JPH11264926A - Camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the small-sized, low-cost camera which is capable of photography even after a zoom lens barrel on a subject side shifts in position with an external force, etc. SOLUTION: Of the zoom lens barrel built in this camera, the zoom cam barrel 27 is supported rotatably on a fixed barrel 30 and a 1st group lens barrel 21 which freely moves is fitted onto the cam barrel 27. On a fixed barrel 30, PR31 and PR32 are arranged which detect the entire rotation range of the cam barrel 27 divisionally as plural zones. When the one-group lens barrel 21 moves from its original position owing to an external force, the PR31 and PR32 detect the zoom position range after the movement and the camera side is made to recognize the detect zoom position range after the movement as the position range of the one-group lens barrel 21, thereby carrying on subsequent photography.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera having a zoom lens barrel in which at least one lens barrel projects and retreats from the front of the camera body.

[0002]

2. Description of the Related Art In recent years, in cameras with a zoom function, in order to reduce the size of the entire camera and increase the zoom magnification,
The lens barrel tends to have a configuration in which a front lens barrel portion protrudes from the camera body and is extended. In the camera having such a configuration, as shown in the schematic diagram of FIG. 9, when an external force F acts on the front lens frame 102 at the time of shooting, the camera moves in the direction inside the camera body 101 and the front lens frame 102 It can be out of position.

Conventionally, a so-called closed-loop type in which a zoom encoder for position detection is provided on a lens barrel or a cam for driving to solve the above-mentioned problem, and the encoder is combined with a DC motor for driving. This problem was solved by adopting a lens barrel drive system. According to this lens barrel, even if the position of the lens barrel changes due to external force or the like, the change in the position can be detected by the encoder, so that the correction can be made.

For example, JP-A-6-347683 discloses an example of a lens barrel corresponding to the abnormal operation of the lens barrel.
JP-A-7-218807, JP-A-9-23021
All of the devices disclosed in Japanese Patent Application Laid-open No. 5-2005 detect an abnormal operation by using an encoder output for detecting the position of the lens barrel.

[0005] As a driving method of the zoom lens frame, a driving method using a stepping motor controlled by a driving pulse as a driving source is more costly than a combination of a DC motor and a zoom encoder as described above. It is well known that it is also advantageous in terms of space. For example, Japanese Patent Application Laid-Open No. Hei 5-188267 uses a stepping motor as a driving source of a zoom lens barrel, and uses a photosensor for detecting a home position.

In the inner focus type zoom lens barrel, when the front lens barrel is displaced by an external force,
The most problematic is the positional relationship between the zoom lens and the focus lens. According to the focusing method often used in conventional silver halide cameras, the position of the focus lens is determined based on the position of the zoom lens and distance information obtained by distance measurement. No deviation is allowed. Therefore, position detection management by a zoom encoder has been indispensable.

In contrast, in an electronic camera or a video movie, which adopts a contrast focusing method in which focusing is performed by detecting a high-frequency component of an image sensor signal without depending on distance information, a position of a zoom lens and a focus lens is determined. No strict relationships are required.

[0008]

In the case of a contrast focusing system such as the above-mentioned electronic camera, if the front lens barrel is slightly displaced due to an external force or the like, there is no particular problem in photographing. It is not necessary. However, when the focusing method such as the electronic camera described above is employed and a stepping motor is used as a driving source, if the front lens frame displacement is increased to a certain extent or more, it can only be corrected when returning to the home position. However, if the photographing is continued without knowing that the front lens frame is largely displaced, the following problem occurs.

That is, the distance between the zoom lens and the focus lens is not the original distance, and the focus lens may collide with one of the adjacent zoom lenses during focusing.

In addition, when the subject distance is calculated from the relationship between the zoom lens position and the focus lens position after focusing, and this subject distance information is used for camera control information such as a strobe light, the camera may have a large blur. The error of the control information increases, deteriorating the image quality.

