JP4566611B2 - Lens barrel and optical apparatus having the same - Google Patents

Description

  The present invention provides a lens barrel suitable for moving a lens holding frame that holds optical elements such as a focusing lens group and a zoom lens group in the optical axis direction, a digital camera including the lens barrel, a video camera, The present invention relates to an optical device such as a camera for silver salt film.

  Conventionally, in a lens barrel, a straight guide bar is used to move a lens holding frame that holds a lens group moving in the optical axis direction in the optical axis direction (Patent Document 1).

  In Patent Document 1, a bar is sandwiched between a lens barrel member and a fixed lens barrel, and is fixed by screwing in the direction of the optical axis.

  Also, there is known a mounting method in which a lens barrel is detachably mounted on a camera body or two lens barrel members are detachably mounted using a bayonet mechanism (Patent Document 2).

Patent Document 2 discloses a lens hood attachment device in which a lens hood is detachably attached to a lens barrel using a bayonet claw.
JP 2000-180698 A JP 2002-202548 A

  The method of clamping the straight guide bar of the lens holding frame moving in the optical axis direction between the lens barrel member in the lens barrel and the fixed lens barrel and tightening the screws in the optical axis direction is as seen from the optical axis direction. There is a large portion occupied by a flange portion for screwing the member and the fixed barrel, the lens cross-sectional area is increased, and the lens barrel tends to be enlarged.

  The present invention provides a lens that can be easily reduced in size while preventing the lens barrel from expanding in the radial direction by appropriately setting a structure for holding a straight guide bar of a lens holding frame that moves in the optical axis direction. An object of the present invention is to provide a lens barrel and an optical apparatus having the same.

The lens barrel of the present invention is a lens barrel formed by bayonet-coupling a barrel member and a fixed barrel, and has a bar, and one end of the bar is fitted to the barrel member with a fitting backlash. The other end is fitted and held in the fixed barrel with a fitting backlash, and the bar transmits the driving force from the driving means to the lens holding frame that holds the lens and is movable in the optical axis direction. It has the function to perform.
In addition, the lens barrel of the present invention is a lens barrel formed by bayonet-coupling a barrel member and a fixed barrel, and includes a lens holding frame that holds two bars and a lens movable in the optical axis direction. One end of each of the two bars is fitted and held in the lens barrel member with fitting backlash, and the other end is fitted and held in the fixed barrel with fitting backlash, and the lens holding The sleeve portion provided in the frame is fitted with one bar, and the U-groove portion provided in the lens holding frame is fitted with another bar.

  In particular, the amount of bayonet applied in the bayonet connection between the lens barrel member and the fixed lens barrel is smaller than the amount of fall of the bar due to the fitting backlash of the bar.

  According to the present invention, by appropriately setting the configuration for holding the straight guide bar of the lens holding frame that moves in the optical axis direction, it is easy to reduce the size while preventing the lens barrel from expanding in the radial direction. A lens barrel and an optical apparatus having the lens barrel can be achieved.

  1 is a cross-sectional view of the main part of a lens barrel of Example 1 of the present invention, FIG. 2 is a perspective view of the lens barrel of Example 1 of the present invention as viewed obliquely from above in the optical axis direction, and FIG. The perspective view which decomposed | disassembled each member in order to demonstrate Example 1, FIG. 4 is sectional drawing for demonstrating each member of Example 1 of this invention.

  1-4, 1 is the first lens group closest to the object side, 2 is a second lens group that moves in the optical axis direction during zooming (zooming), 3 is a third lens group, 4 is This is a fourth lens group that moves in the optical axis direction during zooming and focus adjustment.

  Reference numeral 5 denotes a fixed barrel fixed to a camera body (not shown), and 6 denotes a first lens barrel (lens barrel member), which holds the first lens group 1, and a bayonet 5 a of the fixed barrel 5 and the first lens mirror. The cylinders 6 are connected by a bayonet 6a.

