Semiconductor integrated circuit device

Abstract: There is disclosed a semiconductor integrated circuit device in which a semiconductor integrated circuit substrate (2) provided with an electromagnetic coil (3) from which lead wires are drawn out is movably arranged within a magnetic field (M). When a current is caused to flow in the magnetic coil through the conductors, a force in the direction of a magnetic field is exerted on the electromagnetic coil. Thus, this semiconductor integrated circuit device can operate as an actuator allowing the entirety of the substrate to be movable in either a positive or a negative direction of the magnetic field. When the substrate (2) is moved interlocking with a measurement object, an induced current flows in the electromagnetic coil (3). Accordingly, by measuring this current, it is possible to operate this device as a sensor capable of measuring changes in the physical quantity, etc. of the measurement object.

Description: This invention relates to a semiconductor integrated circuit device, and more particularly to a semiconductor actuator utilizing an electromagnetic force, or a semiconductor sensor utilizing an electromagnetic induction. Recently, with development of Compact Disks (CDs) of digital audio disks, Laservision Disks (LVDs) of video and acoustic information media, write once Read Many-type optical disks, and rewritable photomagnetic disks, etc., it has been strongly required for an optical pickup to be small-sized and light in weight. To meet such a requirement, in place of an optical pickup of a structure wherein optical parts such as lens or mirror, etc. are combined with each other, an optical integrated circuit type pickup to which the integrated circuit technology established in the manufacturing field of LSI is applied has been proposed. For example, see Toshiaki Suhara, Shogo Ura, and Hiroshi Nishihara (Department of Electronics, Osaka University), 'Optical Integrated Disk Pickup Head', "Optronics" monthly published, No. 2, pp. 149-154 (1989), or the documents JP-A- 61296540 and US-A- 4,779,259. However, in case that the above-mentioned optical integrated type pickup is used in an actual playback equipment such as a CD player or an LVD player, etc., it is required to affix or mount an actuator for control. In this case, following the conventional form, an optical head of a structure which will be described below will be provided. This optical head is composed of, e.g., a cylindrical magnet, a cylindrical bobbin, and a semiconductor chip on which an optical integrated circuit-type pickup is formed. The cylindrical bobbin is of a hollow structure in which the diameter of the hollow portion is larger than that of the cylindrical magnet. This cylindrical bobbin is mounted on the cylindrical magnet so that it is seated thereon. One end surface of the cylindrical bobbin is closed and the semiconductor chip is affixed on that end surface. Further, an electromagnetic coil is provided on the cylindrical side surface of the cylindrical bobbin so as to surround it. In this case, a magnetic field is formed by magnetic lines of force directed from one end surface of the cylindrical magnet toward the other end surface thereof. These magnetic lines of force penetrate through the end surface of the bobbin and the semiconductor chip surface. When a current is caused to flow in the electromagnetic coil on the side surface of the bobbin, an electromagnetic force attempting to move the electromagnetic coil, i.e., the bobbin toward either a positive or a negative direction of the longitudinal axis of the cylindrical magnet is produced by "Fleming's left-hand rule". Accordingly, since a quantity of movement of the semiconductor chip in the axial direction of the magnet can be adjusted by the direction of a current caused to flow and the intensity of that current, this mechanism will form a focusing actuator. However, since the sizes of the electromagnetic coil and magnet are considerably larger that of the semiconductor chip, there was the problem that the advantage of the semiconductor chip being small is not exhibited. In addition, because the number of parts is large, there was left room for improvement from viewpoint of assembling steps and cost. US-A-4779259 discloses a semiconductor integrated circuit device comprising a semiconductor integrated circuit substrate having an optical integrated circuit type pickup comprising a laser diode, a beam splitter, and a photo detector. According to the present invention, such a device is characterised by the substrate being further provided with two or more electromagnetic coils formed on a surface of the semiconductor integrated circuit substrate by an integrated circuit technology, and from which a pair of conductors lead; a magnet for creating a magnetic field (M) mounted to a mounting base; and the substrate being movably supported by elastic support means with respect to the mounting base within the magnetic field (M); wherein the direction and intensity of current supplied to the coils and the conductors controls the angle of the substrate to perform a tracking operation. Preferred embodiments of the invention are defined in the dependent claims. In accordance with a preferred embodiment of this invention, when a current is caused to flow in one of the magnetic coils through