Because of the above-mentioned problems, even in the above-mentioned electronic camera and the like, in a zoom lens barrel in which the front lens barrel can move forward and backward, a zoom lens drive structure using a stepping motor as a drive source has a zoom encoder. It was difficult to adopt it when not in use.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and automatically corrects a displacement of a zoom lens barrel on a subject side due to an external force or the like to continue photographing. It is an object of the present invention to provide a camera having a small-sized, low-cost zoom lens barrel capable of performing the following.

[0013]

According to a first aspect of the present invention, there is provided a camera, wherein at least one lens frame projects from the front surface of the camera body and is driven forward and backward, and the zoom lens frame is driven forward and backward. A driving source for pulse driving, a driving unit for controlling the driving source, a control unit for controlling the position of the zoom lens barrel, and a transmitting unit for transmitting the driving force of the driving source to the zoom lens barrel, A plurality of position detecting means for detecting a zoom position of the zoom lens barrel. In the camera, when performing the zoom drive of the zoom lens frame, the driving force of the drive source is transmitted to the zoom lens frame via the transmission means to drive the zoom lens frame forward and backward. Then, the zoom position of the zoom lens barrel is detected by a plurality of position detecting means, and if the driving state is not normal, correction is performed by the control means.

According to a second aspect of the present invention, in the camera according to the first aspect, the driving source is a stepping motor, the transmitting means is a cam member, and the plurality of position detecting means are provided. The zoom position is detected by detecting the displacement of the cam member.

According to a third aspect of the present invention, there is provided the camera according to the first or second aspect, further comprising: a calculating means for calculating zoom position information from a driving pulse signal for driving the driving source or the stepping motor. Comprising a correction means for correcting the calculated zoom position information during the zooming operation according to the outputs of the plurality of position detection means,
The calculated zoom position information is corrected according to the output of the position detecting means.

According to a fourth aspect of the present invention, in the camera according to the second aspect, the cam member is a cam cylinder having a cam groove formed on the periphery of a cylindrical portion, and the plurality of position detecting means. Are arranged along the circumferential direction on the circumference of the cylindrical portion of the cam cylinder.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a camera showing an embodiment of the present invention. In the camera of the present embodiment, the operation of the entire camera is controlled by the system controller 8 as control means. The system controller 8 has a release switch (SW) 11 for instructing the operation switch group to start shooting, a zoom-up switch (SW) 9 for instructing zoom-up, and a zoom-down switch (SW) 10 for instructing zoom-down.
Are connected, and respective operation outputs are input.

In the above-mentioned camera, when a photographing start is instructed by the release switch 11, a subject image taken through the photographing optical system of the zoom lens barrel 1 is converted into an electric signal by an imager 2, which is an image pickup device. The electric signal is sampled and held by the imaging circuit 3, and the output video signal is A / D converted by the A / D conversion circuit 4. The focusing circuit 7 detects contrast information for focusing driving of the photographing lens from the high frequency component of the digital video signal output from the A / D conversion circuit 4, and the contrast information is input to the system controller 8. The system controller 8 drives the focus motor 29 incorporated in the zoom lens barrel 1 via the focus motor control circuit 6 to drive the zoom lens barrel 1 for focusing.
The focused video signal is A / D converted by the A / D conversion circuit 4 and output to an external storage medium or the like.

Prior to the above photographing, zoom up
When the down switches 9 and 10 are operated, based on the zoom operation instruction, the system controller 8 drives the zoom motor 26 built in the zoom lens barrel 1 via the zoom motor control circuit 5 to obtain the photographing optics. The zoom drive of the system is performed.

The zoom lens barrel 1 mainly includes a fixed frame 3
0 (see FIG. 2) and the first group lens frame 21 as the photographing optical system.
, The first group lens 22 that is positioned closest to the subject and protrudes from the camera body during shooting, and the second group lens 23 and the third group lens 2 that are housed in the zoom cam frame 27.
4, a fourth group lens 25 serving as a focus lens, a zoom motor 26 serving as a zoom drive source to which a stepping motor is applied, and transmission means driven by the zoom motor 26, which are rotatably supported by a fixed frame 30. The first group lens frame 21, the lens groups 23 and 24, and the auxiliary frame 2
A zoom cam frame 27 that supports the zoom lens 8 so that it can move forward and backward, and the focus motor 29 that drives the focus of the fourth lens group 25.
PR (two photoreflectors), the auxiliary frame 28 for focus driving that supports the fourth lens group 25 with the focus motor 29 attached thereto and freely moves forward and backward, and the position detecting means for detecting the rotation state of the zoom cam frame 27. A) 31,
PR (B) 32.

