JP2000111778A - Lens barrel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a lightweight and compact lens barrel having a high- performance optical system being comparable to a single focus lens. SOLUTION: As for this lens barrel, a photographing lens which can be switched to plural focal distances by simple constitution is composed of four groups and constituted by arranging a diaphragm at two places, for example. To put it concretely, the lens barrel provided with at least the first diaphragm means A which is arranged between first lenses in a photographing optical system and which can regulate the quantity of light transmitted through the photographing optical system and the second diaphragm means B which is arranged between second lenses in the photographing optical system and which can regulate the quantity of light transmitted through the photographing optical system are constituted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens configuration for realizing a small, high-performance bifocal or trifocal camera.

[0002]

2. Description of the Related Art There are various techniques for switching the focal point of an optical system, but conventionally, it has been general to change the focal length to a different one by adding it to an optical device. For example, there are a front type and a rear type that are additionally provided as a variable power optical system before / after a fixed lens optical system of an optical apparatus. This front type is equipped with a telephoto (TELE) or wide-angle (WIDE) variable power lens unit when necessary in front of a standard (STAN) lens,
It is a telephoto conversion lens attached to a DE system lens and has a TELE specification. However, it needs to be inserted and removed every time the focus is switched. In order to eliminate the complexity of this switching, for example,
Japanese Patent Application Laid-Open No. 63-43114 proposes a "lens structure capable of switching the focal length" in which one front conversion lens group (magnification lens group) is rotatably installed in front of a fixed lens optical system. In some cases, this can be easily reversed by manipulating the zoom lever to obtain a zoom effect of three focal lengths of telephoto, standard, and wide-angle.

[0003] On the other hand, as a rear type, for example, a bifocal camera (commonly called TELE /) is used in which a rear conversion lens group is inserted behind a fixed lens (standard lens) optical system.
WIDE camera). In addition, recently, zoom lenses that can continuously change the focal length by changing the distance between constituent lenses have been frequently used.

[0004]

However, if the variable power lens group is added to the above-described fixed lens optical system, there is a common problem in the lens group configuration that the total number of lenses increases. At the same time, in the rear type, optical performance such as the entire optical system becomes darker and the like. In addition, wide-angle (W
Even at the time of IDE) specification, an unnecessary lens group is interposed, and a mechanism for inserting and removing the conversion lens group is required for both, so miniaturization is difficult. Furthermore, Japanese Patent Application Laid-Open No. 63-43114
According to the switchable lens structure disclosed in Japanese Patent Application Laid-Open No. H10-264, it is easy to use by simple switching, but it is extremely difficult to reduce the size because the attached lens structure rotates in front of the fixed lens optical system. it is obvious.

Also, in the case of a zoom lens, the lens structure in the lens barrel does not change even at a standard focal length, so that the zoom lens tends to be unnecessarily large and heavy. A difficult-to-process lens such as a spherical lens is used, which is a factor of high cost. In a normal camera taking lens, the position where the diaphragm is installed is provided only at one position between the lenses in the optical system. Therefore, optically, the position of the aperture provided at a predetermined position in the lens group determines the characteristics of the photographing lens. However, such a fixed photographing lens having a specification capable of switching the focal length is used. The presence of the stop provided only at one location is one of the factors that make the design itself difficult. Therefore, on the premise of such a basic configuration having only a single diaphragm, an increase in the number of lenses inevitably occurs in order to realize a high-performance photographing lens close to a single focus lens. Upsizing was inevitable. Therefore, an object of the present invention is to realize a lens barrel having a high-performance optical system that is lightweight and small and has a performance equivalent to that of a single focus lens.

[0006]

The present invention employs the following means in order to solve the above problems and achieve the object. That is, by reviewing the basic configuration of the aperture in the prior art, for example, by arranging the aperture at at least two positions, a photographing lens having a simple configuration and capable of switching a plurality of focal lengths is configured. According to the first invention, the first diaphragm means disposed between the first lenses in the photographing optical system and capable of regulating the amount of light passing through the photographing optical system, and the second diaphragm means in the photographing optical system There is proposed a lens barrel including a second diaphragm unit disposed between the lenses and capable of regulating the amount of light passing through the photographing optical system.

