JP2002258138A - Lens barrel and photographing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens barrel and a photographing device in which the detection of the position of a lens holding member by using an optical position detecting means or a magnetic position detecting means can be performed inside a lens barrel without occupying a large space and also the influence of fitting backlash between the sleeve part and the guide member of the lens holding member is reduced. SOLUTION: In the lens barrel having a lens holding member 3 which is provided with a sleeve part 6 fitted in a guide member 10 extending in the optical axis direction and which is guided by the guide member and is driven in an optical axis direction, reference position detecting means 7 and 9 to detect that the lens holding member is positioned at a reference position, and moving amount detecting means 4 and 2 to detect the moving amount of the lens holding member from the reference position, one constituting component 7 of the reference position detecting means and one constituting component 4 of the moving amount detecting means are provided at the sleeve part, and the other constituting component 9 of the reference position detecting means and the other constituting component 2 of the moving amount detecting means are packaged on the same base plate 21 attached to a lens barrel main body 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel for detecting the position of a lens holding member driven in an optical axis direction, and a photographing apparatus equipped with the same, such as a film camera, a digital still camera, or a video camera. It is.

[0002]

2. Description of the Related Art As a zoom lens for a video camera, for example, there is a zoom lens composed of four lens groups of a fixed convex, a movable concave, a fixed convex, and a movable convex in order from the subject side.

FIGS. 3A and 3B show a lens barrel structure of a general zoom lens having a four-group lens structure. (B) shows a cross section taken along line AA in (A).

The four lens groups 201a to 201d constituting the zoom lens are composed of a fixed front lens 201.
a, a variator lens group 201b that performs a zooming operation by moving along the optical axis, a fixed afocal lens 201c, and a focal plane maintenance and focusing during zooming by moving along the optical axis. And a focusing lens group 201d.

The guide bars 203, 204a, and 204b are arranged in parallel with the optical axis 205, and guide and stop the moving lens group. The DC motor 206 is a driving source for moving the variator lens group 201b.

The front lens 201a is held by the front lens barrel 202, and the variator lens group 201b is
It is held at 1. Also, the afocal lens 201
c denotes an intermediate frame 215 and a focusing lens group 201d.
Are held by the RR moving ring 214.

The front lens barrel 202 is positioned and fixed to a rear lens barrel 216. A guide bar 203 is positioned and supported by the two lens barrels 202 and 216, and a guide screw shaft 208 is rotatably supported. I have.
The guide screw shaft 208 is driven to rotate by the rotation of the output shaft 206 a of the DC motor 206 being transmitted through a gear train 207.

A V-moving ring 211 for holding the variator lens group 201b includes a pressing spring 209 and the pressing spring 20.
And a ball 210 which engages with a screw groove 208a formed in the guide screw shaft 208 by a force of 9 by the DC motor 206.
By being driven to rotate, 8 moves forward and backward in the optical axis direction while being guided and regulated by the guide bar 203.

Guide bars 204a, 204 are provided on the rear barrel 216 and the intermediate frame 215 positioned in the rear barrel 216.
04b is fitted and supported. The RR moving ring 214 can advance and retreat in the optical axis direction while being guided and rotated by the guide bars 204a and 204b.

Guide bars 204a and 204 are provided on an RR moving ring 214 for holding the focusing lens group 201d.
b is formed with a sleeve portion that is slidably fitted to the RR moving ring 2 in the optical axis direction.
14 and are integrated with each other.

The stepping motor 212 rotationally drives a lead screw 212a formed integrally with its output shaft. The RR moving ring 21 is attached to the lead screw 212a.
The RR moving ring 214 moves in the optical axis direction while being guided by the guide bars 204a and 204b by the rotation of the lead screw 212a with the engagement of the rack 213 assembled to the rack 4.

As a drive source for the variator lens group, a stepping motor may be used in the same manner as the drive source for the focusing lens group.

The front lens barrel 202, the intermediate frame 215, and the rear lens barrel 216 form a lens barrel body that substantially accommodates a lens or the like.

When the lens group holding frame is moved by using such a stepping motor, after detecting that the holding frame is located at one reference position in the optical axis direction using a photo interrupter or the like, The absolute position of the holding frame is detected by continuously counting the number of drive pulses applied to the stepping motor.

