JP4115211B2 - Lens device, camera system and camera - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a drive control device for an optical member in an optical apparatus, and more particularly to an apparatus suitable for an optical apparatus having an autofocus function.
[0002]
[Prior art]
In recent years, AF (autofocus) single-lens reflex cameras have increased the speed of adjusting the focus on the subject, and have significantly improved the ability to focus on a moving subject (moving object). Can be taken. This increase in focus adjustment speed can be realized by driving the focus lens unit with a powerful motor of a high rotation and high torque type, which increases costs and power consumption.
[0003]
A servo AF control method capable of causing the moving object to follow the focus will be described with reference to FIG.
[0004]
This figure shows the state from the start to the stop of the movement of the focus lens unit, the vertical axis represents the movement speed of the focus lens unit, and the horizontal axis represents time. When moving an object, the speed generally changes in the order of acceleration range → constant speed range → deceleration range due to inertia, and the hatched portions in the figure represent the acceleration range and the deceleration range.
[0005]
In the servo AF control method, before the focus lens unit moves, the defocus amount (focus shift amount) with respect to the subject is detected by a phase difference detection method or the like, and the drive amount of the focus lens unit is calculated according to the defocus amount. Then, focusing is performed by driving the focus lens unit for the calculated driving amount.
[0006]
When the subject is a moving object, it is considered that the subject is moving even while the focus lens unit is moving. For this reason, it is necessary to detect the defocus amount and calculate the drive amount of the focus lens unit even while the focus lens unit is moving. This is generally referred to as “overlap control” (see Patent Document 1).
[0007]
This overlap control is a method that improves the focus followability with respect to moving objects by correcting the amount of movement of the focus lens unit according to the amount of movement of the moving object. It is performed multiple times. This is because when the overlap control is performed in the acceleration / deceleration range, the movement speed of the focus lens unit is unstable, so the amount of movement of the focus lens unit during the defocus amount detection process and the lens drive amount calculation process during overlap control This is because a slight shift occurs in the correction, and as a result, the followability of focusing on the subject is deteriorated.
[0008]
The reason why overlap control is performed a plurality of times is to improve focus accuracy by reducing the focus shift to the subject. In addition, the overlap control is performed not only for moving objects but also for stabilizing the roughness of focus accuracy for a stationary subject.
[0009]
FIG. 8 shows the specific contents of the overlap control with the passage of time. When the focus lens unit reaches a constant speed range where overlap control is possible, (1) the current position of the focus lens unit is detected. Next, the defocus amount is detected. Here, the charge accumulation time in a plurality of CCD line sensors in the phase difference detection method is shown. The charge accumulation time varies depending on the illuminance of reflected light from the subject.
[0010]
When the detection of the defocus amount is completed, (2) the current position of the focus lens unit is detected again. By these operations (1) and (2), it is possible to know at which position of the focus lens unit the defocus amount is detected, and the optical ratio according to the position of the focus lens unit is corrected by the subsequent calculation. can do.
[0011]
Next, the focus lens unit drive amount for focus adjustment is calculated based on the defocus amount detection result, and the focus lens unit position detection result in (1) (2) above is calculated. The drive amount is corrected, and the actual drive amount of the focus lens unit is derived.
[0012]
Finally, (3) the current position of the focus lens unit is detected again. This is because defocus amount detection ((1) (2)) is performed while the focus lens unit is moving, and is used to derive the amount of movement of the focus lens unit from the point of defocus amount detection. The movement amount up to (3) is subtracted from the calculation result of the driving amount of the lens unit to correct the final arrival position of the focus lens unit.
[0013]
More specifically, in (1) and (2) in FIG. 9, the position of the focus lens unit is detected. This is for deriving the position of the focus lens unit when the defocus amount is detected. In the case of a constant speed, the position of the focus lens unit when the defocus amount is detected from the lens position at (2)-the lens position at (1) / 2 + (1). It can be regarded as the center.
[0014]
The lens position is detected twice because the charge accumulation time of the CCD line sensor changes depending on the amount of reflected light from the subject. Therefore, the position of the focus lens unit before and after accumulation is detected, and the average value is calculated as the defocus amount. This is because the center of the position of the focus lens unit at the time of detection (that is, the center of the charge accumulation time of the CCD line sensor) is used.
[0015]
If the lens position at (1) = 10 mm and the lens position at (2) = 30 mm, the position of 20 mm of the focus lens unit is the center of the position when the defocus amount is detected.
[0016]
On the other hand, when the defocus amount is detected during acceleration, the charge accumulation time is constant, but the moving speed of the focus lens unit at the time of detecting the lens position twice is different ((1) and (2)). If the same calculation as described above is performed, the center of the charge accumulation time for the calculation is closer to the (1) side than the actual accumulation time center position. (In the case of acceleration, the center of the charge accumulation time is the position on the (2) side). Therefore, in order to accurately detect the lens position, it is necessary to detect the acceleration of the focus lens unit. As can be seen from the above description, the position detection of the focus lens unit is important in performing servo AF control such as overlap control.
[0017]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-023046 (paragraph 0003, FIG. 7, etc.)
[0018]
[Problems to be solved by the invention]
As described above, it is necessary to accurately detect the position of the focus lens unit when detecting the defocus amount in servo AF control such as overlap control, and the movement control method of the focus lens unit has further speed stability. It has been demanded.
[0019]
Contrary to this, with the recent increase in autofocus speed, the focus lens unit has to be moved at a high speed, so that a more powerful motor can be used or a focus drive mechanism (such as a deceleration mechanism or a lens barrel) can be used. The power transmission mechanism such as a cam mechanism is reduced in weight. By using a powerful motor and reducing the weight of the focus drive mechanism, the mechanical strength of the components used is relatively reduced, and naturally the load torque is also reduced.
[0020]
As a result, the speed control method of the focus lens unit is complicated, and the number of devices that cannot obtain a stable speed is increasing. Furthermore, due to these factors, the overall strength of the lens barrel including the focus drive mechanism becomes weaker than before, and in particular, when the motor is started, deformation of the focus drive mechanism such as bending, tilting, and twisting occurs. The stability of the speed of the lens unit is becoming increasingly difficult to obtain.
[0021]
Here, FIG. 9 shows that the movement speed and position detection of the focus lens unit are adversely affected by deformation due to insufficient mechanical strength of the focus drive mechanism such as the lens barrel and the speed reduction mechanism.
[0022]
In the figure, the vertical axis represents the actual focus lens movement (dotted line) and the detected pulse conversion movement (solid line) of the focus lens, and the horizontal axis represents time.
[0023]
Here, the configuration of the actual focus drive mechanism will be described. The motor is directly connected to the speed reduction mechanism, where the motor output is decelerated and the torque is increased. In general, this speed reduction mechanism is configured by overlapping a plurality of gears. The gear of the final stage of the speed reduction mechanism is connected to the gear of the cam barrel that drives the focus lens barrel.
[0024]
Further, as described above, in order to configure an encoder for detecting the position and speed of the focus lens, a pulse plate having slits formed at equal intervals in the circumferential direction on one gear in the speed reduction mechanism. The light interrupting part and the light receiving part of the photo interrupter are arranged so as to sandwich the pulse plate. The photo interrupter electrically detects passage of light through the slit by the pulse plate and blocking of the light and outputs a pulse signal.
