JP5504086B2 - Filter switching device - Google Patents

Description

  The present invention relates to a filter switching device for switching filters according to shooting conditions, and more particularly to a filter switching device for switching an infrared filter between daytime and nighttime in an imaging device for continuous shooting day and night.

  In the field of surveillance cameras, there are many requests to install a camera outdoors, and there are also many requests to monitor with the same camera at night as well as at night. As shown in Japanese Patent Application Laid-Open No. 57-119577 (Patent Document 1), the sensitivity curve of an image sensor generally extends to the infrared region more than the sensitivity curve of the human eye. For example, an infrared cut filter is used to take an image in a color mode, and at night, the infrared cut filter is removed from the road and the sensitivity is increased in a black and white mode.

  When the infrared cut filter is removed from the optical path, the entire optical path length changes and the focus shifts. To prevent this, a dummy filter with the same optical path length as the infrared cut filter is inserted in the visible light. Yes. Regarding the configuration of an image pickup apparatus that attempts to pick up a low-illuminance subject with high sensitivity by replacing the infrared cut filter with a dummy filter, JP-A-7-107355 (Patent Document 2) and JP-A-11-239356 (Patent Document) Document 3), Japanese Patent Application Laid-Open No. 2000-162668 (Patent Document 4) and the like.

  Utility Model Registration No. 3147474 (Patent Document 5) discloses an infrared cut switching device aiming at reducing the thickness and size of a mechanism for blocking and transmitting infrared rays and making one component removable. Yes. The infrared cut switching device described in Patent Document 5 is a device in which the size of the device is reduced as compared with the conventional product by downsizing the electric drive portion. However, since the infrared cut switching device described in Patent Document 5 employs a drive system using a rotary magnet, as in the conventional product, the drive portion is still thicker than the filter portion, leading to the device. There are few degrees of freedom in the embedded arrangement. Further, in the case of a drive system using a rotary magnet, rotation output is converted to linear motion, so that it is necessary to bond parts such as arms and levers to the magnet or insert molding. For this reason, there are many concerns such as an increase in mold costs, positioning of the magnet in the NS pole rotation direction, and precautions when handling magnetized products.

JP-A-57-119577 Japanese Unexamined Patent Publication No. 7-107355 Japanese Patent Laid-Open No. 11-239356 JP 2000-162668 A Utility Model Registration No. 3147474

  Therefore, the object of the present invention is to use a system in which the filter is moved directly by a voice coil motor without using a drive system using a rotary magnet, and there is no protrusion in the thickness direction of the drive part, and design flexibility is greatly increased. It is to provide an improved filter switching device.

  As a result of diligent research in view of the above object, the present inventors have found that a voice coil motor constituted by a permanent magnet provided in a holder and an air-core coil provided in a filter member, instead of a rotational drive means. Thus, the present inventors have found that a filter switching device with a small number of parts can be obtained by a method in which the filter member is linearly moved, so that the drive portion does not protrude in the thickness direction.

That is, the filter switching device of the present invention is a filter switching device for switching between blocking and transmission of infrared rays according to shooting conditions,
A holder made of a non-magnetic material having an opening corresponding to the optical path of the imaging device;
A movable filter member made of a non-magnetic material provided with an infrared cut filter, which is slidably arranged in the holder;
In order to put the infrared cut filter in and out of the optical path provided in the holder, it comprises driving means for sliding the movable filter member,
The drive means is a voice coil motor constituted by a permanent magnet provided on at least one side of the opening of the holder and a flat air-core coil provided on the movable filter member. .

  The permanent magnet is provided on both sides of the opening of the holder, and between the pin member made of a magnetic body provided on the movable filter member and the one permanent magnet or the other permanent magnet. Self-holding means for holding the movable filter member in a state where the infrared cut filter is put into or out of the optical path even when the voice coil motor is in a non-energized state due to magnetic attraction force. It is preferable to provide.

  The permanent magnets are preferably magnetized in the thickness direction, and are combined so that magnetic poles of different polarities face the air-core coil.

