Patent Description:
<CIT> discloses an anti-vibration optical device with an image blur corrector housed into a housing to be located between an objective lens group and an eyepiece group and including an erecting prism, a supporting mechanism rotatably supporting the erecting prism and an actuator for rotating the erecting prism via the supporting mechanism, an angular velocity detection sensor for detecting an angular velocity of the erecting prism, and a controller for controlling the actuator on the basis of the angular velocity of the erecting prism detected by the angular velocity detection sensor.

In <CIT>, the controller controls the actuator such that the erecting prism is oriented in the same direction as in an initial state.

However, since the arrangement of the erecting prism at a middle position between the objective lens group and the eyepiece group is premised in the anti-vibration optical device described in <CIT>, the controller cannot accurately correct an image blur even if controlling the actuator such that the erecting prism is oriented in the same direction as in the initial state when the erecting prism is arranged other than at the middle position between the objective lens group and the eyepiece group.

Further pertinent prior art is disclosed in <CIT>, <CIT>, <CIT>, <CIT>.

The present invention was developed in view of the above situation and aims to provide an anti-vibration telescope capable of improving a flexibility in the arrangement of an erecting prism and accurately correcting an image blur.

According to the present invention, an anti-vibration telescope according to claim <NUM> is provided.

According to the aspect of the present invention, it is possible to improve a flexibility in the arrangement of the erecting prism and accurately correct an image blur.

The configuration of an anti-vibration optical device according to a first embodiment of the present invention is described with reference to <FIG> below. Throughout this specification, the same elements are denoted by the same reference signs.

<FIG> is a sectional view showing an anti-vibration optical device <NUM> according to the first embodiment of the present invention. <FIG> is a sectional view along line II-II in <FIG>. <FIG> is a configuration diagram showing the configuration of the anti-vibration optical device <NUM>. It should be noted that a longitudinal direction, a width direction and a height direction of the anti-vibration optical device <NUM> are respectively a direction along an X axis, a direction along a Y axis and a direction along a Z axis in figures for the convenience of description.

As shown in <FIG>, the anti-vibration optical device <NUM> is, for example, constituted as a monocular for observing a target. The anti-vibration optical device <NUM> includes a housing <NUM>, an objective lens group <NUM> serving as a first optical element, an eyepiece group <NUM> serving as a second optical element, an image blur corrector <NUM>, a first angular velocity detection sensor <NUM> serving as a first detector, a second angular velocity detection sensor <NUM> serving as a second detector, an operation unit <NUM> and a controller <NUM>. It should be noted that although the anti-vibration optical device <NUM> is constituted as a monocular (specifically, a monocular telescope) in the present embodiment, there is no limitation to this and the anti-vibration optical device <NUM> may be constituted as an imaging device further including an imaging element.

The housing <NUM> is a tubular (specifically, cylindrical) member extending along the longitudinal direction. The objective lens group <NUM>, the eyepiece group <NUM>, the image blur corrector <NUM>, the first angular velocity detection sensor <NUM>, the second angular velocity detection sensor <NUM> and the controller <NUM> are provided in the housing <NUM>.

The objective lens group <NUM> is provided (fixed) on a front side (left side of <FIG>) serving as one side of the housing <NUM> via an annular (specifically, circular annular) objective lens frame <NUM>. The objective lens group <NUM> has a positive refractive power as a whole and is composed of a positive lens G1 and a negative lens G2 successively arranged from an objective side (left side of <FIG>) toward an eyepiece side (right side of <FIG>). An optical axis <NUM> of the objective lens group <NUM> extends along the longitudinal direction through a center of the objective lens group <NUM>. A rear focus <NUM> of the objective lens group <NUM> is formed on an eyepiece side of the objective lens group <NUM>.

The eyepiece group <NUM> is provided (fixed) on a rear side (right side of <FIG>) serving as another side of the housing <NUM> via an annular (specifically, circular annular) eyepiece frame <NUM>. The eyepiece group <NUM> has a positive refractive power as a whole and is composed of a negative lens G3, a positive lens G4 and a positive lens G5 successively arranged from the objective side (left side of <FIG>) toward the eyepiece side (right side of <FIG>). An optical axis <NUM> of the eyepiece group <NUM> extends along the longitudinal direction through a center of the objective lens group <NUM> to overlap the optical axis <NUM> of the objective lens group <NUM>. A front focus <NUM> of the eyepiece group <NUM> is formed on an objective side of the eyepiece group <NUM>.

The objective lens group <NUM> and the eyepiece group <NUM> are so arranged that the rear focus <NUM> and the front focus <NUM> coincide. In this way, if a user observes a target from the eyepiece group <NUM> with the objective lens group <NUM> facing toward the target, a real image of the target formed at the position of the rear focus <NUM> of the objective lens group <NUM> (i.e. the front focus <NUM> of the eyepiece group <NUM>) can be enlarged and observed.

As shown in <FIG> and <FIG>, the image blur corrector <NUM> is an anti-vibration unit for correcting an image blur in the housing <NUM> due to hand shake or the like. The image blur corrector <NUM> is housed into the housing <NUM> to be located between the objective lens group <NUM> and the eyepiece group <NUM>. Further, the image blur corrector <NUM> includes an erecting prism <NUM>, a gimbal mechanism <NUM> serving as a supporting mechanism and an actuator <NUM>.

The erecting prism <NUM> is a prism for converting an inverted image into an erect image. The erecting prism <NUM> is, for example, of the Schmidt-Pechan type and configured to include a roof prism <NUM> and an auxiliary prism <NUM>. It should be noted that the erecting prism <NUM> is not limited to the Schmidt-Pechan type and may be, for example, a Porro type prism, an Abbe-Koenig type prism, a Schmidt prism or an Amici prism. Further, a reflection surface constituting the erecting prism <NUM> may be partially or entirely constituted by a plane mirror.

The gimbal mechanism <NUM> is a supporting mechanism rotatably supporting the erecting prism <NUM>. The gimbal mechanism <NUM> includes an outer frame <NUM> fixed inside the housing <NUM>, an inner frame <NUM> rotatably supported inside the outer frame <NUM> via a first pivot <NUM> extending along the height direction and a prism frame <NUM> rotatably supported inside the inner frame <NUM> via a second pivot <NUM> extending along the width direction. The erecting prism <NUM> is fixed in the prism frame <NUM>.

