Light control apparatus

The apparatus includes an upper substrate and a lower substrate, each of which has an optical aperture, at least one light control unit, a spacer arranged between the upper substrate and the lower substrate to provide a space in which the light control unit can move, and a drive unit arranged on the upper substrate to drive the light control unit. The drive unit includes a magnet arranged at a center of rotation of the light control unit and an electromagnetic drive source including a coil core and a winding coil, the coil core being arranged in such a way as to be opposed to the magnet. A positioning member is provided on the upper substrate. The distance between the coil core and the magnet is kept constant by the positioning member.

TECHNICAL FIELD

The present invention relates to a light control apparatus.

BACKGROUND ART

With improvements in the performance of portable devices having an image pickup function and small-size optical apparatuses such as micro video scopes in recent years, there are demands for improvements of the optical components such as lenses, stops and optical filters used therein. Specifically, there are increasing demands for replacement of conventional fixed focal length lenses, fixed aperture stops, and optical filters having fixed characteristics respectively with adjustable focus lenses, variable stops, and optical filters having variable characteristics, and various techniques for reducing the sizes of optical components used in small-size image pickup devices have been developed.

FIG. 9is a plan view showing the construction of a conventional electromagnetic driving apparatus. In the electromagnetic driving apparatus shown inFIG. 9, which is taught by patent literature 1, a taking lens902is held by a base plate901, and a coil core (yoke)903arranged around the taking lens902and a magnet (permanent magnet)905forma closed magnetic circuit. The two ends903a,903bof the coil core903are opposed to the magnet905. A winding coil904for energizing is wound around the coil core903. The arrangement of the winding coil on the base plate in this construction allows a reduction in the diameter of the apparatus.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

The present invention provides a light control apparatus characterized by comprising: an upper substrate and a lower substrate, each of which has an optical aperture; at least one light control unit; a spacer arranged between the upper substrate and the lower substrate to provide a space in which the light control unit can move; and a drive unit arranged on the upper substrate to drive the light control unit, wherein the drive unit includes a magnet arranged at a center of rotation of the light control unit and an electromagnetic drive source including a coil core and a winding coil, the coil core being arranged in such a way as to be opposed to the magnet, a positioning member is provided on the upper substrate, the distance between the coil core and the magnet is kept constant by the positioning member.

In the light control apparatus according to the present invention, it is preferred that the positioning member restrict the position of the coil core in a direction in the plane of the upper substrate.

In the light control apparatus according to the present invention, it is preferred that the positioning member include two positioning members.

In the light control apparatus according to the present invention, it is preferred that the positioning member include a projection provided on the upper substrate and a hole provided in a portion of the coil core, and that positioning be attained by fitting the projection into the hole of the coil core.

In the light control apparatus according to the present invention, it is preferred that the positioning member include a projection extending along an optical axis direction on the upper substrate and exist on both sides of the magnet, and that positioning of the coil core be attained by abutting the coil core on a side surface of the positioning member.

In the light control apparatus according to the present invention, it is preferred that the projection of the positioning member be arranged in the vicinity of the magnet.

In the light control apparatus according to the present invention, it is preferred that the projection of the positioning member be made of a magnetic material.

ADVANTAGEOUS EFFECTS OF INVENTION

The light control apparatus according to the present invention is advantageous in that the distances between the magnet and the two ends of the coil core are uniform to enable stable operation.

DESCRIPTION OF EMBODIMENTS

In the following, embodiments of the light control apparatus according to the present invention will be described in detail with reference to the drawings. It should be understood that the embodiments described in the following are not intended to limit the present invention.

In the following, the basic construction of a light control apparatus will be described with reference toFIGS. 1 and 2.FIGS. 1 and 2show the basic construction of a light control apparatus100.FIG. 1is an exploded perspective view, andFIG. 2is a perspective view of the light control apparatus100in the assembled state.