[0025]
The encoder configured in this manner is disposed at a location near the motor in the speed reduction mechanism. This is because, when placed close to the focus lens in the speed reduction mechanism, it is necessary to form the slits of the pulse plate very finely in order to obtain the required moving amount detection resolution, which makes it difficult to manufacture the pulse plate. By accompanying. In other words, since the resolution as an encoder is improved when a pulse plate having as many slits as possible is arranged on the motor side within an easy manufacturing range, such an arrangement is common.
[0026]
However, when the encoder is arranged on the motor side, the gear to which the encoder is attached to the gear of the final stage, and the gear of the cam cylinder that drives the focus lens barrel, and the gear of the final stage (gear). As shown in FIG. 4, the actual amount of movement of the focus lens and the amount of movement detected by the encoder (converted value) are caused by the deformation between the lenses and the deformation at the engagement portion between the focus lens barrel and the cam tube. ) Will shift.
[0027]
4 will be further described. When the motor is started, the movement of the focus lens is started. However, the detected movement amount by the encoder is approximately the rotation of the motor because the encoder is disposed near the motor. The amount of movement of the focus lens increases correspondingly, but increases with a slight delay due to the deformation of the focus drive mechanism (the gear connecting portion and the lens barrel engaging portion) described above.
[0028]
To summarize the above, in autofocus control, the focus lens is focused by controlling the movement speed and movement amount of the focus lens, but this control is performed by controlling the rotation speed and rotation amount of the motor that is the drive source. It is common to do it. However, due to the deformation of the focus drive mechanism, there is a delay in the actual movement speed and movement amount of the focus lens with respect to the detection result of the rotation speed and rotation amount of the motor. For this reason, the delay may have an adverse effect on the AF control.
[0029]
Here, as an example of what causes deformation in the focus drive mechanism, the case where the rigidity of the housing of the reduction mechanism and the strength of the gear are weak, the tilt of the gear shaft that supports the gear, and the component that supports the focus lens Mainly weak mechanical rigidity, such as twisting or tilting of the lens barrel (the engaging portion of the lens barrel and the cam barrel), can be considered. It is also known that this rigidity changes due to the difference in the relationship between components depending on the position of the focus lens and the position of the zoom lens.
[0030]
FIG. 10 shows the influence of the delay in movement of the focus lens described in FIG. 9 on the servo AF control (overlap control).
[0031]
In the figure, the vertical axis represents the speed (B) of the focus lens and the detection speed (pulse speed: A) by the encoder, and the horizontal axis represents time. As described with reference to the movement amount graph in FIG. 9, the lens speed B increases with respect to the pulse speed A with respect to the speed. For the pulse speed A, a target speed width C is set. What makes the target speed wider? This is to suppress control oscillation.
[0032]
When the pulse speed A enters the range of the target speed width C (D time in the figure), it is considered that the focus lens has reached the target speed (the constant speed range described in FIGS. 7 and 8 has been reached) for control purposes. And overlap control is performed (time E in FIG. 10).
[0033]
However, in E time, the focus lens is actually still accelerating. For this reason, as described above when the overlap control is performed at the time of acceleration, a focus shift occurs in the servo AF control, and as a result, a photograph out of focus is taken.
[0034]
In the present invention, due to the deformation of the power transmission mechanism, even if there is a delay in the actual moving amount or moving speed of the lens unit with respect to the operating amount or operating speed of the drive source detected by the encoder or the like, It is an object of the present invention to provide a lens device, a camera system, and a lens device that can perform control substantially matching the movement amount of the lens unit.
[0035]
[Means for Solving the Problems]
In order to achieve the above object, a lens device or a camera according to the present invention includes a movable lens unit, a drive source, a power transmission mechanism that transmits the power of the drive source to the lens unit, and moves the lens unit. A signal output means for outputting a signal each time the drive source is operated by a predetermined amount; and a storage means for storing correction information corresponding to the deformation amount of the power transmission mechanism when the power of the drive source is input to the power transmission mechanism And calculation means for calculating lens movement information representing the movement amount or movement speed of the lens unit based on the signal output from the signal output means and the correction information stored in the storage means.
[0036]
As a result, due to the deformation of the power transmission mechanism, there is a difference (delay) in the actual moving amount and moving speed of the lens unit with respect to the operating amount and operating speed of the drive source obtained from the output signal of the signal output means. However, it is possible to perform control that substantially matches the actual movement amount of the lens unit.
[0037]
For example, in overlap control for automatic focus adjustment, it is determined whether or not the focus lens unit is being driven at a constant speed based on lens movement information representing the movement speed calculated by the calculation means, and is being driven at a constant speed. Sometimes, the focus adjustment state of the photographing optical system is detected, and further, using the lens movement information indicating the movement amount, the focus lens unit is driven to perform the calculation for obtaining the focus.
[0038]
Thereby, due to the deformation of the power transmission mechanism, there is a difference (delay) in the actual moving amount and moving speed of the focus lens unit with respect to the operating amount and operating speed of the drive source obtained from the output signal of the signal output means. Even in such a case, the overlap control can be started after the focus lens unit is reliably driven at a constant speed, and accurate lens position detection can be performed during the overlap control.
[0039]
The amount of deformation of the power transmission mechanism is the device temperature, the drive direction of the drive source, the drive amount from the start of the drive source, the elapsed time from the start of the drive source, the acceleration of the drive source, the device attitude, and the drive position of the lens unit. In many cases, it varies depending on the driving conditions such as the voltage applied to the driving source. By using correction information corresponding to these driving conditions, control that substantially matches the actual movement amount of the lens unit regardless of the driving conditions ( For example, it is possible to perform focus detection at an appropriate timing in overlap control and focus lens drive with high focus accuracy.
[0040]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
FIG. 1 shows a system configuration of an autofocus single-lens reflex camera according to the first embodiment of the present invention.
[0041]
In the figure, reference numeral 1 denotes a lens device, and 13 denotes a single-lens reflex camera to which the lens device 1 is detachably attached.
[0042]
In the lens apparatus 1, reference numeral 2 denotes a focus lens unit including a focus lens for focusing a subject image and a lens barrel for holding the focus lens. The lens apparatus 1 includes the focus lens unit 2 and a lens lens (not shown). An imaging optical system including a variable magnification lens unit and the like is provided.
[0043]
Reference numeral 2a denotes a cam ring provided with a cam that is driven to rotate around the optical axis to move the focus lens unit 2 substantially parallel to the optical axis. Reference numeral 3 denotes a motor, and 3a denotes a speed reduction mechanism that decelerates and transmits the power of the motor 3 to the cam ring 2a and rotates the cam ring 2a around the optical axis. The speed reduction mechanism 3a is configured using a plurality of gears. The speed reduction mechanism 3a and the cam ring 2a constitute a power transmission mechanism.
[0044]
Reference numeral 4 denotes an encoder that outputs a pulse signal at every predetermined rotation angle of the motor 3, and is composed of the pulse plate and the photo interrupter described above. The pulse plate is provided so as to be able to rotate integrally with a gear close to the motor 3 in the output shaft of the motor 3 or the speed reduction mechanism 3a. For this reason, the rotation (rotation amount or rotation speed) of the motor 3 can be detected by the pulse signal output from the encoder 4.
