated. If the AF start switch 27 is turned off during this process, the process proceeds from step S207 to step S209 to write OFF in the AF start switch memory,
Focus flag and AFNG flag check processing (S213,
The process of returning from S215) to S201 is repeated.

Normally, since the focus adjustment lens 12 is moved to the in-focus position by the AF processing in S205, the focus flag is set to 1, the processing returns from S213 to the power down processing (S213), and the AF operation is ended. (S11
1). Further, during the AF processing of S205, the collimation object is not stationary, is too dark, or the contrast is too low.
When the G flag is set to 1, the focus adjustment lens movement processing is started from S215 and the focus adjustment lens 12 is moved to the infinite end in-focus position (S221, S223). Then, the focus adjustment lens 12 is moved to a predetermined position based on the infinite end (a predetermined number of AF pulses), and then the power-down processing is returned to (S225), and the AF operation is ended. The predetermined position moves to a position where the auto level 10 is most frequently used, for example, a position where the auto level 10 is focused at a distance of 15 m. By this lens movement processing, the lens position can be known when the focus is changed to the manual focus operation, and since the position is frequently used normally, subsequent focus adjustment becomes easy. The arithmetic / control circuit 23 detects that the focus adjustment lens 12 has reached the infinity in-focus position by a sensor (not shown), the overall position detection code plate, or by the AF motor 31 becoming unrotatable. .

When the processing returns to the power-down processing, the AF operation is ended, and when the AF start switch 27 is on, the AF start switch memory is ON, so that S113, S117,
From S119 to S121, the power is turned off and the AF
When the start switch 27 is OFF, the process proceeds from S113 to S115 to write OFF in the AF start switch memory, and the process proceeds from S119 to S121 to turn off the power.
Then, it waits for the AF start switch 27 to be turned on.

In any case, when returning to the power down process, the power supply to the electromagnetic clutch 50 is cut off and the power is turned off.
After F, the power supply to the circuits other than the arithmetic / control circuit 23 is cut off, and the electromagnetic clutch 50 becomes disengaged, so that manual focus adjustment becomes possible.

If the AF start switch 27 is turned off and then turned on again during the VDD loop process, S20
The process proceeds from S7 to S211, but since the AF start switch memory is initially OFF, the process proceeds from S211 to S217, ON is written in the AF start switch memory, and the process 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 process is repeated until the focus is achieved or until it is detected that the focus cannot be obtained. Therefore, the user is troubled by the focus adjustment process. It is possible to carry out survey work without fail. When the automatic focus adjustment is completed, the electromagnetic clutch 50 is disengaged, so that the manual focus adjustment can be performed without performing the mode switching operation such as the fine adjustment.

If the armature 57 is separated from the rotor 52a and the electromagnetic clutch 50 is disengaged during the VDD loop process for some reason, the AF switch 29 is turned off, and the process returns from S203 to the power down process.
F operation is stopped.

Next, 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 reintegration flag are checked (S3
01, S303, S305), the first time is all S1
Since it is still cleared in 11, the AF sensor is caused to start integration, the integration result is input as AF sensor data, and 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 or not this calculation result is valid. The calculation result may be invalid when the collimation object has a too low contrast, a repeating pattern, or the subject brightness is too low. Since a valid calculation result is usually obtained, the case where the calculation result is valid will be described first.

When the calculation result is valid, focus check processing is performed, and if focus is achieved, the focus flag is set to 1 and
If it is 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 in focus
After returning to the D loop processing, the processing from S207 onward is executed, and when out of focus, the processing proceeds to 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.
Is a process of calculating the drive amount of the AF motor 31 (the number of AF pulses output by the encoder 33) required to move the focus adjustment lens 12 to the position.

When the pulse calculation process is started, the driving direction of the AF motor 31 and the number of AF pulses are calculated from the defocus amount (S331). The number of AF pulses is set in the AF pulse counter 23a of the arithmetic and control circuit 23, the AF motor 31 is DC-activated, and a pulse check process is executed (S333, S335). The value of the AF pulse counter 23a is decremented by 1 each time one AF pulse is output from the encoder 33.

