JPH04134307A - Zoom driving device for camera - Google Patents

Abstract

PURPOSE:To easily detect a zoom position and to enable zoom driving with high accuracy by driving motors which drive a variator and a compensator respectively while detecting their rotations with pulses. CONSTITUTION:A front fixed lens 1, the variator 2, the compensator 3, a stop 4, master lenses 5 and 7, a beam splitter 6, a finder mirror 8, and a CCD unit 9 are arranged, and the variator 2 and compensator 3 are movable along the optical axis S. In the zoom driving, the variator 2 and compensator 3 are driven by the zoom driving motor and focus driving motor respectively while the pulses of those motors are detected so that the ration of the movement quantity of the variator 2 and the movement quantity of the compensator 3 becomes an integral multiple. Consequently, the positions of the variator 2 and compensator 3 can easily be detected by counting the pulses, and the position relation can be calculated from the ratio of the movement quantities speedily with high accuracy.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a zoom drive device for a camera that moves a zoom lens in the optical axis direction so as to continuously change the focal length, and in particular to a camera zoom drive device that moves a zoom lens in the optical axis direction so as to continuously change the focal length. Coupling device (CCD)
The present invention relates to a zoom drive device suitable for an electronic still camera using an electronic still camera.

[Conventional technology]

In recent years, there has been active development of electronic still cameras that store still images on memory cards such as SRAM, magnetic disks, etc. instead of conventional film. Electronic still cameras have advantages over silver halide cameras, such as instantaneousness, convenience, mobility, and economy, and their development is likely to accelerate in the future.

This type of electronic still camera uses a solid-state imaging device such as a CCD as a means for converting a subject into an electrical signal.

When a CCD is used as an image sensor, accurate information regarding the subject distance is required because the latitude of the CCD is narrow. This is because if the information regarding the subject distance is not accurate, the light adjustment during flash photography will be insufficient, making it impossible to perform appropriate exposure compensation and making it impossible to obtain a clear image.

Further, there is a demand for such electronic still cameras to be able to take pictures more easily, and there is a demand for one equipped with a zoom device so that the focal length of the photographic lens can be continuously changed. Furthermore, electronic still cameras equipped with a zoom device require even more highly accurate data regarding subject distance. In addition, in order not to impair the portability and maneuverability of electronic still cameras, zoom lenses are equipped with
An inner focus type zoom lens is desirable, as the overall length of the lens does not change and there is no air pumping within the lens barrel, which prevents dust from entering the optical system. In particular, since a CCD with a narrow latitude is used, it would be inconvenient if dust gets into the optical system, and an inner focus type zoom lens is advantageous in this respect.

For this reason, the applicant has developed a camera equipped with an autofocus (AF) device and an inner focus type zoom lens, in which a variator, which is a variable power lens, a correction system, and a focus system lens are used when driving the zoom. We proposed a device that calculates the subject distance from the focusing position of a certain compensator.

[Problem to be solved by the invention]

By the way, inner focus type zoom lenses are
The variator and compensator are driven during zoom driving, but in order to drive them synchronously while maintaining a predetermined optical relationship, it is necessary to drive the variator and compensator with separate motors. That is,
If these synchronous drives were to be mechanically interlocked and driven using a cam cylinder or the like, the shape of the cam cylinder would be complicated, the work would be complicated, and the manufacturing cost would increase.

In addition, when calculating the subject distance using the above-mentioned subject distance calculation device, high accuracy is required for the zoom drive, and it is also necessary to accurately detect the respective positions of the variator and compensator and their positional relationship at the time of focusing. There is.

Further, although the variator and compensator differ in the amount of movement and the weight of the lens, in order to perform accurate zoom driving, they must be driven synchronously so that they always have a predetermined optical relationship.

Therefore, in order to obtain accurate information regarding the subject distance, this invention drives the variator and compensator for zooming as accurately as possible, even if they use separate motors, and also facilitates the position and positional relationship between them. can be detected,
Moreover, it is an object of the present invention to provide a zoom drive device for a camera that can reliably drive a variator and a compensator that have different amounts of movement while maintaining a predetermined optical relationship.