According to a second aspect of the present invention, there is provided a camera having a photographic optical system capable of switching a focal length comprising at least three or more lens units having different relative movement amounts in the optical axis direction. Placed between the lens groups of
First diaphragm means for regulating the amount of light passing through the photographing optical system, and second diaphragm disposed between the second lens group of the photographing optical system and regulating the amount of light passing through the photographing optical system Means are provided. Third
According to the invention of the above (1), the first (1)
The lens barrel according to the second aspect of the present invention is provided with a diaphragm switching means for switching and driving the second diaphragm means.

As described above, a structure in which a plurality of apertures are arranged between lenses in a lens barrel, and switching to a corresponding aperture according to a focal length to be used, enables a lens optical system suitable for each focal length. Is obtained.

[0009]

1A and 1B show the appearance of a "trifocal switching" type lens-integrated single-lens reflex camera to which the present invention is applied. The state shown in FIG. 1A is a collapsed state in which the taking lens 1 is stored in the lens barrel 2 when the main switch (not shown) of the camera is OFF.
The camera exhibits the shortest length in this collapsed state. When the main switch is turned on at the time of use, the photographing lens 1 is extended forward to be in a photographing standby state.

When the focal length switching lever 3 is further operated in one direction, as shown in FIG. 1B, the constituent lens groups (groups 1 to 4) of the taking lens 1 move forward of the lens barrel 2 along the optical axis. It can be seen that the configuration is such that the focal length is changed. That is, the photographing lens 1 includes a plurality of constituent lens groups (first to fourth groups) and a plurality of aperture units (not shown) to be described later. The plurality of aperture units are incorporated in a mechanism that moves along the optical axis together with a predetermined lens group. Note that the lens configuration exemplified here is referred to as a “trifocal type” having four groups.

FIGS. 2A and 2B show the concept of the basic structure of a single focus lens for a general single-lens reflex camera. Wide (WIDE) at the time of wide-angle shooting as shown in FIG.
The system is a short focus "retro focus type" in order to make the back focus longer than the focal length. In other words, it can be understood that this wide-angle lens configuration is a retrofocus type in which a lens having a negative power, a diaphragm 10, and a lens having a positive power are arranged as shown in the figure from the direction of the subject on the optical axis.

On the other hand, a telephoto (TELE) system at the time of telephoto photographing as shown in FIG. 2B is a long focal length "telephoto type" in order to shorten the overall length. In other words, it can be understood that the telephoto lens configuration is a telephoto type in which a lens having a positive power, a diaphragm 10 and a lens having a negative power are arranged as shown in the figure from the direction of the subject on the optical axis. In addition to the above, a basic configuration called an “elnostar type” (not shown) is also used.

Incidentally, for example, a standard (STAN) lens configuration having a focal length of about 50 mm as an intermediate between the wide-angle system and the telephoto system has a symmetrical power distribution before and after the stop. is there. In the standard system, a "Gauss type" whose front and rear groups are almost symmetrical with respect to the aperture is used. In the case of a zoom lens having a high zoom ratio, the number of lens groups and the number of lenses tend to increase, which tends to be large and expensive. Furthermore, it is extremely difficult to secure the performance equivalent to a single focus lens because it is necessary to ensure a predetermined or higher optical performance over the entire area. In addition to the overall zoom ratio, performance is important as well as miniaturization.

Therefore, in the embodiment of the present invention, by incorporating a high-performance multifocal lens into a single-lens reflex camera with a lens, a so-called “system single lens” is equivalent to a combination of a camera body and about three single-focus lenses. The present invention realizes a lens barrel for a camera having a performance that is extremely small and excellent in operability.

Hereinafter, the gist of the present invention will be described in more detail with reference to a plurality of embodiments. (First Embodiment) FIG. 3 shows a first embodiment of the present invention.
(A) to (d) illustrate the configuration of a trifocal type optical system. The configuration shown in FIG. 3A is a retracted lens optical system composed of four lens groups (one to four groups), and each group has the following positive / negative power. That is, in order to correctly capture an image on the imaging plane 23 located behind the focal plane shutter 22 via the quick return mirror 21, one group has negative power, the second group has positive power, the third group has positive power, and the fourth group has negative power. , Respectively.