  For example, the structure disclosed in the above-mentioned Patent Document 2 can be applied to the attachment / detachment mechanism between the barrel member 6 and the fixed barrel 5 by the bayonet mechanism.

  Reference numeral 7 denotes a bar rotatably held between both ends of the fixed lens barrel 5 and the first lens barrel 6, and has a feed screw portion 7a and a gear portion 7b. Reference numeral 8 denotes a bar that is rotatably held between both ends of the fixed barrel 5 and the first lens barrel 6, and has a feed screw portion 8a and a gear portion 8b.

  One end of each of the bars 7 and 8 is fitted and held in the lens barrel member 6 with a fitting backlash, and the other end is also fitted and held in the fixed lens barrel 5 with a fitting backlash. The lens barrel 5 is bayonet-coupled. At this time, the bayonet engagement amount in the bayonet connection between the lens barrel member 6 and the fixed lens barrel 5 is smaller than the amount of fall of the bar due to the fitting play of the bars 7 and 8.

  9 holds the second lens group 2, the sleeve portion 9 a is fitted to the bar 7, is held rotatably by the driving force from the driving means 33 such as a stepping motor and is movable in the optical axis direction, and the U groove portion 9 b However, the second lens barrel (lens holding frame) 10 fitted to the other bar 8 and whose rotation is restricted is a second lens rack for driving the second lens barrel 9 in the optical axis direction. The second lens barrel 9 is rotatably held by the rack fastening portions 9c and 9d.

  A rack spring 11 is hung on the second lens rack 10, and the second lens rack 10 is shifted to the second lens barrel 9, and the engagement portion with the feed screw 7 a of the second lens rack 10 is sandwiched between the backlashes. They are biting together.

  A photo reflector 12 is fixed to the first lens barrel 6 and detects the position of the second lens barrel 9 in the optical axis direction.

  13 is a gear holding member fixed to the first lens barrel 6, 14 is a gear held between the first lens barrel 6 and the gear holding member 13, and meshes with the gear 7b of the bar 7, and 15 is the first lens. A gear 16 that is held between the lens barrel 6 and the gear holding member 13 and meshes with the gear 14, and 16 is a stepping motor (driving means) that is secured to the first lens barrel 6 with a screw 44 and meshes with the gear 14. When the gear 16a rotates, the gear 15, the gear 14, and the gear 7b rotate, the feed screw portion 7a rotates, and the second lens rack 9 moves in the optical axis direction by the second lens rack 10.

  Reference numeral 17 denotes a third lens barrel that holds the third lens group 3 and is attached to the fixed barrel 5. Reference numerals 18 and 19 denote screws that fix the third lens barrel 17 to the fixed barrel 5. Reference numeral 20 denotes a third lens. A light amount adjusting device 21 attached to the lens barrel 17 is a screw for attaching the light amount adjusting device 20 to the third lens barrel 17.

  22 holds the fourth lens group 4, the sleeve portion 22a is fitted to the bar 8, and is rotatably held by the driving force from the driving means 34 such as a stepping motor so as to be movable in the optical axis direction, and the U groove portion 22b. Is a fourth lens barrel (lens holding frame) 23 that is fitted to the bar 7 and whose rotation is restricted, and 23 is a fourth lens rack for driving the fourth lens barrel 22 in the optical axis direction. The four lens barrels 22 are rotatably held by rack fastening portions 22c and 22d.

  Reference numeral 24 denotes a rack spring hung on the fourth lens rack 23. The fourth lens rack 23 is shifted to the fourth lens barrel 22, and the engagement portion with the feed screw 8a of the fourth lens rack 23 is sandwiched between the back and forth. Engage without any problems. Reference numeral 25 denotes a photo reflector fixed to the fourth lens barrel 22, which detects the position of the fourth lens barrel 22 in the optical axis direction.