[Means to solve the problem]

For the above purpose, the zoom drive device according to the present invention includes:
A variator, which is a variable power lens, and a compensator, which is a correction and focus lens, are combined, and while maintaining a predetermined optical relationship between the variator and the compensator, the variator is driven to focus by a zoom drive motor. Equipped with an inner focus type zoom device that continuously changes the focal length by being driven by each motor.
In a camera with an autofocus device, the rotation of the zoom drive motor and focus drive 1 motor is detected by pulses, and the ratio of the amount of movement of the variator to the amount of movement of the compensator per pulse is an integral multiple. Further, a step motor is used as the zoom drive motor, a DC motor is used as the focus drive motor, and the rotation of the output shaft of the focus drive motor is converted into pulses to detect the rotation. It is said that

Furthermore, focusing on the fact that the pulses of the respective drive motors are detected for both the variator drive and compensator drive during zoom drive, the rotation of the zoom drive motor is transmitted to the zoom feed screw. , a zoom mechanism unit in which a connecting frame linked to the zoom feed screw is moved forward and backward along the zoom feed screw, and a zoom moving frame holding the variator is linked to the link frame; and the focus drive motor. a focus mechanism section that transmits the rotation of the focus feed screw to a focus feed screw, advances and retreats a connecting frame linked to the focus feed screw along the focus feed screw, and links the compensator to the link frame, Another feature is that the components constituting the zoom mechanism section and the components constituting the focus mechanism section are common.

[For production]

During zoom driving, the variator and compensator are driven by a zoom driving motor and a focus driving motor, respectively, while pulses of these driving motors are detected. Therefore, the positions of the variator and compensator can be easily detected by counting the number of pulses of the drive motor when the variator and compensator move from the reference position to the zoom position during zoom driving. . Moreover, since the ratio of these moving amounts per pulse is an integral multiple, the positions and positional relationships of these can be calculated quickly and with high precision using the CPU. Then, the subject distance can be calculated by referring to the positions of the variator and compensator at the zoom position.

Note that during focus drive, only the ° compensator is driven by the focus drive motor and moves to the in-focus position.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The camera zoom drive device according to the present invention will be specifically described below based on the illustrated embodiments.

FIG. 1 is a cross-sectional view of a digital still camera having an inner focus type zoom device taken along a vertical plane including an optical axis S. This camera has a fixed front lens 1, a variator 2, a convencator 3, an aperture 4, a master lens 5.7, a beam splitter 6, a finder mirror 8, and a CCD unit 9 arranged in order from the front on the optical axis S. ing.

The variator 2 and convencator 3 are movable along the optical axis S, and zoom drive and autofocus drive are performed by this movement, and during zoom drive, the variator 2 and convencator 3 maintain a predetermined optical relationship. During focus drive, the convencator 3 moves to the in-focus position.

Further, the light split by the beam splitter 6 passes through the AE lens 10 and enters the AE sensor 12 and the dimming sensor 13 via the half mirror 11. The diaphragm 4 is controlled based on information on the subject brightness obtained by the AE sensor 12, and the light emission of a strobe (not shown) is controlled by the light control sensor 13. A portion of the finder mirror 8 is configured as a half mirror, and the image is incident on the CCD unit 9 in the mirror-up state and captured as a photographed image. Further, the light refracted by the finder mirror 8 is incident on the finder section 80, and the photographer can see the subject through the eyepiece section 81.

In addition, there is an AF mirror 14 on the rear surface of the finder mirror 8.
The light transmitted through the finder mirror 8 and refracted by the AF mirror 14a enters the autofocus (AF) device 14 disposed at the bottom of the camera, and the amount of defocus is measured. become.

That is, this camera uses the so-called TTL method.

FIG. 2 is a schematic exploded perspective view of a zoom mirror chest for holding the variator 2 and convencator 3 and driving them along the optical axis S. Lens barrel body 15
A front lens frame 16 holding the front fixed lens 1 and a filter frame 17 are fixedly attached to the front part of the lens. This lens barrel body 15 includes a zoom movement frame 2 holding a variator 2.
Focus movement frame 30 holding 0 and convencator 3
is housed in the lens barrel body 15 so as to be movable in the direction of the optical axis S.

A presser plate 41 is disposed behind the focus movement frame 30, and a spring presser 42 is disposed behind the presser plate 41.

