JP3288960B2 - Brush mounting structure for zoom lens barrel encoder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a brush mounting structure for an encoder of a zoom lens barrel.

[0002]

2. Description of the Related Art In a zoom lens camera,
The focal length information is detected by the relative sliding between the brush and the code plate having a predetermined pattern provided in the lens barrel. Since the code plate is flat, it hardly protrudes even when attached to the cylindrical surface of the lens barrel member, and can be embedded only by slightly shaving the peripheral surface of the lens barrel, so that it can be provided on a thin member. On the other hand, the brush is formed so as to protrude from the peripheral surface of the lens barrel member because it needs to come into contact with the code plate, and since screws are mainly used as fixing means, there are many restrictions on the installation position. For example, a thin lens barrel member does not have enough thickness to embed or screw a brush. Also, it is not desirable to cut a thin lens barrel member in the radial direction or to provide a screw hole from the viewpoint of light shielding properties and strength. On the other hand, if a special brush installation space or a brush mounting portion is provided in the lens barrel, the lens barrel is undesirably increased in size. That is, it has been difficult to arrange the brush in the lens barrel with good space efficiency and without reducing the strength and light-shielding properties of the lens barrel.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and relates to a zoom lens barrel which is excellent in space efficiency, does not involve an increase in the size of the lens barrel, and has strength and light shielding of the lens barrel. It is an object of the present invention to obtain an encoder brush mounting structure that does not impair the performance with a simple configuration.

[0004]

Brush attachment structure of an encoder of the present invention SUMMARY OF THE INVENTION is arranged in the zoom lens barrel, the code plate and a brush for detecting the focal length relative sliding by feeding and retracting operation of the lens barrel, and f Rikoido In a zoom lens barrel having a helicoid lens barrel member having a focal length, a brush for detecting a focal length is attached to a helicoid peak of the helicoid lens barrel member.
It is characterized in that it is embedded in a recess formed by cutting off the part .

[0005] The mountain section of the helicoid brush is buried,
The other helicoid lens barrel member formed wider than the other helicoid peaks on the same peripheral surface and screwed with the helicoid lens barrel member in which the brush is embedded is screwed into the wide helicoid peak. It is desirable to have a wide helicoid valley that fits.

The helicoid peak in which the brush is buried has a communication hole inside which connects the outer peripheral surface and the inner peripheral surface of the helicoid lens barrel member in the radial direction, and the brush passes through the communication hole. It is preferable that a contact terminal with the code plate protrudes from the peripheral surface opposite to the helicoid.

The brush is preferably screwed to the helicoid lens barrel. Even if the screw has a certain length, it can be fixed securely because of the thickness of the helicoid.

[0008] The helicoid lens barrel member provided with the brush is advanced and retracted in a direction parallel to the optical axis when rotating in the forward and reverse directions with respect to the camera body. The zoom lens barrel further includes the brush. Helicoid lens barrel member can be rotated relatively without changing its relative position in the direction parallel to the optical axis,
The camera body includes a rectilinear reciprocating cylinder guided straight in a direction parallel to the optical axis, and the code plate is provided on the peripheral surface of the rectilinear reciprocating cylinder, with the longitudinal direction facing in the circumferential direction. It is preferable that the brush and the code plate slide relative to each other in the circumferential direction by the relative rotation of the helicoid lens barrel member and the rectilinear moving cylinder.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A zoom lens barrel 10 is attached to a camera body of a compact camera (not shown), and includes a first lens unit L1, a second lens unit L2, and a third lens unit L2.
Zooming is performed by changing the relative distance between the lens units L3 and the distance of each lens unit from the film surface, and focusing is performed by moving the second lens unit L2 in a direction parallel to the optical axis O. Before describing the brush mounting structure of the encoder according to the present invention, the overall configuration and operation of the zoom lens barrel 10 will be described with reference to FIGS.

An aperture plate 11 having an opening 11a for determining an exposure area for a film is fixed inside the camera body, and a fixed lens barrel 13 is fixed to a front portion of the aperture plate 11. A female helicoid 14 is formed on the inner peripheral surface of the fixed lens barrel 13, and three rectilinear guide grooves 15 parallel to the optical axis O are formed on the inner peripheral surface of the fixed lens barrel 13.