The pulse check process is a process for controlling the drive speed of the AF motor 31 according to the value of the AF pulse counter 23a. That is, when it is larger than the number of overlap integration prohibition pulses, the AF motor 31 is driven at high speed to bring the focusing lens 12 closer to the in-focus position in a shorter time, and the overlap integration is also executed. When it becomes, the overlap integration is stopped while being driven at a high speed, and when the number of pulses becomes less than the constant speed control start pulse, the counter value becomes 0 while the AF motor 31 is PWM-controlled at a low speed to prevent overshoot. This is a process of stopping the AF motor 31.

When the pulse check processing is started, the value of the AF pulse counter 23a is compared with the number of overlap integration inhibition pulses (S341), and when the counter value is larger, S3 is set.
Proceed to step 43, set the overlapping flag to 1, and
The overlap sensor is started to start the AF sensor 21.
AF sensor data is input from and the defocus calculation is executed (S345). Then, if a valid calculation result is obtained, the process proceeds to the drive direction check process, and if a valid calculation result is not obtained, the process returns (S347).

The drive direction check process is performed by the AF motor 31.
The AF pulse number is calculated based on the AF sensor data obtained by integration during driving, and is set in the counter.
When the driving direction is changed, the AF motor 31 is braked and stopped. The brake of this embodiment is a process of reversing the drive current of the AF motor 31 to generate a reverse drive force in the AF motor 31 and stopping the AF motor 31 in a short time.

When the driving direction check process is started, the overlapping flag is set to 1 and the searching flag is set to 0, and the previous and present driving directions of the focus adjusting lens 12 are compared from the calculation result ( S361, S363). Normally, since the directions are the same, the number of AF pulses at the integration intermediate point is calculated, the calculated value is set in the counter, and the process returns (S363, S365). When the drive direction is changed, the AF motor 31 is braked and stopped, the overlapping flag is set to 0, the reintegration flag is set to 1, and the process returns to the VDD loop processing (S36).
3, 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. At this time, since the overlapping flag is set to 1, the pulse check processing is started from S301 until the counter value becomes less than the number of overlap prohibition pulses,
S341 to S347, S36 of the driving direction check process
From 1 to S365, the process returns to the VDD loop process and returns to the pulse check process.

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

The processing from S349 to S355 is processing for ending the 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 at a low speed to control the AF motor 31 to stop when the number of AF pulses is 0 (S349, S351, S35).
3). When the AF motor 31 is stopped, the overlapping flag is set to 0, the reintegration flag is set to 1, and the process returns to the VDD loop processing (S353,
S355).

When the process returns to the VDD loop processing and next enters S205, 0 is set in the overlap flag and the searching flag and 1 is set in the re-integration flag, so that the re-integration is performed from S305. Start processing.

In the re-integration process, the defocus amount is obtained to check whether or not the subject is in focus. When the subject is in focus, the focusing flag is set to 1, and when the subject is not focused, the focus is adjusted again. This is a process of driving the lens 12. Here, if the focus flag is set to 1 and the process returns to the VDD loop processing, the power-down processing is exited from S213, and A
A standby state is waited for the F start switch 27 to be turned on.

The above is the processing in the case of normal focusing, but also in the case of difficulty in focusing or in the case of inability to focus, the VDD loop processing is exited in the unfocusable state and the processing returns to the power down processing. .

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 AF sensor data,
Defocus calculation processing is executed (S301, S30
3, S305). If the effective defocus amount cannot be obtained because the contrast of the object is too low, the search integration process is started from S309.

The search integration process is a process of performing integration and defocus calculation while driving the AF motor 31 from the closest focus position to the infinite focus position so that an effective defocus amount can be obtained. If an effective defocus amount cannot be obtained even by this search integration processing, A
After setting the FNG flag to 1 and moving the focus adjustment lens 12 to a predetermined position (S215, S221, S223, S2).
25) and returns to the power down process.

When the search integration process (search process) is started,
First, the AF motor 31 is driven for search (first, driven in the short-distance focusing direction), the search-in-progress flag is set to 1, and
The integration is started by the AF sensor 21, and when the integration is completed, the integrated value is fetched as AF sensor data, and the defocus amount is obtained by the defocus calculation (S311,
S313, S315). If the effective defocus amount is obtained here, the drive direction check is completed (S317), but if it is not obtained, the process returns to the VDD loop processing and the processing from S207 is executed (S317, S31).
9).