FIG. 4 shows an electrical configuration of a camera body in a conventional imaging apparatus. In this figure, FIG.
The components of the lens barrel described in (1) are given the same reference numerals as in FIG.

Reference numeral 221 denotes a solid-state imaging device such as a CCD;
Is a drive source of the variator lens group 201b, and includes a motor 206 (or a stepping motor), a gear train 207, a guide screw shaft 208, and the like.

Reference numeral 223 denotes a focusing lens group 201d.
And includes a stepping motor 212, a lead screw shaft 212a, a rack 213, and the like.

Reference numeral 224 denotes a drive source of the diaphragm device 235 disposed between the variator lens group 201b and the afocal lens 201c.

Reference numeral 225 denotes a zoom encoder, and 227 denotes a focus encoder. Each of these encoders detects the absolute position of the variator lens group 201b and the focusing lens group 201d in the optical axis direction. When a DC motor is used as the variator driving source as shown in FIG. 11, an absolute position encoder such as a volume is used, or a magnetic type is used.

When a stepping motor is used as a drive source, a method of continuously counting the number of operation pulses input to the stepping motor after arranging the holding frame at the reference position as described above is used. General.

Reference numeral 226 denotes an aperture encoder, which employs a system in which a Hall element is disposed inside an aperture drive source 224 such as a motor and detects the rotational positional relationship between a rotor and a stator.

A CPU 232 controls the camera. A camera signal processing circuit 228 performs predetermined amplification, gamma correction, and the like on the output of the solid-state imaging device 221. The contrast signal of the video signal that has undergone these predetermined processes passes through the AE gate 229 and the AF gate 230. That is, the optimum signal extraction range for exposure determination and focusing is set by this gate in the entire screen. The size of this gate is variable,
There may be a case where a plurality is provided.

Reference numeral 231 denotes an AF signal processing circuit which processes an AF signal for AF (auto focus), and generates one or a plurality of outputs related to a high frequency component of a video signal. 233 is a zoom switch, and 234 is a zoom tracking memory. Zoom tracking memory 234
Stores information on the focusing lens position to be set in accordance with the subject distance and the variator lens position during zooming. Note that C is used as the zoom tracking memory.
The memory in the PU 232 may be used.

For example, the photographer sets the zoom switch 23
3 is operated, the CPU 232 determines the current variator as a detection result of the zoom encoder 225 so that the predetermined positional relationship between the variator lens and the focusing lens calculated based on the information of the zoom tracking memory 234 is maintained. The absolute position in the optical axis direction of the lens and the calculated position of the variator lens to be set, and the current absolute position of the focus lens in the optical axis direction as a detection result of the focus encoder 227 and the calculated focus lens should be set. The drive control of the zoom drive source 222 and the focussing drive source 223 is performed so that the positions match each other.

In the auto focus operation, the CPU 2 sets the output of the AF signal processing circuit 231 to a peak so that
Reference numeral 32 controls the driving of the focusing drive source 223.

Further, in order to obtain an appropriate exposure, the CPU 2
Reference numeral 32 designates the average value of the output of the Y signal passing through the AE gate 229 as a predetermined value, and controls the driving of the aperture driving source 224 so that the output of the aperture encoder 226 becomes the predetermined value, thereby controlling the aperture diameter.

FIG. 5 shows a conventional driving method of a lens holding frame driven in the optical axis direction, such as the V moving ring 211 and the RR moving ring 225 described above. The lens holding frame 303 as a V moving ring or an RR moving ring is
01 is received via the lead screw 312 and the rack 308 meshing with the lead screw 312, and is driven in the optical axis direction.

At this time, the drive control of the lens holding frame 303 is performed using the photo interrupter 309.
After detecting that 03 is at the reference position, the absolute position of the lens holding frame 303 is detected by continuously counting the number of drive pulses applied to the stepping motor 1.

In some cases, the reference position detection using the photo interrupter 309 is not performed, and the lens holding frame 303 is set as the reference position by abutting the end of the movable range.