FIG. 2 shows a schematic external perspective view of the zoom lens barrel. The above PR (A) 31, PR (B) 3
2 are arranged in a row on the fixed frame 30 in the direction orthogonal to the optical axis O along the circumferential direction. And the above-mentioned zoom cam frame 2
On the outer periphery of 7, zone detection patterns 33 and 34, which are reflection members, are affixed to the outer periphery of the outer periphery of the outer periphery 7 in a direction orthogonal to the optical axis O so as to face the passing position of PR (A) 31 and PR (B) 32. ing. PR of the zone detection patterns 33 and 34
(A) 31 and PR (B) 32 are shared.

By examining the two output signals of the PR (A) 31 and PR (B) 32 based on the reflected light of the zone detection patterns 33 and 34, the zoom cam frame 27 is moved from the retracted position to the zoom position at present. It is possible to identify which of the divided zoom zones described below is located.

The zoom cam frame 27 is a cylindrical member, and the first lens frame 21 is slidably fitted on the outer periphery of the zoom cam frame 27. The zoom cam frame 27 is inserted into a cam groove 27 a provided in the cam frame 27. The drive pin is fitted. Further, the first lens group frame 21 is guided linearly along the lens optical axis O by a linear guide groove provided in the protruding portion 30 a of the fixed frame 30.

Therefore, when the zoom cam frame 27 is rotated by the zoom motor 26, the first lens group frame 21 is driven forward and backward from the retracted position to the telephoto position in the optical axis direction. Further, inside the zoom cam frame 27, a second group lens 23, a third group lens 24, and an auxiliary frame 28 are held so as to be able to advance and retreat.
When the zoom cam frame 27 is rotated by the zoom motor 26, the zoom cam frame 27 is driven forward and backward from the retracted position to the telephoto position in the optical axis direction.

During zoom driving, the focus motor 29 also moves integrally with the advance and retreat of the auxiliary frame 28. At the same time, the focus motor 29 is driven to rotate according to a predetermined tracking curve, and the fourth lens group 25 is moved to each zoom position. To the in-focus position.

FIG. 3 is a view showing the extended position of each lens group in the zoom lens barrel 1 when the zoom state changes from the wide end to the telephoto end. The extending position of the fourth lens unit 25 differs depending on the subject distance at that time.

FIG. 4 is a diagram showing the extension position curve of each lens group when the lens group is driven from the retracted position to the telephoto end via the wide end. FIG. 5 shows PR (A) 31 and PR (B) with respect to the rotation angle of the zoom cam frame 27.
32 and the zoom division zones to be divided and the zone detection patterns 33, 34, PR (A) 31, PR
It is a figure which shows the positional relationship of (B) 32.

The zoom division zones indicating the lens group movement ranges shown in FIGS. 4 and 5 are zones that can be recognized by ON / OFF output signals based on the reflection state of the zone detection patterns of PR (A) 31 and PR (B) 32. Zoom cam frame 27
Is divided into six zoom division zones from the retracted position to the telephoto end position in accordance with the rotation angle of.

That is, the six zoom division zones include a collapsed zone ZSD in the range of the collapsed position and a collapsed zone Z
Zone ZA within collapsed movement between SD and wide end zone ZB
And the wide end zone ZB in the vicinity including the wide end.
And a wide-side intermediate zone ZC and a tele-side intermediate zone Z between the wide-end zone ZB and the tele-end zone ZE.
D and a tele-end zone ZE in the vicinity including the tele-end.

By examining the on / off output signals of the PR (A) 31 and PR (B) 32, it is possible to detect which zoom division zone of the rotation position range the zoom cam frame 27 is actually in.