[0045]
Reference numeral 5 denotes an absolute position sensor for detecting the absolute position (zone) of the focus lens unit 2, which is composed of a conductive pattern formed on the outer periphery of the cam ring 2a and a detection contact on which the conductive pattern slides. Yes. A zone having a predetermined width in which the focus lens unit 2 is located is detected by the absolute position sensor 5, and the absolute position of the focus lens unit 2 is detected from the information on the switching of the zone and the count value of the pulse signal from the encoder 4. Can do.
[0046]
Reference numeral 6 denotes an EEPROM which is a nonvolatile memory. The EEPROM 6 has a correction value corresponding to the amount of deformation (deflection, twist, tilt) of the power transmission mechanism constituted by the speed reduction mechanism 3a, the focus lens unit 2 and the cam ring 2a when the power of the motor 3 is input. Are stored on the basis of simulation results and the like at the design stage. The correction value may take a different value for each lens device due to manufacturing errors of individual lens devices, component variations, and the like. Further, as the correction value, a change with time with respect to the mechanical strength of the focus lens unit 2 may be taken into consideration, and a different value may be stored depending on the usage time. The EEPROM 6 also stores optical information (sensitivity, focus error information, etc.) corresponding to the position of the focus lens unit 2.
[0047]
Reference numeral 7 denotes a lens microcomputer (hereinafter referred to as a lens microcomputer) that controls the entire lens apparatus 1, and includes an arithmetic circuit 7a, a communication circuit 7b, an internal memory 7c, a timer circuit (not shown), an A / D circuit, and the like. It is equipped.
[0048]
Reference numeral 8 denotes a contact unit having a plurality of contacts for performing serial communication with a camera microcomputer (hereinafter referred to as camera microcomputer) 12 mounted on the camera 13 side.
[0049]
Reference numeral 9 denotes a temperature sensor for detecting the ambient temperature of the lens device 1 or the internal temperature of the lens device 1, and reference numeral 10 denotes an attitude sensor for detecting the tilt angle (posture) of the lens device 1. The temperature sensor 9 and the attitude sensor 10 may be mounted in the camera 13. In this case, temperature information and attitude information are communicated from the camera microcomputer 12 to the lens microcomputer 7 through the contact unit 8.
[0050]
In the camera 13, reference numeral 11 denotes a focus detection unit including a pair of CCD line sensors (not shown) and a focus detection optical system that forms an image of light incident from the photographing optical system on the pair of CCD line sensors. This is for performing focus detection by a phase difference detection method for detecting a defocus amount of the photographing optical system from a phase shift between two images formed on the CCD line sensor.
[0051]
The camera microcomputer 12 controls the entire camera 13. There are many other control systems in the camera 3, but the description is omitted here.
[0052]
In FIG. 1, a solid line means an electrical connection, and a dotted line means a mechanical connection. Furthermore, the arrow means the direction of electrical input / output.
[0053]
The operation of this camera system will be described below. When the camera microcomputer 12 detects that the lens device 1 is mounted by a mounting sensor (not shown), it tries to communicate with the lens microcomputer 7 through the contact unit 8. Through this communication, the camera microcomputer 12 confirms that the lens apparatus 1 has been normally mounted, and the lens microcomputer 7 and the camera microcomputer 12 each perform a predetermined initialization operation.
[0054]
Next, when an instruction to start autofocus is input to the camera microcomputer 12 by the user's switch operation, the camera microcomputer 12 operates the focus detection unit 11 to detect the defocus amount of the photographing optical system. The camera microcomputer 12 calculates the target drive amount (including the drive direction) of the focus lens unit 2 necessary for obtaining the focus based on the detected defocus amount, and sends the target microcomputer 7 to the lens microcomputer 7 through the contact unit 8. Transmits driving amount information.
[0055]
The lens microcomputer 7 activates the motor 3 and starts the movement of the focus lens unit 2 when the information about the target drive amount is transmitted from the camera microcomputer 12. Information on the target drive amount from the camera microcomputer 12 is stored in the internal memory 7 c of the lens microcomputer 7.
[0056]
A pulse signal is output from the encoder 4 along with the rotation of the motor 3, and this pulse signal is input to the lens microcomputer 7. The lens microcomputer 7 derives the rotation amount of the motor 3 from the count value of the pulse signal, and derives the rotation speed of the motor 3 from the input interval time of the pulse signal.
[0057]
The lens microcomputer 7 starts the timer circuit simultaneously with the start of the motor 3. Further, the lens microcomputer 7 transmits information indicating that the focus lens unit 2 is under acceleration control to the camera microcomputer 12 through the contact unit 8 simultaneously with the activation of the motor 3.
[0058]
Thereafter, the lens microcomputer 7 always reads the pulse signal that is the output of the encoder 4. Here, the lens microcomputer 7 (arithmetic circuit 7 a) uses the pulse signal from the encoder 4, the correction value stored in the EEPROM 6, and the detection value by the temperature sensor 9 and the attitude sensor 10 to detect the focus lens unit 2. Information indicating the movement amount and the movement speed is calculated. This calculation method will be described later.
[0059]
Then, the calculated movement amount and movement speed of the focus lens unit 2 are respectively compared with the target drive amount and the target speed (preset) stored in the internal memory 7c.
[0060]
When the lens microcomputer 7 (the arithmetic circuit 7a) determines that the moving speed of the focus lens unit 2 has reached the target speed, information indicating that the focus lens unit 2 is being driven at a constant speed with respect to the camera microcomputer 12. Is transmitted through the contact unit 8. The camera microcomputer 12 starts the above-described overlap control when receiving information indicating that the constant speed driving is being performed from the lens microcomputer 7.
[0061]
Further, the camera microcomputer 12 transmits a communication request for information indicating the amount of movement up to the present time to the lens microcomputer 7 in order to know the current position of the current focus lens unit 2. In response to the communication request, the lens microcomputer 7 transmits the movement amount information up to the present ((1) in FIG. 7).
[0062]
When confirming that the movement amount information has been transmitted, the camera microcomputer 12 operates the focus detection unit 11 to detect the defocus amount of the photographing optical system. When the defocus amount detection is completed, the camera microcomputer 12 transmits a request for communication of movement amount information up to the present time to the lens microcomputer 7 in order to know the current position of the current focus lens unit 2 again. In response to the communication request, the lens microcomputer 7 transmits the movement amount information up to the present to the camera microcomputer 12 ((2) in FIG. 7).
[0063]
When the camera microcomputer 12 confirms that the movement amount information has been transmitted, the camera microcomputer 12 calculates the stop position A of the focus lens unit 2 for obtaining focus. This stop position A is the average position B at the time of focus detection of the focus lens unit 2 calculated using the driving amount information of the focus lens unit 2 obtained in (1) and (2) of FIG.
(Lens position at (2) -Lens position at (1)) / 2 + Lens position at (1)
And the optical information (sensitivity, focus error information, etc.) at the average position A transmitted from the lens microcomputer 7 and stored in the EEPROM 6 are calculated. Detailed contents of this calculation will be described later.
[0064]
When the calculation of the stop position A is completed, the camera microcomputer 12 transmits a request for communication of movement amount information up to the present time to the lens microcomputer 7 in order to know the current position of the focus lens unit 2 again. In response to the communication request, the lens microcomputer 7 transmits movement amount information up to the present to the camera microcomputer 12 ((3) in FIG. 7).