A notch 13a (FIG. 4) is formed in the fixed lens barrel 13 in a direction parallel to the optical axis O.
The zoom gear 16 is attached to a. Zoom gear 16
Is supported so as to be rotatable about an axis substantially parallel to the optical axis O, and the tooth surface of the pinion portion protrudes from the cutout portion 13a to the inside of the fixed lens barrel 13. A zoom motor M is provided in the camera body, and rotation of a drive shaft of the zoom motor M is transmitted to the zoom gear 16 via a reduction gear train (not shown).

A male helicoid 18 formed near the rear end of the outer peripheral surface of the first outer cylinder 17 is screwed into the female helicoid 14 of the fixed lens barrel 13. The width of the male helicoid 18 in a direction parallel to the optical axis O is formed so as not to be exposed to the external appearance when the first outer cylinder 17 extends at the maximum. This first outer cylinder 17
Further, a plurality of outer peripheral gear portions 19 parallel to the male helicoid 18 are provided on the same peripheral surface on which the male helicoid 18 is formed. The teeth of each of the outer peripheral gear portions 19 are formed in a direction parallel to the optical axis O, and the zoom gear 16 meshes with the teeth. Further, on the inner peripheral surface of the first outer cylinder 17, three rotation transmission grooves 17a are formed in a direction parallel to the optical axis O.

Further, the male helicoid 18 of the first outer cylinder 17 is provided.
A brush 70 for detecting the focal length is provided in the portion. The brush 70 will be described later.

A first linear guide ring 20 is disposed inside the first outer cylinder 17. The first straight guide ring 20 and the first
The rear ends of the outer cylinders 17 are connected to each other so as to be relatively rotatable, and are not relatively moved in a direction parallel to the optical axis O. On the outer peripheral surface near the rear end of the first rectilinear guide ring 20, three (only two are shown in FIG. 4) rectilinear guide projections 24 are arranged radially outward at predetermined intervals in the circumferential direction. It is protruding. Each of the rectilinear guide projections 24 is slidably engaged with three rectilinear guide grooves 15 formed on the inner peripheral surface of the fixed lens barrel 13 and parallel to the optical axis O.
Are guided straight to the fixed lens barrel 13.

The first outer cylinder 17 and the first straight guide ring 20 described above.
Constitute the first extension step portion of the zoom lens barrel 10. When the zoom gear 16 is rotated in a predetermined lens feeding direction by the zoom motor M, the first feeding step portion rotates the first outer cylinder 17 via the outer peripheral gear portion 19, and the female helicoid 14 and the male helicoid 18 Depending on the relationship, the first outer cylinder 17 is extended from the fixed lens barrel 13 while rotating. at the same time,
The first outer cylinder 17 is rotatably supported in the circumferential direction with respect to the first outer cylinder 17.
The rectilinear guide ring 20 moves in a direction parallel to the optical axis O together with the first outer cylinder 17 while being guided rectilinearly with respect to the fixed lens barrel 13.

On the outer peripheral surface of the first rectilinear guide ring 20, a code plate 8 constituting a focal length detecting mechanism together with the brush 70 is provided.
0 is affixed. This code plate 80 will be described later.

A female helicoid 27 in the same direction as the female helicoid 14 is formed on the inner peripheral surface of the first rectilinear guide ring 20. On the inner peripheral surface of the first rectilinear guide ring 20, three rectilinear guide grooves 28 are further formed at predetermined intervals in the circumferential direction in parallel with the optical axis O.

Inside the first rectilinear guide ring 20, a drive cam ring 30 having a male helicoid 29 screwed to the female helicoid 27 on its outer peripheral surface is provided. The male helicoid 29 is formed on the entire outer peripheral surface of the drive cam ring 30. A male helicoid 2 is provided on the entire inner peripheral surface of the drive cam ring 30.
A female helicoid 31 is formed in a direction opposite to that of the female helicoid 9.

Inside the drive cam ring 30, a second rectilinear guide ring 33 is provided. The second rectilinear guide ring 33 and the drive cam ring 30 are coupled to each other at their rear ends so as to be relatively rotatable, and are not relatively moved in a direction parallel to the optical axis O.

