JPH01271919A - Optical information recording and reproducing device - Google Patents

Abstract

PURPOSE:To remove harmful noise and to perform high-speed and stable reproducing by narrowing down a light beam to a minute spot, forming information track strings corresponding to information bits each other at the time of recording and defocusing the light beam at the time of reproducing. CONSTITUTION:When recording information onto an optical card 7, light beams emitted by a semiconductor laser 1 pass through a collimate lens 2, are divided by a diffraction grating into a main beam for recording and two sub beams for tracking, after that, the main beam is narrowed down on the recording face of the optical card through beam splitter (BS) 4 and a lambda/4 plate 5 by an objective lens 6 and the information is recorded. When reproducing it, the objective lens 6 is moved by a fixed distance from the optical card by an actuator. Consequently, the light beams irradiates the medium face of the card 7 in a defocused state. Their reflected light retrogrades, is reflected by the BS 4, further, reflected by a non-polarizing BS 8, passes through a converging lens 11 and an aparture 12, makes incident on a photodiode array 13 and the information is reproduced.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an optical information recording/reproducing device for recording and/or reproducing information on an optical information recording medium, and particularly relates to an optical information recording/reproducing device for recording and/or reproducing information on an optical information recording medium, and particularly for recording information on a plurality of tracks at the same time. The present invention relates to a reproducible device.

(Prior Art) Conventionally, various types of media such as optical disks, optical cards, and optical tapes have been known as media for recording and reproducing information using light. Each of these has its own characteristics and purpose. The optical cards are used differently depending on the purpose, etc., but optical cards are expected to be used more widely in the future due to their ease of manufacture, portability, and ease of access. Various methods can be considered for scanning the optical card with a light beam irradiated onto the optical card.

A method in which the irradiation position of the light beam is moved relatively linearly on the medium in a reciprocating motion, and the beam irradiation position is sequentially moved relatively on the medium in a direction orthogonal to the reciprocating motion has a simple mechanism. It has characteristics such as a large effective space on the medium.

An example of an optical information recording/reproducing apparatus employing such a method is shown in FIG. 5, which is a block diagram of the apparatus.

In the figure, 41 is an optical card on which information is to be recorded; 43
is the optical head (the part surrounded by the dotted line in Fig. 5), 44
4 is a light beam; 45 is a mounting table on which the optical card 41 is placed;
8 is a laser, and 49 is a collimator lens. 50
17 is a polarizing beam, and 70 is a quarter-wave plate. The combination of these two members allows light traveling from the top to the bottom of the figure to pass through, but light traveling from the bottom to the top is bent in the right angle direction. Reference numeral 51 denotes a pickup lens that functions to condense parallel light onto the optical card 41.

52 is a light sensor, 53 is a preamplifier, and 54 is an autofocusing sensor. , 55 is an auto-tracking servo, 56 is a decoder, 57 is an interface, 58 is a combination, 59 is an encoder, 60 is a laser driver, and 61 is a stepping motor which functions to move the optical head 43 in a direction perpendicular to the paper surface. .

Numerals 62 and 63 are pulleys, and a belt 64 is wrapped around the pulleys 62 and 63. The optical card 4 is attached to the belt 64.
A mounting table 45 is attached for placing and fixing 1. The pulley 62 is attached to the shaft of a motor 66, and the optical card 4 is rotated by the rotation of the motor 66.
1 reciprocates in the direction of the arrow in the figure.

Next, the operation of the apparatus shown in FIG. 5 will be explained.

First, we will discuss the case of regeneration. In FIG. 5, the light beam oscillated from the laser 48 is collimated by the collimator lens 49, passes through the polarizing beam sinter 50 and the quarter-wave plate 70, and is further focused by the pickup lens 51. , a minute spot is formed on the optical card 41. The reflected light from the optical card 41 undergoes a change p4 depending on whether or not an information pit appears in the irradiated part of the minute spot, and this modulated light is again turned into parallel light by the pick array plane R51, and is converted into parallel light by the polarizing beam sinter 50. The light is incident on the optical sensor 52.