The erecting prism <NUM> is so arranged that a center of gravity thereof is located on an extension of the first pivot <NUM> and an extension of the second pivot <NUM>. Specifically, the erecting prism <NUM> is so arranged that a center of gravity synthesized by the prism frame <NUM> and the erecting prism <NUM> fixed to the prism frame <NUM> is located on the extension of the second pivot <NUM> and a center of gravity synthesized by the inner frame <NUM>, the prism frame <NUM> and the erecting prism <NUM> supported by the inner frame <NUM> is located on the extension of the first pivot <NUM>. In this way, the erecting prism <NUM> can be rotated with a minimum drive force by the actuator <NUM> (first actuator <NUM>, second actuator <NUM>).

In the present embodiment, the erecting prism <NUM> (specifically, the first and second pivots <NUM>, <NUM>, i.e. the center of gravity of the erecting prism <NUM>) is provided to be located closer to the eyepiece group <NUM> than the objective lens group <NUM>. In this way, an aperture of the objective lens group <NUM> can be increased without enlarging the erecting prism <NUM> as compared to a configuration in which the erecting prism <NUM> is provided at the middle position <NUM> between the objective lens group <NUM> and the eyepiece group <NUM> (i.e. at a position equidistant to the objective lens group <NUM> and the eyepiece group <NUM>, specifically the middle position <NUM> between a rear principal point <NUM> of the objective lens group <NUM> and a front principal point <NUM> of the eyepiece group <NUM>). Further, the weight reduction and miniaturization of the anti-vibration optical device <NUM> can be realized by the miniaturization of the erecting prism <NUM>.

Further, the erecting prism <NUM> (specifically, the first and second pivots <NUM>, <NUM>, i.e. the center of gravity of the erecting prism <NUM>) is preferably provided to be located between the middle position <NUM> between the rear principal point <NUM> of the objective lens group <NUM> and the front principal point <NUM> of the eyepiece group <NUM> and the rear focus <NUM> of the objective lens group <NUM> (front focus <NUM> of the eyepiece group <NUM>).

Further, the erecting prism <NUM> is so set that a resonant frequency thereof has a value between <NUM> and <NUM>. Specifically, the erecting prism <NUM> is so set that the resonant frequency when the prism frame <NUM> and the erecting prism <NUM> rotate about the second pivot <NUM> has a value between <NUM> and <NUM> and the resonant frequency when the inner frame <NUM>, the prism frame <NUM> and the erecting prism <NUM> rotate about the first pivot <NUM> has a value between <NUM> and <NUM>. The resonant frequency is set to have a suitable value since it is largely affected by moments of inertia about the pivots and a spring constant.

It is known that a hand shake frequency is generally in a range of <NUM> to <NUM> when the user uses the anti-vibration optical device <NUM> while holding the anti-vibration optical device <NUM> by hand. To cancel out the hand shake of the user and correct an image blur, the erecting prism <NUM> needs to be rotated in accordance with the hand shake frequency as a result. When the resonant frequency of the erecting prism <NUM> has properties almost close to those of the hand shake frequency of the user, the actuator <NUM> (first actuator <NUM>, second actuator <NUM>) can efficiently correct the image blur with a minimum drive force.

The actuator <NUM> is a driver for rotating the erecting prism <NUM> in two directions via the gimbal mechanism <NUM>. The actuator <NUM> includes the first actuator <NUM> for rotating the inner frame <NUM> about the first pivot <NUM> and the second actuator <NUM> for rotating the prism frame <NUM> about the second pivot <NUM>.

The first actuator <NUM> is a driver mounted between the inside of the outer frame <NUM> and the outside of the inner frame <NUM>. The first actuator <NUM> is configured to include a first coil <NUM> mounted inside the outer frame <NUM>, a first position detection sensor <NUM> mounted inside the outer frame <NUM> to be housed inside the first coil <NUM>, and a first magnet <NUM> mounted outside the inner frame <NUM> to face the first coil <NUM>. By causing a current to flow in the first coil <NUM>, the inner frame <NUM> having the first magnet <NUM> mounted thereon can be rotated about the first pivot <NUM> with respect to the outer frame <NUM>. Relative position information of the first coil <NUM> and the first magnet <NUM> can be detected by the first position detection sensor <NUM>.

The second actuator <NUM> is a driver mounted between the inside of the inner frame <NUM> and the outside of the prism frame <NUM>. The second actuator <NUM> is configured to include a second coil <NUM> mounted inside the inner frame <NUM>, a second position detection sensor <NUM> mounted inside the inner frame <NUM> to be housed inside the second coil <NUM>, and a second magnet <NUM> mounted outside the prism frame <NUM> to face the second coil <NUM>. By causing a current to flow in the second coil <NUM>, the prism frame <NUM> having the second magnet <NUM> mounted thereon can be rotated about the second pivot <NUM> with respect to the inner frame <NUM>. Relative position information of the second coil <NUM> and the second magnet <NUM> can be detected by the second position detection sensor <NUM>.

Although the gimbal mechanism <NUM> is composed of the outer frame <NUM>, the inner frame <NUM> and the prism frame <NUM> in the present embodiment, there is no limitation to this and, for example, the gimbal mechanism <NUM> may be composed only of the outer frame <NUM> fixed inside the housing <NUM> and the prism frame <NUM> rotatably supported inside the outer frame <NUM> via a pivot. In this case, the actuator <NUM> does not include the first and second actuators <NUM>, <NUM> and is composed of a driver mounted between the inside of the outer frame <NUM> and the outside of the prism frame <NUM>.

The first angular velocity detection sensor <NUM> is a two-axis angular velocity detection sensor for detecting a first angular velocity A, which is an angular velocity of the housing <NUM>, specifically an angular velocity corresponding to the inclination of the housing <NUM> due to hand shake or the like. Although the first angular velocity detection sensor <NUM> is mounted inside the housing <NUM> in the present embodiment, there is no limitation to this and, for example, the first angular velocity detection sensor <NUM> may be mounted on the outer frame <NUM>.