the conductors, a right-handed magnetic field is produced in the direction in which the current flows- in accordance with "Ampere's right-handed screw rule". In this case, since the magnetic lines of force penetrate through the electromagnetic coil, an attractive force or a repulsive force in a direction of the magnetic lines of force is exerted on the electromagnetic coil. As a result, the semiconductor integrated circuit substrate also moves in the positive or negative direction of the magnetic lines of force in the direction of the magnetic field. This permits the semiconductor integrated circuit device to operate as a subminiature actuator. Accordingly, since it is possible to move a semiconductor intergrated circuit substrate having a predetermined function and to carry out a positioning control thereof, an optical head for recording/playback of an optical disk, which is smaller and lighter than the conventional optical head, can be advantageously provided. Further, in the above-mentioned semiconductor integrated circuit device, when an arrangement is employed such that a semiconductor integrated circuit substrate can interlock with an object to be measured to move the semiconductor integrated circuit substrate, an induced electromotive force to prevent changes in magnetic flux penetrating through the electromagnetic coil is produced in the electromagnetic coil in accordance with Lenz's law. As a result, an induced current flows. By taking out this induced current through the conductors to measure it by a galvanometer, it is possible to know a quantity in changes of the measurement object. This permits the semiconductor integrated circuit device to operate as a subminiature sensor. Accordingly, in the case of moving this semiconductor integrated circuit substrate within a magnetic field, or changing that magnetic field, by measuring an induced current produced in the coil, such a device can be advantageously used as a semiconductor integrated circuit device having a subminiature sensor function for measuring changes in a physical quantity such as displacement, pressure, magnetism, or the like. In the accompanying drawings:- FIG. 1 is a perspective view showing an example of a conventional optical head; FIG. 2 is a cross sectional view of the optical head shown in FIG. 1; FIG. 3 is a conceptual view for explaining an embodiment of a semiconductor integrated circuit device included as background to this invention; FIG. 4 is a view showing the structure of an optical head which is included as background to this invention; FIG. 5 is a cross sectional view of the optical head, taken along the line V-V in FIG. 4; FIG. 6 is a view showing the front side of a semiconductor integrated circuit substrate in the optical head shown in FIG. 4; FIG. 7 is a view showing the back side of the semiconductor integrated circuit substrate shown in FIG. 6; FIG. 8 is a view showing a flexible printed wiring board in the optical head shown in FIG. 4; FIG. 9 is a top view showing the front side of an embodiment of the semiconductor integrated circuit device constructed in accordance with the present invention; FIG. 10 is a view showing the structure of an optical head which is a further embodiment of this invention; and FIG. 11 is a cross sectional view of the optical head, taken along the line XI-XI in FIG. 10. Prior to description of embodiments of this invention, a conventional optical head will be described for helping the understanding of this invention. The conventional optical head is constituted as shown in FIGS. 1 and 2. In FIGS. 1 and 2, a semiconductor chip 101 on which an optical integrated circuit type pickup is formed is mounted or affixed on a cylindrical bobbin 112. An electromagnetic coil 110 is provided on the cylindrical surface of the bobbin 112. The bobbin 112 is mounted, in an insertion hole 118, on a cylindrical portion 117 of a lower yoke 116 of a magnet 114 so that it is seated thereon, and is movable in the axial direction of the cylindrical portion 117 (A-A direction). In this case, a magnetic field exists by the magnet 114. When a current is caused to flow in the electromagnetic coil 110 through lead wires 111, an electromagnetic force is exerted on the electromagnetic coil 110, so that it moves in the A-A direction. By this operation, it is possible to carry out, e.g., a focusing servo of the semiconductor chip 101. In this example, the electromagnetic coil 110 and the magnet 114 form a focusing actuator. The background to this invention is constituted as shown in FIG. 3. In FIG. 3, this semiconductor integrated circuit device 1 is such that an electromagnetic coil 3 is provided on a semiconductor integrated circuit substrate 2. A pair of conductors 4 are drawn out from the electromagnetic coil 3. Further, the semiconductor integrated circuit substrate 2 is movably disposed within a magnetic field M. In FIG. 3, when a current is caused to flow in the electromagnetic coil 3 through the conductors 4, a right-handed magnetic field is produced toward the direction in which that current flows in accordance with "Ampere's right-handed screw rule". In this case, since lines of magnetic force based on the magnetic field M are penetrated through the electromagnetic coil 3, an attractive force or a repulsive force in the direction 5 of the magnetic field M is exerted