[0065]
When the camera microcomputer 12 confirms that the movement amount information has been transmitted, the stop position A described above, the average position B of the focus lens unit 2 at the time of focus detection, and the position of the focus lens 2 at (3). Are used to set a new target driving amount of the focus lens unit 2 for focusing on the subject. It can be derived from the following formula.
[0066]
New target drive amount
= Stop position A of the calculation result-(current position (3)-average position B at the time of focus detection)
This is the calculation result stop position A when the focus lens unit 2 is at the average position B, and the focus lens unit 2 has moved to the position (3) in FIG. This is because the movement must be deducted.
[0067]
When the new target drive amount from the current position obtained in (3) of FIG. 7 is calculated in this way, the camera microcomputer 12 transmits the new target drive amount to the lens microcomputer 7 as the overlap drive amount. The lens microcomputer 7 continues driving control of the focus lens unit 2 with respect to the received new target driving amount.
[0068]
Here, a method for calculating the stop position during the above-described overlap control will be described. The EEPROM 6 of the lens apparatus 1 stores focus movement amount information with respect to the movement amount of the focus lens unit 2. This is called sensitivity information, and changes depending on the position and focal length of the focus lens unit 2. On the other hand, the focus detection unit 11 outputs a defocus amount with respect to the subject, that is, a focus shift amount (a shift amount on the focus surface). In order to perform focusing by correcting the shift amount on the focus surface, it is necessary to convert the shift amount on the focus surface into the drive amount of the focus lens unit 2.
[0069]
Therefore, the sensitivity information is transmitted to the lens microcomputer 7 and used as one of the calculation coefficients. In addition to this, the lens microcomputer 7 stores manufacturing focus error information for each lens device, and the camera microcomputer 12 transmits the sensitivity information and the focus error information from the lens microcomputer 7 during focus detection. .
[0070]
Through these operations, it is possible to perform focusing control with higher accuracy by calculating using each information at the position of the focus lens unit 2 at the time of focus detection.
[0071]
In the series of operations described above, if there is an error in the position information of the focus lens unit 2, it is expected that the focus correction by the overlap control will be adversely affected. For this reason, in this embodiment, the following method is adopted in order to eliminate the error factor.
[0072]
The above-described movement amount information of the focus lens unit 2 is transmitted to the camera microcomputer 12 based on the pulse signal from the encoder 4, but in the power transmission mechanism (3a, 2a, 2) due to recent high speed AF. The effects of deformation such as bending, falling, and twisting cannot be ignored. Therefore, in the present embodiment, correction according to various conditions of the lens device 1 (driving conditions of the motor 3) is added to the movement amount information of the focus lens unit 2 transmitted from the lens microcomputer 7 to the camera microcomputer 12. The details of the correction will be described with reference to FIGS.
[0073]
First, FIG. 2 shows an elapsed time from when the motor 3 is started to when the lens microcomputer 7 receives a request for transmitting the movement amount information of the focus lens unit 2 from the camera microcomputer 12 (counting time by an internal timer circuit). The correction value corresponding to the amount of deformation in the power transmission mechanism corresponding to is shown for each range of movement amount information. The correction value is stored in the EEPROM 6 as a data table, and the correction value read from the data table according to the movement amount information and the elapsed time is obtained from the focus lens unit 2 obtained based on the pulse signal from the encoder 4. Subtract from the amount of movement information.
[0074]
This is because, as described with reference to FIG. 10, after the motor is started, the deformation amount of the power transmission mechanism changes according to the elapsed time. By this correction, the correspondence between the count value of the pulse signal from the encoder 4 (that is, the rotation amount of the motor 3) and the movement amount of the focus lens unit 2 can be taken.
[0075]
A correction value corresponding to the deformation amount of the power transmission mechanism corresponding to the count value of the pulse signal from the encoder 4 up to the present time is stored in the EEPROM 6 as a data table, and the pulse count value at that time is stored from this data table. Accordingly, the correction value read out may be subtracted from the count value of the pulse signal from the encoder 4. Thereby, even if the lens microcomputer 7 is an inexpensive one that does not have a timer function, the movement amount information that is equivalent to the case where the movement amount information is corrected according to the elapsed time since the start of the motor 3 is corrected. be able to.
[0076]
FIG. 2 shows correction values corresponding to the deformation amount in the power transmission mechanism according to the temperature detected by the temperature sensor 9 such as a thermistor provided in the lens device 1. This correction value is also stored in the EEPROM 6 as a data table. Then, the correction value read from the data table according to the detected temperature is subtracted from the pulse signal count value from the encoder 4. This is effective when the load torque generated in the power transmission mechanism changes with temperature and the characteristics shown in FIG. 10 change, and the accuracy of the movement amount information (that is, the focusing accuracy) is further improved. It becomes possible.
[0077]
Further, FIG. 2 shows deformation in the power transmission mechanism in accordance with the tilt information of the lens apparatus 1 (or camera 13) detected by the posture sensor 10 such as a gravitational acceleration sensor and the current moving direction of the focus lens unit 2. The correction value corresponding to the amount is shown. This correction value is also stored in the EEPROM 6 as a data table, and the correction value read from the data table in accordance with the tilt information and the movement direction information of the focus lens unit 2 is subtracted from the count value of the pulse signal from the encoder 4. .
[0078]
For example, when the attitude of the lens apparatus 1 is upward while the focus lens unit 2 is moving toward the subject, the torque required to drive the focus lens unit 2 is increased as compared to when the attitude is horizontal. On the other hand, when the posture of the lens apparatus 1 is downward, the torque required to drive the focus lens unit 2 is reduced compared to the case where the posture is horizontal.
[0079]
Thus, it is effective when there is a change in the characteristics shown in FIG. 10 depending on the attitude of the lens apparatus 1 and the moving direction of the focus lens unit 2, and the accuracy of the movement amount information (that is, the focusing accuracy) is further improved. It is possible to improve.
[0080]
FIG. 2 shows a correction value corresponding to the amount of deformation in the power transmission mechanism according to the voltage applied to the motor 3 detected by a voltage sensor (not shown). This correction value is also stored as a data table in the EEPROM 6, and the correction value read from the data table in accordance with the detection information of the applied voltage is subtracted from the count value of the pulse signal from the encoder 4. This is because the driving torque of the motor 3 changes depending on the applied voltage. This is effective when the characteristics shown in FIG. 10 change due to the use of a depleted battery or the like. It is possible to improve the focusing accuracy.
[0081]
Further, when the acceleration when the output interval time of the pulse signal from the encoder 4 changes (that is, the acceleration of the motor 3 changes) can be calculated by the lens microcomputer 7, as shown in FIG. The correction value corresponding to the deformation amount in the power transmission mechanism can also be stored in the EEPROM 6 as a data table. Then, the correction value read from the data table according to the calculated acceleration is subtracted from the count value of the pulse signal from the encoder 4. This replaces any change in load torque or change in starting torque of the motor 3 with the change in acceleration in the power transmission mechanism, and corrects the movement amount information in accordance with the acceleration. By correcting the movement amount information in accordance with the acceleration, the above-described correction based on the temperature, posture, and applied voltage is not necessary, and an inexpensive system can be configured.