The second angular velocity detection sensor <NUM> is a two-axis angular velocity detection sensor for detecting a second angular velocity B, which is an angular velocity of the erecting prism <NUM>, specifically an angular velocity corresponding to the inclination of the erecting prism <NUM>. The second angular velocity detection sensor <NUM> is mounted on the prism frame <NUM>. It should be noted that, in the present embodiment, the first and second angular velocity detection sensors <NUM>, <NUM> are both composed of a gyro sensor using a MEMS technology.

As shown in <FIG>, the operation unit <NUM> is composed of an operation switch for instructing the start or end of an image blur correction process. The operation unit <NUM> outputs an operation signal corresponding to such an operation to the controller <NUM>.

In the present embodiment, as shown in <FIG>, the controller <NUM> controls the actuator <NUM> on the basis of the first angular velocity A output from the first angular velocity detection sensor <NUM> and the second angular velocity B output from the second angular velocity detection sensor <NUM>. However, there is no limitation to this and the controller <NUM> may control the actuator <NUM> on the basis of the first angular velocity A output from the first angular velocity detection sensor <NUM>, the second angular velocity B output from the second angular velocity detection sensor <NUM>, relative positions of the first coil <NUM> and the first magnet <NUM> output from the first position detection sensor <NUM> and relative positions of the second coil <NUM> and the second magnet <NUM> output from the second position detection sensor <NUM>.

The controller <NUM> is composed of a CPU serving as a computer. It should be noted that the controller <NUM> can also be composed of a plurality of microcomputers.

Further, a memory <NUM> is built in the controller <NUM>. The memory <NUM> is a computer-readable recording medium for recording a proportionality coefficient k to be described later. The memory <NUM> records a processing program (e.g. image blur correction process) or an algorithm program to be executed in the controller <NUM>. It should be noted that although the memory <NUM> is built in the controller <NUM> in the present embodiment, there is no limitation to this and, for example, the memory <NUM> may be provided separately from the controller <NUM>.

Next, a binoculars <NUM> provided with the anti-vibration optical devices <NUM> is described with reference to <FIG>.

<FIG> is a sectional view showing the binoculars <NUM> provided with the anti-vibration optical devices <NUM>.

As shown in <FIG>, the binoculars (specifically, binocular telescope) <NUM> includes a pair of the anti-vibration optical devices <NUM>, <NUM> serving as a pair of monoculars (specifically, monocular telescopes), and a coupling member <NUM> coupling the pair of anti-vibration optical devices <NUM>, <NUM>. A pair of the image blur correctors <NUM>, <NUM> are respectively independently provided in the pair of anti-vibration optical devices <NUM>, <NUM>.

In the present embodiment, the pair of anti-vibration optical devices <NUM>, <NUM> include a pair of the first angular velocity detection sensors <NUM>, <NUM> and a pair of the controllers <NUM>, and the pair of controllers <NUM> respectively control a pair of the actuators <NUM>, <NUM> on the basis of the first angular velocities A output from the pair of first angular velocity detection sensors <NUM>, <NUM>. However, the pair of anti-vibration optical devices <NUM> are not limited to this and, for example, a single first angular velocity detection sensor <NUM> may be mounted only on one of the pair of anti-vibration optical devices <NUM> and each controller <NUM> may control each actuator <NUM> on the basis of the first angular velocity A output from the single first angular velocity detection sensor <NUM>. Further, the pair of anti-vibration optical devices <NUM>, <NUM> may include a single controller <NUM>. In this case, the single controller <NUM> controls the pair of actuators <NUM>, <NUM> in parallel on the basis of the first angular velocities A output from the pair of first angular velocity detection sensors <NUM>, <NUM>.

Next, the image blur correction process according to the first embodiment of the present invention is described with reference to <FIG>.

<FIG> is a flow chart showing the image blur correction process according to the first embodiment of the present invention.

First, if the image blur correction process is started by a start operation on the operation unit <NUM> by the user, advance is made to Step S10.

As shown in <FIG>, in Step S10, the first angular velocity detection sensor <NUM> detects the first angular velocity A, which is an angular velocity of the housing <NUM> of the anti-vibration optical device <NUM>. Then, the first angular velocity detection sensor <NUM> outputs the detected first angular velocity A to the controller <NUM>, and advance is made to Step S20.

Subsequently, in Step S20, the controller <NUM> determines whether or not the first angular velocity A output from the first angular velocity detection sensor <NUM> is zero. Return is made to Step S10 if the first angular velocity A is zero (in the case of Yes), i.e. if the housing <NUM> of the anti-vibration optical device <NUM> is not inclined due to hand shake or the like, whereas advance is made to Step S30 if the first angular velocity A is not zero (in the case of No).

Subsequently, in the case of No in Step S20, the second angular velocity detection sensor <NUM> detects the second angular velocity B, which is an angular velocity of the erecting prism <NUM> rotatably supported by the gimbal mechanism <NUM>, in Step S30. Then, the second angular velocity detection sensor <NUM> outputs the detected second angular velocity B to the controller <NUM>, and advance is made to Step S40.

Subsequently, in Step S40, the controller <NUM> controls the actuator <NUM> on the basis of the first angular velocity A output from the first angular velocity detection sensor <NUM> and the second angular velocity B output from the second angular velocity detection sensor <NUM>, and return is made to Step S10.

Specifically, in Step S40, the controller <NUM> controls the actuator <NUM> such that the second angular velocity B is a product of the first angular velocity A and the proportionality coefficient k on the basis of the first angular velocity A output from the first angular velocity detection sensor <NUM>, the second angular velocity B output from the second angular velocity detection sensor <NUM> and the proportionality coefficient k recorded in the memory <NUM> in advance.

Next, why the actuator <NUM> is controlled such that the second angular velocity B is a product of the first angular velocity A and the proportionality coefficient k is described with reference to <FIG>.

<FIG> is a schematic diagram showing why the actuator <NUM> is controlled such that the second angular velocity B is a product of the first angular velocity A and the proportionality coefficient k. It should be noted that a single objective lens and a single eyepiece are respectively shown as the objective lens group <NUM> and the eyepiece group <NUM> in <FIG>.