On the outer peripheral surface near the rear end of the second rectilinear guide ring 33, three rectilinear guide protrusions 36 (only two are shown in FIG. 4) are arranged at predetermined intervals in the circumferential direction. It protrudes outward in the direction. Each of the rectilinear guide projections 36 is formed on the inner peripheral surface of the first rectilinear guide ring 20 by the three rectilinear guide grooves 28.
Are slidably engaged with each other. Thus, the second straight guide ring 33 is guided straight to the fixed lens barrel 13 via the first straight guide ring 20.

The second outer cylinder 40 is located between the first outer cylinder 17 and the first rectilinear guide ring 20, and is provided near the rear end of the outer peripheral surface (only one is shown in FIG. 4). Shown) rotation transmission protrusion 4
1 is slidably engaged with three rotation transmission grooves 17 a formed in the inner peripheral surface of the first outer cylinder 17 in parallel with the optical axis O. Therefore, the second outer cylinder 40 is guided relative to the first outer cylinder 17 so as not to rotate relative to the first outer cylinder 17 and to be relatively movable in a direction parallel to the optical axis O.

On the front end surface of the driving cam ring 30, a rib 37 having a constant thickness in the radial direction of the driving cam ring 30 is provided. The rib 37 has three notches 38 formed therein. The second outer cylinder 40 is located on the front end side of the inner peripheral surface,
Three engagement projections 39 that can be fitted into the cutouts 38 are provided to protrude radially inward. By engaging the notch 38 with the engagement projection 39 and further fitting the decorative ring 42 to prevent the two from coming off, the drive cam ring 30
And the second outer cylinder 40 are integrated such that neither relative rotation about the optical axis O nor relative movement in a direction parallel to the optical axis O is performed.

That is, when the second outer cylinder 40 is rotated along with the first outer cylinder 17 being extended, the drive cam ring 30 is also integrally rotated. In response to this rotation, the drive cam ring 30 integrated with the second outer cylinder 40 is extended from the first rectilinear guide ring 20 forming the first step portion due to the relationship between the female helicoid 27 and the male helicoid 29.

The drive cam ring 30 and the second straight guide ring 3 described above.
The third and second outer cylinders 40 constitute a second extension step portion of the zoom lens barrel 10. First outer cylinder 1 that constitutes the first feeding step portion
When the 7 rotates and is extended from the fixed lens barrel 13, the second outer cylinder 40 is rotated in conjunction with the first outer cylinder 17 due to the relationship between the rotation transmission groove 17 a and the rotation transmission protrusion 41. The drive cam ring 30 that receives the rotation of the second outer cylinder 40 is a female helicoid 2
Due to the relationship between 7 and the male helicoid 29, the fixed barrel 13 is fed out from the first straight guide ring 20 together with the second outer cylinder 40 while rotating in the same direction as the rotation direction of the first outer cylinder 17. At the same time, the second straight guide ring 33 is
0 and the first linear guide ring 2 due to the relationship between the linear guide protrusion 36 and the linear guide groove 28.
While being guided straight to 0, it moves in a direction parallel to the optical axis O together with the drive cam ring 30.

Inside the driving cam ring 30, a third outer cylinder 45 is provided.
Are arranged. The above-mentioned second straight guide ring 33 is located inside the third outer cylinder 45. Second straight guide ring 33
A plurality of guide rails 33 are provided in parallel with the optical axis
a is formed. On the other hand, on the inner peripheral surface of the third outer cylinder 45, a plurality of guide rails 45a (only one is shown in FIG. 4) that is engaged with the guide rail 33a are formed. The guide rails 45a provided on the third outer cylinder 45 are the guide rails 33a provided on the second linear guide ring 33, respectively.
The third outer cylinder 45 is linearly guided relative to the second linear guide ring 33 so as to be relatively movable in a direction parallel to the optical axis O.