Further, each of the zoom movement frame 20 and the focus movement frame 30 has support rods 21 and 31 along the optical axis S, oriented rearward in the zoom movement frame 20 and forward in the focus movement frame 30. Coil springs 22.32 are fitted onto these supporting rods 21.31. The restoring force of the coil spring 22 is applied between the zoom movement frame 20 and the presser plate 41, and the coil spring 32 is applied between the focus movement frame 30 and the front wall 15a of the lens barrel body 15. Resilience is energized. Therefore, due to the restoring force of these coil springs 22 and 32,
The zoom movement frame 20 is moved in a direction away from the presser plate 41, and the focus movement frame 30 is moved in a direction away from the front wall 15a of the lens barrel body 15. In addition, a leaf spring 43 is attached to the focus movement frame 30, and the restoring force of the leaf spring 43 may cause the focus movement frame 30 to
and the zoom movement frame 20 to soften the impact when they collide.

In addition, three support holes 1 are provided in the front wall portion 15a of the lens barrel body 15.
5b is formed, and the presser plate 41 also has three support holes 41.
A is formed between these support holes 15b and 41a.
Each end of the book guide bar 44 is retained. Then, this guide bar 44 or the moving frame 20.30
These movements pass through through holes 23.33 formed in the center of each support rod 21.31, or through cutouts 24.34 formed in each movement frame 201.30. The center of the lens 2.3 incorporated in the frame 20.30 is guided to move correctly on the optical axis.

The zoom movement frame 20 and the focus movement frame 30 housed in the lens barrel main body 15 are connected to input pins 25 and 35, which are provided on each of the movement frames 20 and 30 and protrude upward, respectively. It is accommodated in a state facing elongated holes 15d and 15e formed along the optical axis S in the body 15c of the main body 15.

A zoom drive base frame 50 to which the drive mechanism of the variator 2 is assembled is attached to the side of the barrel 15c of the lens barrel main body 15.
and a focus drive base frame 60 to which the drive mechanism of the convencator 3 is assembled.

A zoom feed screw 51 is rotatably supported in the zoom drive base frame 50 in parallel with the optical axis S by bearings 50a and 50b formed at the front and rear ends of the zoom drive base frame 50. has been done. A connecting frame 52 is rotatably fitted into the zoom feed screw 51, and a driving engagement portion 52a that projects downward from the connecting frame 52 is formed on the lens barrel body 15. The input pin 25 of the zoom movement frame 20 is engaged with the input pin 25 of the zoom movement frame 20. Further, a guide pin (not shown) is provided on the side of the connecting frame 52.
This guide pin is loosely inserted into a guide hole 50c formed in the zoom drive base frame 50 in a long hole shape parallel to the optical axis S. A collar holding portion 52c is formed on the side surface of the connecting frame 52 and communicates with the portion through which the zoom feed screw 51 is inserted. 53 is accommodated so as not to rotate with respect to the connecting frame 52.

The zoom feed screw 51, the connecting frame 52, and the screw collar 5
3 is an enlarged view of the state in which the zoom feed screw 51 is engaged with a screw collar 53. Further, the top of the thread 51a of the zoom feed screw 51 is appropriately cut out so that the zoom feed screw 51 and the connecting frame 52 have a "loose fit" relationship with a minimum clearance. As shown in FIG. 2, the restoring force of the leaf spring 52d fixed to the connecting frame 52 is applied to the zoom feed screw 51, so that the screw collar 53 and the zoom feed screw 51
and are securely screwed together.

Further, a light shielding plate 52e is attached to the connecting frame 52.

A collar 51b1, an encoder ring 51c, and an encoder plate 51d are provided in this order at the front end of the zoom feed screw 51, and a collar 51e and a driven gear 54 are provided at the rear end. The zoom feed screw 51 is supported by the zoom drive base frame 50 via the collars 51b and 51e.

A zoom drive motor 55 including a step motor is attached to the rear end of the zoom drive base frame 50, and a drive gear 55a fitted to the output shaft of the zoom drive motor 55 is connected to the driven gear 54. They mesh together.

Furthermore, photointerrupters 56 and 57 are arranged at the top of the zoom drive base frame 50, and the photointerrupters 56 and 57
6 monitors the rotation angle of the zoom feed screw 51 in conjunction with the encoder plate 51d, and a photo interrupter 5
7 monitors the initial position of the connecting frame 52 in conjunction with the light shielding plate 52e.

In FIG. 2, 58 is a buffer rubber, and 59 is a leaf spring that presses the zoom feed screw 51 against the front end of the zoom drive base frame 50 via the collar 51e.