  26 is a gear holding member fixed to the fixed barrel 5, 27 is pinched and held between the fixed barrel 5 and the gear holding member 26, and a gear is engaged with the gear 8b of the bar 8, and 28 is a gear holding member with the fixed barrel 5. A gear 29 held between the members 26 and meshed with the gear 27 is a stepping motor 29 fixed to the fixed barrel 5 with a screw 30 and meshed with the gear 28. When the output gear 29a rotates, the gear 28, the gear 27, the gear 8b rotates, the feed screw portion 8a rotates, and the fourth lens barrel 22 is moved in the optical axis direction by the fourth lens rack 23. Reference numeral 31 denotes a low-pass filter fixed to the fixed barrel 5, and 32 denotes an image pickup element fixed to the fixed barrel 5.

  The bars 7 and 8 of this embodiment have a function of holding the driving force from the driving means to the lens holding frames 9 and 22 that are movable in the optical axis direction.

  Further, in this embodiment, there are a plurality of bars (two in this embodiment, but two or more), and lens holding frames 9 and 22 for holding lenses movable in the optical axis direction. Of these, the sleeve portion 9 a provided in one lens holding frame 9 is fitted with one bar 7, and the U-groove portion 9 b provided in the lens holding frame 9 is fitted with another one bar 8.

  In this embodiment, one end of the bar 7 is fitted and held in the first lens group barrel 6, and the other end is fitted and held in the fixed barrel 5. The first lens group barrel 6 and the fixed barrel 5 is bayonet-coupled, and the bayonet engagement amount B is smaller than the amount of tilting of the bar 7 due to the looseness of the fitting of the bar 7, so that the first lens group barrel in the lens cross section viewed from the optical axis direction 7 and the fixed barrel 5 can be eliminated, and the lens barrel can be reduced in size.

  In this embodiment, the length of the bars 7 and 8 shown in FIG. 1 is L, and the first lens is B with respect to the amount B of the bayonet 5a of the fixed barrel 5 and the bayonet 6a of the first lens barrel 6 shown in FIG. The receiving diameter of the bars 7 and 8 of the lens barrel 6 and the fixed lens barrel 5 is φa, the receiving fitting length is l, the diameter of the bars 7 and 8 is φA, the bar 7 from the rotation center (optical axis center) of the bayonet. The length from the rotation center of the bayonet to the bayonet portion is R, and the amount B of the bayonet is smaller than the amount of collapse of the bars 7 and 8 due to the backlash of the bars 7 and 8.

That is, as shown in FIG. 1, the diameter of the bars 7 and 8 is φA, the length of the bars 7 and 8 is L, the receiving diameter of the bars 7 and 8 is φa, the receiving length of the bars 7 and 8 is l, and the bayonet hook When the amount is B,
B <L * (a-A) / l
The conditions are satisfied.

In this embodiment, as shown in FIG. 1, the diameter of the bars 7 and 8 is φA, the length of the bars 7 and 8 is L, the receiving diameter of the bars 7 and 8 is φa, and the receiving length of the bars 7 and 8 is as follows. l, when the bayonet engagement amount is B, the length from the rotation center of the bayonet to the rotation center of the bars 7 and 8 is r, and the length from the rotation center of the bayonet to the bayonet portion is R,
B <(L * (a−A) / l) * R / r
The conditions are satisfied.

  It should be noted that this condition is sufficient if at least one of the two bars 7 and 8 satisfies this condition.

  FIG. 5 shows a block configuration in Embodiment 1 of the imaging apparatus of the present invention. In this figure, the same reference numerals as those in FIGS. 2, 3, and 4 are applied to the components of the lens barrel described in FIGS.

  In FIG. 5, reference numeral 33 denotes a drive source (drive means) for the second lens group 2, which includes a stepping motor 16, a gear 14, a gear 15, a second lens rack 10, a rack spring 11, and the like.