The light control apparatus100includes an upper substrate111having an optical aperture112and a rotary shaft hole113, a lower substrate121having an optical aperture122and a rotary shaft hole123, a drive blade131serving as alight control unit on which an incident light control member133is arranged, a spacer141arranged between the upper substrate111and the lower substrate121to provide a space allowing rotation of the drive blade131, and an electromagnetic drive source150that rotationally drives the drive blade131.

The upper substrate111and the lower substrate121are arranged in order along an optical axis AX in such a way that the optical aperture112provided at the center of the upper substrate111and the optical aperture122provided at the center of the lower substrate121are arranged concentrically on the optical axis AX.

A magnet132functioning as a rotary shaft132is directly attached to the rotational center of the drive blade131. The drive blade131is arranged between the upper substrate111and the lower substrate121. The magnet132is magnetized in a radial direction. The lower end part of the magnet132is fitted in the rotary shaft hole123of the lower substrate121, and the upper end part of the magnet132passes through the rotary shaft hole113of the upper substrate111so that the magnet132extends along the optical axis AX.

The incident light control member133is, for example, a lens or a filter. The incident light control member133may be constructed as a stop having an optical aperture instead of a lens or a filter.

The electromagnetic drive source150includes a substantially rectangular U-shaped coil core (yoke)153and winding coils151,152wound thereon. Two end parts154,155of the coil core153are opposed to each other. The electromagnetic drive source150is arranged on the upper substrate111in such a way as to surround the optical aperture112. The upper part of the magnet132passing through the rotary shaft hole113is located between and opposed to the two end parts154,155of the coil core153.

The electromagnetic drive source150and the magnet132constitute a drive unit. In this drive unit, since the coil core153and the magnet132form a closed magnetic circuit, a strong magnetic force is generated. The drive blade131is driven by the drive unit. More specifically, as certain currents are supplied to the winding coils151,152, the magnet132disposed between the end parts154,155rotates about its axis . This rotation causes the drive blade131to swing about the magnet132between a first stopping position and a second stopping position in a plane perpendicular to the direction of the optical axis AX to change the position of the incident light control member133.

When the drive blade131is at the first stopping position, the incident light control member133is located at a position at which it is kept away from the optical aperture112of the upper substrate111and the optical aperture122of the lower substrate121. In this state, the drive blade131abuts on the inner wall of the spacer141to be kept stationary at the position. In this state, light incident on the optical aperture is not controlled regulated by the light control member133.

On the other hand, when the drive blade131is at the second stopping position, the incident light control member133is located at a position at which it overlaps the optical aperture112of the upper substrate111and the optical aperture122of the lower substrate121. In this state, the drive blade131abuts on the inner wall of the spacer141to be kept stationary at the position. In this state, light incident on the optical aperture is controlled or regulated by the light control member133.

FIGS. 3 and 4show the construction of a light control apparatus200according to a first embodiment.FIG. 3is a plan view, andFIG. 4is a perspective view.

The light control apparatus200according to the first embodiment includes two positioning members261,262in addition to the structure of the light control apparatus100shown inFIGS. 1 and 2. In the following description, the components same as those in the basic construction of the light control apparatus100will be denoted by the same reference characters and will not be described in further detail.

As with the electromagnetic drive source150in the basic construction, an electromagnetic drive source250in the first embodiment includes a substantially rectangular U-shaped coil core (yoke)253and winding coils251,252wound thereon. Two end parts254,255of the coil core253are opposed to each other. The electromagnetic drive source250is arranged on the upper substrate111in such a way as to surround the optical aperture112. The upper part of the magnet132passing through the rotary shaft hole113is located between and opposed to the two end parts254,255of the coil core153.

The positioning members261,262in the form of two projections extending along the optical axis AX are fixed to the upper substrate111. The positioning members261,262are fitted in positioning holes256,257provided in the portion of the coil core253on which winding coils are not wound, at positions distant from the magnet132. It is preferred that the positioning members261,262be made of a magnetic material, because the use of the positioning members261,262made of a magnetic material do not lead to a decrease in the magnetic fluxes generated by the electromagnetic drive source250, enabling stable driving.

