JP2009014912A - On-vehicle camera having two focal distances - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an on-vehicle camera having two focal distances which is strong against vibration and impact and stably holds a lens at positions of two focal distances. <P>SOLUTION: The on-vehicle camera having two focal distances is equipped with a camera body 10 and a lens part 11. The lens part 11 is equipped with a first electromagnet 13 on an imager side and a second electromagnet 14 on a subject side along an optical axis O, and a movable element 12 freely moving along the optical axis O between the electromagnets. The movable element 12 is equipped with a movable lens 18. The camera body 10 is equipped with a timing pulse generation circuit 16 applying driving pulses to the first electromagnet 13 and the second electromagnet 14. By changing the polarity of the driving pulse, the movable element 12 is moved to the first electromagnet 13 side or the second electromagnet 14 side by magnetic attractive force and magnetic repulsive force. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an in-vehicle camera mounted on a moving body such as a vehicle, and more particularly to an in-vehicle camera having two focal lengths of wide angle and telephoto.

  The in-vehicle camera is provided to image the front of the vehicle while driving to detect objects such as preceding vehicles, people, and obstacles, and is connected to an electronic control unit (Electronic Control Unit). Used for inter-vehicle distance control.

  An in-vehicle camera includes a solid-state imaging device and a lens, but there is a need to image a distant object and a wide angle near the front (middle and short distance) depending on the situation during travel. For example, when driving on a highway at high speed or driving at night, it is highly necessary to focus on an object at a distance, and when driving at a low speed on a general road, focus on an object in a wide-angle field of view at a medium or short distance. Therefore, the necessity for imaging becomes higher. Therefore, it is necessary to change the focal length of the camera for “telephoto” (long focal length) and “wide angle” (short focal length) depending on the situation during traveling. As methods for meeting this requirement, a method of simply installing two in-vehicle cameras having different focal lengths in a vehicle and a method using a zoom lens (Patent Document 1) have been proposed.

In addition, a camera having two focal lengths for setting the in-focus position to two positions has been proposed (Patent Document 2). In this camera, a movable iron piece is attached to a lens barrel to which a lens is fixed, and a return spring is attached to the movable iron piece, and when it is used for a “wide angle”, the movable iron piece is resisted by the electromagnetic force of the electromagnet against the spring force of the return spring. When moving away from the shutter portion and for “telephoto”, the driving of the electromagnet is stopped and the movable iron piece is brought closer to the shutter portion by the spring force of the return spring. As described above, the return focal length and the electromagnet are used to easily set the two focal lengths by moving the lens barrel on which the lens is fixed to the “telephoto” position and the “wide angle” position.
JP 62-254652 A JP 11-72693 A

  However, in the method of installing two in-vehicle cameras having different focal lengths in the vehicle, two cameras are required, so that there is a problem that the cost is increased and the installation space is increased. Further, the camera disclosed in Patent Document 1 has a problem that the cost is increased and the mechanism is complicated. In particular, the mechanism for fixing the set focal length is complicated, and the focal position may fluctuate due to the influence of vibration and shock in an in-vehicle environment. The camera disclosed in Patent Document 2 is advantageous in terms of cost, but has a problem that it is vulnerable to vibration and impact because it holds the position of the lens barrel to which the lens is fixed using a return spring.

  An object of the present invention is to provide an in-vehicle camera having two focal lengths that is resistant to vibration and impact and can stably hold a lens at a position of two focal lengths.

The in-vehicle camera having two focal lengths of the present invention includes a first electromagnet and a second electromagnet arranged at two positions along the optical axis,
A movable lens and a permanent magnet attached, and a movable element attached to be movable along the optical axis between the first electromagnet and the second electromagnet;
An electromagnet driving section for applying a driving pulse to the first electromagnet and the second electromagnet;
It has.

  When the camera focal length is set to the first focal length, the electromagnet driving section applies a drive pulse as shown in (A) below, and when the camera focal length is set to the second focal length, A drive pulse is applied as follows.

(A) A driving pulse is applied to the electromagnet so that the electromagnet has a polarity for attracting the first permanent magnet, and the electromagnet is in contact with the second permanent magnet. A drive pulse is applied so as to have a polarity that repels the magnet.

(B) A driving pulse is applied to the electromagnet so that the electromagnet has a polarity repelling the first permanent magnet, and the electromagnet is applied to the second permanent magnet. A drive pulse is applied so as to have a polarity for attracting the magnet.

