JPS6118392B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The invention relates to a multilayer optical data record carrier and a playback device associated therewith, in particular a multilayer optical data record carrier having a plurality of data information tracks in different data layers formed on at least one side of a record carrier substrate or base member. The present invention relates to a reproducing device comprising a record carrier included therein and selection means for selectively reading one of such data tracks with a scanning light beam, producing an electrical read signal corresponding to the data on the scanning track. The multilayer record carrier and playback device of the invention is particularly useful for high density information recording. For example, one application of the present invention is the recording and playback of audio and video signals of television programs.

Such devices have been proposed in US Pat. No. 3,430,996 and US Pat. No. 3,518,442. The optical data recording carrier disclosed herein records data by means of notches in two tracks provided on opposite sides of a light-transmissive substrate. However, such conventional record carriers and their associated playback devices have drawbacks. This is because the record carrier has only one data layer per side and is read by passing a light beam through the record carrier, which includes a light diffusing layer between the two data layers. .
As a result, these record carriers cannot store as much data as the record carrier of the present invention, and they are expensive and difficult to manufacture. Additionally, the playback device requires separate focusing optics for the photodetector and light source. This is because the detector and the light source are located on opposite sides of the record carrier. Conventional playback devices therefore cannot be made as compact as the embodiments of the present invention employing reflective record carriers by arranging the detector and the light source on the same side with respect to the record carrier.

Such a device employing a light-reflecting optical data storage carrier was proposed in Philips Technical Review (Vol. 33, No. 7, pp. 178-180, published in 1970, by K. Compan and P. Kramer). ing. The device proposed here uses a common optical element with the photodetector and the light source placed on the same side with respect to the record carrier. However, this record carrier has the disadvantage that the optical data is recorded as pits or notches in a single layer formed by pressing the record from a master in a manner known in the art.
As a result, only approximately 30 minutes of television programs can be recorded on large record carriers with a diameter of 30 cm, ie conventional long-play records. Since the entire surface of the record carrier containing the data bits is coated with metal so as to reflect the light beam, several data layers could not be recorded on the same side of the record carrier as in the present invention. Unlike the background surface, the data pits reflect the light beam away from the detector and the pits are detected by the detector due to the absence of light, resulting in a lower signal-to-noise ratio than in the present invention. During the electrical reading signal you will get.

US Pat. No. 3,501,586 discloses a technique relating to an optical data record carrier and its reproducing device. However, the invention disclosed therein does not mention anything about a multilayer data record carrier such as the present invention.

It is therefore an object of the invention to provide an improved optical data record carrier of high storage density having a plurality of data tracks recorded in different data layers provided on at least one side of the substrate of the record carrier. be.

Another object of the present invention is to provide a simple and economical multilayer data record carrier in which highly accurate optical data tracks are formed without forming pits or grooves in the record carrier.

Yet another object of the invention is to provide a multilayer data record carrier having a plurality of optically reflective data layers, using a light source and a detector arranged on the same side of the record carrier and at least some optical elements in common. The object of the present invention is to provide a playback device that is extremely compact and inexpensive.

A further object of the invention is to provide a record carrier in which light reflected from data spots is detected to generate an electrical read signal with a high signal-to-noise ratio.

A further object of the invention is to provide an improved reproduction device comprising selection means for selectively reproducing data tracks on different data layers formed on such a multilayer data record carrier.

It is another object of the invention to provide such a reproducing device which selects a data track to be reproduced by simply and accurately shifting the focus of the reading light beam from one track to another. be.

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show a reproducing apparatus for reproducing a reflective multilayer optical data recording carrier 10 as shown in FIG. 3 in which optical material is used for data spots,
This playback device consists of a light source 1 provided on the same side of the record carrier.
2 and a photodetector 14. According to this reflective reproducing device, the device can be made more compact, and the objective lens 16 is placed in the same optical path for the reflected light from the record carrier 10 to the detector 14 and the transmitted light from the light source 12 to the record carrier. This has the advantage that it is possible to use at least several optical elements such as: Therefore, costs can be reduced, and since the light beam passes through the optical element twice in opposite directions, defects in the optical system, such as lens aberrations, can be eliminated.