The focus drive base frame 60 has a symmetrical shape with the zoom drive base frame 50, and includes a focus feed screw parallel to the optical axis S in bearings 60a and 60b formed at the front and rear ends. 61 is rotatably supported.

A connecting frame 62 is rotatably fitted into the focus feed screw 61, and a driving engagement portion 62a that projects downward from the connecting frame 62 is formed on the lens barrel body 15. The focus moving frame 3 is inserted into the elongated hole 15e.
It is engaged with the input pin 35 of No. 0.

Further, a guide pin 62b is protruded from the side of the connecting frame 62, and this guide pin 62b is connected to a guide hole 6Gc formed in the focus drive base frame 60 in a long hole shape parallel to the optical axis S. It is loosely inserted into. A collar holding portion 62c is formed on the side surface of the connecting frame 62 and communicates with a portion through which the focusing feed screw 61 is inserted.
A screw collar 63 that is screwed into the connecting frame 62 is housed so as not to rotate with respect to the connecting frame 62.

The linkage state of the focus feed screw 61, the connection frame 62, and the screw collar 63 is the same as the linkage state of the zoom feed screw 51, the connection frame 52, and the screw collar 53 described above.
The top of the screw thread of the focus feed screw 61 is appropriately cut out so that the focus feed screw 61 and the connecting frame 62 have a "loose fit" relationship with a minimum clearance. Note that the restoring force of the plate spring 62d fixed to the connecting frame 62 is applied to the focus feed screw 61 to ensure that the screw collar 63 and the focus feed screw 61 are screwed together.

Further, a light shielding plate 62e is attached to the connecting frame 62.

A collar 61b is attached to the front end of the focusing feed screw 61.
One encoder ring 61c and one encoder plate 61d are provided in this order, and a collar 61e and a driven gear 64 are provided at the rear end. In addition, this focus feed screw 61
is supported by the focus drive base frame 60 via the collars 61b and 61e.

The rear end of the focus drive base frame 60 has a D
A focus drive motor 65 using a C motor is attached to the output shaft of the focus drive motor 65.
An encoder plate 68 is fitted, and an appropriate gear train 65 is fitted.
It is linked to the driven gear 64 via a.

Further, photo interrupters 66 and 67 are arranged on the upper part of the focus drive base frame 6o, the photo interrupter 66 monitors the rotation angle of the focus feed screw 61 in conjunction with the encoder plate 61d, and the photo interrupter 67 The initial position of the connecting frame 62 is monitored in conjunction with the light shielding plate 62e.

In FIG. 2, 69 is a buffer rubber, and 7o is a leaf spring 71 that presses the focus feed screw 61 against the rear end of the focus drive base frame 60 via the collar 61b.
is the substrate. Further, a photo interrupter 72 is linked to the encoder plate 68, and the rotation angle of the focus drive motor 65 is monitored by the photo interrupter 72.

FIG. 4 schematically shows the drive mechanism of the variator 2 and convencator 3. The zoom drive motor 55 uses a step motor that rotates 18 degrees per pulse, and the focus drive motor 65 uses a step motor that rotates 18 degrees per pulse. A DC motor is used. The zoom drive motor 55 receives zoom drive information sent from the CPU 91 or signal lines Z1, Z2, and Z3.
, Z4, and the focus drive motor 65
The focus information sent from the CPU 91 is inputted to the signal lines F1 and F2. Further, the photointerrupter 56.57 outputs the reference position signal of the variator 2 to the CPU 91 via signal lines P1 and F2, and the photointerrupter 66.67 outputs the reference position signal or signal of the convencator 3. It is output to the CPU 91 via lines P3 and F4. In addition, the output signal of the photointerrupter 72 is sent to the CPU 9 via the signal line P5.
1 and the rotation angle of the focus drive motor 65 is monitored by counting the output signal. Furthermore, the CPU 91 has a non-volatile memory “E”.
PROM 92 is connected and the E 2P R
Correction data, which will be described later, is sent from the OM 92 to the CPU 91.