The camera according to the present embodiment has the above-described configuration. When an external force acts on the first lens frame 21 protruding from the camera body and the camera greatly moves toward the body, Alternatively, the first group lens frame 21 during the zoom drive
When the external force acts on the zoom motor 26, the original zoom position data stored in the system controller 8 and the actually detected zoom division zone, that is, the zoom position of the zoom cam frame 27, The range will vary greatly. For example, in FIG. 5, there is a difference that the actual zoom cam frame 27 is at the ZC position while the zoom position at which the drive instruction is given by the system controller 8 is located within the zoom division zone ZD or ZE. Occurs.

Therefore, in the camera according to the present embodiment, the fact that the zoom position data for which the drive instruction has been issued is different from the zoom division zone indicating the actual zoom position range is different.
When detected by R (A) 31 and PR (B) 32,
The zoom motor 26 is once driven to rotate the zoom cam frame 27 so as to be retracted to the position of the wide end zone ZB.
When the zoom division zone detected in PR (A) and PR (B) is the retractable operation zone ZA, on the contrary, it is extended to the position corresponding to the wide end zone ZB.

At the same time as driving to the wide end zoom ZB, the zoom position data in the system controller 8 is rewritten to data giving the wide end. This processing corrects the abnormal operation state due to the external force, and the normal photographing sequence can be continued thereafter.

The photographing sequence, zoom processing, and abnormal processing operation for correcting deviation in the camera of this embodiment will be described in more detail with reference to the flowcharts of FIGS. When the power switch of the camera is turned on, the processing of the shooting sequence shown in the flowchart of FIG. 6 is started. First, in step S1, a zoom process of a subroutine for executing the zoom drive is called.
This zoom processing will be described later with reference to the flowchart of FIG. In step S2, it is determined whether the release switch 11 is on or off. If the release switch 11 is off, the process returns to step S1, and if it is on, the process proceeds to step S3.

In step S3, a subject image is fetched from the above-described photographic lens optical system, converted into an electric signal by the imager 2, and a focusing process and an imaging process are performed. The image information of the subject is stored in a memory card or the like. On a recording medium. The process returns to step S1 until there is an instruction to end shooting (step S4).

Next, the zoom processing of the subroutine called in step S1 will be described with reference to the flowchart of FIG. In step S11, it is determined whether the zoom-up switch 9 or the zoom-down switch 10 is on or off. If either of them is on, the process proceeds to step S12. If both are off, the process jumps to step S20.

The zoom mode is entered in step S12, and pulse driving of the zoom motor 26 is started in step S13. In step S14, the output drive pulse value P is added or subtracted to count up or count down. In step S15, zoom position data corresponding to the drive pulse value P is calculated. The zoom position data is data indicating a zoom state of the extended position of the zoom lens from the retracted position to the wide end position or the tele end position, and corresponds to the rotation angle of the zoom cam frame 27 in FIG. .

In step S16, the normal mode for the zoom position is entered. In step S17, PR (A) 31, PR
(B) one of the zoom division zones ZSD to ZE indicating the actual rotation position range of the zoom cam frame 27 detected by the output of 32, and zoom position data based on the drive pulse value P which is the calculated set value; That is, a comparison is made with the set rotation angle of the zoom cam frame 27 in FIG. If the set zoom position data based on the drive pulse value P matches the detected zoom division zone, it is determined that the state is normal, and step S
Proceed to 19. However, if the rotation angle of the zoom cam frame 27 based on the drive pulse value P does not match the detected zoom division zone, the zoom cam frame 27 moves before the zoom drive and the zone changes, and it is determined that the zone is not normal. Jump to step S18.

In step S18, the zoom position data stored in the system controller 8 is stored in PR (A) 3.
1, corrected to the zoom position data existing in the zoom division zone detected in PR (B) 32.

In step S19, the PR (A) 31, P
If it is not detected that the divided zone detected in R (B) 32 has changed in particular, the process returns to step S11. When the change is detected, some external force is applied to the first lens group frame 21.
Is determined, that the zoom position is deviated, the process jumps to step S21, and the abnormal process of the subroutine is called.

On the other hand, if the zoom switch is off in the determination in step S11, the process jumps to step S20. In this step S20, if the zoom division zone has not changed from the time of the previous determination, this routine ends. It returns to the main routine of FIG. If the zoom division zone has changed from that at the time of the previous determination, it is considered that some external force has acted on the first lens group frame 21 and has moved. Therefore, the process jumps to step S21, and the abnormal process of the subroutine is called.