In <FIG>, a plane extending along the longitudinal direction is referred to as a reference plane <NUM>. The reference plane <NUM> is parallel to an extending direction of the housing <NUM> when the housing <NUM> of the anti-vibration optical device <NUM> is not inclined due to hand shake or the like. As shown in <FIG>, if the housing <NUM> is inclined by a swing angle C in a direction indicated by an arrow <NUM> (i.e. counterclockwise direction) due to hand shake or the like, the controller <NUM> needs to control the actuator <NUM> such that the erecting prism <NUM> is rotated by a rotation angle D in a direction indicated by an arrow <NUM> (i.e. clockwise direction) to correct such hand shake, i.e. to cause a ray incident on the objective lens group <NUM> along a direction parallel to the reference plane <NUM> (longitudinal direction) to be emitted along the longitudinal direction from the eyepiece group <NUM>. It should be noted that the swing angle C is a swing angle of the housing <NUM> with respect to the reference plane <NUM>, and the rotation angle D is a rotation angle of the erecting prism <NUM> with respect to the reference plane <NUM>.

Here, the rotation angle D of the erecting prism <NUM> is a product of the swing angle C of the housing <NUM> and the proportionality coefficient k. The first angular velocity A, which is an angular velocity of the housing <NUM>, detected by the first angular velocity detection sensor <NUM> is a value obtained by differentiating the swing angle C of the housing <NUM> by time. On the other hand, the second angular velocity B, which is an angular velocity of the erecting prism <NUM>, detected by the second angular velocity detection sensor <NUM> is a value obtained by differentiating the rotation angle D of the erecting prism <NUM> by time. Specifically, either of a value obtained by dividing the rotation angle D by the swing angle C and a value obtained by dividing the second angular velocity B by the first angular velocity A is the proportionality coefficient k.

Since the position of the erecting prism <NUM> is located closer to the eyepiece group <NUM> than the objective lens group <NUM> in the present embodiment, the proportionality coefficient k is set to be negative in advance. In this case, the controller <NUM> controls the actuator <NUM> such that the erecting prism <NUM> is rotated in a direction opposite to a swing direction of the housing <NUM> with respect to the reference plane <NUM>.

The proportionality coefficient k is based on relative position-related information of the erecting prism <NUM> with respect to the objective lens group <NUM> and the eyepiece group <NUM>. Specifically, the proportionality coefficient k is known to satisfy the following Equation (<NUM>) from a result of ray tracking. It is assumed that a first distance E is a distance between the objective lens group <NUM> (specifically, the rear principal point <NUM> of the objective lens group <NUM>) and the erecting prism <NUM> (specifically, the first and second pivots <NUM>, <NUM>, i.e. the center of gravity of the erecting prism <NUM>), a second distance F is a distance between the eyepiece group <NUM> (specifically, the front principal point <NUM> of the eyepiece group <NUM>) and the erecting prism <NUM> (specifically, the first and second pivots <NUM>, <NUM>, i.e. the center of gravity of the erecting prism <NUM>) and a third distance G is a distance between the eyepiece group <NUM> (specifically, the front principal point <NUM> of the eyepiece group <NUM>) and the front focus <NUM> of the eyepiece group <NUM> (rear focus <NUM> of the objective lens group <NUM>).

If the first, second and third distances E, F and G are respectively <NUM>, <NUM> and <NUM> as an example of the present embodiment, the proportionality coefficient k is -<NUM>. Thus, if the swing angle C of the housing <NUM> is +<NUM>°, the controller <NUM> controls the actuator <NUM> such that the rotation angle D of the erecting prism <NUM> becomes -<NUM>°.

Although the proportionality coefficient k is set only in accordance with Equation (<NUM>) in the present embodiment, there is no limitation to this and, for example, a correction value due to frictional resistance or the like may be added in view of the frictional resistance or the like during the operation of the gimbal mechanism <NUM> in addition to Equation (<NUM>). In this case, the image blur correction of the housing <NUM> can be more accurately performed.

To correct the hand shake of the swing angle C, i.e. to cause a ray incident on the objective lens group <NUM> along the direction parallel to the reference plane <NUM> to be emitted along the longitudinal direction from the eyepiece group <NUM>, the controller <NUM> controls the actuator <NUM> such that the second angular velocity B, which is an angular velocity of the erecting prism <NUM>, is a product of the first angular velocity A, which is an angular velocity of the housing <NUM>, and the proportionality coefficient k.

From the above, the controller <NUM> controls the actuator <NUM> such that the second angular velocity B is a product of the first angular velocity A and the proportionality coefficient k on the basis of the first angular velocity A output from the first angular velocity detection sensor <NUM>, the second angular velocity B output from the second angular velocity detection sensor <NUM> and the proportionality coefficient k recorded in the memory <NUM> in advance, whereby the image blur correction of the housing <NUM> can be accurately performed by the image blur corrector <NUM> (specifically, the erecting prism <NUM> of the image blur corrector <NUM>) even if the erecting prism <NUM> is provided other than at the middle position <NUM> between the objective lens group <NUM> and the eyepiece group <NUM>. In other words, it is possible to improve a flexibility in the arrangement of the erecting prism <NUM> and accurately correct an image blur.

Finally, the image blur correction process is finished by an end operation on the operation unit <NUM> by the user.

Next, functions and effects by the present embodiment are described.

The anti-vibration optical device <NUM> according to the present embodiment includes the housing <NUM>, the objective lens group <NUM> provided on the one side of the housing <NUM>, the eyepiece group <NUM> provided on the other side of the housing <NUM>, the image blur corrector <NUM> housed into the housing <NUM> to be located between the objective lens group <NUM> and the eyepiece group <NUM> and including the erecting prism <NUM>, the gimbal mechanism <NUM> rotatably supporting the erecting prism <NUM> and the actuator <NUM> for rotating the erecting prism <NUM> via the gimbal mechanism <NUM>, the first angular velocity detection sensor <NUM> for detecting the first angular velocity A, which is an angular velocity of the housing <NUM>, the second angular velocity detection sensor <NUM> for detecting the second angular velocity B, which is an angular velocity of the erecting prism <NUM>, and the controller <NUM> for controlling the actuator <NUM> on the basis of the first and second angular velocities A, B.

According to this configuration, it is possible to improve a flexibility in the arrangement of the erecting prism <NUM> and accurately correct an image blur by using the first angular velocity A, which is an angular velocity of the housing <NUM>, in addition to the second angular velocity B, which is an angular velocity of the erecting prism <NUM>.