on the electromagnetic coil 3. As a result, the semiconductor integrated circuit substrate 2 also moves in the positive or negative direction 5 of the magnetic field M. This permits the semiconductor integrated circuit device 1 to operate as an actuator. In the above-mentioned semiconductor integrated circuit device 1, when an arrangement is employed such that the semiconductor integrated circuit substrate 2 is interlocked with a measurement object to be moved therewith, an induced electromotive force to prevent changes in the magnetic flux penetrating through the electromagnetic coil is produced in accordance with "Lenz's law". As a result, an induced current flows. By taking out this induced current through conductors 4 to measure it by a galvanometer (not shown), it is possible to know a quantity of changes of the measurement object by an inverse operation. This permits the semiconductor integrated circuit device 1 to operate as a sensor. This optical head 11 shown in Figs. 4 and 5 comprises a semiconductor integrated circuit substrate 12, a magnet 15 for producing a magnetic field and a flexible printed wiring board 16 as support means serving as conductors. An optical integrated circuit type pickup 18 is formed on the front side 12A of the semiconductor integrated circuit substrate 12, and an electromagnetic coil 13 is formed on the back side 12B thereof. The front side 12A opposite to the optical disk D of the semiconductor integrated circuit substrate 12 and the side 12B corresponding to the back side thereof and opposite to the magnet 15 are shown in FIGS. 6 and 7, respectively. The optical integrated circuit type pickup 18 comprises a laser diode 18L, a focusing grating coupler 18C, a grating beam splitter 18S, and photo detectors 18D. The laser diode 18L generates a laser beam. This laser beam is conducted to the focusing grating coupler 18c through an optical waveguide layer (not shown) of the semiconductor integrated circuit substrate 12. The focusing grating coupler 18C changes the laser beam so as to take a form of spots by the object lens action to focus it onto information pits on the recording surface of the optical disk D. The laser beam is reflected on the surface of the information pits. The reflected light is incident back to the focusing grating coupler 18C for a second time, and is then conducted to the grating beam splitter 18S. The grating beam splitter 18S splits the reflected light into two light paths. These two split light rays are incident to four photo detectors 18D. These photo detectors 18D output electric signals corresponding to a quantity of incident light rays. From these electric signals, information signals and signals for servo control control are provided. Further, the electromagnetic coil 13 is provided on the side 12B. Lines of magnetic force based on a magnetic field produced by the magnet 15 penetrate through the electromagnetic coil 13 on the semiconductor integrated circuit substrate 12. The flexible printed wiring board 16 is constituted, as shown in FIG. 8, by assembling an elastic member 16S like a metal film for rendering suitable rigidity and elasticity and lead wires 16L of conductors for wiring into a film like matrix 16M having elastic and insulating properties like a plastic material. The electrical connection between the lead wires 16L and the optical integrated circuit type pickup 18 or the electromagnetic coil 13 is carried out through land terminals 16T. This flexible printed wiring board 16 is constituted, as shown in FIGS. 4 and 5, by bending the both end portions of a belt-shaped flexible printed wiring board to cover the surface of the magnet 15 in a manner to take a form of cylinder or leaf spring. Further, the semiconductor integrated circuit substrate 12 is mounted or affixed on the surface of this flexible printed wiring board 16 just above the magnet 15. Accordingly, the semiconductor integrated circuit substrate 12 is resiliently supported by the flexible printed wiring plate 16. Thus, this substrate can move in the direction of the optical disk D (B-B direction). In this case, the portion of the flexible printed wiring board 16 immediately above the focusing grating coupler 18C of the optical integrated circuit type pickup 18 is cut out in the form of a window as indicated by reference symbol 16W of FIG. 8. Thus, an arrangement such that irradiation of a laser beam is not prevented is provided. The operation of the optical head 11 will now be described. When a control current is caused to flow in the electromagnetic coil 13 through the lead wires 16L by a power supply (not shown), a new right-handed magnetic field with respect to the control current direction is produced in the electromagnetic coil 13. Accordingly, an electromagnetic force in the B-B direction is exerted on the electromagnetic coil 13. As a result, since the force in the B-B direction is also exerted on the semiconductor integrated circuit substrate 12, it is possible to move the optical head 11 in the positive or negative direction of the optical disk D. Thus, focusing servo of the optical head 11 can be carried out. The method of forming the electromagnetic coil provided on the semiconductor integrated circuit substrate and the configuration of the electromagnetic coil will now be described. The electromagnetic coil 13 is formed