[0082]
FIG. 3 shows position information detected by the absolute position sensor 5 and unillustrated changes when the amount of deformation of the power transmission mechanism changes depending on the position of the focus lens unit 2 and the focal length (zoom position) of the lens apparatus 1. The correction value corresponding to the amount of deformation in the power transmission mechanism corresponding to the position information of the double lens unit is shown. The correction value is read from the data table stored in the EEPROM 6, and the read correction value is subtracted from the pulse signal count value from the encoder 4.
[0083]
Here, a method of correcting the movement amount information using the correction value will be described.
[0084]
First, the absolute correction amount shown in FIG. 2 is derived according to the elapsed time from the start of movement of the focus lens unit 2 or the movement amount (pulse count value of the encoder 4). For example, when the count value of the pulse signal from the encoder 4 is 25 pulses, the absolute correction amount is 30 + Δp.
[0085]
Here, Δp is a correction amount for further correcting the movement amount information in accordance with the temperature, posture / movement direction, applied voltage, acceleration, focus position, and zoom position.
For example, when the applied voltage to the motor 3 is 3.5 V, Δp is 3 pulses and the count value of the pulse signal from the encoder 4 is 25 pulses, but the movement amount of the focus lens unit 2 is 25− (30 + 3) = -8 pulses. Therefore, there is a delay of 30 + 3 = 33 pulses. Here, the calculation result is minus 8, but if this result is reflected as it is, the focus unit 2 must be driven in the reverse direction. However, since the data table of FIG. 2 has a data structure for preventing the focus unit 2 from moving until 30 pulses are driven (data structure indicating that the lens does not move until 30 pulses), In the case of a negative result, the actual movement amount of the focus lens unit 2 is 0 pulse.
[0086]
In other words, the camera microcomputer 12 can know the exact position of the focus lens unit 2 by transmitting the corrected movement amount information of 0 pulse to the camera microcomputer 12. That is, in the pulse detection of the encoder 4, the motor 3 is rotated by 25 pulses, but the focus lens unit 2 is not actually moved (or hardly moved) due to the deformation of the power transmission mechanism. It will be.
[0087]
On the other hand, the lens microcomputer 7 also accurately calculates whether the focus lens unit 2 is accelerating or driving at a constant speed by calculating the actual moving speed of the focus lens unit 2 based on the corrected movement amount information. Can be judged.
[0088]
As a result, in the series of autofocus control described above, the overlap control is started after the focus lens unit 2 has surely entered the constant speed driving state, and accurate position information of the focus lens unit 2 is also obtained in the overlap control. Can be performed, and high-precision focusing can be performed.
[0089]
In addition, the kind of correction value demonstrated above may be selected only according to the motor drive conditions requested | required of a system, and may be selected combining all or some.
[0090]
The correction amounts shown in FIGS. 2 and 3 may be obtained by simulation based on mechanical strength calculation. For example, an optimum value is derived by a preliminary test using an actual machine and stored in the EEPROM 6 in the manufacturing process. Therefore, the best system can be constructed.
[0091]
FIG. 4 shows a program flowchart of the lens microcomputer 7 in the present embodiment. The operation of the lens microcomputer 7 (mainly the arithmetic circuit 7a) will be described in more detail with reference to FIGS.
[0092]
From the figure
"Steps (abbreviated as S) 100, 101"
When the lens device 1 is mounted on the camera 13, power is supplied to the lens microcomputer 7 from the camera 13 side, and the lens microcomputer 7 performs a predetermined initialization process. When the initialization process is completed, the state of various switches (not shown) provided in the lens apparatus 1 is detected, and the detection result is stored in the internal memory 7c.
[0093]
"Step 102"
The lens microcomputer 7 checks whether or not the camera microcomputer 12 has transmitted the drive instruction and target drive amount information for the focus lens unit 2. If the drive command has not been transmitted, the process returns to step 101 to detect the state of the switches again. The communication from the camera microcomputer 12 is processed by an interrupt process (which will be described later) of the lens microcomputer 7, and necessary information (for example, the above drive command) is stored in the lens microcomputer 7 in the interrupt process. Is stored in the internal memory 7c.
[0094]
"Step 103"
When a drive command for the focus lens unit 2 is transmitted from the camera microcomputer 12 in step 102, the lens microcomputer 7 starts the motor 3 and drives the focus lens unit 2 toward the target drive amount included in the drive command. To start. At this time, the lens microcomputer 7 sets a moving flag indicating that the focus lens unit 2 is moving and an acceleration / deceleration flag indicating that the focus lens unit 2 is moving to the camera microcomputer 12 ( The moving flag = 1, the acceleration / deceleration flag = 1), and the flag information is transmitted to the camera microcomputer 12. The camera microcomputer 12 receives the information of the acceleration / deceleration flag = 1 and does not perform overlap control even when the focus lens unit 2 is moving. The lens microcomputer 7 starts an internal timer simultaneously with the start of the motor 3.
[0095]
The lens microcomputer 7 counts the pulse signal output from the encoder 4 with an internal counter, and simultaneously derives the moving speed of the focus unit 2. Here, what is derived from the cycle of the pulse signal is the rotational speed of the motor 3, and as described with reference to FIG. 10, it differs from the actual moving speed of the focus unit 2 due to the deformation of the power transmission mechanism. There is a possibility.
[0096]
Therefore, in the present embodiment, the internal counter value of the lens microcomputer 7 indicating the movement amount of the focus unit 2 is added to the current movement amount, driving time, temperature, posture, acceleration, applied voltage, shown in FIGS. Correction is performed using correction amounts according to various motor driving conditions such as lens position information, and a time interval at which the corrected actual movement amount changes is derived as the movement speed of the focus unit 2.
[0097]
Further, the voltage applied to the motor 3 is controlled so that the detected moving speed (the derived moving speed) reaches the target moving speed and constant speed driving is performed at the target moving speed.
[0098]
"Step 104"
Thereafter, the lens microcomputer 7 confirms whether or not the above-described derived movement speed (actual movement speed of the focus unit 2) reaches a preset target movement speed, and constant speed driving is started. . If it is determined that the detected moving speed is constant speed driving at the target moving speed, the routine proceeds to step 105. On the other hand, if it is determined that the detected moving speed is different from the target moving speed (accelerating or decelerating not being driven at a constant speed), the routine proceeds to step 106.
[0099]
"Step 105"
Since the moving speed detected in step 104 has reached the target moving speed, the lens microcomputer 7 clears the acceleration / deceleration flag set in step 103 (that is, adds information as information indicating that constant speed driving is being performed). This flag information is transmitted to the camera microcomputer 12. Upon receiving this flag information, the camera microcomputer 12 starts overlap control.
[0100]
"Step 106"
The lens microcomputer 7 compares the target driving amount of the focus lens unit 2 transmitted from the camera microcomputer 12 with the moving amount up to the present, and confirms whether or not the target driving amount has been reached. Here, when the movement amount up to the present does not reach the target drive amount, the process returns to Step 103, and when the movement amount up to the present reaches the target drive amount, the process proceeds to Step 107.
[0101]
"Step 107"
Since the movement amount of the focus lens unit 2 has reached the target drive amount, the lens microcomputer 7 stops the motor 3 and further moves the flag to notify the camera microcomputer 12 that the focus lens unit 2 is stopped. Is cleared (moving flag = 0), and the flag information is transmitted to the camera microcomputer 12.
