KR850001424Y1 - Apparatus comprising an electrically controllable reflection device for detecting a radiation beam - Google Patents

Abstract

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Description

Electrically Controlled Reflector for Radiation Beam Detection

1 is a schematic diagram showing an optical path of an apparatus for recording and reproducing a video signal.

2 is a perspective view showing a partial cross-sectional view of a mechanical unit for supporting an optoelectronic and optical device and a light source and for supporting and rotating an information disc.

3 is a perspective view of the apparatus of FIG. 2 viewed from another direction.

4 is an exploded perspective view of a reflector used in the apparatus of FIGS. 2 and 3 associated with an electromagnetic pivoting device and a bearing device.

The present invention relates to a device including an electric control panel for deflecting a radiation beam in a direction based on an electric control signal, wherein the reflecting device has a base provided with a reflecting surface and with respect to the pivoting axis through a limited pivot angle. It includes a reflective element capable of electrically pivoting.

The device of the above-mentioned type is known from the applicant's swing mirror device for a video disc player in US Pat. No. 4,123,146. In the optical path between the reflecting surface of the video disc and the laser, the turning mirror device is configured to be integrated in the video disc player. The light beam emitted by the laser can be reflected by the pivoting mirror device through a limited range of angles under the influence of the electric control signal, so that the light beam focused by the objective lens at the read point on the disc is automatically controlled electronically. Can track information tracks on a video disc. For a supplementary explanation of the video disc, reference is made to a series of items on pages 178-193, 1973, vol. 7, no. 33, "philips Technical Review".

Reflectors must meet precise mechanical needs. The reflecting surface must have high precision flatness, not only when stationary but especially when in motion. The control circuit incorporating the pivoting element should have a bandwidth of about 20 KHz. Parasitic resonances in the mechanical parts of the control circuit, especially in the reflecting element, must not occur in the frequency range up to about 200 Hz. The reflecting element must therefore have inconsistent mechanical properties, ie small moments of inertia, high stiffness and low mass with respect to the pivoting axis. It has been found that these needs cannot be easily set by known swing mirror devices. Another problem is that reflective surfaces located on the base surface are exposed to atmospheric effects and are prone to mechanical injury.

It is an object of the present invention to provide a device of the type described above in the introduction, which has important additional advantages besides a satisfactory combination of the above mechanical properties and a more effectively protected reflecting surface. The present invention is characterized in that the base element of the half element includes an optical body composed of a plurality of separating portions, and a reflecting surface is placed between the separating portions of the optical body. By designing a reflecting element such as an optical body including a plurality of separating parts, it is possible to obtain a reflecting element in which the thickness of the reflecting element measured in the vertical direction of the reflecting surface increases from the periphery of the reflecting surface toward the center of the reflecting surface. . Therefore, for a given degree of stiffness, the moment of inertia and mass of the reflecting element can be made smaller than when an equivalent rigid plane mirror is used. The parts of the optic lying on the plane of the reflecting element opposite the radiation source also contribute to the stiffness of the reflecting element. The reflective surface is sealed between the separate portions of the optic and can therefore be made of a material having a relatively high degree of mechanical weakness or atmosphere.

An embodiment of the present invention is characterized in that the optical body is actually in the form of a cube and the reflecting surface is placed on the diagonal surface of the cube. The cube provides a satisfactory combination of low moment of inertia and low mass and stiffness. The optics may be suitably used in embodiments in which the base surfaces of the prisms include two prisms disposed opposite one another and a reflecting surface placed on one of the at least two prisms. According to another embodiment of the present invention, the reflective surface may have a polarization separation layer. Such collisions are known, but the use of polarization separation layers in signal mirrors has been avoided in view of the risks associated with relatively large ductility and mechanical damage. If, for example, a radiation source providing a single polarized radiation beam such as a laser and a so-called 1 / 4λ plate are used, for example a suitable optical path for a video disc player can be realized by the use of a polarization separating layer. The reflecting surface of the reflecting element then reflects the light beam from the laser but passes through the light beam reflected and modulated by the information carrier.

