JPS6185642A - Reproducer of optical information - Google Patents

Abstract

PURPOSE:To simplify the constitution and miniaturize an optical information reproducer by using a photodetecting mechanism which can receive simultaneously the beams from a photodetection area including a spot of reproduction light and having a larger area than said spot. CONSTITUTION:A photodetecting mechanism 2 consists of a photoguiding part 21 and a photodetecting part 22. A photodetecting end face 211 of the part 21 is set at such a size that can receive at one time the reflected beams sent from a photodetecting area including a spot of the reproduction light of a recording part 41 and having a larger area than said spot. Owing to addition of the part 21 having such face 211, the face 211 can be set static to a recording medium 4 while the spot of the reproduction light is scanned vertically and is not required to follow the movement of the spot. While a mechanism is added to shift in steps the face 211 in parallel to the horizontal direction by a distance equal to a scan pitch against the horizontal scan of said spot done by a light illumination mechanism 1. In this case, it is required that at least one of the mechanism 1 and the medium 4 can move. This omits a servo mechanism and an optical system of high performance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an optical information reproducing device that optically reproduces information.

[Prior art]

In recent years, optical information recording that can record information such as audio and video as changes in the shape, dimensions, etc. of bits (concave parts) or blocks (convex parts), and read this optically and reproduce it as audio and video. Media have become widely used, and various types of recording media such as optical disks, optical cards, and optical tapes have been put into practical use.

In such recording media, it is generally desirable to increase the recording capacity and make the media more compact. Therefore, high-density recording is performed by reducing the size of bits or blocks and arranging them closely. Currently, the size of a bit or block is extremely small, approximately 1 pm or less, and therefore the spot diameter of the reproduction light used to reproduce information must be converged to approximately the same size as the bit or block. It is.

Therefore, in the reproduction of such high-density information, it is necessary to scan the reproduction light irradiation spot with extremely high positional accuracy in the recording section of the recording medium, and there is also vibration caused by warping of the recording medium. It is also necessary to ensure that the focus of the optical system is positioned on the recording section so that the spot diameter of the reproduction light is less than a certain level with high precision.
For this reason, conventional playback devices are provided with a tracking control mechanism that controls the scanning direction and a focusing control mechanism that controls the depth position of the focal point of the optical system. Specifically, when the recording light or reproduction light from the light irradiation mechanism is irradiating the recording part of the recording medium, a part of the reflected light from the recording part or the transmitted light of the recording part is divided into four parts, for example. The beam is split using a single wavelength plate, beam splitter, etc., and based on this split light, displacement of the position of the irradiation spot in the scanning direction and optical axis direction is detected, and a servo mechanism is driven to cancel this displacement. It is common to have a so-called optical system common type configuration in which the position of the light spot in the scanning direction and the optical axis direction is feedback-controlled.

And for high-performance position control? ζ needs to be able to be detected based on the t-divided light even when the position of the spot in the recording section is slightly displaced by, for example, several tenths of a micrometer. From this point of view, in the light irradiation mechanism, An objective lens having a large numerical aperture, a short focal length, and a shallow depth of focus is used, and this objective lens is arranged close to the recording section at a distance of approximately m.

A reproducing apparatus for reproducing such high-density information requires a high-performance servo mechanism and an optical system, so it must be quite complicated and expensive.

However, in recent years, recording media have come to be used for a wide variety of purposes. For example, optical cards or optical sheets do not require high-density recording and can record numbers, names, numbers, etc.
In some cases, it may be sufficient to record simple information such as an address sparsely using large 12 bits or a splitter; in such cases, the bit or block size can be made considerably larger. However, even in such a case, using a playback device equipped with a high-performance tracking control mechanism and focusing control mechanism as described above will not fully utilize its features, even though the device is expensive. In the end, there is a lot of waste and it is extremely uneconomical.

[Purpose of the invention]

The present invention has been made based on the above-mentioned circumstances, and an object of the present invention is to provide optical information that is small in size, simple in structure, and inexpensive, suitable for reproducing optical information with a relatively low recording density. The purpose of this invention is to provide a playback device.

