JP2000019379A - Driving controller for photographing optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep the moving speed of a focusing lens constant at the time of performing scanning operation while maintaining the scanning operation with high accuracy by providing a control means for controlling the driving of the focusing lens based on a value related to the moving speed calculated by a speed calculation means. SOLUTION: When a lens-side MPU 204 calculates a target pulse number NO, it drives a motor 209 through a motor driving circuit 205, acquires an actual encoder pulse number Npt per unit time through a motor encoder 206 in a process for storing charges and decides whether or not the acquired pulse number Npt exceeds the target pulse number NO. The MPU 204 decreses the rotating speed of the motor 209 in the case that the pulse number Npt exceeds the target pulse number NO and accelerates the rotating speed of the motor 209 in the case that the pulse number Npt is equal to or under the target pulse number NO.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a movement of an image plane during a scanning operation for detecting a state in which focus can be determined by moving a focusing lens when focus cannot be determined. To control the driving of the focusing lens.

[0002]

2. Description of the Related Art Conventionally, in a camera having an AF sensor, when it is impossible to determine the focus, a focusing lens (corresponding to a "photographing optical system that moves for focusing") is moved. (Hereinafter, referred to as a scanning operation) that moves the image plane to detect a state in which focusing can be determined.

In such a scanning operation, for example, when the brightness of the subject or the sensitivity of the image sensor in the AF sensor is low, the accumulation time of the image sensor needs to be long in order to reliably determine the focus. is there. Therefore, Japanese Patent No. 2
Japanese Patent Application Laid-Open No. 615679 discloses a technique for determining a limit value of a moving speed of an image plane (hereinafter, referred to as an image plane moving speed limit value) based on luminance of a subject and sensitivity of an image sensor in an AF sensor when performing a scanning operation. It has been disclosed.

Incidentally, it is known that the amount of movement of the image plane with respect to the amount of movement of the focusing lens varies depending on the focusing lens position and the zoom position (focal length). For example, with the zoom position fixed,
When the focusing lens is moved from the closest end to the infinity end, the image plane movement coefficient γ indicating the movement amount of the image plane with respect to the unit movement amount of the focusing lens becomes small as shown in FIG.
It fluctuates from large to small.

Therefore, when the focusing lens is moved in the direction in which the image plane movement coefficient γ increases during the scanning operation, the image plane movement speed is accelerated and exceeds the above-mentioned image plane movement speed limit value. It was likely.

That is, when the moving speed of the focusing lens is calculated using the image plane moving coefficient γ at the start of the scanning operation, and the focusing operation is performed at the calculated moving speed, the scanning operation is performed. In such a case, there is a possibility that a situation may occur in which focus determination cannot be performed. Therefore, the existing camera moves the focusing lens at a speed lower than the calculated moving speed so that the scanning operation can be reliably performed even if the moving speed of the image plane is accelerated.

[0007]

However, in such a camera, even when the moving speed of the focusing lens is calculated in a state where the image plane moving coefficient γ is maximized, the moving speed is slower than the calculated moving speed. The focusing lens moves at the speed. For this reason, the moving speed of the image plane may be unnecessarily slowed, and the efficiency of the scanning operation may be significantly reduced.

As a method for improving the efficiency of the scanning operation, for example, an image plane moving coefficient γ corresponding to a focusing lens position is sequentially acquired during the scanning operation, and focusing is performed based on the acquired image plane moving coefficient γ. A method of sequentially changing the moving speed of the lens can be considered. However, in such a method, since the moving speed of the focusing lens is not stable, there is a problem that the possibility of inducing camera shake is increased and an operator is given an impression that the lens has performed an unnatural operation.

Therefore, the present invention according to the first to third and seventh aspects provides a photographing optical system capable of maintaining a constant moving speed of a focusing lens during a scanning operation while maintaining high accuracy of a scanning operation. It is an object to provide a drive control device. In addition, the invention according to claims 4 to 6 and 8 is an imaging optical system that can reliably suppress the fluctuation of the moving speed of the focusing lens during the scanning operation while maintaining the efficiency of the scanning operation high. It is an object to provide a drive control device.

[0010]

According to a first aspect of the present invention, there is provided a photographing optical system drive control device that moves a focusing lens to detect an in-focus state by moving a focusing lens. In the photographing optical system drive control device for controlling the driving of the focusing lens to move, the moving amount of the image plane with respect to the unit moving amount of the focusing lens is indicated, and among the image plane moving coefficients that change according to the position of the focusing lens, Speed calculating means for calculating a value (N0) related to the moving speed of the focusing lens during the scanning operation based on the maximum value (γmax); and a value (N0) related to the moving speed of the focusing lens calculated by the speed calculating means. Control means for controlling driving of the focusing lens.

In the photographic optical system drive control device according to the first aspect, the value (N0) relating to the moving speed of the focusing lens is converted into the moving speed of the focusing lens during the scanning operation or converted into such a moving speed. Means possible values. According to a second aspect of the present invention, in the imaging optical system drive controller according to the first aspect, an image plane movement coefficient indicating a movement amount of an image plane with respect to a unit movement amount of the focusing lens is equal to or smaller than that of the focusing lens. The image processing apparatus further includes a coefficient selection unit that selects a maximum image plane movement coefficient (γmax) during a scanning operation from a recording unit that is recorded in advance in association with the position, and the speed calculation unit includes an image plane movement coefficient selected by the coefficient selection unit. A value (N0) relating to the moving speed of the focusing lens during the scanning operation is calculated based on the coefficient (γmax).