A female helicoid 31 provided on the inner peripheral surface of the drive cam ring 30 is screwed to the rear outer peripheral surface of the third outer cylinder 45.
A male helicoid 46 is formed. When the drive cam ring 30 performs the feeding rotation, a rotational force is applied to the third outer cylinder 45, and the third outer cylinder 45 is guided straight by the second straight guide ring 33. Therefore, the third outer cylinder 45 is
During the rotation of the lens barrel 0, the fixed barrel 1 does not rotate integrally with the fixed lens barrel 1 due to the relationship between the male helicoid 46 and the female helicoid 31.
3 is extended from the drive cam ring 30 while traveling straight in a direction parallel to the optical axis O. That is, the third outer cylinder 45 constitutes the third extension step of the lens barrel, and the third helicoid 4
The width of 6 in the direction parallel to the optical axis O is set so as not to be exposed to the exterior when the third outer cylinder 45 is extended at the maximum.

Inside the third outer cylinder 45, a first lens group frame 47 is provided.
Are fixed, and the first lens group L1 is held by the first lens group frame 47.

On the peripheral surface of the second rectilinear guide ring 33, three second group guide slits 50a for guiding the second lens unit L2 and the third lens unit L3 are guided in parallel with the optical axis O. Three group guide slits 50b are alternately formed in the circumferential direction.

The second lens unit L2 is held by a second unit lens frame 48a constituting the second unit unit 48, and the third lens unit L3 is held by a third unit lens frame 49a supported in a third unit support ring 49. Have been. The second group unit 48 has three slide plates 51 on the outer peripheral surface, and the three slide plates 51 are slidably guided by three second group guide slits 50a in a direction parallel to the optical axis O. Similarly, the third group support ring 49 has three slide plates 52 on the outer peripheral surface, and the slide plates 52 are slidably guided by three third group guide slits 50b in a direction parallel to the optical axis O. I have. Therefore, the second group unit 48 (the second group lens frame 48)
a) and the third group support ring 49 (third group lens frame 49a)
It is possible to independently slide in the second straight guide ring 33 in parallel with the optical axis. The second group unit 4
A compression spring 56 for removing backlash is disposed between the eighth and third group support rings 49, and the second group unit 48 is urged forward and the third group support ring 49 is moved rearward.

The second group unit 48 and the third group support ring 49
Is the optical axis O with the extension operation of the zoom lens barrel 10.
A predetermined operation is performed in a direction parallel to. Specifically, the slide plate 51 of the second group unit 48 and the slide plate 52 of the third group support ring 49 are respectively provided with guide pins 5 in the radial direction.
8, 59 are protrudingly provided. A cam groove (not shown) having a predetermined shape corresponding to the guide pins 58 and 59 is formed on the inner peripheral surface of the drive cam ring 30.
8, 59 are slidably fitted. The cam groove for guiding the guide pin 58 and the cam groove for guiding the guide pin 59 have mutually non-linear skewed shapes. Therefore, when the drive cam ring 30 and the second rectilinear guide ring 33 rotate relatively,
The second lens unit L2 and the third lens unit L3 make a predetermined relative movement in a direction parallel to the optical axis O via the guide pins 58 and 59.

The second group unit 48 has a shutter block 53. The shutter block 53 has a female screw 53a on a shaft portion thereof, and a male screw 48b of the second lens frame 48a is screwed to the female screw 53a.
The shutter block 53 includes a focusing motor, and rotates the second lens unit 48 according to the female screw 53a and the male screw 48b to light the second lens group L2 based on the subject distance signal from the distance measuring device and the focal length signal by zooming. Focusing is performed by moving in the direction parallel to the axis O. The shutter block 53 includes a shutter blade 5 that also opens and closes according to a subject luminance signal.
Five. The shutter block 53 includes an FP
Drive signals for a focusing operation and a shutter opening / closing operation are sent via a C substrate (flexible printed circuit board) 60.

The FPC board 60 includes a shutter board 60a connected to the shutter block 53 and a code board board 60b connected to the code board 80 attached to the outer peripheral surface of the first straight guide ring 20. Each of the substrates has a certain length that can cope with the expansion and contraction of the zoom lens barrel 10. The other end of the FPC board 60 is connected to a CPU (not shown) in the camera body.