[Structure of the invention]

The above object is a playback device that optically plays back information, and includes a light irradiation mechanism that irradiates a recording section of a recording medium with playback light, and a spot of the playback light that irradiates the recording section during playback. This is achieved by an optical information reproducing device characterized by comprising a light receiving mechanism capable of simultaneously receiving light from a photodetection area having a larger area.

Hereinafter, the present invention will be explained in detail based on specific embodiments with reference to the drawings.

FIG. 1 is an explanatory diagram showing an outline of an embodiment of the present invention,
1 is a light emitting mechanism, 2 is a light receiving mechanism, 3 is a reproducing machine groove, and 4 is a recording medium such as an optical card.

The light irradiation mechanism 1 incorporates a light source for reproducing information. Examples of light sources that can be used include discharge lamps such as xenon lamps and mercury lamps, gas lasers, semiconductor lasers, and light emitting diodes. Among these, semiconductor lasers and light emitting diodes are preferred because they are small and have a simple configuration. The form of the light source is not particularly limited, and for example, a light source such as a light emitting diode array may be used.

Although the light from such a light source may be directly irradiated onto the recording medium 4 without being particularly focused, concentrating the light using an optical system can increase the light utilization efficiency. preferable. The diameter of the spot of the reproduction light on the recording section 41 of the recording medium 4 is set in accordance with the size of the bit or block formed on the recording section 41. For example, the bit or block size is approximately 10pm x 10
When the diameter is about μm or more, the diameter of the reproduction light spot is about 10 pm, which is about the same size as these bits or blocks.
It only needs to be about X10 μm or more, and therefore, when condensing light using an optical system, a simple optical system is sufficient.

The direction in which the reproduction light is irradiated onto the recording section 41 may be perpendicular or oblique to the recording section 41, but it is preferable to irradiate the reproduction light in a direction where the light is easily received by the light receiving mechanism 2, which will be described in detail later. That is, in this example 1ζ, since the configuration is to receive the reflected light from the recording section 41, as shown in Fig. 42 tζ,
It is preferable that the light (indicated by the arrow W) be made to enter the recording section 41 at a slight angle, and the reflected light (indicated by the arrow V) to be received obliquely.

Alternatively, the light from the light source may be made to enter the recording section 41 via, for example, an optical fiber or a light-guiding sheet (in this case, the position of the light source can be selected with a relatively large degree of freedom).

In the reproduction of optical information, it is necessary to continuously scan the reproduction light irradiated onto the recording section 41 by the light irradiation mechanism 1. Alternatively, only one or both of the recording media 4 are configured to be movable. Although this scanning direction also differs depending on the track configuration tζ of bits or blocks formed in the recording section 41, in this example, the scanning direction
A large number of tracks extending in the vertical direction (indicated by arrow P) are formed in parallel in the horizontal direction (indicated by arrow Q). (indicated by arrow P), and the light irradiation mechanism l moves along one track from one end to the other end every time required for - times of vertical scanning. It is configured to be able to move in steps by the width of the track in the horizontal direction (indicated by arrow Q) for each time required for reproduction. After the light spot is scanned in the direction in which the track extends, it is moved stepwise to an adjacent track and scanned again in the direction in which the track extends, and this is repeated to scan the entire recording section 41.

The light receiving mechanism 2 is composed of, for example, a light guiding section 21 and a light detecting section 22, and the size of the light receiving end surface 211 of the light guiding section 21 is as follows.
In the example shown in FIG. 1, the area including the sporatra of the reproduction light in the recording section 41 is set to be larger than this. Here, the spot of the reproduction light refers to an area in which the energy distribution of the reproduction light irradiated onto the recording section, when the reproduction light is irradiated without scanning, has an energy of 142 or more of its peak value. Specifically, when the spot of the reproducing light is continuously scanned vertically and horizontally with respect to the recording section 41 as described above, tζ is Pζ and vertical direction (
Indicated by arrow P. ) and a width corresponding to the scanning pitch D in the horizontal direction (indicated by arrow Q).
A light guide section 21 having a shape is provided.