Further, according to the invention, the controller <NUM> controls the actuator <NUM> such that the second angular velocity B is a product of the first angular velocity A and the proportionality coefficient k set in advance.

According to this configuration, even if the erecting prism <NUM> is provided other than at the middle position between the objective lens group <NUM> and the eyepiece group <NUM>, the image blur correction of the housing <NUM> can be accurately performed by the image blur corrector <NUM> (specifically, the erecting prism <NUM> of the image blur corrector <NUM>). As a result, it is possible to improve a flexibility in the arrangement of the erecting prism <NUM> and accurately correct an image blur.

In a telescope, an erecting prism needs to be used to convert an inverted image into an erect image. However, since an image blur can be corrected using the provided erecting prism <NUM> in the anti-vibration optical device <NUM> according to the present embodiment, optical elements such as a lens and a mirror need not be separately added. By forming the telescope into the configuration of the anti-vibration optical device <NUM>, there is no longer any limitation in the arrangement position, the size and the like of the erecting prism <NUM>, and application to optical devices of various types is possible. According to the anti-vibration optical device <NUM> relating to the present embodiment, effects such as a larger aperture of the objective lens group <NUM>, a higher magnification, a wider field of view, miniaturization and weight reduction can be obtained.

Further, brightness, resolution and the like, which are important optical performances in the telescope, are characterized to be higher as the aperture of the objective lens group <NUM> becomes larger. In the anti-vibration optical device <NUM>, higher optical performances than conventional art can be obtained.

Since the erecting prism <NUM> can be arranged at an optimal position in the anti-vibration optical device <NUM>, the erecting prism <NUM> needs not be enlarged to take in rays on a peripheral edge part of the objective lens group <NUM>. By miniaturizing the erecting prism <NUM>, the entire shape of the anti-vibration optical device <NUM> can be reduced in size and the weight thereof can be reduced. The miniaturization of the erecting prism <NUM> is desirable also in efficient drive by the actuator <NUM>.

Although the anti-vibration optical device <NUM> includes the housing <NUM>, the objective lens group <NUM>, the eyepiece group <NUM> and the image blur corrector <NUM> in the present embodiment, there is no limitation to this and, for example, the anti-vibration optical device <NUM> may be produced and distributed in the form of a unit including the housing <NUM> and the image blur corrector <NUM> without including the objective lens group <NUM> and the eyepiece group <NUM>.

This unit is not covered by the subject-matter of the claims.

Next, the configuration of an anti-vibration optical device <NUM> according to a second embodiment is described with reference to <FIG>. It should be noted that points similar to those in the above first embodiment are not described and points of difference from the above first embodiment are mainly described.

<FIG> is a sectional view showing the anti-vibration optical device <NUM> according to the second embodiment of the present invention.

Although the objective lens frame <NUM> holding the objective lens group <NUM> and the eyepiece frame <NUM> holding the eyepiece group <NUM> are respectively fixed on the front side of the housing <NUM> and the rear side of the housing <NUM> in the above first embodiment, there is no limitation to this and, for example, an objective lens frame <NUM> and an eyepiece frame <NUM> may be respectively provided on a front side of a housing <NUM> and a rear side of the housing <NUM> movably along a longitudinal direction as shown in <FIG>. In such a case, the zooming or focusing of the anti-vibration optical device <NUM> can be performed by moving at least one of the objective lens group <NUM> and the eyepiece group <NUM> along the longitudinal direction. Of course, the zooming or focusing of the anti-vibration optical device <NUM> may be performed by moving at least some of a plurality of lenses constituting the objective lens group <NUM> or the eyepiece group <NUM> along the longitudinal direction.

In the present embodiment, a third position detection sensor <NUM> for detecting first position information of the objective lens frame <NUM> (i.e. the objective lens group <NUM>) serving as a part of relative position-related information is mounted on the front side of the housing <NUM>. A fourth position detection sensor <NUM> for detecting second position information of the eyepiece frame <NUM> (i.e. the eyepiece group <NUM>) serving as another part of the relative position-related information is mounted on the rear side of the housing <NUM>.

As the first position information of the objective lens group <NUM> detected by the third position detection sensor <NUM> changes according to a movement of the objective lens group <NUM>, a first distance E (see <FIG>) between the objective lens group <NUM> (specifically, a rear principal point <NUM> of the objective lens group <NUM>) and an erecting prism <NUM> (specifically, first and second pivots <NUM>, <NUM>) changes. Specifically, the first distance E is based on the first position information. Similarly, as the second position information of the eyepiece group <NUM> detected by the fourth position detection sensor <NUM> changes according to a movement of the eyepiece group <NUM>, a second distance F (see <FIG>) between the eyepiece group <NUM> (specifically, a front principal point <NUM> of the eyepiece group <NUM>) and the erecting prism <NUM> (specifically, the second and second pivots <NUM>, <NUM>) changes. Specifically, the second distance F is based on the second position information.

Accordingly, a controller <NUM> can calculate an optimal proportionality coefficient kv on the basis of the first position information of the objective lens group <NUM> detected by the third position detection sensor <NUM> and the second position information of the eyepiece group <NUM> detected by the fourth position detection sensor <NUM>. Then, the controller <NUM> controls an actuator <NUM> such that a second angular velocity B detected by a second angular velocity detection sensor <NUM> is a product of a first angular velocity A detected by a first angular velocity detection sensor <NUM> and the calculated optimal proportionality coefficient kv, whereby an image blur can be accurately corrected even if the objective lens group <NUM> or the eyepiece group <NUM> is moved for the zooming or focusing of the anti-vibration optical device <NUM>.

Specifically, the controller <NUM> obtains the first position information and the second position information serving as the relative position-related information and controls the actuator <NUM> on the basis of the first angular velocity A, the second angular velocity B, the first position information and the second position information, whereby an image blur can be accurately corrected by an image blur corrector <NUM> (specifically, the erecting prism <NUM> of the image blur corrector <NUM>) even if the objective lens group <NUM> or the eyepiece group <NUM> is moved for the zooming or focusing of the anti-vibration optical device <NUM>.

Next, an image blur correction process according to the second embodiment of the present invention is described with reference to <FIG>.