As the light source 12, for example, a laser light source can be used. The light beam 18 is transmitted from the light source 12 to 1
It then passes through a lens 20 and a light mask 22 in which an aperture, commonly referred to as a "pinhole" element, is formed. The light beam is focused as a small spot by the lens 20 at the position of the circular aperture of the pinhole, so that such aperture forms a light spot and is focused on the object (or information). The light beam 18 passes through a beam splitting mirror 24 and onto a rotating reflecting mirror (distributing mirror) 26 . The outer surface of this rotating reflective mirror is in the form of a pentagon and has five mirrors thereon, each corresponding to five objective lenses 16 carried on a rotating scanner (scan wheel) 28. are doing. A rotating reflective mirror 26 is mounted on the shaft 30 of the scanner 28 so that it is rotated at a constant speed by an electric motor 32 coupled to the scanner. As a result, the rotating reflective mirror 26 rotates at the same speed as the objective lens 16, so that one of the rotating reflective mirrors is always aligned with the corresponding objective lens. Therefore, the rotating reflective mirror 26
is only once when the objective lens 16 rotates across the record carrier 10 to reproduce one of the data track lines 35 on the record carrier as shown in FIG.
The light beam is reflected and distributed by an objective lens 16.

The light beam 18 passes through five objective mirrors 34 mounted on the scanner 28 directly below each objective lens 16.
from one of the rotating reflective mirrors onto one of the mirrors. As a result, the light beam is reflected from the objective mirror 34 via the associated objective lens 16 onto the multilayer optical data record carrier 10 . This light beam is focused by lenses 20 and 16 as a small spot in the focal plane on one of the data layers of the record carrier. The diameter of such a spot has approximately the same size as the width of one of the data track lines 35 of the data layer spots provided on the record carrier.

A selection device is provided to shift the focal plane from one data layer to another to selectively reproduce selected data tracks on such data layer. The movement of this focal plane is controlled by a pinhole type optical mask 22.
and by moving the primary lens 20 in a direction along the beam axis using the electromagnetic coil 36 and associated electrical control circuitry. The coil 36 is a pinhole type mask 2
2 attracts and repels the magnetic contact piece 38 to which it is attached, so that this magnetic contact piece and the lens 20 coupled thereto can be moved towards or away from the record carrier 10. Spring 4
0 to attach the pinhole type optical mask 22. This spring resists the electromagnetic force of the coil 36 and allows for more accurate mask adjustment. However, considering the large distance between the optical mask and the record carrier 10, the mask 2
The ratio between the amount of movement of the object formed by the second pinhole and the amount of movement of the resulting light spot image in the focal plane of the objective lens 16 is equal to the square of the magnification of the objective lens 16. For this reason, the objective lens 16
For a magnification of approximately 10, the displacement of the mask 22 is approximately 100 times greater than the resulting displacement of the focal plane of the light spot on the record carrier. Therefore, considering that the distance between data layers is extremely small, it is possible to accurately adjust the focal plane necessary for selective reproduction of one data layer.

A focused light spot on the record carrier,
One line 35 of the data track is scanned without overlapping adjacent track lines. At 4 1/2 inches (1 inch = 2.54 cm) with respect to the center of the objective lens, this scan in the longitudinal or "X" direction along the track line is performed by the scanner 28 in units of increments. This can be achieved by rotating at a speed of approximately 2500 revolutions per rotation. To perform line-by-line scanning in the lateral or "Y" direction, the data record carrier 10 is moved slowly downwards as indicated by the arrow 41 in any suitable manner, such as by a worm gear arrangement 42. This worm gear arrangement moves the carriage 44 supporting the record carrier and is in mesh with the electric motor 32. The longitudinal movement speed of this record carrier 10 is approximately 420 microns per second for reproducing television signals on a 5 inch wide record carrier. the result,
Each objective lens 16 is capable of scanning an individual data track line 35 of the data tracks on one data layer of the record carrier 10 when the scanner 28 is rotated in the direction of the arrow 43.

The scanning light beam 18 is reflected from the data spot or its surrounding background through the objective lens 16, the objective mirror 34, the rotating reflective mirror 26, and onto the beam separation mirror as a modulated reading light beam.
The beam splitting mirror 24 reflects the modulated read light beam 46 to the detector 14. The detector and photocell produce an electrical output signal corresponding to the modulated light beam. A suitable amplifier and decoder system (not shown) connects this electrical reading signal to the video input terminal of the television receiver or to other utilization equipment connected to the output terminal of the detector.
It can be sent through.

A "taping" plate 45 is provided between the pinhole optical mask 22 and the beam separation mirror 24 to laterally displace the light beam 18 by refracting it. This displacement plate is moved by a galvanometric motor 47 in response to a tracking signal supplied to this input terminal to change the magnitude and direction of the lateral displacement of the light beam 18, so that the beam is being scanned. Stay on the data track. The tracking signal is generated by a servomechanism connected to the output terminal of the detector 14, as also disclosed in US Pat. No. 3,919,697.