In the photographic optical system drive control device according to the second aspect, as a method of calculating the moving speed of the focusing lens, for example, the "moving speed of the image plane at which focusing can be determined" There is a method of dividing by the maximum value (γmax) of the image plane movement coefficients selected by the coefficient selection means.

According to a third aspect of the present invention, in the driving control apparatus of the photographic optical system according to the first aspect, the image plane moving coefficient indicating the moving amount of the image plane with respect to the unit moving amount of the focusing lens. Among them, there is provided a coefficient recording means for pre-recording an image plane moving coefficient (γmax) which becomes the maximum at the time of the scanning operation, and the speed calculating means performs the scanning operation based on the image plane moving coefficient (γmax) recorded by the coefficient recording means. Of the moving speed of the focusing lens at the time (N
0) is calculated.

As a method for calculating the moving speed of the focusing lens, for example, the "moving speed of the image plane at which focus can be determined" is calculated by changing the "image plane moving coefficient (γmax) recorded by the coefficient recording means". , Etc. ". The imaging optical system drive control device according to claim 4, wherein when the focus determination is not possible, an image is captured when a focusing operation is performed to detect a state in which focus determination is possible by moving the focusing lens. In a photographing optical system drive control device that controls the driving of a focusing lens to move a surface, a moving amount of an image plane with respect to a unit movement amount of the focusing lens is indicated, and an image plane moving coefficient that changes according to the position of the focusing lens is indicated Among them, in the course of the scanning operation, based on the image plane movement coefficient corresponding to the position of the focusing lens, the speed sequential calculating means for sequentially calculating the value (Nmax2) relating to the moving speed of the focusing lens and the speed sequential calculating means. When the value (Nmax2) relating to the moving speed of the focusing lens is equal to or less than a predetermined upper limit (Nmax1). The controls the driving of the focusing lens based on the value (Nmax2) on the movement speed, the value on the movement speed (Nmax2) is an upper limit value (Nmax
When the value exceeds 1), control means for controlling driving of the focusing lens based on the upper limit value (Nmax1) is provided.

In the photographic optical system drive control device according to the fourth aspect, the value (Nmax2) relating to the moving speed of the focusing lens is converted into the moving speed of the focusing lens during the scanning operation or converted into such a moving speed. Means possible values.

As a method of calculating the moving speed of the focusing lens, for example, there is a method of dividing the moving speed of the image plane at which focusing can be determined by the image plane moving coefficient. According to a fifth aspect of the present invention, in the photographic optical system drive controller according to the fourth aspect, the control means indicates a moving amount of an image plane with respect to a unit moving amount of the focusing lens, and The upper limit value (Nmax1) is determined based on the maximum value (γmax) of the image plane movement coefficients that change according to the position.

According to a sixth aspect of the present invention, in the driving control apparatus of the photographic optical system according to the fifth aspect, the image plane moving coefficient indicating the moving amount of the image plane with respect to the unit moving amount of the focusing lens is set. A recording means pre-recorded in association with the position of the focusing lens, a coefficient obtaining means for sequentially obtaining an image plane movement coefficient corresponding to the position of the focusing lens in the course of the scanning operation; The value (Nmax2) relating to the moving speed of the focusing lens is sequentially calculated based on the image plane moving coefficient acquired by the coefficient acquiring unit in the process of the above. The maximum image plane movement coefficient (γma
The upper limit value (Nmax1) is determined based on x).

According to a seventh aspect of the present invention, there is provided a photographing optical system driving control apparatus according to any one of the first to third aspects, wherein the moving speed of the image plane during the scanning operation is reduced. A limit value calculating means for calculating a limit value (Vzmax), wherein the speed calculating means calculates the value (N0) relating to the moving speed of the focusing lens by calculating the moving speed of the image plane calculated by the limit value calculating means. Limit value (Vzma
x) An imaging optical system drive control device characterized by using (x).

According to a twelfth aspect of the present invention, there is provided the photographic optical system drive control device according to any one of the fourth to sixth aspects, wherein the moving speed of the image plane during the scanning operation is reduced. A limit value calculating means for calculating a limit value (Vzmax), wherein the sequential speed calculating means sequentially calculates a value (Nmax2) relating to the moving speed of the focusing lens when the image plane calculated by the limit value calculating means is calculated; A photographing optical system drive control device using a speed limit value (Vzmax).

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the following first and second embodiments, description will be made using a camera having the function of the photographing optical system drive control device of the present invention. FIG. 1 is a functional block diagram of a camera according to the first embodiment and the second embodiment.

In FIG. 1, an interchangeable lens 200 is mounted on a camera body 100 by a mounting mechanism (not shown). The interchangeable lens 20 is provided in the camera body 100.
The main mirror 101 and the sub-mirror 102 are arranged on the optical axis of the first lens group 201, the second lens group 202, and the third lens group 203 in the zero.

In the camera body 100, an AF sensor 103 is disposed in the direction of reflection of the sub-mirror 102.
Body side MPU 10 connected to the output of F sensor 103
4 are provided. On the other hand, in the interchangeable lens 200,
First lens group 201 and second lens group 20 on the same optical axis
The second and third lens groups 203 are provided.

FIG. 1 shows an inner focus type optical system in which the rate of change of the image plane movement coefficient γ with respect to the photographing distance is generally large. In each of the embodiments described later, the first lens group 201, the second lens group 202, and the third lens group 203 individually perform the reciprocating operation during zooming, and the second lens group 2 during focusing.
02 performs the forward / backward operation independently according to the defocus amount. That is, the second lens group 202 corresponds to a focusing lens.