[0102]
By receiving this flag information, the camera microcomputer 12 determines that the focus lens unit 2 has reached the target drive position, and proceeds to the next operation.
[0103]
FIG. 5 shows a flowchart regarding communication interruption processing in the lens microcomputer 7. This communication interrupt process is executed by receiving communication from the camera microcomputer 12.
[0104]
"Steps 200 and 201"
When the communication from the camera microcomputer 12 is received first, the lens microcomputer 7 confirms the command data transmitted from the camera microcomputer 12. The command data is code data representing a request content from the camera microcomputer 12 to the lens microcomputer 7, and the lens microcomputer 7 analyzes the code data to determine a request from the camera.
[0105]
The command data includes a drive command for the focus lens unit 2, a request for receiving the target drive amount for the focus lens unit 2, a request for transmission of optical information (sensitivity, focus error information, etc.), and a movement amount information for the focus lens unit 2. There is a transmission request.
[0106]
"Step 202"
The lens microcomputer 7 sets transmission information to the camera microcomputer 12 corresponding to the command data, and transmits the information to the camera microcomputer 12. At this time, when the command data received from the camera microcomputer 12 is a transmission request for the movement amount information of the focus lens unit 2, the lens microcomputer 7 determines whether or not the focus lens unit 2 is currently moving. If it is stopped, the process proceeds to step 203. If it is moving, the process proceeds to step 204.
[0107]
"Step 203"
When the focus lens unit 2 is stopped, the power transmission mechanism is not deformed by the input of power from the motor 3, so the lens microcomputer 7 uses the current count value of the pulse signal from the encoder 4 as it is. 2 movement amount information is transmitted to the camera microcomputer 12.
[0108]
"Step 204"
When the focus lens unit 2 is moving, in order to correct the movement amount information of the focus lens unit 2 using the correction amount corresponding to the deformation of the power transmission mechanism shown in FIGS. The correction amount is read from the data table in the EEPROM 6 in accordance with the elapsed time from the start of movement measured by the internal timer started in step 103. Further, the correction amount corresponding to the motor driving conditions (temperature, posture, acceleration, applied voltage, lens position information) other than the elapsed time shown in FIGS. 2 and 3 is also read, and the current correction amount is used using all the correction amounts. The count value of the pulse signal from the encoder 4 is corrected, and the corrected count value (movement amount information) is transmitted to the camera microcomputer 12.
[0109]
"Step 205"
The lens microcomputer 7 ends the interrupt process when the transmission process is completed.
[0110]
FIG. 6 shows a flowchart of processing related to autofocus control in the camera microcomputer 12.
[0111]
"Steps 300 and 301"
In general, a camera is equipped with a release button, and the operation of the camera 13 is generally started by operating the release button. The release button is a two-stage stroke switch. When only the first stage (first stroke switch) is on, AF and photometry operations are turned on to the second stage (second stroke switch). If it is, the release operation is performed.
[0112]
First, the camera microcomputer 12 determines whether only the first stroke switch S1 is ON. When the first stroke switch S1 is OFF, the routine proceeds to step 300, and when only the first stroke switch S1 is ON, the routine proceeds to step 302.
[0113]
"Step 302"
Since only the first stroke switch is ON, the camera microcomputer 12 outputs an operation start command to the focus detection unit 11 and detects the focus adjustment state (defocus amount) of the photographing optical system for the current subject.
[0114]
"Step 303"
The camera microcomputer 12 determines whether or not the defocus amount is within a predetermined focus range, and if it is within the focus range, the process proceeds to step 308 to end the AF operation. If it is not within the focusing range, the routine proceeds to step 304.
[0115]
"Step 304"
Since the in-focus state has not been obtained, the camera microcomputer 12 transmits a drive command for the focus lens unit 2 to the lens microcomputer 7 in order to move the focus lens unit 2 and adjust the focus. At this time, the camera microcomputer 12 transmits a request for transmission of optical information related to AF to the lens microcomputer 7 in order to calculate the target drive amount of the focus lens unit 2 based on the defocus amount. As a result, optical information is transmitted from the lens microcomputer 7 and is received and stored in a memory (not shown) in the camera microcomputer 12.
[0116]
The camera microcomputer 12 calculates the target drive amount of the focus lens unit 2 based on the defocus amount and the optical information of the lens device 1, and transmits this target drive amount information to the lens microcomputer 7 together with information indicating the drive direction. To do.
[0117]
"Step 305"
The camera microcomputer 12 confirms the state of the lens device 1. This is because the lens microcomputer 7 is a system that communicates the state after the change to the camera microcomputer 12 when the current state of the focus lens unit 2 changes. The state of the lens device 1 related to the present embodiment indicates whether the focus lens unit 2 is being accelerated or decelerated or driven at a constant speed. When the focus lens unit 2 is accelerating / decelerating (moving flag = 1 and accelerating / decelerating flag = 1), the process proceeds to step 307, and driving at a constant speed (moving flag = 1 and accelerating / decelerating flag = 0). If so, go to Step 306.
[0118]
"Step 306"
The camera microcomputer 12 starts overlap control on the assumption that the focus lens unit 2 is driven at a constant speed. The processing contents at this time are performed in the steps of focus detection operation similar to step 302, focus determination similar to step 303, and calculation and transmission of the target drive amount of the focus lens unit 2 similar to step 304. The detailed contents of the overlap control are as described above.
[0119]
“Step 307”
As described in step 107 in FIG. 4, in the lens microcomputer 7, when the movement amount of the focus lens unit 2 does not reach the target drive amount received from the camera microcomputer 12, information on the moving flag = 1 is set as the target drive. When the amount is reached, information on the moving flag = 0 is transmitted to the camera microcomputer 12. By receiving the flag information, the camera microcomputer 12 diagnoses whether or not the driving of the focus lens unit 2 has been stopped. If it is being driven, the process returns to step 305, and if it is being stopped, the process proceeds to step 308.
[0120]
"Step 308"
The camera microcomputer 12 ends the AF control.
[0121]
(Second Embodiment)
In the first embodiment, information corresponding to the actual movement amount of the focus lens unit 2 is obtained by subtracting the correction amount corresponding to the deformation amount of the power transmission mechanism stored in the EEPROM 6 from the count value of the pulse signal from the encoder 4. Although the calculation method has been described, the correction amount is replaced with a function that approximates the movement delay of the focus lens unit shown in FIGS. 9 and 10, and corresponds to the deformation amount of the power transmission mechanism in each motor driving condition. It is also possible to store an approximation function as correction information in the EEPROM, and use the approximation function to calculate information corresponding to the actual movement amount of the focus lens unit by approximation calculation.
[0122]
An approximate calculation method of information corresponding to the actual movement amount of the focus lens unit 2 in the present embodiment will be described with reference to FIGS. 2 and 3. Since the configuration of the camera system to which this embodiment is applied is the same as that of the first embodiment, the components of the camera system will be described with the same reference numerals as those of the first embodiment.
[0123]
When the lens microcomputer 7 receives a transmission request for the movement amount information of the focus lens unit 2 from the camera microcomputer 12, the lens microcomputer 7 calculates a function that approximates the deformation amount of the power transmission mechanism according to the elapsed time from the start of the motor 3 to the present time. , And reading out from the EEPROM 6, and substituting the elapsed time at that time into the function, and calculating the function value (correction amount) at that time. Then, the function value is subtracted from the count value of the pulse signal from the encoder 4 to perform an approximate calculation of the actual movement amount information of the focus lens unit 2.