The above-described zoom lens barrel 10 operates as follows. When the zoom motor M is driven in the extension direction from the retracted state of FIG. 1 or the wide end of FIG. 2, the first outer cylinder 17 is rotated and extended from the fixed lens barrel 13, and the first rectilinear guide ring 20 is fixed. The first while being guided straight by the lens barrel 13
It moves forward with the outer cylinder 17. Then, the second outer cylinder 40
At the same time, the drive cam ring 30 is extended from the first straight guide ring 20 while rotating in the same direction as the rotation direction of the first outer cylinder 17. At the same time, the second straight guide ring 33 is
With 0, it moves straight in a direction parallel to the optical axis O. When the driving cam ring 30 is rotated and fed, the cam groove and the guide pin 58,
Due to the relationship 59, the second lens unit L2 and the third lens unit L3 are moved as a whole forward of the optical axis while relatively moving within the second feeding stage. Further, the third outer cylinder 45 guided straight by the second straight guide ring 33 is moved forward of the optical axis by the rotation of the drive cam ring 30, and the first lens unit L1 is moved to the second lens group.
The lens unit L2 and the third lens unit L3 are relatively moved forward. When the zoom motor M is driven in the storage direction from the telephoto end in FIG. 3, the zoom lens barrel 10 performs the reverse operation. As described above, the zoom lens barrel 10 including the three-stage extending portion includes the first lens unit L1 and the second lens unit L
Zooming is performed by a combined operation of a change in the distance of the second and third lens units L3 from the film surface and the relative movement of each lens unit, and further displaces the second lens unit L2 in a direction parallel to the optical axis O. Focusing by doing.

Next, the focal length detecting mechanism of the zoom lens barrel 10 will be described in detail with reference to FIGS. The FPC board 60 composed of the shutter board 60a and the code board board 60b is guided from outside the fixed lens barrel 13 to the inner peripheral surface on the rear end side of the first rectilinear guide ring 20. The first rectilinear guide ring 20 is formed with an FPC board guide hole 64 that communicates the inner peripheral surface and the outer peripheral surface. The FPC board 60 passes through the FPC board guide hole 64 to form the first rectilinear guide ring 20. It is guided to the outer peripheral surface side. The shutter substrate 60a extends forward of the optical axis, and is supported by the folding plate 65 and folded back from the front end side of the first rectilinear guide ring 20 to the inner peripheral surface side. On the other hand, as shown in FIG.
From the position exposed to the outer peripheral surface side of the first straight guide ring 20 through the substrate guide hole 64, the first straight guide ring 20 is bent in the circumferential direction and follows the outer circumferential surface. In FIG. 5, the shutter substrate 60a is omitted.

On the outer peripheral surface of the first linear guide ring 20, an FPC
A bottomed code plate housing groove (concave groove) 66 is formed in a circumferential direction from a position adjacent to the substrate guide hole 64. The radial depth of the code plate storage groove 66 corresponds to the thickness of the code plate 80, and the bottom surface thereof is
(See FIG. 4). The code plate storage groove 66 is slightly wider than the width (transverse direction) of the code plate 80 in a direction parallel to the optical axis O,
The length in the circumferential direction is slightly longer than the length (longitudinal direction) of the code plate 80. An elongated rectangular code plate 80 is attached along the bottom surface of the code plate storage groove 66 with the longitudinal direction facing the circumferential direction, and one end thereof is connected to the code plate substrate 60b. As a means for attaching the code plate 80 to the code plate storage groove 66, a known means such as an adhesive or a double-sided tape can be used. Although the code plate 80 has a certain thickness, since the depth of the code plate storage groove 66 corresponds to the code plate 80, the code plate 80 forms a substantially uniform cylindrical surface with the outer peripheral surface of the first rectilinear guide ring 20. are doing. Although the code plate substrate 60b and the code plate 80 are described separately,
These are integrally formed as an FPC board.

Although both sides of the code plate substrate 60b are covered with an insulating material, the portion of the code plate 80 affixed to the code plate housing groove 66 has the insulating material removed and the conductive material is exposed. I have. The conductive material portion of the code plate 80 is shown in FIG.
Are the regions indicated by hatching, and five types of electrodes 80 arranged in a direction orthogonal to the longitudinal direction of the code plate 80.
a to 80e. Each electrode is connected to a code plate substrate 6.
The camera is connected to a CPU (not shown) of the camera body via a lead wire in the line 0b.