<FIG> is a flow chart showing the image blur correction process according to the second embodiment of the present invention. <FIG> is a schematic state diagram showing a state where the erecting prism <NUM> is located closer to the eyepiece group <NUM> than the objective lens group <NUM> by movements of the objective lens group <NUM> and the eyepiece group <NUM>. <FIG> is a schematic state diagram showing a state where the erecting prism <NUM> is located at the middle position <NUM> between the objective lens group <NUM> and the eyepiece group <NUM> by movements of the objective lens group <NUM> and the eyepiece group <NUM>. <FIG> is a schematic state diagram showing a state where the erecting prism <NUM> is located closer to the objective lens group <NUM> than the eyepiece group <NUM> by movements of the objective lens group <NUM> and the eyepiece group <NUM>.

First, if the image blur correction process is started by a start operation on an operation unit <NUM> by a user, advance is made to Step S11.

As shown in <FIG>, in Step S11, the first angular velocity detection sensor <NUM> detects the first angular velocity A, which is an angular velocity of the housing <NUM> of the anti-vibration optical device <NUM>. Then, the first angular velocity detection sensor <NUM> outputs the detected first angular velocity A to the controller <NUM>, and advance is made to Step S21.

Subsequently, in Step S21, the controller <NUM> determines whether or not the first angular velocity A output from the first angular velocity detection sensor <NUM> is zero. Return is made to Step S11 if the first angular velocity A is zero (in the case of Yes), i.e. if the housing <NUM> of the anti-vibration optical device <NUM> is not inclined due to hand shake or the like, whereas advance is made to Step S31 if the first angular velocity A is not zero (in the case of No).

Subsequently, in the case of No in Step S21, the second angular velocity detection sensor <NUM> detects the second angular velocity B, which is an angular velocity of the erecting prism <NUM> rotatably supported by a gimbal mechanism <NUM>, in Step S31. Then, the second angular velocity detection sensor <NUM> outputs the detected second angular velocity B to the controller <NUM>, and advance is made to Step S41.

Subsequently, in Step S41, the third position detection sensor <NUM> detects the first position information of the objective lens group <NUM> and the fourth position detection sensor <NUM> detects the second position information of the eyepiece group <NUM>. Then, the third and fourth position detection sensors <NUM>, <NUM> output the detected first position information and second position information to the controller <NUM>, and advance is made to Step S51.

Subsequently, in Step S51, the controller <NUM> calculates the optimal proportionality coefficient kv on the basis of the first position information output from the third position detection sensor <NUM> and the second position information output from the fourth position detection sensor <NUM>, and advance is made to Step S61.

Specifically, in Step S51, the controller <NUM> calculates the optimal proportionality coefficient kv such that the optimal proportionality coefficient kv is negative when the erecting prism <NUM> is located closer to the eyepiece group <NUM> than the objective lens group <NUM>(see <FIG>). In this case, the controller <NUM> controls the actuator <NUM> such that the erecting prism <NUM> is rotated in a direction opposite to a swing direction of the housing <NUM> with respect to a reference plane <NUM>. Specifically, the controller <NUM> controls the actuator <NUM> such that an absolute value of a relative angle of the erecting prism <NUM> with respect to the housing <NUM> is larger than an absolute value of a swing angle C of the housing <NUM>.

By doing so, an image blur correction in the housing <NUM> can be accurately performed even if the erecting prism <NUM> is located closer to the eyepiece group <NUM> than the objective lens group <NUM>. Thus, an aperture of the objective lens group <NUM> can be increased without enlarging the erecting prism <NUM> as compared to a configuration in which the erecting prism <NUM> is provided at the middle position <NUM> between the objective lens group <NUM> and the eyepiece group <NUM>. Further, the weight reduction and miniaturization of the anti-vibration optical device <NUM> can be realized by the miniaturization of the erecting prism <NUM>.

Further, in Step S51, the controller <NUM> calculates the optimal proportionality coefficient kv such that the optimal proportionality coefficient kv is zero when the erecting prism <NUM> is located at the middle position <NUM> between the objective lens group <NUM> and the eyepiece group <NUM> (see <FIG>). In this case, the controller <NUM> controls the actuator <NUM> such that the erecting prism <NUM> is not rotated with respect to the reference plane <NUM>. Specifically, the controller <NUM> controls the actuator <NUM> such that the absolute value of the relative angle of the erecting prism <NUM> with respect to the housing <NUM> is equal to the absolute value of the swing angle C of the housing <NUM>.

Furthermore, in Step S51, the controller <NUM> calculates the optimal proportionality coefficient kv such that the optimal proportionality coefficient kv is positive when the erecting prism <NUM> is located closer to the objective lens group <NUM> than the eyepiece group <NUM> (see <FIG>). In this case, the controller <NUM> controls the actuator <NUM> such that the erecting prism <NUM> is rotated in the same direction as the swing direction of the housing <NUM> with respect to the reference plane <NUM>. Specifically, the controller <NUM> controls the actuator <NUM> such that the absolute value of the relative angle of the erecting prism <NUM> with respect to the housing <NUM> is smaller than the absolute value of the swing angle C of the housing <NUM>.

By doing so, an image blur correction in the housing <NUM> can be accurately performed even if the erecting prism <NUM> is located closer to the objective lens group <NUM> than the eyepiece group <NUM>. Thus, the relative angle of the erecting prism <NUM> with respect to the housing <NUM> can be made smaller as compared to the configuration in which the erecting prism <NUM> is provided at the middle position <NUM> between the objective lens group <NUM> and the eyepiece group <NUM> or a configuration in which the erecting prism <NUM> is provided closer to the eyepiece group <NUM> than the objective lens group <NUM>. As a result, the power saving of the actuator <NUM> can be realized.

From the above, in Step S51, the controller <NUM> calculates such an optimal proportionality coefficient kv that becomes smaller as the position of the erecting prism <NUM> becomes closer to the eyepiece group <NUM> with respect to the objective lens group <NUM>. For example, the optimal proportionality coefficient kv calculated by the controller <NUM> changes in an order of +<NUM>, <NUM>, -<NUM>, -<NUM>, -<NUM> and -<NUM>. In other words, in Step S51, the controller <NUM> calculates such an optimal proportionality coefficient kv that becomes larger as the position of the erecting prism <NUM> becomes closer to the objective lens group <NUM> with respect to the eyepiece group <NUM>.