The pitch p of the zoom feed screw 51 and the focus circumferential speed screw 61 are both 0.5 mm, and the driven gear 54 for driving the variator 2 is used.
The reduction ratio of the driving gear 55a is 1/2, and the reduction ratio of the wave gear 64 for driving the focusing feed screw 61 and the driving gear 65a is 1/8. Further, five through holes are formed in the encoder plate 68 at equal intervals, so that the photointerrupter 72 detects five pulses during one rotation of the focus drive motor 65. Therefore, while the photo interrupter 72 detects one pulse, the focus drive motor 65 rotates at 72 degrees.
It will rotate.

Then, with the subject placed in a fixed position, the variator 2 is moved to an appropriate zoom step, and the convencator 3 is moved and corrected to bring the subject into focus. The position of the convencator 3 in this focused state is determined by the photointerrupter 66, 67, 7, which is the encoder.
Calculate from the output of 2 and use this value as correction data, E
It is stored in 2FROM 92. Further, this correction data is acquired at an appropriate number of zoom stages and stored in the E'FROM 92 as a correction data table.

The operation of the zoom drive device of the camera configured as above is as follows.
This will be explained below.

When a zoom switch (not shown) is turned on, the zoom is driven to change the focal length. The zoom drive is performed by operating the zoom drive motor 55 and the focus drive motor 65 to rotate the zoom feed screw 51 and the focus feed screw 61 in predetermined directions, respectively.

When the zoom drive motor 55 rotates, the drive gear 55
The zoom feed screw 51 rotates via the driven gear 54 and the zoom feed screw 51 . A screw collar 53 is screwed onto the zoom feed screw 51, and the screw collar 53 is housed in a connecting frame 52. The guide pin protruding from the side surface of the connecting frame 52 is loosely inserted into the guide hole 50c formed in the zoom drive base frame 50, so that the connecting frame 52 is guided along the zoom feed screw 51. It will move in the direction of axis S.

Since the zoom movement frame 20 holding the variator 2 is engaged with the connecting frame 52, the variator 2 also moves on the optical axis S as the connecting frame 52 moves.

Further, the rotation of the focus drive motor 65 rotates the focus feed screw 61, and the connection frame 62, which is linked to the focus feed screw 61 via the screw collar 63, moves along the optical axis along the feed screw 61. Move in the S direction.

Since the focus movement frame 30 holding the compensator 3 is linked to this connection frame 62, the compensator 3 also moves on the optical axis S.

When driving the zoom, as described above, the zoom drive motor 55 uses a step motor that rotates 18 degrees per pulse, and the focus drive motor 65 uses the encoder plate 68 to rotate 72 degrees per pulse. In addition, the reduction ratio from the zoom drive motor 55 to the zoom feed screw 51 is 172, and the reduction ratio from the focus drive motor 65 to the focus feed screw 61 is 1.
78, so for each pulse of each motor 55.65, the zoom feed screw 51. Both the focusing feed screw 61 are rotated by 9 degrees. Since the pitch of these feed screws 51.61 is equal to 0.5 mm, both the variator 2 and the compensator 3 move by 0.0125 mm per one pulse of the motor 55.65.

FIG. 5 is a schematic diagram of the photographing optical system, in which the variator 2 moves along a trajectory indicated by V for zoom driving, and the compensator 3 moves along a trajectory indicated by C for zoom correction. In the case of zoom driving, the variator 2 and the compensator 3 are moved along these orbits V1C.
Each drive motor 55.65
is controlled.

Once the subject has been captured at a predetermined magnification, the camera will be released.
4 is activated and drives the compensator 3 so that the photographing lens focuses on the subject. Then, the image will be photographed in a focused state.

Next, calculation of the subject distance will be explained.

It is assumed that the variator 2 and the compensator 3 are in the position shown in FIG. 5 when the zoom is driven and the subject is in focus. Note that the symbol O indicates a subject. Each symbol in the figure means the following value. In addition, in the figure, the right direction is defined as the forward direction.

Xv: Distance from the reference position of the variator 2 during shooting Xc: Distance from the reference position of the compensator 3 during focusing XCI: Infinity position (Inf) of the compensator 3 relative to the zoom drive during shooting The amount of extension of the compensator 3 when the distance is XVC: Distance between the variator 2 and the compensator 3 L: Subject distance
This is the position of the variator 2 when the variator 2 is at the reference position (Wide), and the photointerrupters 56 and 57 detect that the variator 2 is at this reference position. The position of the variator 2 is calculated based on the number of pulses of the zoom drive motor 55 (step motor) driven from the reference position. Further, the reference position of the convencator 3 is the position of the convencator 3 when the zoom system is at the wide end and the focal length is at infinity, and in this reference position, the compensator 3 is at the corresponding position. is detected by the photointerrupters 66 and 67. The position of the compensator 3 is calculated based on the number of pulses of the encoder plate 68 fitted to the output shaft of the focus drive motor 65 (DC motor) driven from the reference position.