The light beam 18 is not coaxial with the rotating reflecting mirror axis 30, and is incident on the rotating reflecting mirror 26 at an angle smaller than the angle formed by the reflecting surface of the mirror and the axis of the shaft. As a result, the reflected light beam is
It rotates at a speed slightly slower than the zero rotational speed and can illuminate the objective lens to illuminate all data lines 35 with substantially uniform intensity. On the other hand, when the light beam illuminates the rotating reflecting mirror 26, if this light beam is parallel to the axis, the reflected beam will rotate at the same speed as the objective lens, so the rotating reflecting mirror will cause the rotating reflecting mirror to In a switching position such that the light beam is transferred from one lens to the other, the objective lens will be illuminated with approximately only half the light beam intensity.

As shown in FIG. 3, one embodiment of a multilayer optical data record carrier includes an opaque, non-reflective recording substrate or base member 48 of opaque plastic, glass, ceramic or metal material. A plurality of data layers 50A, 50B, 50C and 50D are provided on one or both sides of substrate 48. Transparent plastic spacer layer 5 for data layer
Separate by 2. Each data layer consists of spaced lines 35 on the record carrier as shown in FIG.
It has a continuous or parallel track of data spots 54 of light-reflecting material formed along it. The data spots are separated by spaces so that they can represent binary encoded digital information or frequency modulated or pulse width modulated analog information.

The data spots 54 of the data layers 50A to 50D can be formed using a light-reflecting metal material formed by vapor deposition, for example, through a mask having holes corresponding to the data spots. still,
The data spots may also be obtained by etching through a photoresist mask formed by exposure to a light image of the data spots in a conventional manner such as those used to form etched electrical circuit boards. The thickness of the spacer layer 52 is greater than the depth of focus of the objective lens 16, so that when the light beam 18 is focused on one of the data layers, the remaining data layers are out of focus, as shown in FIG. The light beam cannot be blocked as shown in the figure. A protective layer 56 of a transparent plastic material is provided on top of the outermost data layer 50A to prevent the data layer from being subjected to mechanical damage and to separate dust present on the record carrier from said data layer. , to prevent these dust particles from blocking light transmitted to the data layer. This protective layer 5
The dust on the outermost surface of 6 is out of focus for any light spot being focused on any data layer. For this reason, for example, the thickness of the protective layer 56 may be approximately 10 mils (1 mil =
2.54/1000 cm), spacer layer 52 is approximately 5 mils thick, and substrate 48 is approximately 1/8 inch thick, depending on the materials used for such substrates.

The record carrier 10'' of FIG. 4 may be a reflective record carrier similar to the record carrier of FIG. 3, except that the non-light reflective data bits 54 are formed of a light opaque material. Additionally, in the embodiment of Figure 4, a light reflective metal layer 74 is provided between the substrate 48 and the spacer layer 52 underlying the bottom data layer. The record carrier 10'' of FIG. 4 is a reflective record carrier even if none of the surrounding background materials of the layers are light reflective materials. Of course, if the substrate is formed using a dimensionally stable metal rather than plastic, the reflective layer 74 can be a surface of the substrate.

Thus, in the light-reflecting multilayer optical data storage carrier shown in FIG. The light reflective multilayer optical data recording carrier shown in FIG. A plurality of non-reflective opaque data layers are provided on the same side of the reflective base member separated by transparent spacers having a thickness greater than the depth of focus of the objective lens, each data layer having a transparent material only at the data spots. Since the remaining part is transparent, when the light beam is focused on the lower data layer, the amount of light beam that is blocked by the upper data layer can be minimized, and therefore all the data layers can be focused from the same side. Easy and good reading by focusing the light beam on each layer,
Therefore, in a reproducing device, the light source and the photodetector are arranged on the same side, and an objective lens or the like is commonly used for focusing the light beam on the data layer and detecting the reflected light, thereby making the device extremely compact and inexpensive. I can do it.

The data layer 50 and spacer layer 52 of FIGS. 3 and 4 can be formed into separate sheets and glued together and then attached to the substrate by a suitable solvent for the plastic material. However, strips of photographic film exposed and developed with different data tracks can be used as both the data layer and the spacer layer. This is because the spacer layer can be formed by a transparent film packing layer. After passing the film strip through a glue or solvent tank, it is attached to a substrate, which is then passed through a pressure roller for further drying.