  Reference numeral 34 denotes a drive source (drive means) for the fourth lens group 4 and includes a stepping motor 29, a gear 27, a gear 28, a fourth lens rack 23, a rack spring 24, and the like.

  Reference numeral 35 denotes a drive source for the light quantity adjusting device 20 such as a diaphragm disposed between the second lens group 2 and the third lens group 3.

  The photo reflectors 12 and 25 detect the absolute positions of the second lens group 2 and the fourth lens group 4 in the optical axis direction, arrange the holding frames 9 and 22 at the reference positions, and then apply them to the stepping motors 16 and 29, respectively. By continuously counting the number of operation pulses to be input, the second lens group 2 and the fourth lens group 4 are moved and detected in the optical axis direction.

  Reference numeral 36 denotes an encoder of a light amount adjusting device, which employs a system in which a Hall element is disposed inside a light amount adjusting drive source 35 such as a motor and detects the rotational positional relationship between the rotor and the stator.

  A CPU 37 controls various operations of the camera. A camera signal processing circuit 38 performs predetermined amplification, gamma correction, and the like on the output from the image sensor 32. The contrast signal of the video signal subjected to these predetermined processes passes through the AE gate 39 and the AF gate 40.

  That is, an optimum signal extraction range for exposure determination and focusing is set by the gates 39 and 40 in the entire screen. The sizes of the gates 39 and 40 may be variable, or a plurality of gates may be provided.

  Reference numeral 41 denotes an AF signal processing circuit for processing an AF signal for AF (autofocus), which generates one or a plurality of outputs related to high-frequency components of the video signal output from the AF gate 40 and inputs it to the CPU 37. Yes. Reference numeral 42 is a zoom switch, and 43 is a zoom tracking memory. The zoom tracking memory 43 is information on the position of the focusing lens (fourth lens group) 4 in the optical axis direction to be set according to the subject distance and the position of the variator lens (second lens group 2) in the optical axis direction during zooming. Remember. Note that the memory in the CPU 37 may be used as the zoom tracking memory 43.

  For example, when the zoom switch 42 is operated by the photographer, the CPU 37 maintains a predetermined positional relationship between the second lens group 2 and the fourth lens group 4 calculated based on information in the zoom tracking memory 43. As described above, the current count value, which is the absolute position of the second lens group 2 in the optical axis direction, the calculated position where the second lens group 2 is to be set, and the absolute value of the current fourth lens group 4 in the optical axis direction. The second lens group driving source 33 and the fourth lens group driving source 34 are driven and controlled so that the counted value as the position matches the calculated position where the focus lens 4 should be set.

  Further, in the autofocus operation in the present embodiment, the CPU 37 drives and controls the fourth lens group drive source 34 so that the output from the AF signal processing circuit 41 shows a peak.

Further, in order to obtain proper exposure, the CPU 37 sets the average value of the output of the Y signal that has passed through the AE gate 39 as a predetermined value, and the light amount adjusting device drive source so that the output of the light amount adjusting device encoder 36 becomes this predetermined value. 35 is driven and controlled to control the amount of light.

  In the above configuration, one end of the bars 7 and 8 is fitted and held in the first lens barrel 6, and the other end is fitted and held in the fixed barrel 5, and fixed to the bayonet portion 6 a of the first lens barrel 6. By connecting the bayonet portion 5a of the lens barrel 5 with a bayonet so that the bayonet hooking amount B is smaller than the amount of tilting of the bar due to the fitting looseness of the bars 7 and 8, the lens cross section viewed from the optical axis direction can be obtained. The flange portion for tightening the screw between the first lens barrel 6 and the fixed barrel 5 can be eliminated, and the lens barrel is downsized. In addition, a small optical device is achieved by using this lens barrel.