by using the multilayer interconnection formation technology which is one of integrated circuit technologies to etch a spiral coil pattern on the surface of a silicon substrate to vacuum-deposit aluminum, etc. thereon. The pattern of the electromagnetic coil is not limited to a square spiral shown in FIG. 7. Further, patterns of circle, ellipse, or other curves may be used. This coil pattern may be constructed not only in a planar spiral form but also in a three-dimensional spiral or helical form in layer direction in the same manner as in an ordinary electromagnetic coil by the application of the multilayer interconnection technology. The number of coil patterns on a single semiconductor integrated circuit substrate is not limited to one as in the pattern shown in FIG. 7. In an embodiment of the present invention, two coil patterns or more are adopted. As shown in FIG. 9, there is an arrangement to provide two electromagnetic coils 13A and 13B so that the optical integrated circuit type pickup 18 is put therebetween. In this case, by adjusting control currents caused to flow in individual electromagnetic coils, it is possible to alter the directional angle of a laser beam with respect to the optical disk D. By making use of this, tracking servo of the optical head can be also carried out. In addition, the electromagnetic coil may be provided on either side of the semiconductor integrated circuit substrate 12. An optical head which is a further embodiment of a semiconductor integrated circuit device according to this invention is shown in FIGS. 10 and 11. This optical head 21 differs from the optical head 11 in the first embodiment in that four elastic supporters 26 are affixed on the semiconductor integrated circuit substrate 12 as support means in place of the flexible printed wiring board 16 of the optical head 11 in the first embodiment shown in FIG 9. These supporters 26 may be not only in the form of coil, rod and plate, etc., but also in other forms. In addition, the number of supporters is not limited to four as in the embodiment. Also in this embodiment, by causing a control current to flow in the electromagnetic coil 13 through conductors (not shown) by a power supply (not shown), it is possible to carry out focusing servo. Further, in the same manner as shown in FIG. 9, an arrangement is employed to provide two electromagnetic coils to carry out tracking servo. In addition, similarly to the first embodiment, there is no limitation in connection with the number of coil patterns, etc. In addition, the semiconductor integrated circuit device of this invention can be applied not only as a semiconductor integrated circuit device having an actuator function and a semiconductor integrated circuit device having a sensor function, but also as a semiconductor integrated circuit device having an actuator function and a sensor function combined with each other. For example, an approach may be also employed to further provide a velocity coil for detecting a velocity of the optical head on the semiconductor integrated circuit substrate 12 to constitute a miniaturized optical head having a function to detect a velocity at the time of track jump motion.

Claims: A semiconductor integrated circuit device comprising a semiconductor integrated circuit substrate (2,12) having an optical integrated circuit type pickup (18) comprising a laser diode (18L), a beam splitter (18S), and a photo detector (18D); characterised by the substrate being further provided with two or more electromagnetic coils (13A,13B) formed on a surface of the semiconductor integrated circuit substrate by an integrated circuit technology, and from which a pair of conductors (4,16L) lead; a magnet (15) for creating a magnetic field (M) mounted to a mounting base; and the substrate being movably supported by elastic support means (16) with respect to the mounting base within the magnetic field (M); wherein the direction and intensity of current supplied to the coils and the conductors controls the angle of the substrate to perform a tracking operation. A device according to claim 1, wherein the support means is a bent flexible printed wiring board (16). A device according to any one of the preceding claims, wherein the semiconductor integrated circuit substrate (2,12) is additionally movable is the direction of an optical axis of a laser beam emitted from the optical integrated circuit type pickup (18). A semiconductor integrated circuit device according to any one of the preceding claims, wherein the semiconductor integrated circuit device is additionally arranged so that the semiconductor integrated circuit substrate (2,12) interlocks, in use, with a measurement object to induce a current in an additional electromagnetic coil whereby the semiconductor integrated circuit device is operable as a sensor. A device according to claim 4, wherein the sensor is a sensor for measurement of displacement. A device according to claim 4, wherein the sensor is a sensor for measurement of pressure. A device according to claim 4, wherein the sensor is a sensor for measurement of magnetism.

Inventors: SUGIURA SATOSHI, SUZUKI JUN, SUGIURA, SATOSHI, SUZUKI, JUN
Applicants: PIONEER ELECTRONIC CORP, PIONEER ELECTRONIC CORPORATION
Application year: 1990
Main classification: G01D5
IPC codes: H01F7, G01D5, H01L41, G11B7, G01B7