The light guide portion 2 having the light receiving end surface 211t having such a size
1, the light-receiving end surface 211 can remain stationary with respect to the recording medium 4 while the spot S of the reproduction light is being scanned in the vertical direction, and it is not necessary to make it follow the movement of the spot S. That is, in this example, during the vertical scanning period of the reproduction light beam (spora) S by the light irradiation mechanism 1, the light receiving end surface 211i is kept stationary with respect to the recording medium 4, and
In conjunction with the lateral scanning of the spot S of reproduction light by the light irradiation mechanism 1, a moving mechanism ( (not shown).

Of course, this moving mechanism may be any mechanism that can move at least one of the light irradiation mechanism and the recording medium. Further, instead of step movement, movement at a constant speed may be used.

This light-receiving end surface 211 is preferably arranged as close as possible to the recording portion of the recording medium 4, and the distance between the two is preferably about 0.1 to 10 mm, for example.

Although FIG. 1 shows an example in which reflected light is received, if the recording medium 4 has a light transmission type structure, as shown in FIG. recording section 41 of
It may be arranged so as to face the surface of the recording section 41 opposite to the surface irradiated with the reproduction light so as to receive the light transmitted through the t-wavelength.

Further, the light receiving mechanism 2 may be configured to be integrally combined with the light irradiating mechanism 1 to form a line image sensor extending along the tracks of the recording section 41.

The light guiding section 21 may be constructed by bundling a large number of optical fibers as shown in FIG. 1 or 4, or may be constructed using a light guiding sheet or a rod lens array. When the light guide section 21t is configured by an optical fiber, the diameter of one light 7 eyer is, for example, about 1 μm to 1 mm, and a lens may be formed at the light receiving end of the light guide section 21t. Optical fibers may also be used.

When optical fibers are used, the connection portion between the light guide section 21 and the light detection section 22 may be bundled into a cylindrical shape, or as shown in FIG. 5, a CCD line sensor may be used to connect the light detection section 22t- In this case, a large number of optical fibers may be arranged in parallel, bundled into a plate, and connected to the CCD line sensor.

The photodetector 22 basically obtains an electrical signal corresponding to a change in the amount of received light, and is a photomultiply, CC, etc.
D (Charge coupled device),
Ordinary photoelectric conversion elements such as photodiodes and phototransistors can be used.

In the light receiving mechanism 2, the light guide section 21i may not be provided, but may be arranged close to the light detecting section 22t and the recording section 41 to directly receive light.

Alternatively, a light scattering plate may be disposed between the light receiving end surface 211 of the light guide section 21 and the recording section 41, and the light scattered by the light scattering plate may be made to enter an optical fiber having a large numerical aperture.

FIG. 6 shows a recording medium 40t consisting of a rotating optical disk.
An example of the case where reproduction is performed using - is shown, where IO is a light irradiation mechanism and 20 is a light reception mechanism. This recording medium 40 has a recording portion 42 formed in the shape of a donut plate, and the recording portion 42 has a large shape extending spirally from the center toward the outside along the circumferential direction at intervals of . This recording medium 40 is of a type in which tracks are formed by sparsely arranging bits or blocks, and this recording medium 40 is placed at a predetermined position on a turntable (not shown) through its center hole 43, and the turntable By rotating the recording medium 40t at a constant rotational speed, information is reproduced by relatively scanning the reproduction light from the light irradiation mechanism 10 along a spiral track. That is, the light irradiation mechanism 10 is directed in the radial direction of the recording medium 40 (indicated by arrow T).

) along the width of the recording section 42 at a constant speed or at a speed matching the format of the recording medium. A light-receiving end surface 2 having the same length as the part 420 width and a width slightly larger than the diameter of the light spot.
For example, a light guide section 23t formed by bundling optical fibers having
The light guiding section 23 is fixedly arranged so as to face the scanning area in the recording section 42 of the spot of the reproduction light, and the bottom end of the light guiding section 23 is connected to a light detecting section 24 made of, for example, a CCD line sensor. In this example, since the recording medium 40 is rotated, the light irradiation mechanism 10 only needs to linearly scan the spot of the reproduction light in one direction, and there is no need to move the light receiving end surface 201 at all. Therefore, the configuration becomes simpler.