As shown in FIGS. 6 to 8, the brush 70
Is embedded in the male helicoid 18 of the first outer cylinder 17. The male helicoid 18 is provided with a wide thread portion 18a wider than the other thread portions, and a part of the wide thread portion 18a is lower than the outer peripheral surface of the wide thread portion 18a. It is a mounting recess 18b. A communication hole 18c communicating with the inner peripheral side of the first outer cylinder 17 is formed in a part of the bottom surface of the brush attachment recess 18b. Communication hole 18c
A screw hole 18d is drilled in the vicinity of, and a positioning projection 18e is further projected.

The brush 70 is provided in the brush mounting recess 18b.
Is attached. The brush 70 is a press-formed product of a conductive material (metal plate), and a pair of contact terminals (conductive terminals) 71 and 72 extend from the support portion 73. Further, a screw receiving hole 74 and a positioning hole 75 are provided in the support portion 73. With the positioning hole 75 engaged with the positioning projection 18e, the screw receiving hole 74 and the screw hole 18d
Is fixed with a fixing screw 76, the brush 70
7 is fixed at a predetermined position with respect to the brush mounting recess 18b (FIG. 7). Since the brush 70 is buried in the brush attachment recess 18b, the brush 70 does not protrude radially outward from the male helicoid 18 in the fixed state. The female helicoid 14 of the fixed lens barrel 13 has a wide thread root (not shown) that is screwed with the wide thread 18a. Therefore, the extension operation of the first outer cylinder 17 is not hindered by attaching the brush 70.

When the brush 70 is fixed to the first outer cylinder 17,
The tips of the contact terminals 71 and 72 project toward the inner peripheral surface of the first outer cylinder 17 through the communication hole 18c. As described above, there is a slight gap in the radial direction between the inner peripheral surface of the first outer cylinder 17 and the outer peripheral surface (code plate 80) of the first linear guide ring 20 because the second outer cylinder 40 is located. . The projecting amounts of the contact terminals 71 and 72 are set in anticipation of the radial gap, and the contact terminals 71 and 72 elastically contact the outer peripheral surface of the first rectilinear guide ring 20. As shown in FIG. 5, the contact terminals 71 and 72 are located at positions corresponding to the code plate 80 attached to the first straight guide ring 20 in a direction parallel to the optical axis O. Therefore, when the zoom lens barrel 10 is assembled, the contact terminals 71 and 72 of the brush 70 and the code plate 80 are in contact with each other. Although not shown, the first outer cylinder 17 and the first straight guide ring 20
Between the brush 70 and the code plate 80
A part of the cylindrical surface is cut out so as not to hinder the contact of the cylinder.

During zooming, the first outer cylinder 17 and the first rectilinear guide ring 20 rotate relative to each other while moving integrally in a direction parallel to the optical axis O. That is, the brush 70 (the contact terminals 71 and 72) and the code plate 80 are slid by the zoom operation, and the contact position relatively changes in the circumferential direction of the lens barrel.
When the brush 70 slides in the longitudinal direction of the code plate 80, the electrodes 80a to 80e of the code plate 80 conduct a predetermined combination according to the sliding position and output predetermined focal length information. Are combined with each other to form a predetermined pattern.

For example, in the retracted state of the zoom lens barrel 10 (FIG. 1), the contact terminals 71 and 72 of the brush 70 are set to A shown in FIG. 5 by the rotation phase of the first outer cylinder 17 and the first straight guide ring 20. It contacts the code plate 80 at the position. In the position A, the contact terminal 71 is in contact with the electrode 80b, and the contact terminal 72 is in contact with the electrode 80e, and the electrode 80b and the electrode 80e are conducted (pattern 1). In the focal length detecting mechanism of the present embodiment, since the code plate 80 is connected to the CPU of the camera body, the pair of contact terminals 71 and 72 serve as conducting means as described above, and two different terminals on the code plate 80 side. The electrodes are conducted. The CPU operates the electrode 80b obtained at the position A.
It is determined that the conduction state between the and the electrode 80e is the lens barrel storage position.