  When the camera focal length is set to the first focal length, the following operation is performed.

  When a driving pulse is applied to the first electromagnet in the electromagnet driving unit so as to have a polarity that attracts the permanent magnet (referred to as a first state), the permanent magnet in the movable element magnetically attracts from the first electromagnet. Received and attracted. At the same time, in the first state, the drive pulse is applied to the second electromagnet so that the permanent magnet has a repulsive polarity, so that the permanent magnet in the movable element receives a magnetic repulsive force from the second electromagnet. Pulled apart. As a result, the movable element moves at a high speed toward the first electromagnet by a strong attraction force with respect to the first electromagnet, and is attracted to the first electromagnet. In this state, the camera focal length is the first focal length.

  When the camera focal length is set to the second focal length, the following operation is performed.

  In the first state, when a driving pulse having the opposite polarity to the first electromagnet and the second electromagnet is applied (referred to as the second state), the permanent magnet in the movable element is attracted to the second electromagnet. And receives a repulsive force from the first electromagnet. As a result, the movable element moves at a high speed toward the second electromagnet by a strong attracting force with respect to the second electromagnet, and is attracted to the second electromagnet. In this state, the camera focal length is the second focal length.

  Thus, the holding position of the movable lens can be set to one of two positions (a first position where the permanent magnet is attracted to the first electromagnet and a second position where the permanent magnet is attracted to the second electromagnet). As a result, the focal length of the camera is set to one of two sizes according to their positions.

  In the present invention, the first state (first focal length) and the second state (second focal length) are changed by changing the applied polarity of the drive pulse for the first electromagnet and the second electromagnet. ) Can be set arbitrarily. In each state, the permanent magnet is magnetically attracted to and held by either the first electromagnet or the second electromagnet (bistable), so that it is resistant to vibration and impact.

  In this invention, when the permanent magnet is attracted to the first electromagnet or the second electromagnet, it is possible to perform control to stop the application of the drive pulse. By controlling in this way, useless current consumption is eliminated.

  In another embodiment of the present invention, a plurality of the first electromagnets and the second electromagnets are arranged around the optical axis, and the permanent magnets are arranged around the optical axis as the first electromagnet and the second electromagnet. A plurality are arranged so as to face each other. Moreover, they are arranged at equal intervals.

  In still another embodiment of the present invention, the first electromagnet and the second electromagnet may be changed to a first permanent magnet and a second permanent magnet, respectively, and the permanent magnet provided on the movable element may be changed to an electromagnet. it can. The electromagnet drive unit applies a drive pulse as shown in (C) below when the camera focal length is set to the first focal length, and (D) when the camera focal length is set at the second focal length. The drive pulse is applied as shown in FIG.

(C) A driving pulse is applied to the electromagnet so that the electromagnet is attracted to the first permanent magnet and has a polarity repelled from the second permanent magnet.

(D) A drive pulse is applied to the electromagnet so that the electromagnet has a polarity repelled by the first permanent magnet and attracted by the second permanent magnet.

  According to this invention, by applying a drive pulse to the first electromagnet and the second electromagnet, the permanent magnet integrated with the movable lens is selected as either the first electromagnet or the second electromagnet. It can be adsorbed and the state can be stably maintained. For this reason, it is strong against vibration and impact.

  FIG. 1 shows an example of mounting an in-vehicle camera (hereinafter referred to as a camera) having two focal lengths according to an embodiment of the present invention.

  As shown in the figure, the camera is connected to an ECU (Electronic Control Unit) 2 and is mounted above the windshield in the vehicle 3. The camera 1 can select an angle of view of 10 ° (first angle of view) and an angle of view of 50 ° (second angle of view), and the focal length is set to be long at the first angle of view. (First focal length). At the second angle of view, the focal length is set short (second focal length). The first focal length is selected when the night shooting mode is set to secure night vision at night, and the second focal length is used for white line detection or pre-crash. Therefore, it is selected when the middle / short-distance shooting mode is set.

  In normal times, the medium / short-distance shooting mode is selected, and white line detection and detection of an oncoming vehicle and a preceding vehicle at a short distance are performed. As described above, the angle of view set in the camera 1 in this case is 50 °, and the second focal length capable of detecting an object from about 20 to 30 m from the front of the vehicle 1 is set.