In this configuration, the coil core253and the upper substrate111are in engagement with each other, whereby the position of the coil core253is restricted in directions in the plane of the upper substrate111. In consequence, the distances between the magnet132and the end parts254,255of the coil core253can be kept constant. In other words, the distance L1between one end part254and the magnet132can be kept to be equal to the distance L2between the other end part255and the magnet132, and this relationship can be maintained.

The constant distances between the magnet132and the end parts254,255of the coil core253make the rotational force acting on the magnet132uniform, enabling the drive blade131to rotate stably. Moreover, since positioning of the coil core253and the magnet132can be attained only by the fitting of the positioning members261,262, assembly of the apparatus can be made easy.

FIGS. 5 and 6show the construction of a light control apparatus300according to a second embodiment.FIG. 5is a plan view, andFIG. 6is a perspective view.

The light control apparatus300according to the second embodiment differs from the light control apparatus200according to the first embodiment in that two positioning members361,362are provided in the vicinity of the magnet132. Apart from this, the construction of the light control apparatus300is the same as the light control apparatus200according to the first embodiment, and the same components will be denoted by the same reference characters and will not be described in further detail.

The positioning members361,362are provided in the form of two walls on the upper substrate111, between which the magnet132is located. The positioning members361,362extend along the optical axis AX and are opposed to each other with the distances between the magnet132and them being equal to each other.

As described above, since the distances between the positioning members361,362and the magnet132are determined beforehand, the distance between the magnet132and the coil core153can be kept constant by abutting the end parts154,155on the sides of the positioning members361,362respectively. In the case of the light control apparatus according to the first embodiment, it is necessary that not only the positioning members261,262but also the holes256,257of the coil core253be made at high precision. In contrast, in the case of the light control apparatus according to the second embodiment, the distance between the magnet132and the coil core153is determined directly only by the positioning members361,362, and therefore more stable driving can be expected.

The construction, operations, and advantages other than those described above are the same as those of the first embodiment.

FIGS. 7 and 8show the construction of a light control apparatus400according to a third embodiment.FIG. 7is a plan view, andFIG. 8is a perspective view.

The light control apparatus400according to the third embodiment differs from the light control apparatus200according to the first embodiment in that two positioning members461,462are provided in the vicinity of the magnet132. Apart from this, the construction of the light control apparatus400is the same as the light control apparatus200according to the first embodiment, and the same components will be denoted by the same reference characters and will not be described in further detail.

As with the basic construction of the electromagnetic drive source150, an electromagnetic drive source450in the third embodiment includes a substantially rectangular U-shaped coil core (yoke)453and winding coils451,452wound thereon. Two end parts454,455of the coil core453are opposed to each other. The electromagnetic drive source450is arranged on the upper substrate111in such a way as to surround the optical aperture112. The upper part of the magnet132passing through the rotary shaft hole113is located between and opposed to the two end parts454,455of the coil core453.

The positioning members461,462are provided as two projections on the upper substrate111, between which the magnet132is located. The positioning members461,462extend along the optical axis AX and are opposed to each other with the distances between the magnet132and them being equal to each other. The positioning members461,462are fitted in positioning holes456,457provided in the portion of the coil core453on which winding coils are not wound, at positions near the magnet132.

Positioning of the coil core453and the magnet132can be attained by engagement of the coil core453with the positioning members461,462. Since the positioning members461,462are arranged in the vicinity of the magnet132, the distance between the coil core453and the magnet132can be maintained more precisely, enabling more stable operations.

The construction, operations, and advantages other than those described above are the same as those of the first embodiment.

INDUSTRIAL APPLICABILITY

As described above, the light control apparatus according to the present invention is useful as a small-size optical component used in a small-size image pickup apparatus.

REFERENCE SIGNS LIST