The zoom lens barrel 10 has a wide end (FIG. 2).
The first outer cylinder 17 and the first straight guide ring 2
The brush 70 is relatively rotated with respect to the code plate 80 downward in FIG. The contact position between the brush 70 (the contact terminals 71 and 72) and the code plate 80 at the wide end is shown as a position B in FIG. Between the position A corresponding to the lens barrel storage position and the position B for detecting the wide end, no electrode (hatched portion) is provided on the sliding locus of the brush 70 on the code plate 80.
No focal length signal is detected. In the position B, the contact terminal 71 is the electrode 80a, and the contact terminal 72 is the electrode 8a.
When they come into contact with 0d, respectively, the electrodes 80a and 80d are conducted (pattern 2). Since this combination (pattern 2) is different from the combination (pattern 1) of the electrodes energized at the position A (storage position), the CPU detects that the lens barrel has been extended to the wide end.

When the lens barrel extends from the wide end, the brush 70 and the code plate 80 slide relative to each other, and the contact terminals 71
And the contact terminal 72 include the electrode 80b and the electrode 80c (pattern 3), the electrode 80a and the electrode 80c (pattern 4), and the electrode 8
Ob and the electrode 80d (pattern 5) are repeatedly contacted in the combination order to make them conductive. Each of the patterns 3 to 5 is a combination of electrodes different from the conductive patterns 1 and 2 described above. The above pattern 3,
When the conduction is performed in any combination of 4, 5, the CPU
, The focal length divided into a predetermined number between the wide end and the tele end is detected. Specifically, in the present embodiment, the space between the wide end and the tele end is divided into 19 steps, and this is detected using the three modes of the patterns 3, 4, and 5, so that the pattern 3 to the pattern 5 Is repeated six times (seven times only for pattern 3). For example, by setting pattern 3 as a reference code and counting how many times the reference code is detected, the 19-stage focal length is detected without confusion. be able to.

When the first outer cylinder 17 and the first rectilinear guide ring 20 further rotate relative to each other with the feeding operation, the brush 70 reaches the C position where the contact terminals 71 and 72 are in contact with the electrodes 80a and 80b, respectively ( Pattern 6). The combination in which the electrode 80a and the electrode 80b conduct is different from any of the patterns 1 to 5 described above. When this pattern 6 is detected, the CPU sets the zoom lens barrel 10
At the telephoto end (FIG. 3).

The detection of the focal length in the storing operation of the lens barrel is performed in the same manner as described above. Although not described in detail to avoid repetition of the description, the first rotation relative to the lens barrel storage direction is performed.
The focal length is detected based on the sliding relationship between the brush 70 and the code plate 80 provided on the outer cylinder 17 and the first straight guide ring 20, respectively.

As described above , a concave portion is formed in a helicoid crest that is inevitably thicker than a smooth cylindrical surface.
Since the brush is attached to the concave portion , the brush can be attached without losing the strength of the lens barrel even with a thin lens barrel member, and there is no need to secure an extra space for attaching the brush. Since the helicoid portion does not appear on the exterior, the appearance is not impaired. In the above embodiment, in particular, the outer peripheral surface of the lens barrel member and the inner peripheral surface of the lens barrel member are formed in the brush mounting recess formed lower than the outer peripheral surface of the helicoid peak. Although a communication hole communicating with the peripheral surface is formed, the periphery of the communication hole is surrounded by helicoid peaks, so that high light-shielding properties can be secured.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the third outer cylinder 45 provided with the male helicoid 46 can move relative to the second rectilinear guide ring 33 in a direction parallel to the optical axis, and the relative rotation is restricted. . Therefore, a long code plate is attached to the outer peripheral surface of the second rectilinear guide ring 33 in the direction parallel to the optical axis,
It is also possible to attach a brush to the male helicoid 46 portion of the outer cylinder 45 by the aforementioned method. However, the extending direction of the contact terminal of the brush is adapted to be able to cope with relative sliding in the optical axis direction. With zooming, the third outer cylinder 45 and the second rectilinear guide ring 33 relatively move in a direction parallel to the optical axis, and with this, the brush and the code plate slide relatively to detect the focal length. . That is, the configuration in which the brush is attached to the helicoid portion can be applied to other than the encoder that relatively slides in the circumferential direction. In this case, the third outer cylinder 4
Since 5 is also a straight member for the fixed lens barrel 13, it is possible to electrically connect a brush instead of a code plate to the focal length detection circuit of the camera body. However, if the brush side is used as the electrode member, the width increases, so from the viewpoint of reducing the size of the brush provided on the helicoid portion,
As in the above embodiment, it is desirable that the code plate be an electrode member, and the brush be a conducting means for conducting a plurality of electrodes of the code plate.