Similar to the known mirror device, the device according to the present invention is a pivot bearing device for pivotally supporting a reflecting element, in particular an optical body, in relation to a frame, and pivoting torque to the optical body by means of a frame and a control signal. The former includes a pivoting device, wherein the pivot bearing device includes a fixed bearing device rigidly connected to the frame and a pivoting device about the pivoting axis, and a bearing device connected to an optical body. The pivoting device includes a pivoting device capable of pivoting and a stationary bearing device on the frame, which is also electromagnetically interoperable with the stationary pivoting device and is firmly connected to the optical device.

According to an embodiment of the present invention, the pivoting axis is disposed in the plane where the reflecting surface is disposed, the pivoting axis extends through the center of mass of the optical body, and the pivoting motion is performed so that the optical body is in equilibrium at any pivoting position. The optical body is supported in the neutral equilibrium by the bearing device, and each pivotable pivoting device is supported at the position where the side of the pivoting axis and the optical body intersect.

The advantage of this embodiment is that the mass and the moment of inertia are minimal, and the increased bandwidth can be obtained because the external torque which does not pass the radiation beam during the turning of the reflective surface and the external torque to return the optic to the zero position does not act on the optic. Is there.

If an optical body is composed of a cube containing two identical free angles having a reflective surface in the form of a polarization separation layer interposed between two free angles, another embodiment of the device according to the present invention is reflected information by means of a radiation beam. And an apparatus for decoding information on a carrier, said information carrier being an information structure for modulating the radiation beam reflected by the information carrier. This embodiment includes a reflection source, a photoelectric conversion device for converting radiation beam modulation to electrical modulation, a front side and a front side facing the radiation source, and a top surface facing the information carrier and a bottom surface corresponding thereto, and left, It includes a cube having a right side, wherein the front side and the top side belong to one landscape and the rear side and the bottom side belong to the other landscape. In this embodiment, each of the two landscapes of the reflecting element is transparent to the radiation beam, and the photoelectric converter is reflected by the information carrier and placed in the path of some radiation beams coming out of the lower surface of the entry shield, and the pivotable bearing. The device and the pivotable electrodynamic pivoting device are characterized in that they are arranged on at least one of the two sides of the cube.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

The video disc 2 which is rotated about the axis of rotation 1 in FIG. 1 is read out by the light beam 3 provided by the objective lens 4 which is schematically shown. The light beam is obtained by the semiconductor laser 5. Between the semiconductor laser and the objective lens, a lens 6, a reflector 7 which can be electrically rotated, and a so-called 1/4? Plate 8 are placed. The light beam reflected by the video disk 2 passes again through the 1 / 4λ plate, passes through the reflector 7 and the lens 9 and is finally focused on the photoelectric device 10. The reflector 7 for reflecting the light beam 3 pivots about the pivot axis 11 perpendicular to the drawing.

By the apparatus shown in FIG. 4 and hereafter described herein, the reflecting device is electrically pivoted within a limited angle range in response to the electrical control signal. The reflective surface 12 is driven to reflect light from the laser 5. However, the light beam reflected by the video disk is transmitted to the optical electronic device 10 without being substantially affected. This will be described in more detail later in this specification. The reflecting device is composed of an optical body and includes a base body including separating parts 13 and 14 and a reflecting surface 12 is inserted between these separating parts.

The disc 2 is in the form as described above in Applicant's US Patent No. 4,074,282 (PHA 20742). The disk comprises two transparent disk elements 15, 16 spaced by two metal voids 18, 17, so that a closed space is formed between the two disk elements. . On the side facing the space 19, a special layer is vacuum deposited on the disk elements 15, 16, and the special layer is a metal in which pits having a unit of micron size can be burned by the light beam 3; It consists of. The disc 2 is supported by a rotating plate 19 having a diameter of 10 cm and driven by the electric motor 20. The disk is fixed on the rotating plate 19 by a knit 22 fitted on the screw shaft 22 connected to the rotating plate 19.