Each of these groups may be constituted by a plurality of lenses or only one lens.
In the lens configuration of the first embodiment, the aperture units A to C are arranged at the positions indicated by arrows between the lenses of each group, and all the aperture units A to C are arranged in the normal retracted state.
Is open. (The aperture units A to C control the aperture with a plurality of known blades.) By changing the position of this lens optical system, the focal length is changed to form a wide-angle wide (WIDE), standard standard (STAN) or telephoto (TELE) state as a whole. are doing.

The structure shown in FIG. 3B is a wide-angle (WID)
E) The lens system in the state (focal length f = 28 mm, aperture value F2), with the group spacing between the first and second groups widened,
With respect to one group of the negative power on the subject side, the total of the second, third, and fourth groups is positive, positive, and negative power, and the whole is positive power. This is a so-called “retro focus type” lens configuration, which is suitable for a wide-angle lens configuration. At this time, each of the aperture units A to C has the aperture unit A in a driving state, and the other aperture units B and C
Are open and are not driven.

FIG. 3C shows a lens system in a standard (STAN) state (focal length f = 50 mm, aperture value F2). In this standard condition, the first and second groups, the third and fourth groups approach, while the distance between the second and third groups increases. In this state, the front side (subject side) of the aperture unit B has a negative / positive power configuration, and the rear side of the aperture unit B has a positive / negative power configuration. Such a configuration sandwiches the aperture unit B at the center. It is a form close to a symmetric shape. This is a lens type suitable for a standard system lens. At this time, only the aperture unit B is in a driving state.

FIG. 3D shows a lens system in a telephoto (TELE) state (focal length f = 100 mm, aperture value F2.8). In this state, the first, second, and third groups approach, and the third , The distance between the four groups is widened. The first to third groups have negative / positive / positive power, the whole group has positive power, the fourth group has negative power, and only the aperture unit C is in the driving state. It can be seen that this configuration corresponds to a “telephoto type” suitable for a telephoto system.

In general, in a zoom optical system, the position of an aperture unit is invariable between fixed lenses,
While it was difficult to ensure high performance in all focal ranges, the present invention, on the other hand, has a completely new concept of changing the position of the aperture unit so that a lens system suitable for the focal length can be obtained. By using, high performance can be realized with a small number and a small number.

The collapsed state shown in FIG. 1A corresponds to the state shown in FIG. 3A, and the state shown in FIG.
It can be understood from this that the state corresponds to the state shown in FIG.
FIG. 4 illustrates one schematic configuration of a photographing lens system in which, for example, three aperture units are incorporated. This example is 4
The photographic lens is configured by providing three aperture units in an optical system having a group configuration. The aperture units A to C arranged at three locations are independently arranged orthogonally to the optical axis between the respective lens groups, and a stepping motor M (actuator) as a drive source (actuator) of the aperture units A to C is provided. 3
0a to 30c), an aperture operation is performed as one representative of the photographing lens, and a predetermined amount of light is applied to a quick return mirror 21 or a focal plane shutter 22 and an image forming surface 23 disposed at a subsequent stage. Is provided.

FIG. 5 shows an example of assembling a plurality of aperture blades constituting the aperture units A to C. The stepping motor 30 serving as a drive source of the aperture unit has a pinion 31 on its rotating shaft, and an aperture base plate 32 attached by penetrating the pinion 31 of the stepping motor 30, and a gear portion 35 meshing with the pinion 31. , A diaphragm ring (aperture sector) 37 that performs a diaphragm operation, and a diaphragm lid 40 that protects the diaphragm blades adjacent to these diaphragm blades are assembled as shown in FIG. One aperture unit is formed.

Bosses (pins) 33 are provided at three places on one side of the drawn ground plate 32, and bosses (pins) 36 are provided at three places on one side of the drive ring 34. Each of the plurality of diaphragm blades 37 is formed with a long and thin guide (guide hole) 38 and a fulcrum hole 39. The bosses (pins) 36 are movably fitted along the guides (guide holes) 38 of the diaphragm blades 37 and combined with each other, and the bosses (pins) 33 are inserted into fulcrum holes 39 of the diaphragm blades 37. Each is fitted and combined.

The pinion 31 of the step motor 30
Meshes with the gear portion 35 to rotate the drive ring 34. With this rotation, the three diaphragm blades 37 gradually approach or separate in the optical axis direction about the respective fulcrum holes 39. Or to perform a diaphragm operation for changing the width of the optical path.

