JP2005347868A - Mirror tilting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-sized mirror tilting device having a large tilting range. <P>SOLUTION: A moving section is composed of a mirror 113 reflecting light beams, a mirror stage 114 holding the mirror on a top face and a bearing 115 vertically fixed at the center of the rear of the mirror stage and to the rear. The bearing is brought into contact at the front end of a spindle 112 at one point, and used as a pivot bearing capable of being freely tilted to fixing sections (a base 111 and the spindle 112). Four direct-acting actuators are used, and arranged at the intervals of 90° centering around the spindle. Magnets 116 are fixed on the rear of the mirror stage on the movable side as the direct-acting actuators, and coils 117 are fixed so as to be opposed to the magnets to the base as the fixing side. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a mirror tilting device, and more particularly to a mirror tilting device suitable for an optical wireless transmission device that performs data transmission by transmitting and receiving an optical signal modulated by a data signal.

  Generally, when transmitting a signal via optical radio, an LED (light emitting diode) or a laser diode is used as a light emitting element on the transmission side. Among these, in an apparatus that transmits a signal using an LED, since the effective emission angle of the LED is wide, the transmission light spreads when transmitted over a long distance, the optical power reaching the reception side decreases, and the signal cannot be transmitted.

  In order to solve this, for example, an indoor optical wireless transmission device as shown in FIG. 11 has been proposed (see Patent Document 1 below). In this optical wireless transmission device, a light emitting means 16 is provided in one device (base unit 14) separately from the light emitting section 15 for data signal transmission, and pilot light 16A for optical axis alignment is transmitted from the light emitting means 16. In the other optical wireless transmission device (slave unit 17), the optical axis direction is turned and the pilot light 16A is received by the light receiving device 18, and the optical axis is adjusted based on the received light level of the pilot light 16A. It is configured. This device 17 rotates a light transmitting device (not shown) that collimates LED light by a parabolic reflector and narrows the beam diameter, and a light receiving device 18 having a narrow directivity angle by a stepping motor or the like so that both are horizontally and vertically oriented. Scanning is performed to find a point where the output level of the light receiving means is maximum in the two-dimensional coordinates.

  In order to perform optical axis alignment with the optical wireless transmission device described above, it is necessary to simultaneously rotate the light receiving device including the light receiving element and its optical system, and the light emitting device including the light emitting element and its optical system. Therefore, the apparatus used indoors is large. On the other hand, a device 210 as shown in FIG. 12 aimed at miniaturization of an indoor optical wireless transmission device has been proposed (for example, see Patent Document 2 below). This attempts to reduce the size of the apparatus by optimizing the arrangement and configuration of the lenses 212 and 213 to be used, a motor (not shown), a speed reduction mechanism, and the like.

On the other hand, in an outdoor optical wireless transmission apparatus using a laser diode, an optical axis adjustment method using a tiltable mirror 4 and a beam splitter 3 is employed as shown in FIG. As a conventional mirror tilting device, for example, as shown in FIG. 13 (see Patent Document 3 below), a device that tilts a mirror 202 around the X axis and around the Y axis by a biaxial spring 201 has been proposed. . The biaxial spring 201 includes an X axis bridge 203, a Y axis bridge 204, and the like.
Japanese Patent No. 3059870 (FIGS. 14 and 18) JP-A-10-276131 (abstract) Japanese Patent Laid-Open No. 11-2105060 (FIG. 1)

  In the future, optical wireless transmission devices used indoors will be required to be mounted (built in) on devices and mobile bodies (devices) that change their position frequently. However, as described above, the conventional indoor optical wireless transmission apparatus has a large movable part, so it is difficult to reduce the size and to be built in other equipment.

  On the other hand, in an outdoor optical wireless apparatus in which the movable part is only a mirror, it is possible to reduce the size by reducing each optical element. However, in the case of outdoor use, each optical wireless device is usually fixedly installed, and a movable mirror is used to finely adjust the optical axis. In other words, the movable range of the mirror is only very small. In the example shown in FIG. 13, the mirror mounting member, the rotation shaft, and the mirror portion holding member are composed of the same member (plate material), and the movable range of the mirror is an area where the plate material can be twisted. Therefore, even if the outdoor optical wireless device is downsized as it is, there is a limit to use it as an indoor optical wireless transmission device that requires a wide range of swing angles.

  It is an object of the present invention to provide a mirror tilting device that is small and has a large tilting range, and to provide a mirror tilting device that is suitable for a small optical wireless transmission device that is suitable for indoor use.