In the interchangeable lens 200, a lens side MPU 204, a motor drive circuit 205 connected to an output of the lens side MPU 204, a motor encoder 206, a zoom encoder 207 connected to an input of the lens side MPU 204, and a distance An encoder 208, a motor 209 connected to an output of the motor drive circuit 205 and an input of the motor encoder 206, and a transmission mechanism 210 disposed between the motor 209 and the second lens group 202 are provided.

Further, the lens side M in the interchangeable lens 200
The PU 204 has a memory 211 and is connected to the body-side MPU 104 via a communication unit (not shown). A plurality of image plane movement coefficients γ corresponding to the zoom position and the focusing lens position (the position of the second lens group 202) are previously stored in the memory 211 in the lens side MPU 204 in the form of a table as shown in FIG. Have been.

FIG. 3 is an operation flowchart common to the first embodiment and the second embodiment. FIG. 4 is an operation flowchart of the scan operation according to the first embodiment. Hereinafter, the operation of the first embodiment will be described with reference to FIGS. Note that the first embodiment is based on Claim 1,
This corresponds to an embodiment corresponding to the invention described in claims 2 and 7.

Further, claim 1, claim 2, and claim 7
As for the correspondence between the invention described in (1) and the first embodiment, the coefficient selecting means uses “γ
The speed calculation means corresponds to the “processing for calculating N0” by the lens-side MPU 204, and the control means corresponds to the “motor 209” by the motor drive circuit 205, the motor encoder 206, and the lens-side MPU 204. The limit value calculation means corresponds to the “process of calculating Vzmax” by the lens-side MPU 204. Further, the focusing lens corresponds to the second lens group 202, and the recording unit corresponds to the memory 211.

First, with the main power turned on,
The light beam incident on the interchangeable lens 200 is
1. The light reaches the main mirror 101 via the second lens group 202 and the third lens group 203. Main mirror 10
The light beam that has reached 1 is split and guided to the AF sensor 103 via the sub mirror 102. In the AF sensor 103, the subject image is received by the light flux guided as described above, and the accumulation of electric charges is started (S1 in FIG. 3).

In the AF sensor 103, the accumulation time is determined based on the brightness of the subject detected by the illuminance monitor light receiving element (not shown). The AF sensor 103 determines whether or not the accumulation of the electric charge is completed according to the accumulation time thus determined (S2 in FIG. 3). When the AF sensor 103 recognizes that the accumulation of the electric charge is completed by such a determination, the AF sensor 103 supplies an electric signal corresponding to the subject image to the body-side MPU 104.

When the electric signal corresponding to the subject image is supplied from the AF sensor 103 to the body-side MPU 104 in this manner, the second lens group 202 based on the electric signal.
The defocus amount D corresponding to the deviation amount from the in-focus position is calculated (S3 in FIG. 3). Also, the body side MPU 104
Notifies the lens-side MPU 204 of the calculation result of the defocus amount D via a communication unit (not shown).

The lens-side MPU 204 determines whether the defocus amount D has been calculated based on the calculation result of the defocus amount D thus notified (S in FIG. 3).
4). When the lens-side MPU 204 recognizes that the defocus amount D has not been calculated by such a determination, it performs a scanning operation described later (FIG. 3S).
5). On the other hand, when recognizing that the defocus amount D has been calculated, the lens-side MPU 204 shown in FIG.
6 to 3 are performed.

That is, the lens side MPU 204 acquires the current zoom position and focusing lens position via the zoom encoder 207 and the distance encoder 208 (S6 in FIG. 3). The zoom encoder 20
Reference numeral 7 determines the zoom position by detecting the rotational position of a zoom ring (not shown), and notifies the lens side MPU 204 of the zoom position. Further, the distance encoder 208 detects the focusing lens position at each zoom position and notifies the lens side MPU 204.

The lens-side MPU 204 reads out the image plane movement coefficient γ corresponding to the current zoom position and focusing lens position from a table (table shown in FIG. 2) in the memory 211 (S7 in FIG. 3). Lens side MPU2
04 is for moving the second lens group 202 to the in-focus position using the defocus amount D notified from the body-side MPU 104 and the image plane movement coefficient γ read from the table in the memory 211 as described above. Required motor 209
Is calculated by the following equation (S8 in FIG. 3).

N = (D × G × Nm) / (γ × L) where G: the number of rotations of the transmission mechanism 210 corresponding to one rotation of the motor 209 (gear ratio from the motor 209 to the transmission mechanism 210) Nm: The number of encoder pulses corresponding to one rotation of the motor 209 L: The lead lens side MPU 204 of the second lens group 202
Is calculated, the driving of the motor 209 via the motor driving circuit 205 is started (S9 in FIG. 3).

When the driving of the motor 209 is started, the lens side MPU 204 acquires the actual driving amount Np of the motor 209 via the motor encoder 206 (S1 in FIG. 3).
0), it is determined whether or not the actual drive amount Np of the motor 209 obtained in this way matches the drive target amount N (FIG. 3).
S11). The lens-side MPU 204 determines that the actual drive amount Np of the motor 209 is
If the values match, the rotation of the motor 209 is stopped via the motor drive circuit 205 (S12 in FIG. 3).

That is, the rotation of the motor 209 is stopped when the second lens group 202 reaches the in-focus position. By the way, the lens side MPU 204 is
In 4, when it is recognized that the defocus amount D has not been calculated, the scanning operation shown in FIG. 4 is performed. Hereinafter, details of the scanning operation, which is a feature of the present invention, will be described.