  At night, the night shooting mode is set, and as described above, the angle of view set in the camera 1 in this case is 10 °, and the first object that can detect an object up to about 100 to 150 m, which is a long distance, can be detected. The focal length is set. In the night shooting mode, 100 to 150 m ahead is shot intermittently (for example, 1 frame / second, white line detection is 30 frame / second). In this mode, it is possible to irradiate an infrared projector.

  FIG. 2 is a schematic configuration diagram of the camera 1.

  The camera 1 includes a camera body 10 and a lens unit 11 including a lens barrel. The lens unit 11 includes a movable element 12 that can move in the optical axis direction within the lens barrel, a first electromagnet 13 that is fixed within the lens barrel, and a second electromagnet 14. The camera body 10 includes an imager 15 that is a solid-state image sensor and a timing pulse generation circuit 16. The lens unit 11 further includes a fixed lens, which will be described later, closer to the subject than the position of the second electromagnet 14.

  The movable element 12 includes a permanent magnet 17 and a movable lens 18. The movable element 12 is movable between the first electromagnet 13 and the second electromagnet 14 along the optical axis O. In the present embodiment, the position of the first electromagnet 13 is referred to as a first position. The position of the second electromagnet 14 is referred to as a second position. When the movable element 12 moves to the first position, the focal length becomes the telephoto side. The focal length at this time is referred to as a first focal length. When the movable element 12 moves to the second position, the focal length becomes the wide angle side. The focal length at this time is referred to as a second focal length.

  The timing pulse generation circuit 16 applies a driving pulse (timing pulse) to the first electromagnet 13 and the second electromagnet 14. When the movable element 12 is held at the first position (first focal length), a drive pulse having a polarity that the permanent magnet 17 attracts to the first electromagnet 13 is applied to the first electromagnet 13. Apply. At the same time, the permanent magnet 17 applies a driving pulse having a polarity repelling from the second electromagnet 14 to the second electromagnet 14. When the movable element 12 is held at the second position (second focal length), the polarity of the permanent magnet 17 is attracted to the second electromagnet 14 with respect to the second electromagnet 14. Apply a pulse. At the same time, the permanent magnet 17 applies a driving pulse having a polarity repelling from the first electromagnet 11 to the first electromagnet 13. When the movable element 12 moves to the first position or the second position, the permanent magnet 17 continues to be attracted to the first electromagnet 13 or the second electromagnet 14 by the magnetic force at the position. Therefore, after the drive pulse is applied once to each of the electromagnets 13 and 14, no drive pulse is applied thereafter.

  An ECU 20 is connected to the timing pulse generation circuit 16, and the polarity of the drive pulse is given as a switching signal from the ECU 20. The ECU 20 receives a signal from a light SW (fire switch) operated by a driver and a signal from an auto light sensor that detects ambient brightness. Upon receiving these signals, the ECU 20 sets the night shooting mode and sets the switching signal to a level at which the first focal length is set.

  FIG. 3 is a detailed configuration diagram of the lens unit 11.

  The lens unit 11 includes a cylindrical lens barrel 30 and a structure provided in the lens barrel 30.

  In the lens barrel 30, a fixed lens 31 is fixed on the subject side. The front retaining ring 32 has a male screw formed around it, and is fixed by screwing it into a female screw portion provided on the inner periphery of the lens barrel 30. The fixed lens 31 is fixed to a front retaining ring 32 provided on the inner peripheral surface of the lens barrel 30. Inside, the second electromagnet 14 is held by a coil retaining ring 33. The first electromagnet 13 is held by a rear retaining ring 34 on the imager side of the lens barrel 30. Similarly to the front retaining ring 32, the rear retaining ring 34 also has a male screw formed around it, and is fixed by screwing it into a female thread portion provided on the inner periphery of the lens barrel 30.

  The first electromagnet 13 includes a first coil 130, a first yoke 131 made of iron or the like passing through the coil 130, and stoppers 132 and 133 that hold both ends of the first coil 130. And. The second electromagnet 14 includes a second coil 140, a second yoke 141 that penetrates the coil 140, and stoppers 142 and 143 that hold both ends of the first coil 140.

  When a drive pulse is applied to the first coil 130 of the first electromagnet 13, the first yoke 131 is magnetized. When a drive pulse is applied to the second coil 140 of the second electromagnet 14, the second yoke 141 is magnetized. By changing the polarity (+,-) of the drive pulse, the magnetization polarity (N pole, S pole) generated at both ends of these yokes 131, 141 changes.