In order to achieve the above object, the present invention provides a base,
A spindle having a conical tip and fixed on the base;
A mirror that reflects input light;
A mirror support member in which the mirror is supported in the upper surface direction;
A bearing portion fixed so as to be tiltable around the tip of the spindle on the back surface of the mirror support member;
Four magnets fixed at 90 ° intervals around the bearing portion on the back surface of the mirror support member, and four fixed on the upper surface of the base so as to face each of the four magnets. A linear motion actuator comprising at least coils, and tilting the mirror about the tip of the spindle according to a voltage applied to each of the four coils.
It was set as the structure provided.
Further, the four coils are configured such that windings are wound so that a couple acts on the center with two coils sandwiching the tip of the spindle as the center.

  ADVANTAGE OF THE INVENTION According to this invention, a mirror tilting apparatus with a small and large tilting range can be provided, Furthermore, the mirror tilting apparatus suitable for the small optical wireless transmission apparatus suitable for indoor use can be provided.

  Embodiments of the present invention will be described below with reference to the drawings. First, the configuration of the mirror tilting device according to the embodiment will be described with reference to FIGS. FIG. 1 is a plan view of a mirror tilting device according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line AA in FIG. The mirror tilting device according to the embodiment of the present invention includes three parts, a fixed part, a movable part, and a driving means. As shown in FIG. 2, the fixing portion is composed of a base 111 serving as a base of the apparatus, and a spindle 112 fixed to the center of the base 111 and perpendicular to the upper surface of the base 111. . The movable portion includes a mirror 113 that reflects a light beam, a mirror stage 114 that holds the mirror 113 on the top surface, and a bearing 115 that is fixed to the center of the back surface of the mirror stage 114 and perpendicular to the back surface. . The bearing 115 is in contact with the tip of the spindle 112 at a single point, and becomes a pivot bearing that can freely tilt with respect to the fixed portion (base 111, spindle 112).

  As the driving means for freely performing the tilting, four linear actuators are used and arranged at 90 ° intervals around the spindle 112 as shown in FIG. As a linear actuator, a magnet 116 is fixed to the back surface of the mirror stage 114 on the movable side, and a coil 117 is fixed to the base 111 on the fixed side so as to face the magnet 116. The opposing magnet 116 and coil 117 constitute a linear actuator (magnet 116, coil 117).

  FIG. 3 shows the arrangement of the four coils 117 constituting the four linear actuators (magnet 116, coil 117). From this figure, it can be seen that there are two sets of coil arrays sandwiching the spindle 112, and both coil arrays are orthogonal. Here, each coil row is wound with a winding of the coil 117 so that a couple acts around the pivot point, and both ends of the winding are connected to each of the four terminals 119 on the substrate 118. Therefore, by controlling the voltage between the terminals 119, a couple acts on the corresponding coil array, and as a result, the mirror 113 tilts.

  Next, an optical wireless transmission device incorporating the mirror tilting device shown in FIGS. 1 to 3 will be described with reference to FIG. FIG. 4 is a schematic configuration diagram of the optical wireless transmission apparatus. The light emitting / receiving unit 9 of the optical wireless transmission device includes a light emitting element 1 that emits an optical signal modulated by a data signal, a lens 2 such as a collimator lens, and a light control element that divides incident light into transmitted light and reflected light. (Beam splitter) 3, reflection optical system (mirror) 4 having a driving means (not shown) that reflects incident light or outgoing light to the optical wireless transmission device and controls a polarization angle with respect to the optical axis, and a partner (not shown) A lens 5 that condenses pilot light transmitted from the apparatus and a light receiving element 6 that includes a photodiode (hereinafter, appropriately referred to as PD) that receives the pilot light collected by the lens 5 are provided. The light emitting element 1 is connected to the data signal supply unit 7 and the external interface 7A, and the light receiving element 6 and the reflection optical system 4 are connected to the deflection angle control signal supply unit 8. Here, the mirror tilting device of the present invention is used as the reflecting optical system 4 having the driving means.

  In the light emitting / receiving unit 9, the data signal supply unit 7 to which the data signal is supplied from the external interface 7 </ b> A emits an optical signal intensity-modulated into an optical signal corresponding to the data signal from the light emitting element 1, and is collimated by the lens 2. After being shaped into a beam light close to, and split as transmitted light by the light control element 3, it is reflected by the reflective optical system 4 and sent out as transmitted light. Pilot light transmitted from a not-shown counterpart device is reflected by the reflection optical system 4 and divided as reflected light by the light control element 3, then condensed by the lens 5 and received by the light receiving element 6. In the light receiving element 6, the received pilot light is photoelectrically converted and output to the deflection angle control signal supply unit 8 as position information of the counterpart device.