The lens side MPU 204 obtains the current zoom position via the zoom encoder 207 (FIG. 4).
S1). The lens-side MPU 204 performs a plurality of image plane movement coefficients γ associated with the current zoom position (corresponding to all the image plane movement coefficients γ for one row corresponding to the current zoom position in the table shown in FIG. 2). Among them, a value indicating the maximum (hereinafter, referred to as a maximum image plane movement coefficient γmax) is selected (S2 in FIG. 4).

The lens side MPU 204 includes the AF sensor 10
An image plane moving speed limit value Vzmax is calculated based on the luminance of the subject detected by the illuminance monitor light receiving element in 3 (S3 in FIG. 4). Since the method of calculating the image plane moving speed limit value Vzmax is a known technique, the description is omitted here. The lens-side MPU 204 has an image plane moving speed limit value V
When zmax is calculated, the number of encoder pulses per unit time (hereinafter referred to as target pulse number N0) for driving the motor 209 at a constant rotation speed is defined as an image plane moving speed limit value Vzmax, a maximum image plane moving coefficient γmax, and the like. Is calculated using the following equation (S4 in FIG. 4). That is, the lens-side MPU 204 sets the target pulse number N such that the moving speed of the image plane matches the image plane moving speed limit value Vzmax at the focusing lens position indicating the maximum image plane moving coefficient γmax.
Calculate 0.

N0 = (Vzmax × G × Nm) / (γmax × L) where G: the number of rotations of the transmission mechanism 210 corresponding to one rotation of the motor 209 (gear ratio from the motor 209 to the transmission mechanism 210) Nm: The number of encoder pulses corresponding to one rotation of the motor 209 L: the lead of the second lens group 202 When the lens side MPU 204 calculates the target number of pulses N0 in this way, it starts driving the motor 209 via the motor drive circuit 205. (S5 in FIG. 4).

At this time, accumulation of electric charge is started in the AF sensor 103 (S6 in FIG. 4). Lens side MPU2
Reference numeral 04 denotes the actual number of encoder pulses Np per unit time via the motor encoder 206 during the process of driving the motor 209 and accumulating electric charges in this manner.
t is acquired (S7 in FIG. 4), and it is determined whether or not the actual encoder pulse number Npt thus acquired exceeds the target pulse number N0 (S8 in FIG. 4).

When the actual encoder pulse number Npt exceeds the target pulse number N0, the lens side MPU 204 reduces the rotation speed of the motor 209 via the motor drive circuit 205 (S9 in FIG. 4). ),
If the actual number Npt of encoder pulses is equal to or less than the target number N0, the rotation speed of the motor 209 is accelerated via the motor drive circuit 205 (S10 in FIG. 4).

That is, in the processing of FIGS. 4S7 to 4S10, the "motor 20" is set so that the target pulse number N0 is maintained.
9). In the process of performing the “control of the rotation speed of the motor 209” in this manner, the AF sensor 103 determines whether or not the accumulation of the electric charge has been completed (S11 in FIG. 4), and determines the result of the determination in the body. Side MP
A notification is sent to the lens side MPU 204 via U104.

If the lens-side MPU 204 recognizes that the accumulation of the electric charge has not been completed based on the result of the judgment thus notified, the above-described “control of the rotation speed of the motor 209 (FIGS. 4S10) "is repeated.

When the accumulation of the electric charge is completed, the AF sensor 103 supplies an electric signal corresponding to the subject image to the MPU 104 on the body side. In the body side MPU 104,
When the electric signal corresponding to the subject image is thus supplied, the calculation of the defocus amount D is started (S1 in FIG. 4).
2). In the process of calculating the defocus amount D in this manner, the lens-side MPU 204 performs the same processing as the above-described “control of the rotation speed of the motor 209”.

That is, the lens-side MPU 204 obtains the actual number Npt of encoder pulses per unit time via the motor encoder 206 (S13 in FIG. 4), and the actual number Npt of encoder pulses obtained in this manner is equal to the target number of pulses N0. (S1 in FIG. 4)
4). When the actual encoder pulse number Npt exceeds the target pulse number N0, the lens-side MPU 204 reduces the rotation speed of the motor 209 via the motor drive circuit 205 (S15 in FIG. 4), If Npt is equal to or smaller than the target pulse number N0, the rotation speed of the motor 209 is accelerated via the motor drive circuit 205 (S16 in FIG. 4).

In the process of “controlling the rotation speed of the motor 209”, the MPU on the body side is operated.
104 determines whether or not the calculation of the defocus amount D is completed (S17 in FIG. 4), and outputs the determination result to the lens side MPU2.
04 is notified. When the lens-side MPU 204 recognizes that the accumulation of the defocus amount D has not been completed based on the result of the notification notified in this manner, the above-described “control of the rotation speed of the motor 209 (FIG. 4S
16)) is repeated.

When the calculation of the defocus amount D is completed, the body-side MPU 104 determines whether or not the defocus amount D has been calculated (S18 in FIG. 4), and notifies the lens-side MPU 204 of the determination result.

When the lens-side MPU 204 recognizes that the defocus amount D has been calculated based on the result of the notification thus notified, it terminates the scanning operation.
If it is recognized that the defocus amount D has not been calculated, the above-described processing after S6 in FIG. 4 is repeated.
As described above, in the present embodiment, "control of the rotation speed of the motor 209" is performed so that the target pulse number N0 is maintained in the process of performing the scan operation. Therefore, the moving speed of the second lens group 202 is maintained at such a speed that the moving speed of the image plane coincides with the image plane moving speed limit value Vzmax at the focusing lens position showing the maximum image plane moving coefficient γmax.