  A movable element 12 is arranged between the front first electromagnet 13 and the second electromagnet 14 so as to be movable in the direction of the optical axis O. That is, the outer peripheral surface of the movable element 12 and the inner peripheral surface of the lens barrel 30 are formed smoothly, and this outer peripheral surface can slide on the inner peripheral surface of the lens barrel 30 in the optical axis direction (the left-right direction in the figure). It has become. As will be described later, the movable element 12 is provided with a rotation stop on the peripheral surface thereof so that the movable element 12 does not rotate in the circumferential direction. It slides in the direction of O.

  The movable element 12 includes an elongated permanent magnet 17 extending in the direction of the optical axis O on the outermost periphery. Further, the movable element 12 has a movable lens 18 provided on the inner side. The positions of the center lines of the permanent magnet 17 of the movable element 12 in the direction of the optical axis O coincide with the positions of the center lines of the first yoke 131 and the second yoke 141. Further, the magnetic pole on the subject side of the permanent magnet 17 is magnetized to the N pole, and the magnetic pole on the imager side is magnetized to the S pole. Therefore, when the left end portion of the first yoke 131 is magnetized to the N pole and the right end portion of the second yoke 141 is magnetized to the N pole, the permanent magnet 17 generates a repulsive force by the magnetic pole on the subject side. Received and attracted by the magnetic pole on the imager side. As a result, a rightward moving force is generated with respect to the movable element 12. On the contrary, when the left end portion of the first yoke 131 is magnetized to the S pole and the right end portion of the second yoke 141 is magnetized to the S pole, the permanent magnet 17 is attracted by the magnetic pole on the subject side. The repulsive force is received by the magnetic pole on the imager side. As a result, a leftward moving force is generated with respect to the movable element 12.

  When the movable element 12 is in the position shown in FIG. 3, that is, the second position, the permanent magnet 17 is attracted to the second yoke 141 by the magnetic force. Therefore, the movable element 12 is held by the attractive force of the permanent magnet 17 at the second position (second state). In this second state, the first electromagnet 13 and the second electromagnet 13 are connected so that the left end portion of the first yoke 131 is magnetized to the N pole and the right end portion of the second yoke 141 is magnetized to the N pole. When a drive pulse is applied to the electromagnet 14, a rightward force is generated with respect to the movable element 12. Therefore, the movable element 12 moves in the right direction and stops at the position attracted by the first electromagnet 13, that is, the first position. At this time, the movable element 12 is held by the attracting force of the permanent magnet 17 at the first position (first state). Further, in this first state, the first electromagnet 13 and the left end of the first yoke 131 are magnetized to the S pole and the right end of the second yoke 141 is magnetized to the S pole. When a driving pulse is applied to the second electromagnet 14, a leftward force is generated on the movable element 12. Therefore, the movable element 12 moves to the left and stops at the position attracted by the second electromagnet 14, that is, the second position.

  Here, the first electromagnet 13 and the second electromagnet 14 are magnetized so that the left end portion of the first yoke 131 is magnetized to the N pole and the right end portion of the second yoke 141 is magnetized to the N pole. The polarity of the drive pulse to be applied is the same as that of the first electromagnet 13 so that the left end of the first yoke 131 is magnetized to the S pole and the right end of the second yoke 141 is magnetized to the S pole. The polarity of the drive pulse applied to the second electromagnet 14 is completely opposite. Therefore, by selecting the polarity (+, −) of the drive pulse generated by the timing pulse generation circuit 16, it is possible to determine whether the movable element 12 is held at the first position or the second position. .

  As is clear from the above configuration, the movable element 12 is always positioned by the attractive force generated by the magnetic force of the permanent magnet 17. For this reason, even if there is a vibration or an impact, the held position is stable, and the focal length does not shift. Further, when changing the focal length (changing the holding position of the movable element), it is only necessary to apply a drive pulse of reverse polarity to the first electromagnet 13 and the second electromagnet 14 once, and the control is extremely simple. .

  FIG. 4 shows the principle of movement of the permanent magnet 17 provided on the movable element 12.