FIGS. 6A and 6B show the focal length f
And a positional relationship on the optical axis where the lens is extended. The graph of FIG. 6A shows the case of a fixed lens of a trifocal switching type that can switch the focal length f fixedly at three positions of wide angle, standard, and telephoto. For example, this corresponds to the three aperture units A to C shown in FIG.
In this system, three predetermined focal lengths f are switched by causing a dedicated aperture function of either wide-angle, standard, or telephoto.

The graph of FIG. 6B shows a zoom function in which the focal length can be slightly but continuously changed in a certain range before and after three predetermined focal lengths f each of wide angle, standard and telephoto. 9 shows the relationship between the lens extending positions in the case of a taking lens to which is added. in this way,
In addition to any of the dedicated aperture functions switched as desired,
It is understood that the zoom operation can be performed by a lens driving system (not shown).

FIG. 7 exemplifies an electric block diagram showing only a main part according to the gist of the present invention. The CPU 50 for controlling the camera according to the present invention is provided with a main switch 51 of the camera linked to the power supply 53 and a focus switch SW 52 for selectively switching the focal length. In this configuration, the mode for performing the focus switching operation of the camera is performed with only one switch, and only one focus switching switch 52 is provided for this operation. Each time the focus switch 52 is pressed once, a predetermined focal length is sequentially switched, so that the focal length is changed in a “cyclic” manner.

The CPU 50 includes a motor driver 54.
The motor driver 54 includes a focus switching motor 55 (stepping motor M) as a drive source for driving a focus switching drive mechanism such as a cam ring (not shown).
Is performed according to need, either clockwise or counterclockwise rotation.

Further, a transistor 56 for PI drive is connected to the CPU 50, and is connected drivably to a PI 57 for focus detection. This PI 57 for focus detection
Is a device for detecting a focus switching position, not shown, for detecting the focal length of the lens optical system, for example, by detecting the amount of rotation of the cam ring. The disk 5 for pulse generation provided in the PI 57 for focus detection
Reference numeral 8 denotes a member that rotates in unison with, for example, the rotation of a cam ring. In order to generate a pulse from the PI 57, a rotating plate member in which holes through which light passes and portions that block light are alternately arranged in the rotating direction. It is.

Further, the CPU 50 is connected to an EEPROM 59 for rewritably storing data relating to the current focal length of the lens, and rewritably stores data relating to the number of detected pulses and the focal length. In order to switch the focal length, data on the direction of rotation of the motor can be temporarily stored in a rewritable manner.

Next, control when the lens barrel of the present invention is employed in a camera will be described. FIG. 8 shows a "focus switching" subroutine for controlling the lens barrel of the present invention. When the focus switching switch is pressed, (S1) of this subroutine starts from a main routine of a camera sequence (not shown). It is programmed to be called.

In step S2, whether or not the current focal length of the lens is on the shortest focus side (shortest focus) is determined by EEP.
The determination is made based on the data on the ROM (S2). When the focus switch is pressed, if the focal length is not the shortest focal length nor the longest focal length, the process proceeds to step S8. On the other hand, if the shortest focal length,
In step S3, the motor is rotated in the long focal direction. (At this time, the motor is rotated forward) (S3). And
The rotation of the motor is set to a direction flag ON (in the form of "H" level latch) and stored in the EEPROM (S
4).

In the following step S5, it is determined whether or not the next focal length has been reached by referring to the generated pulse amount and the data stored in the EEPROM (S5). If the focal length has not been reached yet, the flow returns to step S3 to continue the normal rotation of the motor. On the other hand, when the next focal length is reached, the motor drive is turned off (S6), and the process returns to the main routine (S7).

In step S8, the direction flag is turned ON / O.
The FF is determined (S8). If the previous focus change was from the short focus side to the long focus side, the direction flag is ON, so it is determined whether or not the lens is currently at the longest focal length (S9). If the focal length has not reached the longest focal length, the process returns to step S3 to further drive the lens toward the long focal length.

In step S10, if the direction flag is OFF in step S8, since the previous focal length switching is from the long focal length side to the short focal length side, the lens is driven to the short focal length side. When the is the longest focus, the motor is reversed (S10). At this point, the recording of the motor rotated in the reverse direction is stored in the EEPROM with the direction flag being OFF (in the form of an "L" level latch) (S11).