The optical sensor 52 detects a change in the amount of modulated light, converts it into an electrical signal, and sends it to the preamplifier 53. A signal for autofocusing is sent from the camera amplifier 53 to the pickup lens 54, and the autofocusing sensor is activated by the signal from the pickup lens 54 to an actuator (not shown).
1 in the direction B, and the distance between the pickup lens 51 and the optical card 41 is controlled so that the light beam 44 is focused on the optical card 41.

Also, a signal is sent from the green amplifier 53 to the auto tracking sensor 55, and the auto tracking sensor 55
The signal is controlled by an actuator (not shown) to move the pickup lens 51 in a direction perpendicular to the plane of the paper so that the light beam 44 is focused at a predetermined position. For auto focusing - is 54 and auto tracking sir N
55, some specific methods have been proposed. For example, the light beam 44 is divided into a plurality of parts using a grating, etc., and the optical card 41 is preliminarily provided with tracks for autofocusing or autotracking. An example has been proposed in which the information is preformatted (hereinafter referred to as a guide track), information is reproduced using at least one of the plurality of light beams, and signals for autofocus and autotracking are extracted using the other beams. There is.

Further, the signal from the preamplifier 53 is sent to a decoder 56 and subjected to necessary electrical processing, and then sent to an interface 57. Information signals are sent from the interface 57 to the computer 58 . Further, a signal is sent from the interface 57 to the encoder 59, and after being modulated as necessary, the laser driver 60 controls the oscillation of the light/heavy laser 48.

Furthermore, signals are sent from the interface 57 to a stepping motor 61 and a motor motor 67, which respectively control the position of the optical head 43 in a direction perpendicular to the paper surface and the rotation of the motor 660.

Next, we will discuss the case of recording. The case of recording is almost the same as the case of reproduction, but in the case of recording, a stronger light is emitted from the laser 48 than in the case of reproduction.

As in the case of reproduction, the light beam is imaged onto the optical card 41, and information is recorded on the optical card 41 according to the modulation of the laser beam. In the case of recording, it is usually necessary to perform autofocusing or autotracking, and various methods have been proposed. For example, at least one strong beam (for writing) and at least one It is divided into weak beams (for focusing or auto-tracking), and writing can be performed using a strong beam while tracing a guide track preformatted on the optical card 1 with one weak beam.

[Problem to be solved by the invention]

In the recording/reproducing apparatus described above, information pits are recorded or reproduced one by one by linear reciprocating motion of the car. However, devices with such a function have the disadvantage that it takes a long time, especially when trying to reproduce a large amount of information. One possible solution to this problem is to increase the speed of the card's reciprocating movement, but
This method has the disadvantage that it increases mechanical vibration, which adversely affects the reproduction signal and increases the load on the card feeding mechanism and motor.

If only playback is required, the speed of the reciprocating movement of the card can be reduced by using a method that reads multiple information tracks at once using a line sensor such as a COD, but this method cannot be used in a device that performs both recording and playback. In order to do so, it becomes necessary to install a separate head exclusively for reading, which inevitably increases the size and complexity of the device, and it is also necessary to newly install autofocus and autotracking mechanisms on the head exclusively for reading. It may disappear.

In addition, in order to read multiple information tracks at once, it is necessary to illuminate the tracks simultaneously, but if an incoherent light source such as an LED is used for this purpose, it is difficult to illuminate the necessary area with high illuminance. Also, the utilization rate of the light decreases when it passes through the beam splitter in the optical head, so the reproduction rate is not high. It becomes difficult to raise it.

If a linearly polarized light source with high brightness, such as a semiconductor radar, is used as a light source, it is possible to use an inlator optical system consisting of a combination of a polarizing beam splitter and a wave plate, which improves the light utilization efficiency, but on the other hand, A new problem arises in that the light reflected from the optical surface of the protective layer of the optical card is superimposed on and interferes with the light reflected from the medium surface, generating noise harmful to signal reproduction.

(Means for Solving the Problems) The present invention has been made for the purpose of solving the problems of the related art, and the purpose is to record information on an optical information recording medium by irradiation with a light beam. In an optical information recording/reproducing device for resurfacing, recording is performed by focusing a light beam into a minute spot to form an information track array on the medium, and recording is performed by focusing a light beam into a minute spot to form an information track array on the medium, and when reproducing information, multiple information tracks are recorded on the medium. This is achieved by using an optical information recording/reproducing apparatus characterized in that it irradiates and reproduces a defocused light beam so as to irradiate an information track array.