FIG. 7 shows an example in which the light irradiation mechanism 100 and the light reception mechanism 200 are arranged close to each other and are integrally attached to an external pressure (not shown), and the light irradiation mechanism 100 has a light emitting diode array. , the light projection opening is close to the recording section 41 of the recording medium 4, and the light from this is obliquely incident on the recording section 41. The light receiving mechanism 200 is composed of a light guiding section 202 made of a converging optical fiber array and having a short light guiding path, and a light detecting section 203 connected to this light guiding section 202. The light receiving end face of the light guide section 202 is arranged close to the light detection area of the recording section 41 so as to receive light from the recording section 41 . According to such a configuration, it is possible to obtain an extremely practical reproducing device that can be sufficiently miniaturized.

Furthermore, in the reproducing apparatus of the present invention, information can be recorded by having a configuration in which the light irradiation mechanism as described above also serves and can irradiate recording light from this, or by providing a light irradiation mechanism exclusively for recording. It is also possible to do this. In the case where a light irradiation mechanism exclusively for recording is provided, it is not necessary to add a servo machine groove to the light irradiation mechanism.

[Function and effect of the invention]

The present invention has been explained in detail above based on specific examples, but
In the present invention, when optically reproducing information recorded by sparsely arranging relatively large bits or blocks, the position of the spot of the reproducing light on the recording section is fixed. The light-receiving mechanism can reliably receive reflected light or transmitted light from a certain position even if it is slightly displaced from a predetermined position, and it also has a considerably wider width in which considerably larger bits or blocks are lined up than in the case of high-density recording. It is sufficient that the spot of the reproduction light scans within the area of Since the size of the spot can be made considerably large to match a large bit or block, there is no need to strictly control the size of this spot below a certain level, and for this reason, focusing control with a servo machine groove is possible. This eliminates the need for a mechanism, and as a result, the light emitting mechanism and light receiving mechanism can be configured extremely easily, and as a result, it is suitable for reproducing optical information with a relatively low recording density, is small, has a simple configuration, and is inexpensive. A device for reproducing certain optical information can be provided.

From this, it is not necessary to specifically focus the light in the light irradiation mechanism, and even when focusing, it is possible to use an objective lens with a small numerical aperture and a deep depth of focus.As a result, the optical system It is possible to reduce the size of the light irradiation mechanism, and it is also possible to make the light irradiation mechanism's ejection opening considerably far away from the recording section of the entire recording medium. It will be advantageous.

Furthermore, in the case where the spot of the reproduction light from the light irradiation mechanism is relatively scanned within the photodetection area, the light receiving mechanism is It is no longer necessary to make the position of the light receiving end surface follow the movement of the spot of reproduction light, and therefore the structure of the moving mechanism required to move the light receiving end surface is simplified.

And like this, the spot size of the playback light during playback! ! Since the L#1 degree is considerably relaxed, information can be recorded using the light irradiation mechanism used for reproduction without requiring a particular servo mechanism during recording. Therefore, the apparatus of the present invention It is possible to perform not only reproduction but also recording of information satisfactorily for practical purposes.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an outline of an embodiment of the present invention, FIG. 2 is an explanatory diagram showing an example of a light irradiation direction and a light receiving direction, and FIG. 3 is an explanatory diagram showing an example of a light detection area. FIGS. 4 to 7 are explanatory diagrams schematically showing other embodiments of the present invention. l...Light irradiation mechanism 2...Light receiving mechanism 3...
Reproducing mechanism 4... Recording medium 41... Recording section 21... Light guiding section 211... Light receiving end surface
22... Photodetection section 40... Recording medium 1
0... Light irradiation mechanism 20... Light receiving mechanism 42.
...Recording section 43...Center hole 201...Light receiving end face 23...Light guide section 24...Light detection section 100...Light irradiation mechanism 200...Light receiving ja structure 202...Light guide Section 203...Photodetection Department Agent Patent Attorney Masahiko Oi Figure 1 Figure 6

Claims (1)

[Scope of Claims] 1) A reproducing device that optically reproduces information, which comprises a light irradiation mechanism that irradiates a recording section of a recording medium with reproduction light, and a light irradiation mechanism that irradiates the recording section with reproduction light during reproduction. 1. An optical information reproducing device comprising: a light receiving mechanism capable of simultaneously receiving light from a light detection region having a larger area including a spot. 2) The optical information reproducing device according to claim 1, wherein the photodetection area is an area that is continuously scanned with reproduction light.