Recently, CCD sensors and CMOS
With an increase in the number of pixels of an optical imaging element such as a sensor, improvement in optical performance of a lens is required. For this reason, if the amount of movement of the lens holding frame 303 is detected by counting the number of driving pulses of the stepping motor, the resolution becomes insufficient.

Therefore, there is a method of covering the lack of resolution by feeding back the measured movement amount information to the stepping motor using a movement amount detection sensor having a higher resolution than the pulse resolution of the stepping motor such as the MR sensor 302. Has been adopted.

[0032]

However, with the recent miniaturization of optical devices, the effective use of space inside the device has become necessary. On the other hand, detection means such as photo interrupters and MR sensors are limited. In order to place it efficiently in the space that was set up, interference with other parts as well as
It is necessary to design in consideration of a space such as a wiring route to each of the photo interrupter and the MR sensor.

For example, as shown in FIG. 5, the photo interrupter light shielding plate 307 is connected to the sleeve portion 30 of the lens holding frame 303.
6 and the MR sensor magnet 304 is disposed in a portion other than the sleeve portion 306 of the lens holding frame 303, it is necessary to consider two systems of wiring and their fixed positions.

The MR sensor 302 is mounted on the lens holding frame 3.
Since it is installed at a position away from the sleeve portion 306 in 03, it is easily affected by rattling that occurs in the fitting portion between the guide bar 310 and the sleeve portion 306, and a detection error is likely to occur.

Therefore, according to the present invention, the position detection of the lens holding member using the optical position detection means such as a photo interrupter or the magnetic position detection means such as an MR sensor is performed in a large space in the lens barrel. It is another object of the present invention to provide a lens barrel and a photographing apparatus which can be performed without occupying the lens barrel, and in which the influence of rattling of the fitting between the sleeve portion of the lens holding member and the guide member is reduced.

[0036]

In order to solve the above-mentioned problems, the present invention has a sleeve portion which is fitted to a guide member extending in the optical axis direction, and is guided by this guide member in the optical axis direction. Driven lens holding member, reference position detecting means for detecting that the lens holding member is located at the reference position, and movement amount detecting means for detecting the movement amount of the lens holding member from the reference position And the reference position detecting means and the movement amount detecting means are each composed of a pair of components, and one of the reference position detecting means and one of the movement amount detecting means are connected to a sleeve portion. And the other component of the reference position detecting means and the other component of the moving amount detecting means are mounted on the same substrate attached to the lens barrel main body or the fixed part.

That is, one of the components of the reference position detecting means (a light shielding member used for optical detection) and the other of the moving amount detecting means (for example, a magnet used for magnetic detection) are both attached to the sleeve portion. By providing such a component, it is possible to mount the other component of the detection means (for example, an optical sensor unit used for optical detection or a magnetic sensor unit used for magnetic detection) on the same substrate, and extra wiring is required. This makes it possible to effectively use the space inside the lens barrel without having to do so.

Further, even when a flexible substrate is used as the wiring, it is not necessary to divide the flexible substrate into two parts or extend one of the flexible substrates, and the wiring can be simplified.

Further, by arranging both detecting means around the sleeve portion of the lens holding member, it is possible to reduce the influence of the looseness between the sleeve portion and the guide member on the detection accuracy.

One component of the reference position detecting means and one component of the moving amount detecting means are provided close to each other on the sleeve portion, and the other component of the reference position detecting means and the moving amount detecting means are provided. By providing the other component on the same substrate in close proximity to each other, the substrate area can be minimized.

[0041]

1 and 2 show a lens holding frame driven in an optical axis direction in a lens barrel (refer to FIG. 3 for an overall configuration) according to an embodiment of the present invention, and a drive unit and a lens holding frame. The main parts related to the position detection unit are shown.

The lens holding frame (lens holding member) 3 includes
A sleeve 6 fitted to a guide bar (guide member) 10 extending in the optical axis direction fixed to the lens barrel main body 20 is integrally attached, and a sleeve extending in the optical axis direction fixed to the lens barrel main body 20 is provided. U-groove 3 engaging with stop bar 11
a.

A rack 8 is attached to the sleeve portion 6, and the rack 8 is engaged with a lead screw 12 which is an output shaft of the stepping motor 1 and extends in the optical axis direction.