  The state of FIG. 4A shows a second state in which the permanent magnet 17 in the movable element 12 is stopped and held at the second position (wide angle side). In this second state, the first electromagnet 13 and the second electromagnet 14 are not energized. When the movable element 12 is moved from the second state to the first position (telephoto side), a driving pulse is applied to the first electromagnet 13 and the second electromagnet 14. At this time, the second electromagnet 14 is applied with a drive pulse having a polarity such that the right end thereof has the same N pole as the magnetic pole at the left end of the permanent magnet. At the same time, the first electromagnet 13 is applied with a drive pulse having a polarity such that the left end thereof is an N pole opposite to the magnetic pole at the right end of the permanent magnet. When controlled in this way, as shown in FIG. 4 (B), the permanent magnet 17 moves to the right by the repulsive force and the attractive force in the right direction from the state held as shown in FIG. 4 (A). Then, it is attracted to the first electromagnet 13 and stops. When the permanent magnet 17 is attracted to the first electromagnet 13 and stops moving, the energization to the first electromagnet 13 and the second electromagnet 14 is stopped. In this state, the permanent magnet 17 is attracted and held by the first electromagnet 13 with its magnetic force ((C) in the figure).

  Next, when the movable element 12 is moved to the second position (wide-angle side) in the state of FIG. (C), the first electromagnet 13 and the second electromagnet 14 are as shown in FIG. A drive pulse having a polarity opposite to that of the drive pulse applied to is applied. At this time, the second electromagnet 14 is applied with a drive pulse having a polarity such that the right end of the second electromagnet 14 has an S pole opposite to the magnetic pole at the left end of the permanent magnet. At the same time, the first electromagnet 13 is applied with a drive pulse having a polarity such that the left end thereof has the same N pole as the magnetic pole at the right end of the permanent magnet. When controlled in this way, as shown in FIG. 4D, the permanent magnet 17 moves to the left by the repulsive force and the attractive force in the left direction from the state held as shown in FIG. Then, it is attracted to the second electromagnet 14 and stops.

  FIG. 5 shows drive pulses for the first and second electromagnets 13 and 14. As shown in the figure, the drive pulse is output at a timing when the permanent magnet 17, that is, the movable element 12 is reversed. The pulse width of the drive pulse is T and is on the order of several ms. Each time a driving pulse is applied once, the polarity of the next driving pulse is reversed. Thereby, every time a drive pulse is applied to the first and second electromagnets 13 and 14, as shown in FIG. 4, the movable element 12 is moved from the first position → the second position → the first position → It is possible to hold in order.

  Next, the mounting structure of the movable element 12 and the electromagnets 13 and 14 will be described with reference to FIG.

  6A is a view of the movable element 12 as viewed from the optical axis direction, and FIG. 6B is a view of the first electromagnet 13 as viewed in the optical axis direction. Since the second electromagnet 14 has the same structure as the first electromagnet 13, the first electromagnet 13 will be described below.

  The movable element 12 includes a ring-shaped lens support 120 made of a hard resin, a movable lens 18 supported on the inner periphery of the range support 120, a permanent magnet 17, and a rotation stopper 121. As shown in the figure, four permanent magnets 17 are embedded in the lens support 120 by insert molding at intervals of 90 °. Since the intervals are 90 °, the permanent magnets 17 are symmetrical with respect to the optical axis O. The rotation stopper 121 is for preventing the lens support 120 from rotating within the lens barrel 30. Since the lens support 120 is slidable in the optical axis direction within the lens barrel 30, there is a possibility that the lens support 120 rotates around the optical axis due to vibration or impact. Therefore, a protrusion-like rotation stop 121 is provided on the outer periphery of the lens support 120, and this is slidably engaged with a groove (not shown) provided on the inner periphery of the lens barrel 12 in the optical axis direction. Yes. Two rotation stoppers are provided at intervals of 180 °, but it is more preferable to provide three or more at equal angles. In addition, the lens support 120 can be made of a nonmagnetic material. In that case, a hole is formed in the non-magnetic material, the permanent magnet 17 is inserted therein, and is fixed with an adhesive.

  As shown in FIG. 6B, the first electromagnet 13 includes a first coil 130, a first yoke 131 made of iron or the like, a first stopper 132, and a first rotation stop 133. And. The first stopper 132 is composed of two stopper portions molded in a ring shape using a hard resin as a material (see FIG. 3), and an open space is formed on the inner periphery. The first electromagnet 13 is formed by sandwiching the first coil 130 between the two stopper portions. Both ends of the first yoke 131 are fitted into two stopper portions, and the first coil 130 is wound around the circumferential surface of the yoke 131.

  Similarly to the permanent magnets 17, four first yokes 131 are provided at intervals of 90 °, and the positions of the center lines in the optical axis O direction are the centers of the four permanent magnets 17. It matches the position of the line.