  It is preferable that a flat yoke made of a ferromagnetic material is provided on the side of the permanent magnet opposite to the air-core coil. It is preferable that a lid made of a ferromagnetic material is provided on the opposite side of the air core coil from the permanent magnet.

  Preferably, the movable filter member includes a dummy filter that transmits infrared rays, and the dummy filter is inserted into the optical path when the infrared cut filter is removed from the optical path.

  In the filter switching device of the present invention, since the drive portion is not protruded in the thickness direction, the degree of freedom in design of other parts and the degree of freedom in assembling arrangement are greatly improved. In addition, since the air core coil is placed directly in the filter section and moved directly, parts such as arms and levers required to convert the drive output from rotation to linear movement are no longer required. In addition, the mold cost can be reduced. Further, it is possible to eliminate thrust loss such as sliding friction when driving output is changed from rotation to linear motion, and power saving can be achieved.

  In the present invention, since the linear motion system is adopted, there is no need for a rotary magnet formed by a parallel magnetic field using a dedicated mold like the rotary drive system that requires a radial magnetic force used in conventional products, and a perpendicular magnetic field is not required. A shaped rectangular parallelepiped magnet can be used. Since a magnet formed by a perpendicular magnetic field has a maximum energy product higher than that of a parallel magnetic field molded product, the linear motion method used in the present invention can save power from the viewpoint of propulsive force and does not require a dedicated mold. Therefore, mold costs can be reduced.

  Since the air-core coil is directly bonded to the filter portion, a dedicated bobbin for the winding or the bearing can be eliminated. This eliminates the need for rotor assembly processing (inside the winding, winding after placing the rotor on the resin bobbin), which is necessary for conventional products, and enables reduction in the number of parts, man-hours, and mold costs. Since the conductive treatment of the winding terminal only needs to be soldered to the flexible board, terminal pins, wiring boards and the like are unnecessary, and the number of parts and man-hours can be reduced.

  Since the driving means is not a rotary type but a direct acting system, a ring-shaped yoke for forming a magnetic closed circuit is not necessary, and a flat-plate yoke can be used. Since this flat yoke can also be used as a lid of a unit that is usually formed of resin or the like, it is possible to reduce the number of parts and molds and the number of assembly steps.

It is the perspective view seen from (a) lid side and (b) the back side showing an example of the filter switching device of the present invention. It is the disassembled perspective view seen from the cover side which shows an example of the filter switching apparatus of this invention. It is the disassembled perspective view seen from the holder side which shows an example of the filter switching apparatus of this invention. It is a front view which shows the positional relationship of the holder of the filter switching apparatus of this invention, and a movable filter member. FIG. 2 is a schematic diagram showing an AA cross section of FIG. It is the disassembled perspective view which looked at the holder and movable filter member of the filter switching apparatus of this invention from the (a) lid side and (b) the back side. It is the perspective view which looked at the holder of the filter switching apparatus of this invention from the (a) lid side and (b) the back side. It is a perspective view which shows the movable filter member of the filter switching apparatus of this invention. It is the perspective view seen from the (a) lid side and (b) the back side which shows an example of the conventional filter switching apparatus. It is the disassembled perspective view seen from the cover side which shows an example of the conventional filter switching apparatus. It is a front view which shows the positional relationship of the holder of a conventional filter switching apparatus, and a movable filter member. FIG. 10 is a schematic view showing a BB cross section of FIG. 9 (a).

<Embodiment>
[1] filter switching device
(1) Overall configuration The filter switching device of the present invention is a filter switching device for switching a filter according to shooting conditions, and is particularly installed in an imaging device for continuous shooting day and night, such as a surveillance camera. It is used as a color camera by removing the infrared cut filter at night and switching to a dummy filter as necessary at night.