When the scanning operation is performed with the rotation speed of the motor 209 kept constant, the moving speed of the image plane becomes maximum at the focusing lens position showing the maximum image plane moving coefficient γmax. Therefore, as in the present embodiment, the moving speed of the image plane at the focusing lens position showing the maximum image plane moving coefficient γmax is equal to the image plane moving speed limit value V.
When zmax is equal to zmax, the moving speed of the image plane does not exceed the image plane moving speed limit value Vzmax regardless of the state of the focusing lens position.

That is, according to the present embodiment, in the process of performing the scanning operation, the moving speed of the image plane is maintained at or below the image plane moving speed limit value Vzmax while the moving speed of the second lens group 202 is kept constant. can do. In addition,
In the present embodiment, since the inventions described in claims 1, 2 and 7 are applied, the maximum image plane movement coefficient γmax is selected by selecting the maximum image plane movement coefficient γmax from the table in the memory 211. Is obtained, for example,
When the invention according to claim 3 is applied instead of claim 2, the maximum image plane movement coefficient γmax is stored in a table in advance, and the maximum image plane movement coefficient γmax stored in this manner is stored.
Is read out, the maximum image plane movement coefficient γmax can be obtained.

Further, in the present embodiment, "when the zoom position fluctuates due to zooming during the scanning operation" or "when the image plane moving speed limit value Vzmax fluctuates due to a change in the brightness of the subject, etc." Is not assumed, for example, the actual encoder pulse number N
Processing for calculating the target pulse number N0 (FIGS. 4S1 to 4) immediately before the processing for determining whether or not pt exceeds the target pulse number N0 (processing corresponding to FIG. 4S8 or FIG. 4S14).
By performing the processing corresponding to S4), it is possible to perform a scanning operation in consideration of “when the zoom position fluctuates” and “when the image plane moving speed limit value Vzmax fluctuates”.

FIG. 5 is an operation flowchart of the scan operation of the second embodiment. In the second embodiment,
This corresponds to an embodiment corresponding to the invention described in claims 4 to 6 and 8. Further, regarding the correspondence between the invention described in claim 4 to claim 6 and claim 8 and the second embodiment, the coefficient obtaining means includes a lens side MP.
The speed sequential calculation means corresponds to the "processing for calculating Nmax2" by the lens-side MPU 204, and the control means corresponds to the motor drive circuit 205, the motor encoder 206, and the In response to the “processing for calculating Nmax1 and the processing for controlling the rotation speed of the motor 209” by the lens-side MPU 204, the limit value calculating means uses “Vzmax” by the lens-side MPU 204.
Process of calculating. Further, the focusing lens corresponds to the second lens group 202, and the recording unit includes
It corresponds to the memory 211.

The difference between the first embodiment and the second embodiment lies in the processing method of the scanning operation. The operation shown in FIG. 3 is different from the first embodiment and the second embodiment. Since the configuration is common, the description is omitted here. Hereinafter, the scan operation of the second embodiment will be described in detail with reference to FIGS. 1, 2, and 5. FIG.

The lens-side MPU 204 acquires the current zoom position and focusing lens position via the zoom encoder 207 and the distance encoder 208 (S1 in FIG. 5). The lens-side MPU 204 reads out the image plane movement coefficient γ corresponding to the current zoom position and focusing lens position from a table (table shown in FIG. 2) in the memory 211 (S2 in FIG. 5).

The lens side MPU 204 includes the AF sensor 10
An image plane moving speed limit value Vzmax is calculated based on the luminance of the subject detected by the illuminance monitor light receiving element in 3 (S3 in FIG. 5). Since the method of calculating the image plane moving speed limit value Vzmax is a known technique, the description is omitted here. The lens-side MPU 204 has an image plane moving speed limit value V
When zmax is calculated, the maximum number of encoder pulses per unit time required to maintain the image plane moving speed limit value Vzmax when moving the second lens group 202 from the current focusing lens position (hereinafter referred to as the maximum pulse number) Nma
x2. ) Is calculated. That is, the lens side MPU 2
04 is the image plane moving speed limit value Vzmax, the image plane moving coefficient γ
Then, the maximum pulse number Nmax2 is calculated by the following equation (S4 in FIG. 5).

Nmax2 = (Vzmax × G × Nm) / (γ × L) where G: the number of rotations of the transmission mechanism 210 corresponding to one rotation of the motor 209 (gear ratio from the motor 209 to the transmission mechanism 210). The number of encoder pulses corresponding to one rotation of the motor 209 L: Read of the second lens group 202 Note that the maximum number of pulses Nmax2 calculated here is shown in FIG. 6 because the image plane movement coefficient γ changes depending on the focusing lens position. Changes as shown.

After calculating the maximum pulse number Nmax2 in this manner, the lens side MPU 204 calculates a plurality of image plane movement coefficients γ (corresponding to the current zoom position in the table shown in FIG. 2) associated with the current zoom position. ), The maximum number of pulses N is determined based on the maximum image plane movement coefficient γmax indicating the maximum value.
The upper limit of max2 (hereinafter referred to as upper limit Nmax1) is determined (S5 in FIG. 5).

In this embodiment, the lens MP
U204 calculates the minimum value of the maximum pulse number Nmax2 using the maximum image plane movement coefficient γmax, and adds a fixed amount (for example, 10 pulses) to the minimum value or a fixed ratio (for example, 20 pulses). %) Is the upper limit Nmax1
And That is, the upper limit value Nmax1 and the maximum pulse number Nmax2
Means a relationship as shown in FIG.