For this reason, when the lead screw 12 rotates together with the stepping motor 1, the lens holding frame 3 is driven in the optical axis direction while being guided by the guide bar 10 by the meshing action of the lead screw 12 and the rack 8.

At this time, since the sleeve 6 is fitted to the guide bar 10 with a certain length, the lens holding frame 3 is driven while maintaining a surface substantially perpendicular to the optical axis.

Further, since the U groove 3a is engaged with the rotation preventing bar 11, the rotation of the lens holding frame 3 around the guide bar is prevented.

The drive of the lens holding frame 3 is controlled by the sleeve 6
An output signal from a reference position detector including a photointerrupter light-shielding plate (light-shielding member) 7 mounted on the substrate and a photointerrupter 9 mounted on a substrate 21 fixed to a lens barrel main body 20, and mounted on a sleeve 6. This is performed using an output signal from a movement amount detector including the sensor magnet 4 and the MR sensor 2.

More specifically, after the lens holding frame 3 is initially driven to a reference position where the photo interrupter light shielding plate 7 blocks light between the light projecting portion and the light receiving portion of the photo interrupter 9, the lens holding frame 3 is moved to the target position. And the sensor magnet 4 moves with respect to the MR sensor 2 so that the MR
When the pulse signal output from the sensor 2 is counted and reaches a count value corresponding to the movement amount (relative position) to the target position, the stepping motor 1 is stopped, and the lens holding frame 3 is stopped at the target position.

Normally, the absolute position control of the lens holding frame 3 can be performed only by the photointerrupter 9 and the drive pulse count of the stepping motor 1, but the MR sensor 2 having a higher resolution than the drive pulse of the stepping motor 1 can be controlled.
By feeding back the pulse signal (position information) from the stepping motor 1 to the stepping motor 1 using a control circuit (not shown), more accurate absolute position control can be performed.

Although the reference position can be set by using the end of the movable range of the lens holding frame 3 and the relative position can be detected by the MR sensor 2 without using the photointerrupter 9, the present embodiment is applicable. Is designed using a photo interrupter that can set the reference position to an arbitrary position in terms of the mechanical configuration.

Here, the photo interrupter light shielding plate 5 and the sensor magnet 4 are arranged on the sleeve 6 at positions close to each other, and extend in the moving direction (optical axis direction) of the lens holding frame 3 respectively.

With this arrangement, the photo interrupter 9 and the MR sensor 2 are also arranged close to each other, and can be mounted on the same very small substrate 21 as shown in FIG. In particular, it is convenient when a flat portion is formed on the lens barrel main body 20 having a curved surface and the substrate 21 is attached as in the present embodiment.

Further, by mounting the photointerrupter 9 and the MR sensor 2 on the same substrate 21 as described above,
A flexible printed circuit board (not shown) for wiring between a control circuit (not shown) and the photo interrupter 9 and the MR sensor 2 is sufficient if the circuit board 21 and the control circuit are connected. There is no need to connect to both sensors or to extend and connect to one of the sensors, and the wiring can be simplified and the space in the lens barrel body 20 can be used effectively.

Further, since the two detectors are arranged around the sleeve 6, the influence of the looseness of the fit between the sleeve 6 and the guide bar 10 on the detection accuracy can be reduced, and the high precision lens position can be obtained. Control can be performed.

In this embodiment, the case where the stepping motor 1 having the lead screw 12 as the output shaft is used as the drive source of the lens holding frame 3 has been described. However, the lead screw may be driven by a DC motor. Alternatively, instead of using a lead screw, another drive source such as a so-called linear actuator may be used.

In this embodiment, the case where the lens holding frame 3 is guided by the guide bar fixed to the lens barrel main body 20 has been described. However, any member having a function of guiding the lens holding frame in the optical axis direction may be used. Others may be used.

In this embodiment, the case where the substrate 21 is fixed to the lens barrel main body 20 has been described. However, the substrate 21 may be fixed to a fixed portion (a portion other than the movable portion) of the lens barrel other than the lens barrel main body. .