(Example) Hereinafter, the optical information recording/reproducing apparatus of the present invention will be described based on an example.

FIG. 1 is a schematic diagram showing a first embodiment of the present invention, and shows an optical system of an optical head. This optical system is an optical head 2 of an optical information recording/reproducing device, which will be explained later using FIG.
It can be accommodated in 2. In FIG. 1, 1 is a semiconductor radar;
2 is a collimator lens, 3 is a diffraction grating, 4 is a polarizing beam sinter, 5 is a quarter wavelength plate, 6 is an objective lens,
7 is an optical card which is a recording medium; 8 is a non-polarizing beam splitter; 19 is an astigmatism generating lens consisting of a combination of a spherical lens and a cylindrical lens; 10 is an optical sensor;
1 is a condenser lens, 12 is an arm/arm, and 13 is a photodiode play.

When recording information on the optical card 7, the light beam emitted from the semiconductor radar l and collimated by the collimator lens e2 is divided into a main beam for recording and two sub beams for tracking using the diffraction grating 3. After being divided into beams, these beams are focused into a minute spot on the recording surface of an optical card 7 by an objective lens 6 via a polarizing beam sinter 4 and a 174-wave plate 5t.

The optical card 7 is reciprocated in the direction of the arrow in the figure by a driving means to be described later, and records a pit row that forms an information pit row on the rack at a spot modulated according to the information to be recorded. Auto-focusing and auto-tracking techniques are required to achieve this, but auto-focusing is based on the fact that the light beam reflected by the optical card 7, passed through the objective lens 6, the 1/4 wavelength plate 5, and the polarized beam sinter 4. After passing through the non-polarized beam sitter 8t, the astigmatism generated in the astigmatism generating lens e9 is detected by the optical sensor 10.
A focus error signal is obtained by detecting it using I can play games. It was. Auto-tracking is performed using the aforementioned sub-beams generated by the diffraction grating 3 by the so-called three-beam method. It is assumed that a guide track for performing auto-tracking is formed in advance on the medium surface of the optical card 7. Since tracking technology using the three-beam method is already well known, detailed explanation will be omitted.

Next, a method for reproducing recorded information will be explained.

During information reproduction, the objective lens 6 is held at a constant distance from the optical card 7 as shown in FIG. 1 by a constant bias current applied to an actuator (not shown). Therefore, after the light beam forms an image on the slit 1" in the air, it irradiates the medium surface of the optical card 7 in a defocused state. The light reflected from the optical card is directed to the object lens 6.
It passes through the 1/4 wavelength plate 5 in the opposite direction to the time of incidence, is reflected by the polarizing beam splitter 4, is further reflected by the non-polarizing beam splitter 8, and is sent to the condenser lens 11. Parable 12
It reaches the 7-oto-diode array 13 through . The position of the spot imaged by the objective lens 6 is located upwardly away from the surface of the optical card 7 by approximately d/n. However, d
represents the thickness of the protective layer of the optical card 7, and n represents the refractive index of the protective layer. When viewed optically, the medium surface is d/n from the surface of the protective layer.
Since it is located below the FE edge, the spot position is approximately symmetrical to the medium surface with the surface of the protective layer as a boundary. The light-receiving surface of the ostomy orifice array 13 is provided at a position conjugate with the medium surface of the optical card 7 irradiated in a defocused state. At this time, the reflected light from the surface of the protective layer is focused on the light receiving surface. The annotation 12 serves to block high-order diffracted light such as the sub beam generated by the diffraction grating 3, and is placed near the imaging position of the light beam behind the condenser lens 11, so that only the 0th-order light is pass. This anno-char is for preventing the sub-beam from becoming noise on the photodiode array 13, and is not necessarily necessary depending on the degree of noise. In addition, when tracking during recording is performed using only one beam without using a sub beam, for example, FFrlfllll beam push, f
In the case of the dual type, the amplifier 12 is not necessary.

FIG. 2 is a diagram showing the relationship between the state of the medium surface during information reproduction and the photodiode array used for signal reproduction and auto-tracking.