  Next, with reference to FIGS. 5 to 7, each part constituting the light emitting / receiving unit 9 will be described in more detail. As the light emitting element 1, a laser diode can be used. The laser diode has a narrow beam of emitted light, and is further made nearly parallel by the lens 2 so that the emitted light can be irradiated to the light control element 3 and the reflection optical system 4 with high efficiency. The wavelength of the laser is not limited to the near infrared, but may be a long wavelength. FIG. 5 shows the configuration of the data signal supply unit 7 in detail. The data signal supply unit 7 converts the data signal from the external interface 7A into a signal that can be transmitted by light, and this signal processing. The light emitting drive unit 10 drives the light emitting element 1 so that the light blinks in response to the received signal.

  When the LAN is considered as an application of the indoor optical wireless transmission system and the signal input from the external interface is 100Base-FX, the signal processing unit 11 in the data signal supply unit 7 is as shown in the block diagram of FIG. 4B / 5B encoder 101 performs 4B / 5B coding for clock self-regeneration, descramble / scramble unit 102 scrambles the data, parallel / serial converter 103 converts the parallel data to serial data, and The NRZ / NRZI conversion unit 104 (and PLL 105) performs signal processing for performing NRZ / NRZI conversion in order to obtain a signal having no DC component, and inputs the data signal to the light emission drive unit 10.

  FIG. 7 is a block diagram showing the configuration of the deflection angle control signal supply unit 8 in detail. The light receiving element 6 of the light emitting / receiving unit 9 photoelectrically converts pilot light from the counterpart device and supplies information such as the presence / absence of received light, the amount of received light, and the light receiving direction to the deflection angle control signal supply unit 8. Based on the information obtained from the light emitting / receiving unit 9, the deflection angle control signal supply unit 8 moves and moves the reflecting optical system 4 so as to align the optical axis of reception with the light from the counterpart device. And a control unit 12 for driving a driving means (not shown) of the reflection optical system 4 in the horizontal direction or the vertical direction.

  Next, with reference to FIG. 8 to FIG. 10, an operation when the deflection angle control signal supply unit 8 controls the deflection angle with respect to the optical axis based on the information obtained from the light emitting / receiving unit 9 will be described. FIG. 8 is a flowchart showing a control procedure of the reflection optical system 4 by the deflection angle control signal supply unit 8, and FIG. 9 shows stepwise reception spots of pilot light received on the light receiving element 6 constituted by four-divided PDs. FIG. 10 is a block diagram showing a configuration for realizing the control procedure of FIG. 8 in the deflection angle control signal supply unit 8.

  Here, as shown in FIG. 9, the light receiving element 6 is constituted by photodiodes (PD-A, PD-B, PD-C, PD-D) divided into 2 × 2 and includes a reflection optical system. The case where 4 is controllable in three dimensions is taken as an example. Hereinafter, description will be made with reference to FIGS. 9 and 10 as appropriate according to the flowchart of FIG. The transmitted light from the counterpart device is an optical signal having a certain frequency. In the light receiving / emitting unit 9, the PD (PD-A, B, C, D) of each of the four divided PDs (light receiving elements 6) is transmitted. The received light is photoelectrically converted and sent to the deflection angle control signal supply unit 8 as an electrical signal (SIG-A, B, C, D) having an amplitude corresponding to the amount of received light (step S1). In the calculation unit 13 in the deflection angle control signal supply unit 8, the respective signal amplitudes are amplified by the amplifiers 21, 22, 23, and 24 (Step S 2), and the amplitude values are obtained by the A / D converters 25, 26, 27, and 28. Is A / D converted to obtain the signal level, that is, the received light amount at each PD-A, B, C, D as a DC value (step S3).

  Subsequently, the microprocessor 29 such as a microcomputer / DSP calculates the difference in the received light level between the PDs (PD-A, B, C, D) facing each other in the horizontal direction (Pan) and the vertical direction (Tilt) ( In step S4), the moving direction and moving amount of the reflecting optical system 4 for setting the received light level difference to 0 are calculated and given to the control unit 12 (steps S5 → S6, steps S9 → S10). The control unit 12 D / A converts the values given by the D / A converters 30 and 31, and supplies them to the drivers 32 and 33 as drive signals. The drivers 32 and 33 drive the reflective optical system 4 in the vertical and horizontal directions, respectively. (Steps S7 → S8, S11 → S12).