After calculating the upper limit value Nmax1, the lens side MPU 204 calculates the upper limit value Nmax1 through the motor drive circuit 205.
9 is started (S6 in FIG. 5). At this time, AF
In the sensor 103, accumulation of electric charge is started (FIG. 5S
7). The lens-side MPU 204 drives the motor 209 in this way, and acquires the actual number Npt of encoder pulses per unit time via the motor encoder 206 in the process of accumulating electric charges (S8 in FIG. 5). It is determined whether or not the actual encoder pulse number Npt obtained in this way exceeds the maximum pulse number Nmax2 (FIG. 5S
9).

If the actual encoder pulse number Npt is equal to or less than the maximum pulse number Nmax2, the lens-side MPU 204 determines whether the actual encoder pulse number Npt exceeds the upper limit value Nmax1. The determination is made (S10 in FIG. 5). If “Npt> Nmax1” or “Nmax2 <Npt ≦ Nmax1” is satisfied by these determinations, the lens-side MPU 204 reduces the rotational speed of the motor 209 via the motor drive circuit 205 (S11 in FIG. 5), and “Npt ≦ When Nmax1 and Npt ≦ Nmax2 ”are satisfied, the rotational speed of the motor 209 is accelerated via the motor drive circuit 205 (S12 in FIG. 5).

Therefore, in the processing of FIGS. 5S8 to 5S12, the rotation speed of the motor 205 is controlled such that the number of encoder pulses per unit time maintains the target value as shown by the thick line in FIG. That is, when the maximum pulse number Nmax2 is equal to or smaller than the upper limit value Nmax1, "control of the rotation speed of the motor 209" is performed so that the maximum pulse number Nmax2 is maintained, and the maximum pulse number Nmax2 is set to the upper limit value Nmax1.
Is exceeded, "control of the rotation speed of the motor 209" is performed so that the upper limit value Nmax1 is maintained.

During the process of “controlling the rotation speed of the motor 209”, the AF sensor 10
3 judges whether or not the accumulation of the electric charge is completed (S1 in FIG. 5).
3) The result of the determination is notified to the lens side MPU 204 via the body side MPU 104. Lens side MPU 204
When it is recognized that the accumulation of the electric charge is not completed based on the result of the determination notified in this manner, the above-described “control of the rotation speed of the motor 209 (FIG. 5S8 to FIG. 5S
12)) is repeated.

When the accumulation of the electric charges is completed, the AF sensor 103 supplies an electric signal corresponding to the subject image to the body side MPU 104. In the body side MPU 104,
When the electric signal corresponding to the subject image is thus supplied, calculation of the defocus amount D is started (S1 in FIG. 5).
4). In the process of calculating the defocus amount D in this manner, the lens-side MPU 204 performs the same processing as the above-described “control of the rotation speed of the motor 209”.

That is, the lens-side MPU 204 obtains the actual number Npt of encoder pulses per unit time via the motor encoder 206 (S15 in FIG. 5), and the actual number Npt1 of encoder pulses thus obtained is equal to the upper limit Nmax1. It is determined whether it exceeds (S16 in FIG. 5). Further, the lens-side MPU 204 determines whether the actual encoder pulse number Npt obtained in this way exceeds the maximum pulse number Nmax2 (S17 in FIG. 5). Further, if “Npt> Nmax1” or “Nmax2 <Npt ≦ Nmax1” holds, the rotational speed of the motor 209 is reduced via the motor drive circuit 205 (S18 in FIG. 5), and “Npt ≦ Nmax1 and Npt If ≦ Nmax2 ”is satisfied, the rotational speed of the motor 209 is accelerated via the motor drive circuit 205 (S19 in FIG. 5).

During the process of “controlling the rotation speed of the motor 209”, the MPU on the body side is controlled.
104 determines whether or not the calculation of the defocus amount D is completed (S20 in FIG. 5), and outputs the determination result to the lens-side MPU2.
04 is notified. If the lens-side MPU 204 recognizes that the accumulation of the defocus amount D has not been completed based on the result of the notification thus notified, the above-described “control of the rotation speed of the motor 209 (FIG. 5S
19)) is repeated.

When the calculation of the defocus amount D is completed, the body-side MPU 104 determines whether or not the defocus amount D has been calculated (S21 in FIG. 5), and notifies the lens-side MPU 204 of the determination result. Lens side MPU2
04, when it is recognized that the defocus amount D has been calculated based on the result of the determination thus notified,
The scanning operation ends.

On the other hand, when the lens side MPU 204 recognizes that the defocus amount D has not been calculated,
After performing the processing of FIG. 5S22 to FIG. 5S24 described below, the processing of FIG. That is, the lens side MPU
204 acquires the current focusing lens position via the distance encoder 208 (S22 in FIG. 5), and stores the image plane movement coefficient γ corresponding to the already detected zoom position and the newly detected focusing lens position in the memory 21.
1 (step S23 in FIG. 5).

The lens side MPU 204 moves the second lens group 20 from the newly acquired focusing lens position.
2, the maximum number of pulses Nmax2 per unit time required to maintain the image plane moving speed limit value Vzmax is calculated (S24 in FIG. 5). Further, the lens side MPU 20
4 repeats the processing from S7 onward in FIG. 5 to perform the same processing as the “control of the rotation speed of the motor 209” described above using the newly calculated maximum pulse number Nmax2.

As described above, in the present embodiment, when the maximum pulse number Nmax2 is equal to or less than the upper limit value Nmax1, the "control of the rotation speed of the motor 209" is performed so that the maximum pulse number Nmax2 is maintained. The maximum number of pulses Nmax2 is the upper limit Nma
If it exceeds x1, "control of the rotation speed of the motor 209" is performed so that the upper limit value Nmax1 is maintained. That is, the moving speed of the second lens group 202 is equal to the maximum pulse number N
Although a small change is shown when max2 is maintained, it is kept constant when the upper limit Nmax1 is maintained.