[0124]
This is because, as described in the first embodiment, the amount of deformation of the power transmission mechanism changes according to the elapsed time after starting the motor 3, and this correction causes the count value of the pulse signal from the encoder 4 to change. The correspondence between the (rotation amount of the motor 3) and the movement amount of the focus lens unit 2 can be taken.
[0125]
An approximate function corresponding to the deformation amount of the power transmission mechanism corresponding to the count value of the pulse signal from the encoder 4 up to the present time is stored in the EEPROM 6, and according to the count value at that time obtained from the function. The correction value may be subtracted from the count value of the pulse signal from the encoder 4. Thereby, even if the lens microcomputer 7 is an inexpensive one that does not have a timer function, the movement amount information that is equivalent to the case where the movement amount information is corrected according to the elapsed time since the start of the motor 3 is corrected. be able to.
[0126]
In addition, an approximate function corresponding to the deformation amount in the power transmission mechanism corresponding to the temperature detected by the temperature sensor 9 such as a thermistor provided in the lens device 1 is stored in the EEPROM 6 and obtained from the function at that time. The correction value corresponding to the detected temperature may be subtracted from the count value of the pulse signal from the encoder 4. This is effective when the load torque generated in the power transmission mechanism changes with temperature and the characteristics shown in FIG. 10 change, and the accuracy of the movement amount information (that is, the focusing accuracy) is further improved. It becomes possible.
[0127]
Furthermore, the approximation corresponding to the deformation amount in the power transmission mechanism according to the tilt information of the lens device 1 (or the camera 13) detected by the posture sensor 10 such as the gravitational acceleration sensor and the current moving direction of the focus lens unit 2 is obtained. The function is stored in the EEPROM 6, and the correction value corresponding to the current tilt information obtained from the function and the moving direction information of the focus lens unit 2 is subtracted from the count value of the pulse signal from the encoder 4. Good.
[0128]
For example, when the attitude of the lens apparatus 1 is upward while the focus lens unit 2 is moving toward the subject, the torque required to drive the focus lens unit 2 is increased as compared to when the attitude is horizontal. On the other hand, when the posture of the lens apparatus 1 is downward, the torque required to drive the focus lens unit 2 is reduced compared to the case where the posture is horizontal.
[0129]
Thus, it is effective when there is a change in the characteristics shown in FIG. 10 depending on the attitude of the lens apparatus 1 and the moving direction of the focus lens unit 2, and the accuracy of the movement amount information (that is, the focusing accuracy) is further improved. It is possible to improve.
[0130]
Further, an approximate function corresponding to the deformation amount in the power transmission mechanism corresponding to the voltage applied to the motor 3 detected by a voltage sensor (not shown) is stored in the EEPROM 6, and the applied voltage at that time obtained from the function is stored. A correction value corresponding to the above may be subtracted from the count value of the pulse signal from the encoder 4. This is because the driving torque of the motor 3 changes depending on the applied voltage. This is effective when the characteristics shown in FIG. 10 change due to the use of a depleted battery or the like. It is possible to improve the focusing accuracy.
[0131]
Further, when the acceleration when the output interval time of the pulse signal from the encoder 4 changes (that is, the acceleration of the motor 3 changes) can be calculated by the lens microcomputer 7, as shown in FIG. The approximate function corresponding to the deformation amount in the power transmission mechanism is stored in the EEPROM 6, and the correction value corresponding to the acceleration at that time obtained from the function is subtracted from the count value of the pulse signal from the encoder 4. Also good. This replaces any change in load torque or change in starting torque of the motor 3 with the change in acceleration in the power transmission mechanism, and corrects the movement amount information in accordance with the acceleration. By correcting the movement amount information in accordance with the acceleration, the above-described correction based on the temperature, posture, and applied voltage is not necessary, and an inexpensive system can be configured.
[0132]
Further, when the amount of deformation of the power transmission mechanism changes depending on the position of the focus lens unit 2 or the focal length (zoom position) of the lens apparatus 1, position information detected by the absolute position sensor 5 or a variable magnification lens (not shown). An approximate function corresponding to the amount of deformation in the power transmission mechanism corresponding to the position information of the unit is stored in the EEPROM 6, and a correction value obtained from the function according to the lens position at that time is obtained from the pulse from the encoder 4. It may be subtracted from the count value of the signal.
[0133]
Here, a method of correcting the movement amount information using the approximate function will be described. The approximate function here is shown as “function” in FIG.
f (x) + Δp
It is represented by However, x is the count value of the pulse signal from the encoder 4, and the value of f (x) is approximately the value on the left side of the “absolute correction amount” shown in FIG. 2 (10 corresponding to the elapsed time or movement amount). , 20, 30, 20, 10). Δp is a correction amount for further correcting the movement amount information in accordance with the temperature, posture / movement direction, applied voltage, acceleration, focus position, and zoom position.
[0134]
First, the absolute position of the focus lens unit 2 is derived by the above approximate function according to the elapsed time or the movement amount (pulse count value of the encoder 4) from the start of movement of the focus lens unit 2. For example, when the count value of the pulse signal from the encoder 4 is 25 pulses,
f (25) = about 30 + Δp.
[0135]
For example, when the voltage applied to the motor 3 is 3V, Δp is 3 pulses. When calculating using these, the step count value stretched by the encoder 4 is 25 pulses, but the actual movement amount of the focus lens unit 2 is 25− (30 + 3) = − 8 pulses, and 30 + 3 = 33 pulses. There is a delay.
[0136]
Although the calculation result is minus 8, if this result is reflected as it is, the focus unit 2 must be driven in the reverse direction. However, since the approximate function in FIG. 2 has a data structure for preventing the focus unit 2 from moving until it is driven by 30 pulses, in the case of a negative result, the actual movement amount of the focus lens unit 2 is 0. It becomes a pulse.
[0137]
In other words, the camera microcomputer 12 can know the exact position of the focus lens unit 2 by transmitting the corrected movement amount information of 0 pulse to the camera microcomputer 12. That is, in the pulse detection of the encoder 4, the motor 3 is rotated by 25 pulses, but in reality, the focus lens unit 2 hardly moves due to the deformation of the power transmission mechanism.
[0138]
On the other hand, the lens microcomputer 7 also accurately calculates whether the focus lens unit 2 is accelerating or driving at a constant speed by calculating the actual moving speed of the focus lens unit 2 based on the corrected movement amount information. Can be judged.
[0139]
As a result, in the series of autofocus control described above, the overlap control is started after the focus lens unit 2 has surely entered the constant speed driving state, and accurate position information of the focus lens unit 2 is also obtained in the overlap control. Can be performed, and high-precision focusing can be performed.
[0140]
As for the types of approximate functions described above, only one may be selected or a combination of all or a plurality may be selected according to the motor driving conditions required for the system.
[0141]
Each approximate function may be obtained by simulation by mechanical strength calculation. For example, an optimum function is derived by a preliminary test using a real machine and stored in the EEPROM 6 in the manufacturing process, thereby constructing the best system. it can.