Sectional drawing of the principal part of Example 1 of this invention The perspective view seen from the optical axis direction slanting top of Example 1 of the present invention The perspective view decomposed | disassembled in order to demonstrate Example 1 of this invention Sectional drawing for demonstrating Example 1 of this invention Explanatory drawing which shows the electrical structure in the optical instrument of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... 1st lens group, 2 ... 2nd lens group, 3 ... 3rd lens group, 4 ... 4th lens group,
5 ... fixed barrel, 5a ... bayonet, 6 ... first lens barrel, 6a ... bayonet,
7 ... Bar, 7a ... Feed screw part 7a, 7b ... Gear part,
8 ... Bar, 8a ... Feed screw part, 8b ... Gear part,
9 ... 2nd lens barrel, 9a ... Sleeve part, 9b ... U groove part,
9c: Rack fastening part, 9d: Rack fastening part,
10 ... second lens rack, 11 ... rack spring, 12 ... photo reflector,
13 ... Gear holding member, 14 ... Gear, 15 ... Gear,
16 ... Stepping motor, 16a ... Output gear,
44 ... screw, 17 ... third lens barrel, 18, 19 ... screw, 20 ... light quantity adjusting device,
21 ... Screw,
22 ... 4th lens barrel, 22a ... Sleeve part, 22b ... U groove part,
22c, 22d ... Rack fastening part,
23 ... Fourth lens rack, 24 ... Rack spring,
25 ... photo reflector, 26 ... gear holding member, 27 ... gear, 28 ... gear,
29 ... stepping motor, 29a ... output gear, 30 ... screw,
31 ... Low-pass filter, 32 ... Image sensor,
33 ... Drive source, 34 ... Drive source, 35 ... Drive source, 36 ... Light quantity adjusting device encoder,
37 ... CPU, 38 ... camera signal processing circuit, 39 ... AE gate,
40... AF gate, 41... AF signal processing circuit,
42 ... zoom switch, 43 ... zoom tracking memory φA ... bar 7, 8 diameter, L ... bar 7, 8 length,
φa: diameters of the bars 7 and 8 of the first lens barrel 6 and the fixed barrel 5;
l: fitting length of the bars 7 and 8 of the first lens barrel 6 and the fixed barrel 5;
B ... Bayonet hanging amount, r ... Length from the center of rotation of the bayonet to the bars 7,
R: Length from the center of rotation of the bayonet to the bayonet

Claims (6)

A lens barrel formed by bayonet coupling of a barrel member and a fixed barrel,
A bar, one end of the bar is fitted and held in the lens barrel member with fitting backlash, the other end is fitted and held in the fixed lens barrel with fitting backlash ,
The bar has a function of transmitting a driving force from the driving means to a lens holding frame that holds the lens and is movable in the optical axis direction . A lens barrel formed by bayonet coupling of a barrel member and a fixed barrel,
A lens holding frame for holding two bars and a lens movable in the optical axis direction;
One end of each of the two bars is fitted and held in the lens barrel member with fitting backlash, and the other end is fitted and held in the fixed lens barrel with fitting backlash,
A lens barrel characterized in that a sleeve portion provided on the lens holding frame is fitted with one bar, and a U-groove portion provided on the lens holding frame is fitted with another bar. 3. The lens barrel according to claim 1, wherein a bayonet engagement amount in the bayonet coupling between the lens barrel member and the fixed lens barrel is smaller than a bar tilt amount due to the backlash of the bar. When the diameter of the bar is φA, the length of the bar is L, the receiving diameter of the bar is φa, the receiving length of the bar is l, and the bayonet engagement amount is B,
B <L * (a-A) / l
The lens barrel according to any one of claims 1 to 3, wherein: The bar diameter is φA, the bar length is L, the bar receiving diameter is φa, the bar receiving length is l, the bayonet hanging amount is B, and the length from the bayonet rotation center to the bar rotation center is r, where R is the length from the center of rotation of the bayonet to the bayonet part,
B <(L * (a−A) / l) * R / r
The lens barrel according to any one of claims 1 to 3, wherein: An optical apparatus comprising the lens barrel according to any one of claims 1 to 5 .