From the calculated position information XV of the variator 2, with reference to a distance table determined in advance, the infinite position X of the convencator 3 corresponding to the position of the variator 2 during the zoom drive is determined. Find 1. That is, with respect to the position of the variator 2 at the zoom position, the position of the convencator 3 when the focal length is at infinity is a predetermined position. Then, it is stored in the ROM of the microcomputer installed in the camera. Therefore, the amount of delivery of the convencator 3 from the Inf position is X.

L is calculated from FIG. 5 by: XCL = Xc Xc+ --- (1).

Next, the position correction ■ΔXCL of the compensator 3 is calculated from the following equation.

ΔXCL = XC2, XC2-1--(2) This (2
) In the formula, XC2-: convencator 3 at the zoom position
Design data for the amount of extension of the compensator 3 XC2mr: Actual data of the amount of extension of the compensator 3 at the relevant zoom position,
It is memorized. In addition, as mentioned above, X(2mr is the data of the amount of movement actually measured in the focused state, and the position of the convencator 3 is set in the E2PROM.
92 to memorize it.

Then, based on the values calculated from the above equations (1) and (2), the subject distance is calculated using the following equation.

In Equation (3), k is the ratio of the amount of defocus of the focal plane to the amount of extension of the compensator 3.f is the focal length Q, and the front principal point position data, which are stored in advance in the distance table of the ROM. There is. Therefore, the subject distance can be calculated from equation (3).

By the way, as shown in FIG. 5, the movement ranges of the variator 2 and the compensator 3 partially overlap. Therefore, collision between the variator 2 and the convencator 3 must be avoided. In order to avoid this collision, it is necessary to drive the drive motors 55 and 65 while constantly checking the distance between the variator 2 and the compensator 3. If, as in this embodiment, the amount of movement of the variator 2 and the convencator 3 per pulse of the zoom drive motor 55 and the focus drive motor 65 is made equal, the above-mentioned interval can be easily calculated. The procedure for avoiding this collision will be explained based on FIG. 6.

When zoom driving is started, the variator 2 and compensator 3 are driven (step 601).

For example, variator 2 and convencator 3 are 568
Assuming that they are separated by a distance corresponding to the pulse, in order to avoid collision between them, the difference between the number of pulses corresponding to the moving distance of variator 2 and the moving distance of convencator 3 must be 568
must be smaller than For this step 60
2, it is determined whether Xv-Xc≦568. If the determination is YES, there will be no collision, and the process returns to step 601 to continue driving the variator 2 and compensator 3. Step 602
If the determination in is NO, it means that there is a risk of collision, so by stopping the driving of the variator 2 and driving only the compensator 3,
-xc≦568 (step 603).

Therefore, even if the variator 2 and the compensator 3 are driven by separate motors, collision between them can be avoided.

〔Effect of the invention〕

As explained above, according to the zoom drive device for a camera according to the present invention, the respective drive motors for driving the variator and the compensator related to the zoom drive are controlled so that the rotation of these drive motors is Therefore, when driving the zoom, the zoom position can be easily detected by counting the number of pulses required for each movement of the variator and the funpensator from the reference position to the zoom position. Can drive zoom with high precision.

Moreover, since the ratio of the amount of movement per pulse of the variator and compensator is set to be an integral multiple, the position and positional relationship of the variator and compensator can be quickly and precisely determined using the CPU installed in the camera. It can be detected with precision. Therefore, it is possible to increase the accuracy of calculating the object distance obtained from these positional relationships.

Furthermore, since the compensation system and focus system compensators are driven by DC motors, focus drive can be carried out quickly, and even if the movement amount is different, it can be driven in synchronization with the variator.
It is possible to maintain a predetermined optical relationship between the variator and the compensator.

Since the processing, variator, and compensator are driven by pulses, the mechanism for driving the variator and the mechanism for driving the compensator can be constructed from common parts. The molding process and molded product management can be simplified, and manufacturing costs can be reduced.