  Two first rotation stoppers 133 are provided at intervals of 180 ° in each of the two stopper portions, and are fitted into holes (not shown) provided in the inner periphery of the lens barrel 12.

  Note that, as described above, the second electromagnet 14 has the same configuration as the first electromagnet 13.

  If it is said structure, since the permanent magnet 17 and the 1st electromagnet 13 are symmetrically arrange | positioned at equal intervals centering on the optical axis O, magnetic force will become equal on the periphery. For this reason, a force in the radial direction of the element is not applied to the movable element 12 during the movement. Thereby, the movable element 120 moves stably and smoothly in the optical axis direction. Further, since the lens unit 11 can be configured simply by fitting parts such as the fixed lens 13 and the movable lens 12 into the lens barrel 11, workability during assembly is also improved.

  The number of rotation stoppers 121 may be four as shown in FIG. 7A, or may be three as shown in FIG. Further, as shown in the figure, the shape may be arbitrary, but these rotation stoppers are arranged at an equal angle so that a force in the radial direction of the element 12 does not occur when the movable element 12 moves. It is desirable that That is, the example shown in FIG. 7A is arranged at intervals of 90 °, and the example shown in FIG. 7B is arranged at intervals of 120 °.

  The permanent magnet 17 may have a cylindrical shape as shown in FIG. 8A, or may be divided into two in the optical axis direction as shown in FIG. 8B. The left side of these figures shows a front sectional view, and the right side shows a side view. Further, the cross-sectional shape may be a rectangle as shown in FIG. 10C, or a triangle as shown in FIG.

  FIG. 9 shows an in-vehicle camera according to another embodiment of the present invention.

  In the configuration, the difference from the camera shown in FIG. 2 is that the mounting locations of the permanent magnet and the electromagnet are reversed. That is, in the camera of the present embodiment, an electromagnet 52 is provided instead of the permanent magnet 17 of the movable element 12, and the first permanent magnet 13 and the second electromagnet 14 fixed in the lens barrel are replaced with the first permanent magnet. A magnet 50 and a second permanent magnet 51 are provided. A driving pulse is applied to the electromagnet 52 of the movable element 12 from the timing pulse generation circuit 16 in the camera body 10.

  FIG. 10 is a configuration diagram of the lens unit 11. In the same figure, the part shown with the same code | symbol as FIG. 3 has shown that it is the same component.

  The electromagnet 53 provided in the movable element 12 includes a yoke 530 extending in the optical axis direction, a coil 531 wound around the yoke 530, and coil holding portions 532 and 533 that hold both ends of the coil 531. Yes. As with the structure shown in FIG. 6B, four electromagnets 53 are arranged on the outer periphery of the movable element 12 at an equal angle of 90 ° so as to be symmetric with respect to the optical axis O. The electric wires for energizing these electromagnets are connected to the electromagnets through long holes (not shown) for passing electric wires provided in the lens barrel 30 in the optical axis direction.

  The first permanent magnet 50 provided at the first position and the second permanent magnet 51 provided at the second position are respectively embedded in the hard resin 500 and the hard resin 501 by insert molding. As shown in FIG. 10, these permanent magnets are provided so that the inner side is the south pole and the outer side is the north pole.

  With the above configuration, the movable element 12 is controlled as follows in order to move it between the first position and the second position.

  When the movable element 12 is moved to the first position (telephoto side), the electromagnet 53 is attracted to the first permanent magnet 50 and repelled from the second permanent magnet 51 with respect to the electromagnet 53. A drive pulse is applied so that That is, with respect to the yoke 530 of the electromagnet 53, the electromagnet is magnetized so that the south pole is magnetized at the left end (subject end) and the north pole is magnetized at the right end (imager end). A drive pulse is applied to 53. In the state shown in FIG. 10, since the movable element 12 is located at the second position (wide angle side), when the drive pulse is applied to the electromagnet 53 from this state as described above, the movable element 12 When receiving a rightward attracting force from the first permanent magnet 50, a rightward repulsive force is received from the second permanent magnet 51. As a result, the movable element 12 moves to the right and stops at the first position. At this time, the yoke 530 of the movable element 12 is attracted to the first permanent magnet 50 by its magnetic force.