[0048]

As described above, a simple structure in which a brush is mounted in a concave portion formed by cutting off a part of a helicoid crest of a lens barrel member is excellent in space efficiency, and the lens barrel can be enlarged. It is possible to obtain an encoder brush mounting structure that does not involve and does not impair the strength or light-shielding properties of the lens barrel.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a zoom lens barrel to which a brush mounting structure according to the present invention is applied in a housed state.

FIG. 2 is a side sectional view at a wide end of the zoom lens barrel of FIG. 1;

FIG. 3 is a side sectional view at a tele end of the zoom lens barrel in FIG. 1;

FIG. 4 is an exploded perspective view of a zoom lens barrel.

FIG. 5 is a development view of a first straight guide ring and a code plate attached to an outer peripheral surface thereof.

FIG. 6 is an exploded perspective view of a first outer cylinder and a brush.

FIG. 7 is a perspective view of an assembled state of the first outer cylinder and the brush.

FIG. 8 is a development view of the first outer cylinder in the vicinity of a portion where the brush is attached.

[Explanation of symbols]

 O Optical axis 10 Zoom lens barrel 13 Fixed barrel 14 Female helicoid 17 First outer cylinder 18 Male helicoid 18a Wide screw thread 18b Brush mounting recess 18c Communication hole 18d Screw hole 18e Positioning protrusion 19 Outer gear 20 First straight guide Ring 30 Drive cam ring 33 Second straight guide ring 40 Second outer cylinder 45 Third outer cylinder 60 FPC board 60a Shutter board 60b Code board board 66 Code board housing groove 70 Brush 71 72 Contact terminal 73 Support portion 74 Screw receiver Hole 75 Positioning hole 76 Fixing screw 80 Code plate 80a to 80e Electrode

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-201307 (JP, A) JP-A-8-292354 (JP, A) JP-A-63-200110 (JP, A) 5713 (JP, U) Japanese Utility Model Showa 60-107815 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02B ⁷ /02-7/105

Claims (5)

(57) [Claims] 1. A code plate and a brush, which are provided in a zoom lens barrel and which constitute an encoder for detecting a focal length by sliding relative to each other by extending and retracting the lens barrel; and constituting the zoom lens barrel. A helicoid barrel member having a helicoid, wherein the brush for detecting the focal length is formed in a concave portion formed by cutting off a part of a helicoid crest of the helicoid barrel member .
A brush mounting structure for an encoder of a zoom lens barrel, wherein the brush mounting structure is embedded in the zoom lens barrel. 2. The helicoid according to claim 1, wherein the helicoid in which said brush is buried is formed wider than other helicoid peaks on the same peripheral surface, The other helicoid lens barrel member screwed with the helicoid lens barrel member having the crest portion of the zoom lens barrel encoder having a wide helicoid valley screwable with the wide helicoid crest portion. Brush mounting structure. 3. The brush mounting structure according to claim 1 , wherein the helicoid ridge in which the brush is buried has a communication hole which radially communicates the outer peripheral surface and the inner peripheral surface of the helicoid lens barrel member. And a brush mounting structure for an encoder of a zoom lens barrel, wherein the brush has a contact terminal protruding through the communication hole on a peripheral surface opposite to the helicoid on a side opposite to the helicoid. 4. A brush mounting structure for an encoder of a zoom lens barrel, wherein the brush is screwed to a helicoid barrel member according to any one of claims 1 to 3 . 5. A brush mounting structure according to any one of claims 1 to 4, helicoid barrel member where the brush is disposed in an optical axis when rotating in forward and reverse with respect to the camera body parallel The zoom lens barrel can be further rotated relative to the camera body without changing the relative position in the direction parallel to the optical axis with the helicoid barrel in which the brush is disposed. The code plate is provided on a peripheral surface of the straight-moving / retreating cylinder so as to face the longitudinal direction in the circumferential direction, and the brush and the cord are provided. The plate is a brush mounting structure of an encoder of a zoom lens barrel that slides relatively in a circumferential direction by relative rotation of the helicoid barrel member and the rectilinear advance / retreat barrel.