The AF motor search drive means the AF motor 3
First, 1 is driven in the direction of the short-distance focus position, and when the focus adjustment lens 12 reaches the short-distance side movement end point and stops, the AF motor 31 is inverted to the focus position of infinity and the focus adjustment lens 12 becomes infinite. After reaching the far-side movement end point and stopping, AF
This is a process of stopping the motor 31. If an effective calculation result is obtained during the search drive, the operation returns to the drive based on the defocus.

When returning to the VDD loop processing and entering 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 S311 is executed. Run. Then, when the focus adjustment lens 12 reaches the infinity in-focus position and no effective calculation result is obtained,
After entering the AFNG processing, setting the AFNG flag to 1 and returning to the VDD loop processing, the focus adjustment lens 12 is moved to a predetermined position (S215, S221, S223, S223).
225), the power down process is completed.

The above is the processing in the case where a valid calculation result is not obtained from the beginning, but a valid calculation result is obtained once, and after focusing, a valid calculation result is not obtained in the reintegration processing. If so, the AFNG process starts from S385,
After the AFNG flag is set to 1 and the process returns to the VDD loop processing, the focus adjustment lens 12 is moved to a predetermined position (S
215, S221, S223, S225), and the power-down process is completed.

As described above, in the present embodiment, since the electromagnetic clutch 50 is in the disengaged state and the AF motor 31 is disengaged until the AF start switch 27 is turned on, the user manually operates the manual focus. Knob 16
The focus can be adjusted by rotating the. When the AF start switch 27 is turned on, the electromagnetic clutch 50 is turned on and the AF motor 31 is connected to execute automatic focus adjustment. Then, when it is detected that focusing is possible or focusing is impossible, the electromagnetic clutch 50 is turned off to disconnect the AF motor 31. Therefore, it is possible to perform manual focus adjustment and auto focus adjustment without performing a manual auto focus switching operation.

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 equipment such as a transit, and further, to a telescope, binoculars, etc. Applicable to telephoto optics.

[0065]

As is clear from the above description, the present invention
The motor drive means is connected to the lens moving means only when the automatic focus adjustment is performed, and is disconnected from the motor drive means when the automatic focus adjustment is not performed, so the lens moving means is normally driven manually without switching operation. When it is desired to adjust the focus, the automatic focus adjustment becomes possible simply by activating the control means, which greatly improves the operability of the focus adjustment.

[Brief description of drawings]

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

FIG. 2 is a plan view of the same auto level.

FIG. 3 is a cross-sectional view showing a main part around a focus adjusting mechanism of the same auto level.

FIG. 4 is a cross-sectional view showing a main part of an embodiment of an electromagnetic clutch of the same focal point adjusting mechanism in a connected state.

FIG. 5 is a sectional view showing a main part of an embodiment of the electromagnetic clutch in a disconnected state.

FIG. 6 is a diagram showing a part of a flowchart of focus adjustment processing of the same auto level.

FIG. 7 is a diagram showing a part of a flowchart relating to the focus adjustment processing of the same auto level.

FIG. 8 is a diagram showing a part of a flowchart of focus adjustment processing of the same auto level.

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

FIG. 10 is a diagram showing a part of a flowchart of focus adjustment processing of the same auto level.

[Explanation of symbols]

 10 Auto Level 12 Focus Adjustment Lens 20 Focus Detection System 21 AF Sensor (Focus Detection Unit) 23 Calculation / Control Circuit (Control Unit) 26 Electromagnetic Clutch Drive Circuit 27 AF Start Switch (Automatic Focus Start Operation Means) 29 AF Switch 30 Focus Adjustment Lens drive system 31 AF motor (motor drive means) 50 Electromagnetic clutch 52 Drive shaft 52a Rotor part 54 Coil 55 Output shaft 57 Armature 58 Spring

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location G03B 13/34

Claims (10)