  1 to 3 show an example of the filter switching device 1 of the present invention. The filter switching device 1 of the present invention includes a holder 3 having an opening 2 corresponding to an optical path Z of an image pickup device (not shown), and two types of filters 4a, which are slidably disposed on the holder 3. A movable filter member 5 provided with 4b and a lid 6 made of a ferromagnetic material are provided. On both sides of the opening 2 of the holder 3, there are provided magnetic field generating means 9 comprising permanent magnets 7a, 7b and a flat yoke 8 made of a ferromagnetic material, while the movable filter member 5 has a flat air core. The coil 10 is externally fitted. The movable filter member 5 can be slid by a voice coil motor constituted by the magnetic field generating means 9 and the air-core coil 10, and the two types of filters 4a and 4b provided in the movable filter member 5 are provided. Can be switched alternately corresponding to the opening 2 provided in the holder 3 and the lid 6.

  For the purpose of driving the movable filter member 5, the permanent magnets 7 a and 7 b may be provided on only one side of the opening 2 of the holder 3. That is, only the permanent magnet 7a or only the permanent magnet 7b may be used. However, when the self-holding means described later is provided, both the permanent magnets 7a and 7b are required.

  At the boundary between the two types of filters 4a and 4b of the movable filter member 5, a lock pin 11 made of a magnetic material for fixing the movable filter member 5 to the position on the filter 4a side or the position on the filter 4b side. Is provided. An electric wire (not shown) is connected to the air-core coil 10 via a flexible wiring board 12. However, there may be no electric wire (not shown), in which case the flexible wiring board 12 is directly connected to the control board member. The number of parts can be reduced by using the flexible wiring board 12 itself as a conduction means. It is preferable that the air-core coil 10 is directly bonded around the movable filter member 5.

  4 shows a holder 3 having permanent magnets 7a and 7b and a flat yoke 8, a movable filter member 5 having two kinds of filters 4a and 4b, and an air-core coil 10 provided on the movable filter member 5. FIG. Show the relationship. FIG. 5 is a schematic view showing the AA cross section of FIG. 1 (a), and FIG. 6 is an exploded perspective view showing the holder 3 and the movable filter member 5. However, in FIG. 5, a part of the movable filter member 5 and the holder 3 is omitted for simplicity. The movable filter member 5 is arranged so as to be slidable along the longitudinal direction of the holder 3, and the magnetic field generating means 9 comprising the permanent magnets 7 a and 7 b and the flat plate yoke 8 and the air-core coil 10. The filter 4a or the filter 4b can be slid to a position corresponding to the opening 2 by the driving force of the voice coil motor.

  FIG. 4A shows a state where the filter 4a is in a position corresponding to the opening 2 of the holder 3 (a state where the filter 4a is inserted into the optical path), and the filter 4b is the opening 2 of the holder 3. FIG. 4 (b) shows a state corresponding to (a state where the filter 4b is inserted in the optical path). Since the movable filter member 5 can be reciprocated by alternately changing the direction of the current supplied to the air-core coil 10, the filter 4a and the filter 4b can be switched alternately.

  In the filter switching device 1 of the present invention, the air-core coil 10 is not energized by the magnetic attractive force between the lock pin 11 provided on the movable filter member 5 and the permanent magnet 7a or the permanent magnet 7b. Even in the state, the state in which the two types of filters 4a and 4b are switched to either one can be maintained. That is, when the filter 4a is in a position corresponding to the opening 2 (the state shown in FIG. 4 (a)), the attractive force of the permanent magnet 7b acts on the lock pin 11 more strongly. The state shown in FIG. 4 (a) can be maintained even after the supplied current is stopped, and when the filter 4b is in a position corresponding to the opening 2 (state shown in FIG. 4 (b)), the lock Since the attraction force of the permanent magnet 7a acts on the pin 11 more strongly, the state shown in FIG. 4 (b) can be maintained even after the current supplied to the air-core coil 10 is stopped.

(2) Holder As shown in FIG. 7, the holder 3 is a rectangular member made of a non-magnetic material for housing the movable filter member 5, and includes a rectangular opening 2 corresponding to the optical path of the imaging device, A rectangular holding hole 31a, 31b for holding the permanent magnets 7a, 7b on both sides of the opening 2, a holding groove 32 for holding the flat yoke 8, and a movable filter member 5 for slidably supporting the movable filter member 5. Support grooves 33a and 33b are provided. On the side wall of the holder 3, screw holes 34a and 34b for attaching the filter switching device 1 to a casing such as a surveillance camera or a printed board are integrally provided.