Next, it is determined whether the motor is rotated in the reverse direction and has reached the next focal length, that is, to the short focal length side (S1).
2). If it has not arrived yet, the process returns to step S10, and the motor continues to rotate in the reverse direction. On the other hand, if it has reached the state, the process proceeds to step S6 to turn off the motor, and returns to the main routine.

According to the control procedure shown in the above-mentioned flowchart, the focal length of the lens can be switched cyclically by a single switch. (Modification 1) In the first embodiment, one focus changeover switch is used. Of course, one changeover switch to the short focus side (wide side) and one changeover switch to the long focus side (tele side) are provided. It is also possible to provide two switches in total. Note that this system is mainly used as a zoom switch of a camera generally used.

(Function and Effect 1) According to the first embodiment, a plurality of mechanical diaphragm units driven by an actuator (motor) are arranged between the lenses in the lens barrel, and the focal length is By switching the drive of a desired aperture unit along with the switching, a lens optical system suitable for each focal length can be obtained. Therefore, as compared with a conventional lens barrel having a structure in which only one stop is provided at a fixed position, it is possible to realize a lightweight, small, and high-performance lens barrel equivalent to a single focus lens.

(Second Embodiment) Next, FIGS. 9 and 10
A configuration of a “bifocal type” lens optical system that can switch between two focal lengths will be described as a second embodiment of the present invention with reference to FIG. FIGS. 9A and 9B show the second
FIG. 3 shows a configuration of a “bifocal type” photographing lens having three apertures in a three-group configuration of the embodiment, where two aperture units A and B are provided before and after.

According to the configuration diagram shown in FIG. 9A, the aperture B is in the operating state. Wide angle state (for example, focal length f = 4
The stop driven in the lens optical system having a stop value of F2) of 0 mm is an example of a stop unit B disposed rearward. That is, the aperture unit B provided behind the two lens groups is driven by the motor M via the motor drive driver according to a command from the CPU. With respect to the aperture unit B, the front group has positive and negative powers and exhibits negative power as a whole, and thereafter the group exhibits positive power.

On the other hand, according to the configuration diagram shown in FIG.
In a telephoto state (for example, with a focal length f = 100 mm and an aperture value of F2.
It is illustrated that the diaphragm driven in the lens optical system of 8) is the diaphragm unit A disposed in front.
That is, it can be seen that the aperture unit A provided behind one lens group is similarly driven by the motor M via the motor drive driver according to a command from the CPU. For the aperture unit A, the front group has positive power, and the rear group has negative power.
It is positive and exhibits negative power as a whole.

Similarly, FIGS. 10 (a) and 10 (b)
FIG. 13 shows another lens system configuration of the “two-focal point type” of the second embodiment, which has a three-group configuration and also has two stops. According to the configuration diagram shown in FIG. 10A, the stop driven in the lens optical system in the wide-angle state is the stop unit A arranged in front. An aperture unit A provided behind one group of lenses is driven by a motor via a motor drive driver instructed by the CPU. The front unit has a negative power with respect to the aperture unit A,
The rear group is positive / negative and exhibits positive power as a whole.

According to the configuration diagram shown in FIG. 10B, the diaphragm driven in the lens optical system in the telephoto state is a diaphragm unit B disposed rearward. In this case, it can be seen that the aperture unit B provided behind the two lens groups is similarly driven by the motor via the motor drive driver instructed by the CPU. The front unit as a whole has positive power and the rear unit has negative power with respect to the aperture unit B.

(Modification 2) FIG. 11 shows a lens optical system using a non-mechanical "liquid crystal diaphragm" in place of the diaphragm unit as a modification of the first or second embodiment. 1 shows the configuration of a system. That is, the feature of this example is an example in which a liquid crystal diaphragm using the light-shielding property of an electro-optical liquid crystal is adopted instead of the mechanical diaphragm blade drive by the motor or the like described above. Liquid crystals are arranged at three locations along the optical axis. More specifically, as shown in the drawing, a liquid crystal diaphragm 70A is arranged behind one group, a liquid crystal diaphragm 70B is arranged between the second and third groups, and a liquid crystal diaphragm 70C is further arranged between the third and fourth groups. It can be seen that this is a four-group trifocal lens optical system.