[Claims] 1. A telephoto optical system for moving a focus adjustment lens along an optical axis to adjust the focus; focus detection means for detecting the focus state via the telescopic optical system; lens movement for moving the focus adjustment lens. A driving means for driving the lens moving means; a clutch means for connecting and disconnecting the motor driving means and the lens moving means; a control means for driving the focus detecting means and the motor driving means to automatically adjust the focus; The control means connects the clutch means when the automatic focus adjustment is executed, and disconnects the clutch means when the automatic focus adjustment is not executed. 2. The automatic focusing device for a telephoto optical system according to claim 1, further comprising a manual driving device for driving the lens moving device by an external operating force, and the control device performing automatic focusing. An automatic focusing device for a telescopic optical system, characterized in that when not present, the clutch means is disengaged so that the operating force of the manual drive means is not transmitted to the motor drive means. 3. The automatic focusing device for a telephoto optical system according to claim 1, further comprising an automatic focusing start operation means, wherein the control means operates the clutch when the automatic focus start operation means is operated. An automatic focusing device for a telescopic optical system, characterized in that means are connected to perform automatic focusing. 4. The automatic focusing device for a telescopic optical system according to claim 1, wherein the clutch means is an electromagnetic clutch means, which is in a disengaged state when not energized and energized. The automatic focusing device of the telephoto optical system, which is characterized in that it is in the connected state while it is being used. 5. The automatic focusing device for a telephoto optical system according to claim 1, wherein the clutch means is an electromagnetic clutch means, and two disengageable shafts are provided.
An armature that can be magnetically attracted and is mounted on one of the two shafts so that thrust movement is possible, and a rotor that is fixed to the other shaft, an electromagnetic coil that is mounted on the rotor, and an armature that is always separated from the rotor. The armature includes an elastic member for urging, and the armature attracts the rotor to connect the two shafts when the coil is energized, and biases the elastic member when the coil is not energized. An automatic focusing device for a telescopic optical system, characterized in that the two shafts are separated from the rotor by the. 6. The automatic focusing device for a telephoto optical system according to claim 1, wherein the clutch means is an electromagnetic clutch means, and two discontinuous shafts are provided.
An armature that is magnetically adsorbable and is mounted on one of the two shafts so that thrust movement is possible, and a rotor that is fixed to the other shaft, a coil that has the rotor as the core, and an armature that is always attached in a direction that separates the armature from the rotor. An elastic member for urging the armature, or one of the armature and the rotor is formed of a permanent magnet, and when the coil is energized in one direction, the armature attracts the rotor and attracts even if the coil is de-energized. When the coil is energized in the other direction in this adsorption state, the armature separates from the rotor and maintains the separated state even when the coil is de-energized. Optical system autofocus device. 7. The automatic focusing device for a telephoto optical system according to claim 1, wherein the control means is
The telescopic optical system characterized in that the clutch means is disengaged after the focus adjustment lens is moved to the in-focus position by the automatic focus adjustment or after it is determined that the in-focus position cannot be moved. Autofocus device. 8. A telephoto optical system for moving the focus adjustment lens along the optical axis to adjust the focus; focus detection means for detecting the focus state via the telescopic optical system; lens movement for moving the focus adjustment lens. Means; manual driving means for driving the lens moving means by an external operating force; motor driving means for driving the lens moving means; clutch means for connecting and disconnecting the motor driving means and the lens moving means; the focus detecting means and the motor driving A control means for driving the means to automatically adjust the focus; the control means always disconnects the clutch means, connects the clutch means when executing the automatic focus adjustment, and controls the focus adjustment lens. When the focus adjustment lens cannot be moved to the focus position, the clutch means is disengaged when the focus adjustment lens is moved to the focus position. Cutting the said clutch means from moving to the predetermined position, telescopic optics autofocus apparatus according to claim. 9. The automatic focusing device for a telephoto optical system according to claim 8, wherein the predetermined position is based on one moving end of a movable range of the focus adjusting lens, and is a lens moving unit by the motor driving unit. An autofocus device for a telephoto optical system, characterized in that the position is detected by the driving amount of. 10. The automatic focusing device for a telescopic optical system according to claim 1, wherein the automatic focusing device for a telescopic optical system is mounted on a surveying instrument.