In the present embodiment, the maximum number of pulses Nmax2 is the maximum number of encoder pulses per unit time necessary to maintain the image plane moving speed limit value Vzmax. As long as the number of pulses does not exceed the maximum pulse number Nmax2, the moving speed of the image plane does not exceed the image plane moving speed limit value Vzmax. Therefore, according to the present embodiment, the moving speed of the image plane can be maintained at the image plane moving speed limit value Vzmax or less while reliably suppressing the fluctuation of the second lens group 202 during the scanning operation.

In the present embodiment, during the scanning operation, "when the zoom position fluctuates due to zooming" or "when the image plane moving speed limit value Vzmax fluctuates due to a change in the luminance of the subject, etc." Is not assumed, for example, the actual encoder pulse number N
It is determined whether pt exceeds the maximum pulse number Nmax2 or the upper limit value Nmax1 (see FIG. 5S9 or 5S10 or FIG. 5).
Immediately before the processing corresponding to “S16 and S17 in FIG. 5”, the processing for calculating the maximum pulse number Nmax2 and the upper limit Nmax1 (FIG. 5S
1 to 5 S5).
The scanning operation can be performed in consideration of "when the zoom position fluctuates" and "when the image plane moving speed limit value Vzmax fluctuates".

Further, in each of the above-described embodiments, the present invention is applied to a camera having a motor 209 in an interchangeable lens 200 as shown in FIG.
The motor drive circuit 205, the motor encoder 206, and the motor 209 are provided in the camera body 100 as shown in FIG. 1, and the present invention can be applied to a camera in which the coupling unit 300 is provided between the camera body 100 and the interchangeable lens 200. is there.

That is, in the camera shown in FIG. 8, the “control of the rotation speed of the motor 209” performed by the lens side MPU 204 in each of the above-described embodiments is replaced by the body side MPU.
This is performed by the PU 104, and the second lens group 202 moves via the coupling unit 300.

[0074]

As described above, according to the first to third aspects of the present invention, the value (N0) relating to the moving speed of the focusing lens is the maximum value (γma) of the image plane moving coefficient.
x). Therefore, the focusing lens can move at a constant speed based on the value (N0) related to the moving speed calculated in this manner.

Therefore, according to the first to third aspects of the present invention, the moving speed of the focusing lens during the scanning operation can be kept constant. According to the fourth aspect of the present invention, the value (Nmax2) relating to the moving speed of the focusing lens is maintained at or below the upper limit (Nmax1). Therefore, according to the fourth aspect of the invention, the moving speed of the focusing lens can be maintained at a predetermined value or less.

By the way, the value (Nmax2) relating to the moving speed of the focusing lens becomes minimum when the focusing lens coincides with "the position where the image plane moving coefficient is the maximum".

Therefore, the upper limit value (Nmax1) of the value (Nmax2) relating to the moving speed of the focusing lens is determined based on the maximum value (γmax) of the image plane movement coefficient. By calculating, the upper limit value (Nmax1) can be made closer to the minimum value of the value (Nmax2) related to the moving speed of the focusing lens. Therefore, according to the invention described in claims 5 and 6,
Variations in the moving speed of the focusing lens can be reliably suppressed.

By the way, when the moving speed of the focusing lens is kept constant, the moving speed of the image plane fluctuates, but the state where the focus can be determined in the situation where the moving speed of the image plane is maximum is maintained. If possible, the focus can be reliably determined regardless of the position of the focusing lens. Also, when the moving speed of the focusing lens is kept constant, the moving speed of the image plane is
It becomes maximum when the focusing lens coincides with “the position where the image plane movement coefficient is maximum”.

According to the seventh aspect of the present invention, when the value (N0) relating to the moving speed of the focusing lens is calculated based on the maximum value of the image plane moving coefficient, the limit value (Vzmax) of the moving speed of the image plane is Used. Further, in the invention according to claim 7, the limit value (Vzmax) of the moving speed of the image plane is:
This corresponds to the maximum value of the moving speed that can maintain the state where the focus can be determined.

That is, in the invention according to claim 7, the value (N0) relating to the moving speed of the focusing lens is calculated so that focusing can be determined in a situation where the image plane moving speed is maximum. Therefore, according to the invention described in claim 7, the moving speed of the focusing lens can be kept constant and the scanning operation can be performed reliably, similarly to the inventions described in claims 1 to 3. .

According to the eighth aspect of the present invention, when calculating the value (Nmax2) relating to the moving speed of the focusing lens based on the image plane moving coefficient corresponding to the position of the focusing lens, the limit value of the moving speed of the image plane is used. (Vzmax) is used. Further, in the invention described in claim 8, the limit value (Vzmax) of the moving speed of the image plane corresponds to the maximum value of the moving speed capable of maintaining the state where the focus can be determined.

That is, the value (Nmax2) relating to the moving speed of the focusing lens calculated according to the invention of claim 8 corresponds to a value at which the scanning operation can be performed most efficiently. Therefore, according to the invention described in claim 8,
Value related to moving speed of focusing lens (Nmax2)
Is smaller than or equal to the upper limit value (Nmax1), the efficiency of the scanning operation can be kept high, and if the value (Nmax2) relating to the moving speed of the focusing lens is lower than the upper limit value (Nmax1), a claim is made. 4 to Claim 5
As in the invention described in (1), the moving speed of the focusing lens can be kept constant.

Therefore, in the cameras to which these inventions are applied, the occurrence of camera shake during the scanning operation is reduced, the accuracy of automatic focusing is improved, and the operator is given the impression that the focusing lens has operated unnaturally. Never give.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of a camera according to a first embodiment and a second embodiment.