It is clear that the invention is not limited only to the embodiments described above, but that many modifications can be made without departing from the scope of the invention.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of a reproducing device for a reflective multilayer optical data recording carrier according to the present invention, FIG. 2 is an enlarged view taken along line 2-2 in FIG. 1, and FIG. FIG. 4 is an enlarged sectional view showing a part of an embodiment of the multilayer optical data recording carrier of the present invention that can be used in the playback device shown in FIG. It is. 10...Multilayer optical data record carrier, 12...Light source, 14...Photodetector, 16...Objective lens, 1
8... Light beam, 20... Main lens, 22... Pinhole type optical mask, 24... Beam separation mirror, 26... Rotating reflecting mirror, 28... Rotating scanner, 30... Rotating reflecting mirror Shaft, 32... Electric motor, 34... Objective mirror, 35... Data track, 36... Coil, 38... Contact piece, 40... Spring, 42... Worm gear device. 44... Carriage, 45... Displacement plate, 46... Modulated reading light beam, 47... Galvanometric motor, 48... Substrate (or base member), 50A, 50B, 50C, 5
0D...Data layer, 52...Spacer layer, 54...
...Data spot, 56...protective layer. 74...Light reflective metal layer.

Claims (1)

Claims: 1. A multilayer optical data record carrier comprising a plurality of optical data layers having optical data information spots recorded on at least one side of a base member, the base member being optically opaque and non-transparent. The plurality of data layers are light-reflective data layers of different data, and only the data spots of each data layer are provided with a light-reflective material, and the rest is transparent, and the adjacent data layers are light-reflective data layers of different data. A light-reflecting multilayer optical data record carrier, characterized in that it is separated by a transparent spacer layer having a thickness greater than the depth of focus of an objective lens for reproducing said data. 2. A multilayer optical data record carrier comprising a plurality of optical data layers having optical data information spots recorded on at least one side of a base member, said base member being reflective and said plurality of data information spots being recorded on at least one side of said base member. The layers are optically opaque and non-reflective data layers of different data, and only the data spots of each data layer are provided with an opaque material and the rest are transparent, and the adjacent data layer is provided with an objective lens for reproducing said data. A light-reflecting multilayer optical data record carrier, characterized in that it is separated by a transparent spacer layer having a thickness greater than the depth of focus of the light reflecting multilayer optical data record carrier. 3. for supporting a multilayer optical data storage carrier having a light source for generating at least one light beam and a plurality of data layers in which optical information spots are recorded in the form of tracks on at least one side of the base member; a support member, focusing means for focusing at least one light beam onto the record carrier with a dimension substantially equal to the width of the data track, and a relative movement between the light beam and the record carrier for effecting scanning. scanning means for scanning the data track with a light beam; and scanning means for propagating the scanning readout light beam from the record carrier to at least one photodetector to transmit the data on the scanning track from the photodetector. reading means for producing a corresponding electrical read signal, wherein the base member is optically opaque and non-light reflective, and the plurality of optical data layers are optically reflective for different data. A data layer, in which a light reflecting material is provided only at the data spot of each data layer, and the rest is transparent, and the adjacent data layer is a transparent spacer layer having a thickness greater than the depth of focus of an objective lens for reproducing the data. separated by, and
selecting means for selectively reading one of the data tracks of a plurality of data layers on one side of the base member to generate a read signal from the selected data track of one layer; A multilayer optical data record carrier reproducing apparatus, characterized in that the means, photodetector and selection means are all arranged on the same side with respect to the record carrier support member. 4 supporting a multilayer optical data record carrier having a light source for generating at least one light beam and a plurality of optical data layers in which optical information spots are recorded in the form of tracks on at least one side of the base member; and focusing means for focusing the at least one light beam onto the record carrier with a size substantially equal to the width of the data track.
scanning means for causing the light beam to scan the data track, including means for causing relative movement between the light beam and the record carrier for scanning; and at least one optical detection means for scanning the scanning reading light beam from the record carrier. reading means for propagating to a photodetector an electrical readout signal corresponding to the data on the scanning track, the base member being reflective;
The plurality of data layers are optically opaque and non-reflective data layers of different data, wherein only the data spots of each data layer are provided with an opaque material and the rest are transparent, and the adjacent data layers are optically opaque and non-reflective data layers of different data. separated by a transparent spacer layer having a thickness greater than the depth of focus of the objective lens for reproducing the
selecting means for selectively reading one of the data tracks of a plurality of data layers on one side of the base member to generate a read signal from the selected data track of one layer; A multilayer optical data record carrier reproducing apparatus, characterized in that the means, photodetector and selection means are all arranged on the same side with respect to the record carrier support member.