[0142]
In each of the above embodiments, the lens interchangeable single-lens reflex camera system has been described. However, the present invention is applicable to all cameras having an autofocus function, such as a lens-integrated camera, a digital camera, a still camera, and a surveillance camera. can do.
[0143]
For example, when the present invention is applied to a lens-integrated camera, the camera microcomputer 12 has the function of the lens microcomputer 7 in each of the above embodiments. In this case, communication performed between both microcomputers in each of the above embodiments is not necessary.
[0144]
In each of the above embodiments, the movement amount detection of the focus lens unit in the autofocus control has been described. However, the present invention is not limited to the autofocus control and the focus lens unit, and power from a drive source such as a motor is used for power transmission. The present invention can be applied when various controls are performed based on the actual moving amount and moving speed of the lens unit transmitted and driven via the mechanism.
[0145]
【The invention's effect】
As described above, according to the present invention, due to the deformation of the power transmission mechanism, the actual movement amount of the lens unit with respect to the operation amount and the operation speed of the drive source obtained from the output signal of the signal output means Even if there is a difference (delay) in the moving speed, it is possible to perform control that substantially matches the actual moving amount of the lens unit.
[0146]
In particular, in overlap control for automatic focus adjustment, it is determined whether the focus lens unit is being driven at a constant speed based on lens movement information representing the movement speed calculated by the calculation means, and is being driven at a constant speed. Sometimes it is possible to detect the focus adjustment state of the photographic optical system, and further use the lens movement information representing the amount of movement to drive the focus lens unit and perform calculations to obtain focus. Even if there is a difference (delay) in the actual moving amount or moving speed of the focus lens unit with respect to the operating amount or operating speed of the drive source obtained from the output signal of the signal output means due to the deformation of the mechanism, the focus The overlap control can be started after the lens unit is reliably driven at a constant speed, and the exact lens position can be determined during the overlap control. Out it can be carried out. Therefore, it is possible to perform overlap control that can obtain extremely high focus accuracy.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a camera system according to a first embodiment of the present invention.
FIG. 2 is a table showing an example of a data table of correction amounts corresponding to each motor driving condition stored in a lens apparatus constituting the camera system.
FIG. 3 is a table showing an example of a data table of correction amounts corresponding to a focus position and a zoom position stored in a lens apparatus that constitutes the camera system.
FIG. 4 is a flowchart showing the operation of a lens microcomputer mounted on the lens device.
FIG. 5 is a flowchart showing interrupt processing of the lens microcomputer.
FIG. 6 is a flowchart showing the operation of a camera microcomputer mounted on a camera constituting the camera system.
FIG. 7 is an explanatory diagram of autofocus control performed in the camera.
FIG. 8 is an explanatory diagram showing the contents of overlap control in the autofocus control.
FIG. 9 is a diagram showing a relationship between an actual lens movement amount in a camera and a movement amount (pulse conversion movement amount) obtained based on a pulse signal from an encoder.
FIG. 10 is a diagram showing a relationship between a lens speed in a camera and a speed (pulse speed) obtained based on a pulse signal from an encoder.
[Explanation of symbols]
1 Lens device
2 Focus lens unit
3 Motor unit
4 Encoder
5 Absolute position sensor
6 EEPROM
7 Lens microcomputer
8 Contact unit
9 Temperature sensor
10 Attitude sensor
11 Focus detection unit
12 Camera microcomputer
13 Camera body

Claims (16)

A movable lens unit;
A driving source;
A power transmission mechanism for transmitting the power of the drive source to the lens unit and moving the lens unit;
A signal output means for outputting a signal each time the drive source operates a predetermined amount;
Storage means for storing correction information corresponding to a deformation amount of the power transmission mechanism when power of the drive source is input to the power transmission mechanism;
Computation means for computing lens movement information representing the movement amount or movement speed of the lens unit based on the signal output from the signal output means and the correction information stored in the storage means, Lens device to do. Drive condition detection means for detecting the drive condition of the drive source;
The calculation means calculates the lens movement information based on the signal output from the signal output means, the correction information stored in the storage means, and the drive condition detected by the drive condition detection means. The lens device according to claim 1. The lens apparatus according to claim 2, wherein the storage unit stores correction information corresponding to the driving condition. As the drive conditions, the apparatus temperature, the drive direction of the drive source, the drive amount from the start of the drive source, the elapsed time from the start of the drive source, the acceleration of the drive source, the apparatus attitude, the drive position of the lens unit The lens device according to claim 2, further comprising at least one of a voltage applied to the driving source. It can be attached to and detached from the camera, and has a communication means for communicating with the camera,
The calculation means determines whether or not the lens unit is being driven at a constant speed based on the calculated lens movement information, and information indicating that the lens unit is being driven at a constant speed when being driven at a constant speed. The lens apparatus according to claim 1, wherein the lens device is transmitted to the camera via the communication unit. The lens apparatus according to claim 5, wherein the lens unit is a focus lens unit that performs focus adjustment by movement. The lens apparatus according to claim 6 and a camera in which the lens apparatus can be attached and detached.
The camera detects a focus adjustment state of a photographing optical system including the focus lens unit in response to receiving information indicating that the focus lens unit is being driven at a constant speed from the lens device. A featured camera system. It can be attached to and detached from the camera, and has communication means for communicating with the camera,
5. The lens apparatus according to claim 1, wherein the calculation unit transmits the calculated lens movement information to the camera via the communication unit. 6. The lens apparatus according to claim 8, wherein the lens unit is a focus lens unit that performs focus adjustment by movement. The lens apparatus according to claim 9 and a camera in which the lens apparatus can be attached and detached.
The camera system uses the lens movement information received from the lens device to perform calculations for driving the focus lens unit to obtain focus. A movable lens unit;
A driving source;
A power transmission mechanism for transmitting the power of the drive source to the lens unit and moving the lens unit;
A signal output means for outputting a signal each time the drive source operates a predetermined amount;
Storage means for storing correction information corresponding to a deformation amount of the power transmission mechanism when power of the drive source is input to the power transmission mechanism;
Computation means for computing lens movement information representing the movement amount or movement speed of the lens unit based on the signal output from the signal output means and the correction information stored in the storage means, Camera. Drive condition detection means for detecting the drive condition of the drive source;
The calculation means calculates the lens movement information based on the signal output from the signal output means, the correction information stored in the storage means, and the drive condition detected by the drive condition detection means. The camera according to claim 11. The camera according to claim 12, wherein the storage unit stores correction information corresponding to the driving condition. As the drive conditions, the apparatus temperature, the drive direction of the drive source, the drive amount from the start of the drive source, the elapsed time from the start of the drive source, the acceleration of the drive source, the apparatus attitude, the drive position of the lens unit The camera according to claim 12, further comprising at least one of a voltage applied to the driving source. The lens unit is a focus lens unit that performs focus adjustment by movement;
The calculation means determines whether the focus lens unit is driven at a constant speed based on the calculated lens movement information, and adjusts the focus of a photographing optical system including the focus lens unit when the focus lens unit is driven at a constant speed. The camera according to claim 11, wherein a state is detected. The lens unit is a focus lens unit that performs focus adjustment by movement;
The camera according to any one of claims 11 to 14, wherein the calculation means performs calculation for driving the focus lens unit to obtain focus using the calculated lens movement information. .

Images