The guide tracks 14-1914-2, . . . preformatted on the medium surface of the optical card 7 are gray-scale tracks, and the information pit rows 15-1, 15-2, . . . are recorded by light spots.・Similarly represents binary information depending on the shade. Illumination area 1 on the medium surface illuminated by the objective lens 6 in a defocused state as described above.
6 is the NA of the irradiation light beam so that at least two or more information pit rows are included.

It is assumed that the relationship between defocus amount etc. has been adjusted0
For example, the thickness of the protective layer of the optical card 7 is 0.4 m.

Assume that the refractive index is 1.5, and the illumination is such that it connects a spot at a position d/n above the protected non-light surface as described above.
If the effective NA of the illumination luminous flux is 0.4, the illumination area 16
The diameter is approximately 230 μm, which is large enough to contain information pit rows for several tens of tracks or more in a normal optical recording format.

Array-shaped small areas 13 indicated by broken lines within the illumination area 16
-1 t 13-2 v...13-10 indicates optically corresponding positions corresponding to each element of the photodiode array 13, and the amount of light in the broken line area is detected.

The reproduced signal of the information pit row 15-1 is obtained as a sum signal of elements 13-3 and 13-4 of the photodiode array, and the reproduced signal of the information pit row 15-2 is obtained as the sum signal of elements 13-3 and 13-4 of the photodiode array.
It is obtained as a sum signal of 3-7 and 13-8. Tracking during signal reproduction is performed based on any one guide track within the illumination area. For example, if guide track 14-1 is used as a reference during playback, element 13-
A tracking error signal can be obtained by taking the difference between the outputs of 1 and 13-2, and auto-tracking can be performed using known means using this error signal.

Autofocusing during signal playback will be discussed later in Part 3.
This will be explained using figures.

Near the center of the illumination area 16, surface reflected light 17 from the original card protection layer is focused in a spot shape. Photodiode array element 13-1.13-2. ...
prevents the reflected light from entering at a position slightly shifted from the position where the surface reflected light 17 exists. Because the surface reflected light 17 is imaged on a minute spot in this way,
It is possible to eliminate the interference fringe noise that is common in high-coherency light sources such as semiconductor radars, making stable signal reproduction and tracking possible.

FIG. 3 is a 10-step diagram schematically showing the system configuration of the optical information recording/reproducing apparatus. The entire device is controlled by an interface 21 by a CPU 20 controlled by a higher-level control device.
It is done through. The optical system of the optical head P shown in FIG. 1 is housed within the optical head 22. When recording information on the optical card 7, the AT/AF sensor connects to the circuit 2 while reciprocating the optical card in the direction of arrow A in the figure.
3′! ! Recording is performed on an optical card using a light beam focused on a spot while performing auto-tracking using the three-beam method and auto-focusing using the astigmatism method.

A position detector 35 is provided within the optical head 22 to detect the relative position of the objective lens in the focusing direction with respect to the actuator.

During playback, while autofocusing is performed using the AT/AF serge circuit 23, the optical card 7 is
and the optical head 22t - the position detector 35 detects and stores the position of the objective lens corresponding to each position of the optical card.Next, the AT/AF sensor moves the position of the objective lens corresponding to each position of the optical card through the circuit 23. Control is started to position the objective lens above the corresponding stored objective lens position by a required amount of defocus. Also, the AT server circuit 24 uses the photodiode array output.
The pit string information read from the photodiode array while performing auto-tracking by this circuit is input to the CPU via the decoder 25 and becomes reproduction information. Reproduction from a plurality of information tracks is performed in this manner, and therefore the reproduction can be completed in a shorter time than when reproduction is performed one track at a time. However, if, for example, one track's worth of information is written and the information is to be immediately reproduced, the switch to the AT sustainer circuit 24 is not performed.
It is also possible to perform reproduction in the same manner as before.

FIG. 4 is a diagram illustrating another embodiment of the present invention, which shows an optical system portion 16 of an optical head used in an optical information recording/reproducing apparatus. The members numbered 1 to 13 in the figure are functionally identical to the members shown in FIG. 1, so their explanation will be omitted. The difference from the embodiment shown in FIG. 1 is that a second
A non-polarizing beam splitter 30 is provided, and a part of the light beam reflected from the medium surface of the optical card 7 is guided to a second optical sensor 32 through a second astigmatism generating optical system 31t. It is that you are.