FIG. 2 is a table configuration example.

FIG. 3 is an operation flowchart common to the first embodiment and the second embodiment.

FIG. 4 is an operation flowchart of a scan operation according to the first embodiment.

FIG. 5 is an operation flowchart of a scan operation according to the second embodiment.

FIG. 6 is a diagram showing a relationship between Nmax1 and Nmax2.

FIG. 7 is a diagram showing a target value of the number of encoder pulses per unit time.

FIG. 8 is a functional block diagram of a camera including a coupling unit.

FIG. 9 is a diagram illustrating a change in an image plane movement coefficient.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 camera body 101 main mirror 102 sub mirror 103 AF sensor 104 body side MPU 200 interchangeable lens 201 first lens group 202 second lens group 203 third lens group 204 lens side MPU 205 motor drive circuit 206 motor encoder 207 zoom encoder 208 distance encoder 209 Motor 210 Transmission mechanism 211 Memory

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H011 AA01 BA21 CA15 CA16 CA19 CA21 2H051 AA06 BA02 DB01 DC15 DD20 FA49 FA76

Claims (8)

[Claims] When the focus cannot be determined, a state in which the focus can be determined by moving a “photographing optical system that moves for focusing” (hereinafter, referred to as a focusing lens). An imaging optical system drive control device that controls the driving of the focusing lens to move the image plane during a scanning operation for detecting the movement of the image plane. Speed calculating means for calculating a value (N0) relating to the moving speed of the focusing lens during the scanning operation, based on a maximum value (γmax) of the image plane moving coefficients which change according to the position of The driving of the focusing lens is controlled based on the value (N0) relating to the moving speed of the focusing lens calculated by the means. Taking optical system drive control apparatus characterized by comprising a control means for. 2. The photographing optical system drive control device according to claim 1, wherein an image plane movement coefficient indicating a movement amount of an image plane with respect to a unit movement amount of the focusing lens is recorded in advance in association with a position of the focusing lens. A coefficient selecting means for selecting a maximum image plane movement coefficient (γmax) during the scanning operation from the recorded recording means, wherein the velocity calculating means comprises an image plane movement coefficient (γm selected by the coefficient selecting means).
ax) calculating a value (N0) related to a moving speed of the focusing lens during the scanning operation. 3. The photographing optical system drive control device according to claim 1, wherein an image plane which is the largest during the scanning operation among image plane movement coefficients indicating an amount of movement of the image plane with respect to a unit movement amount of the focusing lens. A coefficient recording unit that records a movement coefficient (γmax) in advance, wherein the speed calculation unit includes an image plane movement coefficient (γm) recorded by the coefficient recording unit.
ax) calculating a value (N0) related to a moving speed of the focusing lens during the scanning operation. 4. A state in which, when the focus cannot be determined, the focus can be determined by moving a “photographing optical system that moves for focusing” (hereinafter, referred to as a focusing lens). An imaging optical system drive control device that controls the driving of the focusing lens to move the image plane during a scanning operation for detecting the movement of the image plane. Of the image plane movement coefficients that vary according to the position of the focusing lens, a value (Nmax2) relating to the moving speed of the focusing lens is sequentially calculated based on the image plane movement coefficient corresponding to the position of the focusing lens during the scanning operation. Speed sequential calculating means, and a value related to the moving speed of the focusing lens calculated by the speed sequential calculating means. If (Nmax2) is equal to or less than a predetermined upper limit (Nmax1), the driving of the focusing lens is controlled based on the value (Nmax2) related to the moving speed, and the value (Nmax) related to the moving speed is controlled.
2) when (2) exceeds the upper limit (Nmax1), control means for controlling the driving of "part of the imaging optical system" based on the upper limit (Nmax1) is provided. Optical system drive controller. 5. The photographing optical system drive control device according to claim 4, wherein the control unit indicates a moving amount of an image plane with respect to a unit moving amount of the focusing lens, and changes according to a position of the focusing lens. An imaging optical system drive control device, wherein the upper limit value (Nmax1) is determined based on the maximum value (γmax) of the image plane movement coefficients. 6. The photographing optical system drive control device according to claim 5, wherein an image plane movement coefficient indicating a movement amount of an image plane with respect to a unit movement amount of the focusing lens is recorded in advance in association with a position of the focusing lens. And a coefficient acquisition unit for sequentially acquiring an image plane movement coefficient corresponding to the position of the focusing lens during the scanning operation from the recorded recording unit. The speed sequential calculation unit includes the coefficient acquisition unit during the scanning operation. Means for sequentially calculating a value (Nmax2) relating to the moving speed of the focusing lens based on the image plane movement coefficient acquired by the means; A photographing optical system drive, wherein the upper limit (Nmax1) is determined based on an image plane movement coefficient (γmax) which is maximum during operation. Control device. 7. The photographing optical system drive control device according to claim 1, wherein a limit value (Vzma) of a moving speed of an image plane during the scanning operation is set.
x), and the speed calculating means includes a value (N) related to the moving speed of the focusing lens.
0) The photographing optical system drive control device, wherein, when calculating 0), the limit value (Vzmax) of the moving speed of the image plane calculated by the limit value calculating means is used. 8. The photographing optical system drive control device according to claim 4, wherein a limit value (Vzma) of a moving speed of an image plane during the scanning operation is set.
x), and the speed sequential calculating means includes a value (Nma) relating to a moving speed of the focusing lens.
x2) is sequentially calculated using the limit value (Vzmax) of the moving speed of the image plane calculated by the limit value calculating means.