Although a calculation method (i.e. a setting method) of the optimal proportionality coefficient kv has been described above, such a setting method may be directly applied to the setting of the proportionality coefficient k of the first embodiment.

Subsequently, in Step S61, the controller <NUM> controls the actuator <NUM> on the basis of the first angular velocity A output from the first angular velocity detection sensor <NUM>, the second angular velocity B output from the second angular velocity detection sensor <NUM> and the calculated optimal proportionality coefficient kv, and return is made to Step S11.

Specifically, in Step S61, the controller <NUM> controls the actuator <NUM> such that the second angular velocity B output from the second angular velocity detection sensor <NUM> is a product of the first angular velocity A output from the first angular velocity detection sensor <NUM> and the optimal proportionality coefficient kv, and return is made to Step S11. Accordingly, an image blur can be accurately corrected by the image blur corrector <NUM> (specifically, the erecting prism <NUM> of the image blur corrector <NUM>) even if the objective lens group <NUM> or the eyepiece group <NUM> is moved for the zooming or focusing of the anti-vibration optical device <NUM>.

Although Steps S31, S41 and S51 are sequentially performed in the present embodiment, there is no limitation to this and, for example, a sequence of Steps S31 and S41 may be exchanged or Steps S31 and S41 may be simultaneously performed. In these cases, Step S51 may be performed after Step S41.

Further, although the objective lens frame <NUM> and the eyepiece frame <NUM> are respectively provided on the front side of the housing <NUM> and on the rear side of the housing <NUM> movably along the longitudinal direction in the present embodiment, there is no limitation to this and, for example, either one of the objective lens frame <NUM> and the eyepiece frame <NUM> may be provided movably along the longitudinal direction in the housing <NUM>. In this case, only the third or fourth position detection sensor <NUM>, <NUM> corresponding to the objective lens frame <NUM> or the eyepiece frame <NUM> movably provided in the housing <NUM> may be mounted on the front or rear side of the housing <NUM>.

Next, the configuration of an anti-vibration optical device <NUM> according to a third embodiment is described with reference to <FIG>. It should be noted that points similar to those in the above second embodiment are not described and points of difference from the above second embodiment are mainly described.

<FIG> is a sectional view showing the anti-vibration optical device <NUM> according to the third embodiment of the present invention.

Although the third and fourth position detection sensors <NUM>, <NUM> are mounted in the housing <NUM> in the above second embodiment, there is no limitation to this and, for example, a distance detection sensor (e.g. a laser distance detection sensor) <NUM> as shown in <FIG> may be mounted instead of the third and fourth position detection sensors <NUM>, <NUM>.

The distance detection sensor <NUM> is a sensor for detecting distance information between a target and the anti-vibration optical device <NUM>. As the distance information detected by the distance detection sensor <NUM> changes, a first distance E or/and a second distance F change(s). Specifically, the first distance E or/and the second distance F is/are based on the distance information.

Accordingly, a controller <NUM> can calculate an optimal proportionality coefficient kv on the basis of the distance information detected by the distance detection sensor <NUM>. Then, the controller <NUM> controls an actuator <NUM> such that a second angular velocity B detected by a second angular velocity detection sensor <NUM> is a product of a first angular velocity A detected by a first angular velocity detection sensor <NUM> and the calculated optimal proportionality coefficient kv, whereby an image blur can be accurately corrected even if an objective lens group <NUM> or an eyepiece group <NUM> is moved for the zooming or focusing of the anti-vibration optical device <NUM>.

Specifically, the controller <NUM> obtains the distance information serving as relative position-related information and controls the actuator <NUM> on the basis of the first angular velocity A, the second angular velocity B and the distance information, whereby an image blur can be accurately corrected by an image blur corrector <NUM> (specifically, an erecting prism <NUM> of the image blur corrector <NUM>) even if the objective lens group <NUM> or the eyepiece group <NUM> is moved for the zooming or focusing of the anti-vibration optical device <NUM>.

Next, the configuration of an anti-vibration optical device <NUM> according to a fourth embodiment is described. It should be noted that points similar to those in the above second embodiment are not described and points of difference from the above second embodiment are mainly described.

Although the third and fourth position detection sensors <NUM>, <NUM> are mounted in the housing <NUM> in the above second embodiment, there is no limitation to this and, for example, a changeover switch (not shown) may be mounted instead of the third and fourth position detection sensors <NUM>, <NUM>.

A user can switch the changeover switch according to a distance between a target and the anti-vibration optical device <NUM>. If an objective lens group <NUM> or/and an eyepiece group <NUM> is/are moved in a front-rear direction to change the distance between the target and the anti-vibration optical device <NUM>, a first distance E or/and a second distance F change(s).

Accordingly, the controller <NUM> can calculate an optimal proportionality coefficient kv on the basis of distance information by the changeover switch. Then, the controller <NUM> controls an actuator <NUM> such that a second angular velocity B detected by a second angular velocity detection sensor <NUM> is a product of a first angular velocity A detected by a first angular velocity detection sensor <NUM> and the calculated optimal proportionality coefficient kv, whereby an image blur can be accurately corrected even if the objective lens group <NUM> or the eyepiece group <NUM> is moved for the zooming or focusing of the anti-vibration optical device <NUM>.

Next, the configuration of an anti-vibration optical device <NUM> according to a fifth embodiment is described with reference to <FIG> and <FIG>. It should be noted that points similar to those in the above first embodiment are not described and points of difference from the above first embodiment are mainly described.

<FIG> is a sectional view showing the anti-vibration optical device <NUM> according to the fifth embodiment of the present invention. <FIG> is a schematic diagram showing the anti-vibration optical device <NUM> according to the fifth embodiment of the present invention. It should be noted that a single objective lens and a single eyepiece are respectively shown as an objective lens group <NUM> and an eyepiece group <NUM> in <FIG>.

As shown in <FIG> and <FIG>, a reticle <NUM> is installed at the position of a rear focus <NUM> of the objective lens group <NUM> in the anti-vibration optical device <NUM>. The reticle <NUM> is such that crosshairs, scales and the like engraved in a transparent plate material. In this way, the anti-vibration optical device <NUM> can be used as a sight and can measure a distance between a target and the anti-vibration optical device <NUM>, a viewing angle and the like.