  Next, when the movable element 12 is moved from the first position (telephoto side) to the second position (wide angle side), the electromagnet 53 is repelled from the first permanent magnet 50 with respect to the electromagnet 53. In addition, a drive pulse is applied so as to have a polarity attracted by the second permanent magnet 51. That is, with respect to the yoke 530 of the electromagnet 53, the electromagnet is magnetized so that the north pole is magnetized at the left end (subject side end) and the south pole is magnetized at the right end (imager side end). A drive pulse is applied to 53. Then, the movable element 12 receives a leftward repulsive force from the first permanent magnet 50 and simultaneously receives a leftward attractive force from the second permanent magnet 51. As a result, the movable element 12 moves to the left and stops at the second position. At this time, the yoke 530 of the movable element 12 is attracted to the second permanent magnet 51 by its magnetic force.

  Thus, by changing the polarity of the drive pulse applied to the electromagnet 53 provided in the movable element 12, the movable element 12 is moved rightward and held at the first position (telephoto side). Or moved leftward so as to be held at the second position (wide angle side).

The figure which shows the example of attachment of the vehicle-mounted camera which has 2 focal distance which is embodiment of this invention Schematic configuration diagram of camera 1 Configuration diagram of the lens unit 11 The figure which shows the movement principle of the permanent magnet 17 provided in the movable element 12 Diagram showing drive pulse The figure which shows the attachment structure of the movable element 12 and the electromagnets 13 and 14 The figure which shows other examples of the number and shape of a rotation stop The figure which shows the other example of a permanent magnet Schematic configuration diagram of the camera 1 of another embodiment Configuration diagram of the lens unit 11

Claims (5)

In a vehicle-mounted camera that is attached to a vehicle so as to image the front of the vehicle and changes the focal length by moving a movable lens along the optical axis.
A first electromagnet and a second electromagnet disposed at two positions along the optical axis;
A movable element attached with the movable lens and a permanent magnet, and movably attached along the optical axis between the first electromagnet and the second electromagnet;
An electromagnet driving section for applying a driving pulse to the first electromagnet and the second electromagnet,
When the camera focal length is set to the first focal length, the electromagnet driving section applies a drive pulse as shown in (A) below, and when the camera focal length is set to the second focal length, A vehicle-mounted camera having two focal lengths, wherein a drive pulse is applied as described above.
(A) A drive pulse is applied to the first electromagnet so that the first electromagnet has a polarity for attracting the permanent magnet, and the second electromagnet is applied to the permanent electromagnet. A drive pulse is applied so as to have a polarity that repels the magnet.
(B) A drive pulse is applied to the first electromagnet so that the first electromagnet has a polarity that repels the permanent magnet, and the second electromagnet is applied to the permanent electromagnet. A drive pulse is applied so as to have a polarity for attracting the magnet.   The in-vehicle camera having two focal lengths according to claim 1, wherein the electromagnet driving unit stops applying the driving pulse when the permanent magnet is attracted to the first electromagnet or the second electromagnet.   A plurality of the first electromagnets and the second electromagnets are arranged around the optical axis, and a plurality of the permanent magnets are arranged around the optical axis so as to face the first electromagnet and the second electromagnet. An in-vehicle camera having two focal lengths according to claim 1.   A plurality of the first electromagnets and the second electromagnets are arranged at equal intervals around the optical axis, and a plurality of the permanent magnets are arranged at regular intervals so as to face the first electromagnet and the second electromagnet around the optical axis. The vehicle-mounted camera which has two focal distances of Claim 3 currently arrange | positioned individually. In a vehicle-mounted camera that is attached to a vehicle so as to image the front of the vehicle and changes the focal length by moving a movable lens along the optical axis.
A first permanent magnet and a second permanent magnet disposed at two positions along the optical axis;
A movable element attached with the movable lens and an electromagnet, and movably attached along the optical axis between the first permanent magnet and the second permanent magnet;
An electromagnet driving section for applying a driving pulse to the electromagnet,
The electromagnet driving unit applies a driving pulse as shown in (C) below when the camera focal length is set to the first focal length, and the following (D) is set when the camera focal length is set at the second focal length. A vehicle-mounted camera having two focal lengths, wherein a drive pulse is applied as described above.
(C) A driving pulse is applied to the electromagnet so that the electromagnet is attracted to the first permanent magnet and has a polarity repelled from the second permanent magnet.
(D) A drive pulse is applied to the electromagnet so that the electromagnet has a polarity repelled by the first permanent magnet and attracted by the second permanent magnet.

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