  The permanent magnets 7a and 7b are magnetized in the thickness direction, and are combined so that magnetic poles of different polarities face the air core coil 10 provided on the movable filter member 5, and the air core A voice coil motor is formed together with the coil 10.

  As shown in FIG. 2, by providing a flat yoke 8 made of a ferromagnetic material on the side of the permanent magnets 7a, 7b opposite to the air-core coil 10, the thrust by the voice coil motor can be improved. The leakage magnetic flux is reduced, and adverse effects on the members provided around the filter switching device 1 can be prevented. In the present embodiment, the flat yoke 8 is integrated so as to connect both the permanent magnets 7a and 7b. However, two flat yokes 8 are provided so as to correspond to each of the permanent magnets 7a and 7b. It can also be a flat yoke. However, from the viewpoint of improving the thrust by the voice coil motor, an integrated shape is preferable.

(3) Movable filter member As shown in FIG. 8, the movable filter member 5 is formed of a rectangular frame made of a non-magnetic material, and is provided with rectangular holding holes 51a and 51b for holding the filters 4a and 4b, respectively. The holding holes 51a and 51b are provided with spring-like claws 52a and 52b for fixing the filters 4a and 4b. A holding groove 53 for holding the lock pin 11 made of a magnetic material is provided at the boundary between the two types of filters 4a and 4b of the movable filter member 5. Projections for supporting the movable filter member 5 so as to be slidable so as to correspond to the support grooves 33a and 33b provided in the holder 3 on the square of the movable filter member 5 on the side supported by the holder 3 54,54,54,54.

  An air core coil 10 can be externally fitted to the movable filter member 5. The air-core coil 10 can be directly bonded to the movable filter member 5, so that a bobbin for winding is not necessary.

(4) Filter The filters 4a and 4b can be variously combined depending on the purpose, but in the present invention, a combination of an infrared cut filter and a dummy filter that transmits infrared light is preferable. The dummy filter preferably has a refractive index and a thickness so that the optical path length is equal to that of the infrared cut filter. Further, when the dummy filter is not used depending on the purpose, that is, a combination of an infrared cut filter and no filter may be used.

  When the filter switching device is installed on a surveillance camera, etc., it is used as a color camera by switching to an infrared cut filter during the day, and switched to a dummy filter at night (or nothing is used) as a highly sensitive black and white camera. By using it, it can be set as an imaging device for continuous shooting day and night.

(5) Lid The lid 6 is preferably made of a ferromagnetic material. The lid 6 made of a ferromagnetic material functions as a flat yoke. That is, by providing the lid 6 made of a ferromagnetic material, the magnetic field generated from the permanent magnets 7a and 7b is confined inside the filter switching device 1, so that the leakage magnetic flux is reduced and provided around the filter switching device 1. An adverse effect on the formed member can be prevented.

[2] Conventional Filter Switching Device FIGS. 9 to 12 show a conventional filter switching device 101. However, the movable filter member 105 is omitted in FIG. 12 for simplicity. A conventional filter switching device 101 includes a holder 103 having an opening 102 corresponding to an optical path Z of an image pickup device (not shown), and two types of filters 104a and 104b disposed on the holder 103 so as to be slidable. The holder 103 is provided with a motor 108 using a rotary magnet 107, and a lever 109 provided on the rotary magnet 107 of the motor 108 is provided with a movable filter member 105 provided with a lid 106. The movable filter member 105 can be slid to switch the two types of filters 104a and 104b in correspondence with the opening 102 provided in the holder 103 and the lid 106. The holder 103 is provided with a motor housing part 110 for housing the motor 108.