The abnormal processing of the above subroutine will be described with reference to the flowchart of FIG. Step S31
In step S3, the focus motor 29 is driven.
In step 2, the fourth lens unit (focus lens) 25 is moved to the infinity in-focus position. This operation is performed by the third group lens 24 and the fourth lens unit 4 because the zoom lens is not in the normal extended position.
This is a process for preventing interference with the group lens 25.

In step S33, the zoom motor 26 is rotated forward or backward to drive the zoom cam frame 27 to the position of the wide end zone ZB among the zoom divided zones. That is, when the zoom motor 26 is in the zone ZA before driving, the zoom motor 26 is rotated forward as shown in FIG.
7 is driven in the counterclockwise direction and is advanced to the position of the wide end zone ZB. If the zoom motor 26 is in the zones ZC, ZD, and ZE before driving, the zoom motor 26 is rotated in the reverse direction, and the zoom cam frame 27 is driven clockwise to retreat to the wide end zone ZB.

In step S34, PR (A) 31 and PR
(B) The output of 32 is checked to determine whether the zoom cam frame 27 has reached the position of the wide end zone ZB.
If it has reached, the process proceeds to step S35. If not reached, the process jumps to step S36 to jump to the zoom motor 2
It is checked whether or not 6 has been driven more than the predetermined number of pulses, and if it is detected that it has already been driven more than the above number of pulses, it is determined that the zoom drive cannot be performed normally for some reason,
NG processing is performed. That is, a warning display or the like is performed to stop the photographing operation. If it has not been driven by the predetermined number of pulses, the process returns to step S33.

In step S35, the zoom position data is initialized to the wide end position corresponding to the wide end zone ZB, the abnormal processing is completed, and the flow returns from this subroutine to step S11 of the zoom processing routine.

As described above, in the camera according to the present embodiment, the zoom position is detected without applying the zoom encoder, despite the configuration in which the stepping motor is applied to the zoom driving motor. Two P for
By simply arranging the R on the zoom cam frame, even if the lens frame drive position is in an abnormal state, it can be easily corrected, and downsizing and cost reduction can be achieved. For example, even if the first lens group is largely displaced by an external force, or even if the zoom motor loses synchronism, the abnormal state is returned by returning the zoom state to the reference wide end zone ZB. The state can be corrected.

If the amount of movement is small enough so that the displacement of the lens frame falls within the zoom division zone, the focusing method of the present camera is a contrast focusing method. There is no particular problem because the component information is detected and focused. Also, there is no particular problem regarding the flash emission control when the displacement of the lens frame is small.

In the above-described embodiment, the zoom lens barrel 1 to be applied has a zoom optical system in which the first lens group 22 is driven forward and backward between the wide end and the tele end. Was. However, the present invention is not limited to this, and even if the first lens unit is a zoom lens barrel that does not advance or retreat between the wide end and the telephoto end, a modification to which the driving method of the zoom lens barrel according to the above embodiment is applied is proposed. It is possible.

That is, in a zoom lens barrel in which the first group lens does not advance or retreat between the wide end and the tele end, the cam groove for driving the first group lens frame provided on the zoom cam frame is located between the wide end and the tele end. The cam groove has a shape orthogonal to the lens optical axis. Therefore, even if an external force acts on the first lens frame from the subject side, the first lens frame itself does not move in the optical axis direction due to the pressure angle of the cam groove. However, if the stepping motor is being driven for zooming when the external force is applied, the stepping motor may lose synchronism due to an increase in frictional resistance to the rotation of the zoom cam frame due to the external force. . Along with the step-out of the stepping motor, the zoom cam frame largely shifts from the zoom position specified by the system controller, causing a shift in the zoom position of the second group lens, the third group lens, or the auxiliary frame.