[Brief explanation of drawings]

The drawings show a preferred embodiment of a zoom drive device for a camera according to the present invention. Figure 1 shows a camera equipped with a TTL autofocus system and an inner focus type zoom device that is suitable for mounting this object distance measuring device.The digital still electronic camera is cut along a vertical plane that includes the optical axis. FIG. FIG. 2 is a schematic exploded perspective view of the zoom lens barrel. FIG. 3 is an enlarged cross-sectional view of a part of the mechanism that drives the lens and converts the rotational motion of the motor into linear motion. FIG. 4 is a schematic diagram of a portion that drives the lens. FIG. 5 is a schematic configuration diagram of the photographing optical system. FIG. 6 is a flowchart illustrating a procedure for driving the variator and compensator without causing them to collide. 1... Front fixed lens 2... Variator 3...
- Compensator 4... Stop 5.7... Master lens 9... CCD unit 12... AE sensor 13... Light control sensor 14... AF device 14a... AF mirror 20...・Zoom movement frame 30...Focus movement frame 41...Press plate 15...Target body 25...Input pin 35...Input pin 42...Spring holder 43...Flat spring 44・・Guide bar 5
0...Zoom drive base frame 50c...Guide hole 51...Zoom feed screw 51c...Encoder ring 51d...Encoder plate 52...Connection frame 52a...Drive engagement portion 52c ... Collar holding part 52d ... Leaf spring 52e ... Light shielding plate 53 ... Screw collar 54 ... Driven gear 55 ... Zoom drive motor 55a ... Drive gears 56, 57 ... Photo interrupter 60...Focus drive base frame 60g...Guide hole 61...Focus feed screw 61c...Encoder ring 61d...Encoder plate 62...Connection frame 62a...Driving engagement Part 62b... Guide pin 62c... Collar holding part 62d... Leaf spring 62e...
Light shielding plate 63...Screw collar 64...Driven gear 65...Focus drive motor 67...Photo interrupter 68...Encoder plate Patent applicant Fuji Photo Kohki Co., Ltd. Patent applicant Fuji Photo Film Co., Ltd. Company agent Patent attorney Hideto Mochizuki

Claims (3)

[Claims] (1) A variator, which is a variable magnification lens, and a compensator, which is a correction and focusing lens, are combined, and while maintaining a predetermined optical relationship between the variator and the compensator, the variator is driven by a zoom drive motor. In a camera equipped with an autofocus device, which is equipped with an inner focus type zoom device that continuously changes the focal length by driving each motor with a focus drive motor, the rotation of the zoom drive motor and focus drive motor is pulsed. A zoom drive device for a camera, characterized in that the ratio of the amount of movement of a variator to the amount of movement of a compensator per pulse is an integral multiple. (2) Combining a variator, which is a variable magnification lens, and a compensator, which is a correction and focusing lens, and while maintaining a predetermined optical relationship between the variator and the compensator, the variator is driven by a zoom drive motor. In a camera equipped with an autofocus device, which is equipped with an inner focus type zoom device that continuously changes the focal length by driving each of the variators with a focus drive motor, the variator is driven by a zoom drive motor consisting of a step motor. The compensators are each driven by a focus drive motor consisting of a DC motor, the number of pulses when the zoom drive motor is driven is detected, and the rotation of the output shaft of the focus drive motor is converted into pulses to detect the rotation. A zoom drive device for a camera, characterized in that the ratio of the amount of movement of a variator to the amount of movement of a compensator per pulse is an integral multiple. (3) A variator, which is a variable magnification lens, and a compensator, which is a correction and focusing lens, are combined, and while maintaining a predetermined optical relationship between the variator and the compensator, the variator is driven by a zoom drive motor. In a camera equipped with an autofocus device, the rotation of the zoom drive motor is transmitted to the zoom feed screw. a zoom mechanism unit in which a connecting frame linked to the zoom feed screw is moved forward and backward along the zoom feed screw, and a zoom moving frame holding the variator is linked to the link frame; It consists of a focus mechanism section that transmits the rotation of the motor to a focus feed screw, moves a connecting frame linked to the focus feed screw to advance and retreat along the focus feed screw, and links the compensator to the link frame. . A zoom drive device for a camera, characterized in that parts constituting the zoom mechanism and parts constituting the focus mechanism are common.