  In the conventional filter switching device 101, the motor storage section 110 is thicker than the other portions, so that the degree of freedom in assembling the device into the device is limited. Further, in the case of a drive system using the rotary magnet 107, it is necessary to convert the rotational output to linear motion, and it is necessary to bond or insert-mold parts such as the lever 109 to the rotary magnet 107. For this reason, there are many concerns such as an increase in mold costs, positioning of the magnet in the NS pole rotation direction, and precautions when handling magnetized products.

  The motor 108 is formed by the rotary magnet 107, a coil 111 for giving a propulsive force to rotate the rotary magnet 107, a bobbin 112 for winding the coil 111, and the rotary magnet 107. In order to make the magnetic circuit to be closed into a closed circuit, a ring-shaped yoke 113 provided on the outer periphery of the rotary magnet 107 is provided.

  Since the coil 111 is structurally required to be wound around the rotary magnet 107, it is necessary to wind the rotary magnet 107 in a state where the rotary magnet 107 is set in the bobbin 112. Become.

  Further, in order to perform the terminal conduction process of the winding, an operation of tying the winding terminal to a terminal pin (not shown) inserted in the bobbin 112 and performing soldering is also necessary. The winding terminal entangled with the terminal pin for the conduction process is inserted into another circuit board and soldered, and the final lead wire is further soldered. This is because the lead wire cannot be soldered directly to the bobbin 112 or the terminal pin due to insufficient heat resistance strength or terminal insertion strength.

  Further, the ring-shaped yoke 113 needs to be manufactured by using a pipe material or trimming after drawing from a flat metal plate, which causes a cost increase.

1 ... Filter switching device 2 ... Opening 3 ... Holder
31a, 31b ・ ・ ・ Holding holes
32 ・ ・ ・ Holding groove
33a, 33b ... support groove
34a, 34b ・ ・ ・ Screw holes
4a, 4b ... Filter 5 ... Movable filter member
51a, 51b ・ ・ ・ Holding holes
52a, 52b ・ ・ ・ Spring claw
53 ・ ・ ・ Holding groove
54 ... Projection 6 ... Lid
7a, 7b ... permanent magnet 8 ... flat yoke 9 ... magnetic field generating means
10 ... Air-core coil
11 ... Lock pin
12 ・ ・ ・ Flexible wiring board
101 ... Conventional filter switching device
102 ... Opening
103 ・ ・ ・ Holder
104a, 104b ・ ・ ・ Filter
105 ・ ・ ・ Movable filter member
106 ・ ・ ・ Lid
107 ・ ・ ・ Rotating magnet
108 ・ ・ ・ Motor
109 ・ ・ ・ Lever
110 ・ ・ ・ Motor storage
111 ・ ・ ・ Coil
112 ・ ・ ・ Bobbins
113 ... York

Claims (4)

A filter switching device for switching between two types of filters according to shooting conditions,
A holder made of a non-magnetic material having an opening corresponding to the optical path of the imaging device;
A movable filter member made of a non-magnetic material provided with two types of filters, slidably arranged in the holder;
In order to alternately replace the two types of filters with the optical path provided in the holder, it comprises driving means for slidingly moving the movable filter member,
The driving means is constituted by flat permanent magnets provided on both sides of the opening of the holder and flat air-core coils provided on the movable filter member, and the permanent magnets are thick. are magnetized in the direction, Ri Oh a voice coil motor different polarities poles of are combined so as to face the air-core coil,
Due to the magnetic attractive force between the pin member made of a magnetic material provided at the boundary between the two types of filters of the movable filter member and the one permanent magnet or the other permanent magnet, the voice coil motor even when it is in non-energized state, the state is switched to either of the two types of filters, a filter switching device according to claim Rukoto with a self-holding means for holding the movable filter member. 2. The filter switching device according to claim 1 , wherein a flat yoke made of a ferromagnetic material is provided on the side of the permanent magnet opposite to the air-core coil. 3. The filter switching device according to claim 1 , wherein a lid made of a ferromagnetic material is provided on a side of the air-core coil opposite to the permanent magnet. 4. The filter switching device according to any one of claims 1 to 3 , wherein the two types of filters are an infrared cut filter and a dummy filter that transmits infrared rays.

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