FIG. 12 shows a detailed structure of the liquid crystal diaphragm used as the diaphragm unit. As shown, the liquid crystal diaphragm 70 is in a light-shielding state when energized, and its light-shielding pattern is formed concentrically.
It can be seen that they are arranged adjacent to each other in the order of. And
The terminal of each of the narrowed portions 71 to 74 is connected to a portion 75 in the figure.
And is connected to a device (not shown) that switches between energization and controls light shielding.

This light-shielding control is performed as follows.
This is performed by energizing the liquid crystal of 74. That is, each of the diaphragm portions 71 to 71 is based on a previously designed diaphragm diameter required for light shielding.
A size of 74 is formed, and in order to exert the aperture function, only the outermost aperture section 71, aperture sections 71 and 72, aperture sections 71, 72 and 73,
Alternatively, the liquid crystal corresponding to each of the apertures 71, 72, 73, and 74 is controlled to shield light by electrically switching the current so that a desired light-shielding effect is exerted and a function as an aperture is provided. ing.

(Function and Effect 2) According to the second embodiment, a plurality of electric diaphragm units utilizing the light-shielding effect of liquid crystal or the like are arranged between the lenses in the lens barrel as described above, and the focus is adjusted. By switching to a desired aperture unit along with the distance switching, a lens optical system suitable for each focal length can be obtained. Therefore, as compared with a conventional lens barrel having only one diaphragm at a fixed position, it is possible to realize a lightweight, small, and high-performance lens barrel comparable to a single focus lens. In addition, since it is not necessary to use a drive-only actuator such as the mechanical structure illustrated in FIG. 4 as the first embodiment, it is understood that further weight reduction and downsizing are possible.

(Third Embodiment) FIGS. 13 (a) to 13 (c)
Shows the configuration of a three-group trifocal type lens optical system as a third embodiment of the present invention. This is an example in which the present invention is applied to a type having an optical system that can be inserted into and removed from the optical path. This is a four-group configuration, where the first to third groups are always in the optical path, but only the fourth group can be inserted and removed from the optical axis,
It is characterized in that it is retracted to a predetermined position other than the optical axis when unnecessary (for example, at the time of non-telephoto).

According to the configuration diagram of FIG.
In E), the aperture unit A is in a driving state. In the lens optical system in the wide-angle state, the aperture unit A disposed behind the group functions as an aperture according to a command from the CPU. The front group has negative power with respect to the aperture unit A,
The second and third groups placed behind both have positive power and exhibit positive power as a whole. Note that only the fourth group is retracted to a predetermined position other than the optical axis.

According to the configuration diagram of FIG. 13B, the standard (STA
In (N), the aperture unit B is in a driving state. In the lens optical system in the standard state, the aperture unit B disposed behind the two groups similarly functions as an aperture according to a command from the CPU. The first and second units of the aperture unit B have positive power, and the third unit has negative power. Also,
It can be seen that the fourth lens group is also retracted to a predetermined position other than the optical axis.

The configuration shown in FIG. 13C is a telephoto (TELE)
This indicates that the retreated four groups have moved into the optical path and have been inserted at the end. That is, in the lens optical system in the telephoto state, it is understood that the aperture unit C similarly functions as an aperture according to a command from the CPU together with the driving of the four groups on the optical axis. The first to third groups in front of the aperture unit C have positive power, and the rear four groups have negative power. The aperture units A to C employed may be mechanical units or electric units such as liquid crystal.

(Modification 3) As described above, the retracted state of the fourth lens group is shown below the optical axis for convenience as illustrated in FIGS. 13A and 13B, but is limited to the retracted position. For example, in the single-lens reflex camera shown in FIG. 1, for example, it may be arranged in an appropriate space such as a space in front of a strobe unit adjacent to a pentaprism or a side of a photographing lens. It is also possible to adopt a configuration in which the space is effectively used so that it does not become a factor for upsizing.

(Effect 3) According to the third embodiment, for example, since the four lens groups, which are one of the first to fourth groups, enter the optical path only at the time of telephoto, a wide angle In addition, the optical flexibility at the standard time is increased, and the focal length at the telephoto can be easily made longer than that of the first embodiment. In addition, since the lens is retracted to a position other than the optical axis except during telephoto, a lens barrel having a relatively short lens length can be realized.