If a user uses the anti-vibration optical device <NUM> while holding the anti-vibration optical device <NUM> by hand, a housing <NUM> may be inclined upward, downward, leftward or rightward by the user's hand shake. If the housing <NUM> is so inclined that the objective lens group <NUM> faces downward, a controller <NUM> controls an actuator <NUM> such that a rotation angle D (second angular velocity B) of an erecting prism <NUM> is a product of a swing angle C (first angular velocity A) of the housing <NUM> and a proportionality coefficient k. In this way, a ray incident on the objective lens group <NUM> in an X-axis direction of <FIG> from a target passes through the rear focus <NUM> (center position of the reticle <NUM>) of the objective lens group <NUM> after passing through the erecting prism <NUM>. Although inclination in a vertical direction (rotating direction about a Y-axis in <FIG>) is described here, the same applies also to inclination in a lateral direction (rotating direction about a Z-axis in <FIG>).

The controller <NUM> controls the actuator <NUM> such that the rotation angle D (second angular velocity B) of the erecting prism <NUM> is a product of the swing angle C (first angular velocity A) of the housing <NUM> and the proportionality coefficient k, whereby the ray incident on the objective lens group <NUM> passes through the rear focus <NUM> (center position of the reticle <NUM>) of the objective lens group <NUM> without being shifted. As a result, the user observing the target can observe a corrected image without a target image being shifted on the reticle <NUM> even if the housing <NUM> vibrates due to hand shake.

In the present embodiment, the proportionality coefficient k is known to satisfy the following Equation (<NUM>) from a result of ray tracking. It is assumed that a first distance E is a distance between the objective lens group <NUM> (specifically, a rear principal point <NUM> of the objective lens group <NUM>) and the erecting prism <NUM> (specifically, first and second pivots <NUM>, <NUM>) and a fourth distance H is a distance between the erecting prism <NUM> (specifically, the first and second pivots <NUM>, <NUM>) and the rear focus <NUM> of the objective lens group <NUM> (see <FIG>).

If the first and fourth distances E, H are respectively <NUM> and <NUM> as an example of the present embodiment, the proportionality coefficient k is -<NUM>. Thus, if the swing angle C of the housing <NUM> is +<NUM>°, the controller <NUM> controls the actuator <NUM> such that the rotation angle D of the erecting prism <NUM> becomes -<NUM>°.

In the anti-vibration optical device <NUM>, a light emitting element may be installed at the position of the rear focus <NUM> of the objective lens group <NUM>. For example, by installing a light emitting device at the position of the rear focus <NUM> of the objective lens group, light can be irradiated to a target without being shifted even if the housing <NUM> vibrates due to hand shake. In the anti-vibration optical device <NUM>, a light receiving element may be installed at the position of the rear focus <NUM> of the objective lens group <NUM>. For example, by installing a light receiving device at the position of the rear focus <NUM> of the objective lens group, light emitted from the target can be received without being shifted even if the housing <NUM> vibrates due to hand shake.

In the anti-vibration optical device <NUM>, the reticle <NUM> installed at the position of the rear focus <NUM> of the objective lens group <NUM> may be constituted by a transmission-type liquid crystal display. In this case, the user can observe necessary information and the like simultaneously with an image of a target.

In the anti-vibration optical device <NUM>, the reticle <NUM> installed at the position of the rear focus <NUM> of the objective lens group <NUM> may be installed at a position away from the rear focus <NUM> of the objective lens group <NUM> and optically projected to the position of the rear focus <NUM> of the objective lens group <NUM> by a lens or the like.

Next, the configuration of an anti-vibration optical device <NUM> according to a sixth embodiment is described with reference to <FIG>. It should be noted that points similar to those in the above first embodiment are not described and points of difference from the above first embodiment are mainly described.

<FIG> is a sectional view showing the anti-vibration optical device <NUM> according to the sixth embodiment of the present invention.

Although the anti-vibration optical device <NUM> is constituted by a monocular in the above first embodiment, there is no limitation to this and, for example, the anti-vibration optical device <NUM> may be constituted by a binoculars (specifically, binocular telescope) as shown in <FIG>. In this case, the binoculars <NUM> includes a pair of monoculars (specifically, monocular telescopes) <NUM>, <NUM> provided in parallel and a housing <NUM> in which the pair of monoculars <NUM>, <NUM> are provided.

The pair of monoculars <NUM>, <NUM> include a pair of objective lens groups <NUM>, <NUM>, a pair of eyepiece groups <NUM>, <NUM> and a common single image blur corrector <NUM>. The image blur corrector <NUM> includes a pair of erecting prisms <NUM>, <NUM> and a single gimbal mechanism <NUM>. The gimbal mechanism <NUM> includes an outer frame <NUM> fixed inside a housing <NUM>, an inner frame <NUM> rotatably supported inside the outer frame <NUM> via a first pivot <NUM> extending along a Z-axis direction and a prism frame <NUM> rotatably supported inside the inner frame <NUM> via a second pivot <NUM> extending along a Y-axis direction.

Claim 1:
An anti-vibration telescope (<NUM>), comprising:
a housing (<NUM>);
a first optical element (<NUM>) provided on one side of the housing (<NUM>);
a second optical element (<NUM>) provided on another side of the housing (<NUM>);
an image blur corrector (<NUM>) housed into the housing (<NUM>) to be located between the first optical element (<NUM>) and the second optical element (<NUM>), the image blur corrector (<NUM>) including an erecting prism (<NUM>), a supporting mechanism (<NUM>) rotatably supporting the erecting prism (<NUM>) and an actuator (<NUM>) for rotating the erecting prism (<NUM>) via the supporting mechanism (<NUM>);
a first detector (<NUM>) configured to detect a first angular velocity, the first angular velocity being an angular velocity of the housing (<NUM>);
a second detector (<NUM>) configured to detect a second angular velocity, the second angular velocity being an angular velocity of the erecting prism (<NUM>); and
a controller (<NUM>) configured to control the actuator (<NUM>) on the basis of the first angular velocity detected by the first detector (<NUM>) and the second angular velocity detected by the second detector (<NUM>),
the controller (<NUM>) is further configured to control the actuator (<NUM>) such that the second angular velocity is a product of the first angular velocity and a proportionality coefficient set in advance.