The motor 20 is mounted in the frame 23, and the carriage 24 moves radially in the frame. Guide rods 25, 26 are provided in the frame to guide the carriage, on which bearing bushes can slide. The carriage 24 has a gear rack 27 on its side. On the side wall of the frame 23, an internal gear transmission is provided and is equipped with a motor 25 which is capable of pivoting with the aid of bearing bearings. The motor 28 drives the pinion 30 to interact with the gear rack 27. By means of a compression spring, not shown, the motor 28 is inclined in a direction that causes the pinion 30 to be tasted with a prescribed force against the gear rack 27.

The semiconductor laser 5 is provided in the housing 31 and is firmly fixed to the frame 23. This housing also houses the lens 6. Underneath it, in particular as shown in FIG. 3, the carriage 24 also carries a frame 32 for supporting an electrically controllable reflector 7.

Referring to FIG. 4, the optical body is substantially cubic and the reflective surface 12 lies on the diagonal surface of one side. The cube includes two prisms with the bases of the prisms 13 and 14 facing each other, with a reflecting surface on one of the prisms. The surface is provided with a polarization separating layer. These layers are known in nature, and for the wavelength of a semiconductor laser, for example, the polarization separating layers consist of a mixture of magnesium oxide and magnesium fluoride. Seventeen layers of this material, each layer having a thickness of 800-1000 mm 3, are placed on the base surface of one of the two prisms, resulting in a layer having a total thickness of about 1.7 microns. The two separating prisms may be bonded to each other by a general device for bonding optical elements such as lenses to each other. The optical path shown in FIG. 1 can be obtained by using a polarization separating layer and a 1/4 lambda plate. The polarization of the reflected light beam is rotated 90 ° relative to the beam from the laser 5 so that the reflective surface 12 transmits the reflected beam to the lens 9 and the optoelectronic device 10. The 1/4 lambda plate 8 is mounted in the carriage 24 but is not shown in FIGS. 2 and 3. The difference in the polarization direction of the traveling and reflecting beams is schematically indicated by arrows 50 and 51 in the first figure.

The reflector 7 is in addition to the reflector and a pivot bearing device and frame 32 for axially supporting an optical body comprising two prisms 13, 14 in relation to the frame. Belongs to the device including. The pivot bearing device includes a stationary bearing device and has two disks 34A, 34B and bearing devices and pins 33A and 33B that are secured to the cube and that can pivot about the pivot axis. It is firmly connected to the frame 32 in the form of.

Each disk in which the bearing holes 35A and 35B are formed receives one of the free ends of the pins 33A and 33B, respectively, with a slight margin. Furthermore, the apparatus based on the electric control signal includes an electromagnetic pivot apparatus for representing pivot torque in the cube. The device comprises a stationary pivot device in the form of two coils 36A, 36B on both sides of the cube. These coils are firmly connected to the frame 32 and may for example be glued to the disc. A number of electromagnetic pivot devices that interact with the coil are placed on the cube in the form of a series of permanent magnets 37A to 40A on one side of the cube and 37B to 40B on the other side. These magnets are glued to the discs 34A and 34B, respectively, and because the discs are made of a suitable soft magnetic material, the discs are not only as bearing elements for the cube but also for magnetic shorts for the permanent magnets mounted on the discs. It works like a circuit. The magnetization direction of the magnets is chosen such that the device is relatively independent of virtual external storage, for example the magnetic field of the motor 20. For this purpose, the magnets S poles are placed in the direction of the coil 36A by being magnetized in the first direction of the magnets 37A and 39A.

The two other magnets 38A, 40A are magnetized in opposite directions, so that the magnets face the coil 36 as the S pole. The magnets 37B and 39B are S poles, and the magnets 38B and 40B face the coil 36B as the N poles. For further information regarding this electromagnetic pivoting device, reference may be made to Applicant's previous application number (PHN 9707).