(Other Modifications) The present invention is not limited to the above-described embodiments. For example, the gist of each embodiment is an interchangeable lens camera, a simple camera, and a variable power function. The present invention can be similarly applied to a camera with a camera. In addition, various modifications can be made without departing from the spirit of the present invention.

Although the present invention has been described based on the embodiments, the following inventions are included in this specification.
For example, (1) in a camera having a photographing optical system composed of at least three groups or more, a plurality of variable diaphragm means disposed between at least two groups and capable of regulating the amount of light passing through the photographing optical system. A camera having a lens barrel, comprising:

(2) In a camera having a photographing optical system capable of switching the focal length, a plurality of lenses arranged between a plurality of lenses among the lenses of the photographing optical system and capable of regulating the amount of light passing through the photographing optical system. And a diaphragm switching means for switching the operable diaphragm means in accordance with the focal length switching. (3) In a camera having a photographing optical system capable of switching the focal length, a first lens arranged between the first lenses of the photographing optical system and capable of regulating the amount of light passing through the photographing optical system.
And a second lens disposed between the aperture means and the second lens of the photographing optical system and capable of regulating the amount of light passing through the photographing optical system.
A lens having a lens barrel.

(4) The first and second aperture means are:
(3) The lens barrel according to (3), which includes independent aperture driving sources. (5) The lens barrel according to (4), wherein the aperture driving source is a stepping motor.

(6) There is provided a diaphragm switching means for switching and driving the first diaphragm means or the second diaphragm means in accordance with the switching of the focal length, and in the case where the first diaphragm means is driven, The photographing optical system is at a first focal length, and when the second aperture means is driven, the photographing optical system is at a second focal length different from the first focal length (3). The lens barrel described.

(7) The first and second aperture means are:
The lens barrel according to (3), (4) or (5), having a plurality of aperture blades so that the aperture stop aperture can be varied. (8) The lens barrel according to (3), wherein the first and second aperture means have a liquid crystal aperture member made of a liquid crystal having a different light transmission amount between a non-energized state and an energized state.

[0060]

As described in detail above, according to the present invention,
A photographic lens with multiple focal lengths is configured with a simple configuration by arranging the aperture at least at two locations in the lens barrel, and a lens that is lightweight, compact, and has a high-performance optical system comparable to a single focus lens It becomes possible to realize a lens barrel,
This can contribute to a reduction in size and weight of a camera or the like.

[Brief description of the drawings]

1A and 1B show a camera to which the present invention is applied, and FIG. 1A is a perspective view showing a lens-integrated single-lens reflex camera of a “trifocal switching” type in a collapsed state. FIG. 1B is a perspective view showing the configuration of the photographing lens extending forward, as seen through.

FIGS. 2A and 2B show a basic configuration of a single-lens reflex camera for a general single-lens reflex camera, and FIG.
FIG. 2B is an explanatory diagram showing a configuration of a “retro focus type” at the time of wide-angle shooting, and FIG. 2B is an explanatory diagram showing a configuration of a “telephoto type” at the time of telephoto shooting.

FIGS. 3 (a) to 3 (d) show the configuration of a four-group “trifocal type” lens optical system according to the first embodiment of the present invention, and FIG. FIG. 3B is a configuration diagram of a lens optical system in a wide-angle state,
FIG. 3C is a configuration diagram of a lens optical system in a standard state, and FIG.
(D) is a block diagram of a lens optical system in a telephoto state.

FIG. 4 is a schematic configuration diagram of a photographic lens system incorporating a plurality of aperture units.

FIG. 5 is an assembly configuration diagram showing a configuration of an aperture unit.

6 (a) and 6 (b) show the relationship between the focal length of the lens and the lens extension position, and FIG. 6 (a) is a graph for a three-focus switching type fixed lens, and FIG. b)
The graph in the case of a trifocal switching type zoom lens.

FIG. 7 is an electric block diagram of a camera according to the present invention.

FIG. 8 is a “focus switching” subroutine of the camera according to the present invention.