The operation of the device when recording information on the optical card 7 is the same as in the first embodiment, and the light beam is focused into a minute slit on the medium surface of the optical card 7, and the optical sensor Information pit strings are recorded on the medium surface while performing autofocusing and autotracking based on the output.

When performing reproduction, the autofocusing system is controlled by the upper control CPU (not shown) and the second optical sensor 3 is operated.
The system is switched to a second therme system (not shown) based on the output of No. 2. The objective lens 6 of the optical card 7 is located at a distance of approximately d/n (d and n are the same as in the previous explanation) from the narrow surface of the protective layer of the optical card 7.

Moreover, the distance between the medium surface of the optical card 7 and the objective lens 60 is always kept constant even when the optical card position changes.

Auto tracking is also performed in the same way. That is, by providing an optical system that can detect tracking and focusing error signals even under defocused illumination during playback, stable operation is always possible during playback. Reading of information is performed by the photodiode array 13 as in the first embodiment. However, in this embodiment, signal detection for auto-tracking, which was performed by the photodiode array 13, is not performed.

Further, as a modification of this embodiment, the tracking error No. 1 may be detected by the photodiode array 13 as in the first embodiment, and only the focus error signal may be detected by the second optical sensor 32. If the depth of focus of the optical system is sufficiently deep and the required depth can be maintained with mechanical precision alone without autofocusing, the focus error detection system can be omitted. Alternatively, if a focusing error detection system with a sufficiently wide dynamic range is used, the objective lens can be laterally divided to a predetermined focus position for both the recording and reproducing states using one detection system.

(Effects of the Invention) As described above using the embodiments, according to the present invention, the optical system part from the light source to the objective lens is the same as that of the conventional optical head, and a part of the signal detection system part is added. K Yoshi,
It is possible to reproduce information from multiple tracks using the same light source, and it is also possible to remove harmful noise such as interference fringes generated by using a radar light source, making it possible to perform high-speed and stable reproduction. This makes it possible to obtain an optical information recording/reproducing device that is possible.

Although the present invention has been explained using an optical card as an optical storage medium, the subject medium of the present invention is not limited to an optical card, and the present invention can also be applied to devices using various types of media such as optical disks. Needless to say, it is applicable.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating the configuration of an optical head optical system used in a first embodiment of the optical information recording/reproducing apparatus according to the present invention, and FIG. FIG. 3 is a block diagram showing the schematic configuration of the system of the device according to the first embodiment of the present invention, and FIG. 4 is a diagram explaining the illumination area and signal detection method used in the second embodiment of the present invention. FIG. 5 is a block diagram of a conventional optical information recording/reproducing apparatus. l...Semiconductor radar, 6...Objective lens, 7...
Optical card, 13... Photodiode array, 14-
1゜14-2...Guide track, 15-1.15-
2... Information pit row. Agent Patent Attorney Johei Yamashita Figure 1 Figure 2

Claims (5)

[Claims] (1) In an optical information recording and reproducing device that records and reproduces information on an optical information recording medium by irradiating a light beam, when recording, the light beam is narrowed down to a minute spot and corresponds one-on-one to the information pit. 1. An optical information recording and reproducing apparatus characterized in that an information track array is formed by defocusing a light beam by a certain amount so as to irradiate a plurality of information track arrays during reproduction. (2) The amount of defocus during information reproduction is such that the position of the minute spot is approximately d/n (d is the thickness of the protective layer, n is Claim 1 characterized in that the distance is the refractive index of the protective layer.
The optical information recording/reproducing device described in . (3) A photodetector is provided on a surface that is conjugate to the medium surface of the optical information recording medium during information reproduction and at a position different from the focusing position of the light beam reflected from the surface of the protective layer. The optical information recording/reproducing apparatus according to claim 2, characterized in that: (4) Optical information recording according to claim 3, wherein the light source that emits the light beam is a semiconductor laser, and the photodetector is a one-dimensional or two-dimensional arrayed photosensor. playback device. (5) The device according to claim 1, further comprising a focusing means corresponding to each of the recording and reproducing states, and the focusing means can be switched according to the recording and reproducing states. Optical information recording and reproducing device.