Further, in this embodiment, the case where the MR sensor is used for detecting the amount of movement (relative position) of the lens has been described, but other detection means such as an optical detection means using a light source and a plurality of slits are used. You may. In this case, a DC motor or a linear actuator may be used without using a stepping motor as a drive source.

[0059]

As described above, according to the present invention,
Both the one component of the reference position detecting means and the one component of the moving amount detecting means are provided on the sleeve portion, and the other component of these detecting means is mounted on the same substrate, so that extra wiring is required. The space in the lens barrel can be used effectively without the need for wiring.

Furthermore, even when a flexible substrate is used as the wiring, it is not necessary to divide the flexible substrate into two parts or extend one of the flexible substrates, and the wiring can be simplified.

Further, by arranging the two detecting means around the sleeve portion of the lens holding member, it is possible to reduce the influence of the looseness of the fitting between the sleeve portion and the guide member on the detection accuracy, and to achieve a high accuracy. Lens position control can be performed.

One component of the reference position detecting means and one component of the moving amount detecting means are provided close to each other in the sleeve portion, and the other component of the reference position detecting means and the moving amount detecting means are provided. When the other component is provided close to the same substrate on the same substrate, the substrate area can be minimized.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a configuration of a lens holding frame and a driving unit and a position detecting unit thereof according to an embodiment of the present invention.

FIG. 2 is a layout view of a substrate on which an MR sensor for performing the position detection and a photo interrupter are mounted.

FIG. 3 is a configuration diagram of a conventional video camera lens.

FIG. 4 is a block diagram showing an electric circuit of a conventional video camera.

FIG. 5 is a perspective view showing a configuration of a conventional lens holding frame and its driving unit and position detecting unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Stepping motor 2 ... MR sensor 3 ... Lens holding frame 4 ... Sensor magnet 6 ... Sleeve 7 ... Photo interrupter light shielding plate 8 ... Rack 9 ... Photo interrupter 10 ... Guide bar 11 ... Detent bar 12 ... Lead screw 20 ... Barrel Main body 21 Substrate 201a Front lens 201b Variator lens group 201c Afocal lens group 201d Focusing lens group 202 Front lens barrel 203 Guide bar 204a Guide bar 204b Guide bar 206 DC motor 207 Gear Row 211 ... V moving ring 212 ... Stepping motor 213 ... Rack 214 ... RR moving ring 215 ... Intermediate frame 216 ... Rear lens barrel 221 ... Solid imaging device 222 ... Variator lens driving mechanism 223 ... Focusing lens driving mechanism 224 ... Aperture Dogen 225 ... the zoom encoder 226 ... aperture encoder 227 ... focus encoder 228 ... camera signal processing circuit 229 ... AE gate 230 ... AF gate 231 ... AF signal processing circuit 232 ... CPU 233 ... zoom switch 234 ... zoom tracking memory

Claims (5)

[The claims] A lens holding member which is fitted in a guide member extending in the optical axis direction and is driven in the optical axis direction by being guided by the guide member; and wherein the lens holding member is located at a reference position. A reference position detecting means for detecting that the movement has been performed, and a movement amount detecting means for detecting a movement amount of the lens holding member from the reference position, wherein the reference position detecting means and the movement Each of the amount detecting means includes a pair of components, one of the reference position detecting means and one of the moving amount detecting means are provided on the sleeve portion, and the other of the reference position detecting means is provided. A lens barrel, wherein the component and the other component of the movement amount detecting means are mounted on the same substrate attached to the lens barrel main body or a fixed portion. 2. One of the components of the reference position detecting means and one of the components of the moving amount detecting means are provided close to each other to the sleeve portion, and the other component of the reference position detecting means and The lens barrel according to claim 1, wherein the other component of the movement amount detection means is provided on the same substrate so as to be close to each other. 3. The reference position detecting means according to claim 1, wherein the reference position detecting means comprises an optical sensor and a light blocking member for blocking light from entering the light receiving portion from the light projecting portion of the optical sensor. The lens barrel according to item 1. 4. The apparatus according to claim 1, wherein said moving amount detecting means includes a magnet and a magnetic sensor for detecting a magnetic change due to a relative movement between said magnet and said magnet. Lens barrel. 5. An imaging apparatus comprising the lens barrel according to claim 1.