FIGS. 9A and 9B show the configuration of a three-unit “bifocal type” lens optical system according to a second embodiment of the present invention. FIG. 9A shows a wide-angle lens system. FIG. 9B is a configuration diagram of a lens optical system in a telephoto state, and FIG.

FIGS. 10 (a) and 10 (b) show a “bifocal type” lens system configuration of a three-group configuration according to the second embodiment, and FIG. 10 (a) shows a lens optical system in a wide-angle state. FIG. 10B is a configuration diagram of a lens optical system in a telephoto state.

FIG. 11 is a configuration diagram of a lens optical system using a liquid crystal stop as a modification.

FIG. 12 is a front view showing a structure of a liquid crystal diaphragm used in the diaphragm unit.

FIGS. 13 (a) to 13 (c) show a configuration of a three-group trifocal lens optical system according to a third embodiment of the present invention. FIG. 13 (a) shows a wide-angle state. 13B is a configuration diagram of a lens optical system in a standard state, and FIG. 13B is a configuration diagram of a lens optical system in a telephoto state.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photography lens, 2 ... Lens barrel, 3 ... Focal length switching lever, 4 ... Release button, 5 ... Grip part, 6 ... Penta part, 10 ... Aperture (aperture unit), 21 ... Quick return mirror, 22 ... Focal plane Shutter, 23: imaging surface, 30: stepping motor (M), 31: pinion, 32: aperture base plate, 33: boss (pin), 34: drive ring, 35: gear, 36: boss (pin), 37 ... Aperture blades (aperture sector), 38 ... Guide (guide hole), 39 ... Support hole, 40 ... Aperture lid, 50 ... CPU, 51 ... Main switch, 52 ... Focus switch SW, 53 ... Power supply (battery), 54 ... Focus switching motor drive driver 55: Focus switching motor (M) 56: PI (photo interrupter) drive transistor 57: Focus detection PI 58: PA Be generated for the disc, 59 ... EEPROM, 70,70A~7C ... aperture LCD, 71 to 74 ... concentric liquid crystal throttle section.

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[Procedure amendment]

[Submission date] August 20, 1999 (1999.8.2
0)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction contents]

FIGS. 2A and 2B show the concept of the basic structure of a single focus lens for a general single-lens reflex camera. Wide (WIDE) at the time of wide-angle shooting as shown in FIG.
In systems, short focus "retro focus type" is generally used to make the back focus longer than the focal length.
Can be That lens configuration of the wide-angle system, a lens with negative power from the object the direction of the optical axis, aperture 10, the positive power lens is arranged as shown.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction contents]

On the other hand, in a tele (TELE) system at the time of telephoto photographing as shown in FIG. 2B, a long focal length "telephoto type" is generally used in order to shorten the overall length. That lens structure of this telescopic system lenses with a positive power from the object the direction of the optical axis, aperture 10, the negative power lens is arranged as shown. In addition to the above, a basic configuration called an “elnostar type” (not shown) is also used.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0040

[Correction method] Change

[Correction contents]

According to the configuration diagram shown in FIG. 9 (a), the diaphragm which is driven in the lens optical system in the wide angle state (e.g. diaphragm at the focal length f = 40 mm F2) is diaphragm unit B disposed at the rear Is illustrated. In other words, the aperture unit B provided behind the two lens groups is
Motor M via the motor driver
Driven by With respect to the aperture unit B, the front group has positive and negative powers and exhibits negative power as a whole, and thereafter the group exhibits positive power.

Claims (3)

[Claims] 1. An imaging optical system, first aperture means disposed between a first lens in the imaging optical system, and capable of regulating an amount of light passing through the imaging optical system; And a second diaphragm means disposed between the second lenses and capable of regulating the amount of light passing through the photographing optical system. 2. A camera having a photographing optical system capable of switching a focal length, comprising at least three lens groups having different relative movement amounts in the optical axis direction, wherein the camera is disposed between the first lens groups of the photographing optical system. A first aperture means capable of regulating the amount of light passing through the photographing optical system; and a second diaphragm disposed between the second lens group of the photographing optical system and regulating the amount of light passing through the photographing optical system. A lens barrel comprising: a diaphragm unit. 3. The lens barrel according to claim 2, further comprising a diaphragm switching unit that switches and drives the first diaphragm unit or the second diaphragm unit in accordance with the focal length switching. .