The pivoting axis 11 is arranged in the plane on which the reflective surface 12 is placed. Since the optics comprising the combined prisms 13 and 14 are cubic, the mass center of the optics lies in the plane 13. The pivoting axis 11 extends through the center of mass. Moreover, since the pivoting axis 11 extends through the center of mass, the optical body is consequently supported by the pivot bearing device in neutral equilibrium. This means that the cube is in parallel at any pivoted position. It is obvious from this point of view that the permanent magnets 37A to 40A and 37B to 40B, the discs 34A and 34B are symmetrically placed about the pivoting axis 11. The cube shape of the optics becomes effective as the discs 34A and 34B are placed on both sides of the cube that cannot be used for other purposes.

The cube has a front face 41 facing the radiation source and a corresponding back face 42, an upper face 43 facing the information carrier 2, a lower face 44, and a left and right side face 45a, 45b. . The front face 41 and the top face 43 belong to the prism 13, and the back face 42 and the bottom face 44 belong to the prism 14. The two prisms 13 and 14 are transparent to the light beam 3 and are made of glass, for example, of a type suitable for synthetic resin. The radiation beam is modulated by the information contained in the information structure on the disc 2. The reflected radiation beam is directed to the photoelectric converter 10 which converts radiation beam modulation to full modulation. The photoelectric converter 10 is placed in the path of some radiation beams reflected by the disk 2 exiting from the lower surface 44 of the cube. The pivotable bearing devices 34A, 34B and the pivotable electrodynamic devices 37A to 40A and 37B to 40B are each two sides 35A of the cube, ( 35B). Thus the cube is effectively used in the illustrated embodiment. All surfaces of the cube except the rear face 42 have a function. The photoelectric device 10 is mounted on the frame 32 by being mounted on the holder 47. The lens 9 is mounted in the frame 32, that is, the position of the lens can be adjusted with the screws 49 in the mount 48.

In general, the back side can be used to detect the position of the cube. In the case of a neutral journaled reflector, the position of the cube is continuously detected so that the cube can be adjusted towards the zero position of the cube by the electronics with the aid of the control coils 36A, 36B. It is necessary to be. For example, the back surface 42 may provide a reflective layer for reflecting the light beam emitted by the separate light source, the reflection of which is taken out by a photoelectric device provided for this purpose. The amount of reflected light received by the device is based on the cube position. It is also possible to utilize some of the light from the semiconductor laser 5 passing through the reflecting surface 12 and out of the back of the cube to detect the position.

1 shows another position detection method. The zero position of the cube is chosen such that a small angle is obtained between the front face 41 and the light beam 3 incident thereon. A portion of the light beam reflected by the bottom face 41 is returned through the lens 6 and forms an image on the photoelectric position detecting element proximate to the semiconductor laser. Such a device is known in nature and the lens 5 has the advantage that a small amount of reflected light is effectively used because it focuses the reflected light at a small point in the focal plane of the lens.

The frame 23 has a dimension of about 100 × 40 mm. The cube has sides of about 6 mm and has a very high natural resonance frequency due to its high stiffness. An additional advantage of the use of the prism 13 is that due to the presence of synthetic resin or glass between the reflecting surface 12 and the objective lens 4, the position of the pivoting exit 11 as a result of the refraction of light in the glass or synthetic resin can It is clearly moved in the direction. In an ideal case, pivoting axis 11 will be in focus of the objective lens. In many cases, however, this is not possible. It is always desirable to place the pivoting axis in the focal point of the objective lens.

Claims (1)

An optically controllable reflector capable of electrically pivoting about a pivoting axis through a limited pivot angle and electrically deflecting the radiation beam in a direction based on an electrical control signal, comprising a plurality of prisms 13, 14. The base of the reflective element made of a sieve and a reflecting surface 12 are located between the prism of the optical body, which prism is permeable to the firing beam 3, and is reflected on the information carrier 2 to reflect the reflecting device. Radiation beam detection, characterized in that it consists of a photoelectric conversion device (10) installed in the path of the radiation beam passing through, a pivotable disk (34A, 34B) and magnets (37A-40A, 37B-40B) provided on the side of the reflector Electrically controlled reflector for use.