  Next, the movement of the light receiving spot on the quadrant PD-A, B, C, D will be described with reference to FIG. In FIG. 9, reference numeral 6 </ b> A indicates a light receiving spot on the four-divided PD-A, B, C, D when the pilot light is irradiated. In FIG. 9, in step (1), first, the difference between the received light amounts of the PDs A and B facing each other in the vertical direction = A−B is calculated, and the difference = A−B is set to 0 (the lower direction in FIG. 9). The reflection optical system 4 is moved in the vertical direction so that light is irradiated in the direction). Next, in step (2), the difference between the received light amounts of the PDs C and D facing each other in the horizontal direction = CD is calculated, so that the spot is irradiated in the direction in which the difference = CD becomes zero. The reflective optical system 4 is moved in the horizontal direction.

  Thus, in the light emitting / receiving unit 9, the light control element 3 can control the transmission light and the reception light coaxially. As a result, by matching the light transmitted from the counterpart apparatus with the optical axis received by the apparatus, the transmission light of the apparatus is irradiated onto the counterpart apparatus. In the optical wireless transmission device according to the above-described embodiment, the mirror tilting device of the present invention is used as the reflection optical system 4 of the light emitting / receiving unit 9, and the optical axes of transmission light and pilot light are aligned. . This makes it possible to reduce the size of the device as compared with the conventional device that rotates the light receiving device and the light emitting device simultaneously. For example, in comparison with a conventional apparatus, at least a volume ratio of 1/2 or less is achieved.

It is a top view which shows the mirror tilting apparatus of one embodiment of this invention. FIG. 2 is a schematic cross-sectional view taken along line AA showing the mirror tilting device of FIG. 1. It is a top view which shows the structure of the coil of FIG. It is a block diagram which shows an example of the optical wireless transmission apparatus with which the mirror tilting apparatus of FIG. 1 is applied, and the conventional optical wireless transmission apparatus. FIG. 5 is a block diagram illustrating in detail a configuration of a data signal supply unit in FIG. 4. It is a block diagram which shows the signal processing part of FIG. 5 in detail. FIG. 5 is a block diagram illustrating in detail a configuration of a deflection angle control signal supply unit in FIG. 4. 5 is a flowchart showing a control procedure of a reflection optical system by a deflection angle control signal supply unit of FIG. It is explanatory drawing which shows a mode that the light reception spot of the pilot light received on the light receiving element comprised by 4 division | segmentation PD moves in steps. FIG. 9 is a block diagram illustrating a configuration for realizing the control procedure of FIG. 8 in the deflection angle control signal supply unit of FIG. 4. It is a block diagram which shows the conventional optical wireless transmission apparatus. It is a block diagram which shows the conventional optical transmission / reception apparatus of another optical wireless transmission apparatus. It is a block diagram which shows the conventional mirror tilting apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light emitting element 2, 5 Lens 3 Light control element (beam splitter)
4 reflective optics (mirror)
REFERENCE SIGNS LIST 6 light receiving element 6A light receiving spot 7 data signal supply unit 7A external interface 8 deflection angle control signal supply unit 9 light receiving / emitting unit 10 light emission driving unit 11 signal processing unit 12 control unit 13 calculation unit 21-24 amplifier 25-28 A / D converter 29 Microprocessor 30, 31 D / A converter 32, 33 Driver 101 4B / 5B encoder 102 Descramble / scrambler 103 Parallel / serial converter 104 NRZ / NRZI converter 105 PLL
111 Base 112 Spindle 113 Mirror 114 Mirror stage 115 Bearing 116 Magnet (composed of a linear actuator together with the coil 117)
117 Coil 118 Substrate 119 Terminal

Claims (2)

Base and
A spindle having a conical tip and fixed on the base;
A mirror that reflects input light;
A mirror support member in which the mirror is supported in the upper surface direction;
A bearing portion fixed so as to be tiltable around the tip of the spindle on the back surface of the mirror support member;
Four magnets fixed at 90 ° intervals around the bearing portion on the back surface of the mirror support member, and four fixed on the upper surface of the base so as to face each of the four magnets. A linear motion actuator comprising at least coils, and tilting the mirror about the tip of the spindle according to a voltage applied to each of the four coils.
A mirror tilting device configured to include. 2. The coil according to claim 1, wherein the four coils are wound so that a couple acts on the center with two coils sandwiching the tip of the spindle as the center. The mirror tilting device described.

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