In the zoom lens barrel of this modification,
When the above-described shift occurs, by detecting the shift of the divided zone in the above-described zoom state, it is recognized that an abnormality due to an external force has occurred, and the zoom cam frame is moved in the same manner as in the first embodiment. It is once driven to the zone ZB in the wide end range, and the subsequent photographing processing is executed. In this way, it is possible to eliminate the obstacle due to the displacement of the first lens group frame.

Although the camera of the above embodiment has been described as being mounted on an electronic camera, the zoom lens barrel according to the present invention can of course be applied to a silver halide camera or a video movie.

[0052]

As described above, according to the camera of the first aspect of the present invention, an external force acts on the zoom lens barrel moved to a predetermined position by the pulse-driven drive source, or the drive source loses synchronism. Even if the position of the zoom lens barrel shifts from its original position, the position detection means can detect that the shift has occurred and automatically correct the shift, and the zoom position can be adjusted by zooming. It is possible to provide a small-sized and low-cost camera as compared with a camera detected by an encoder.

According to the camera of the second aspect of the present invention,
In addition to the effect of the camera according to claim 1, furthermore, since the position detecting means can be arranged around the cam member, the position detecting means can be arranged on the outer periphery of the zoom lens barrel,
The degree of freedom of arrangement increases, and the electrical connection between the position detecting means and the electric system inside the camera becomes easy.

According to the camera of the third aspect of the present invention,
In addition to the effects of the camera according to claim 1 or 2, zoom position information is calculated in the camera, and the zoom position information can be surely corrected by the zoom position information detected by the position detecting means. .

According to the camera described in claim 4 of the present invention,
In addition to the effect of the camera according to claim 2, a plurality of position detecting means can be arranged along the circumferential direction, and the detected member for the position detecting means can be made common, so that the cam cylinder can be downsized. become.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a main configuration of a camera according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a schematic appearance of a zoom lens barrel of the camera in FIG. 1;

FIG. 3 is a view showing a state in which each lens group of the zoom lens barrel in FIG. 2 is extended in a zoom state.

FIG. 4 is a view showing a payout curve from a retracted position to a telephoto end of each lens group in the zoom lens barrel in FIG. 2;

FIG. 5 is a diagram showing a relationship between a PR output with respect to a zoom cam frame rotation angle and a zoom division zone and a zone detection pattern position of a lens barrel moving position in the camera of FIG. 1;

FIG. 6 is a flowchart of a shooting sequence in the camera of FIG. 1;

FIG. 7 is a flowchart of a zoom process of a subroutine called in the shooting sequence of FIG. 6;

FIG. 8 is a flowchart of an abnormal process of a subroutine called in the zoom process of FIG. 7;

FIG. 9 is a schematic diagram showing a state in which an external force acts on a front lens barrel during photographing in a conventional camera.

[Explanation of symbols]

8 System controller (control means, calculation means, correction means) 21 ... 1 group lens frame (zoom lens frame) 26 ... zoom motor (drive source, stepping motor) 27 ... zoom cam frame (transmission means, cam) Member, cam cylinder) 31 PR (A) (position detecting means) 32 PR (B) (position detecting means)

Claims (4)

[Claims] At least one lens frame projects from a front surface of a camera body and is driven forward and backward, a driving source for pulse driving for driving the zoom lens frame forward and backward, and a drive for the driving source. Control means for performing control to control the position of the zoom lens barrel; transmitting means for transmitting the driving force of the drive source to the zoom lens barrel; and detecting a plurality of positions for detecting the zoom position of the zoom lens barrel. Means, and a camera. 2. The method according to claim 1, wherein the driving source is a stepping motor, and the transmitting unit is a cam member, and the plurality of position detecting units detect the displacement of the cam member to detect the zoom position. The camera according to claim 1, wherein: 3. A calculating means for calculating zoom position information from a driving pulse signal for driving the driving source or the stepping motor; and outputting the calculated zoom position information during the zooming operation to the plurality of position detecting means. 3. The camera according to claim 1, further comprising: a correction unit configured to perform correction according to: 4. The cam member is a cam cylinder having a cam groove formed on the periphery of a cylindrical portion, and the plurality of position detecting means are arranged on the circumference of the cylinder portion of the cam cylinder along a circumferential direction. 3. The camera according to claim 2, wherein the camera is arranged.