JPH02203428A - Optical recording/reproducing device - Google Patents

Abstract

PURPOSE:To detect the accurate position of an optical head without increasing the weight of the optical head nor complicating the structure of the optical head by taking out a part of the light beam received from a light source to the outside of the optical head and receiving the taken-out light beam to the position of the optical head. CONSTITUTION:The light beam of a light source irradiates an optical recording medium 1 and the information is recorded and/or reproduced via an optical head 200. The means 103 - 109 are added to move the head 200 to the medium 1. Then a means 201 takes out partly the light beam of the light source to the outside of the head 200, and a means 202 receives the light beam to detect the position of the head 200. Thus it is not required to add an electric circuit to the head 200 for detection of the position of the head 200. Then the increase of the size of the head 200 itself can be avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical recording and reproducing apparatus that records and/or reproduces information by irradiating an optical recording medium with a light beam.

[Prior Art] Conventionally, there have been various forms of recording media used for recording information using a light beam and reproducing the recorded information using a light beam, such as a card shape, a disk shape, and a tape shape. are known. Among these, optical information recording media formed in the form of cards (hereinafter referred to as "optical cards") are expected to be in great demand as recording media that are easy to manufacture, portable, and easily accessible. It is.

As shown in FIG. 3, such an optical card has a recording area 2 on a part or the entire surface of a rectangular base 1, and pits corresponding to information are formed in advance in the recording area 2. A plurality of information tracks 3 are arranged in a parallel straight line with respect to the longitudinal direction of the information track 3.

The optical card shown in Figure 3 above is read-only, i.e. ROM.
There is also a write-once type that allows writing, and a rewritable type is also conceivable.

In order to record information on such an optical card and to reproduce the recorded information, an optical recording/reproducing apparatus as shown in FIG. 4 is used.

As shown in the figure, in this device, the optical card 1 inserted through the insertion slot 5 is mounted in a frame 6 provided with an insertion slot 5 for inserting the optical card 1 into the device, and the optical card 1 is inserted into the frame 6 in the direction of arrow A-A. ,
A card carrier 7 (hereinafter referred to as a shuttle) that moves back and forth in the direction, and a card carrier 7 that guides the optical card 1 mounted on the shuttle 7 in the longitudinal direction, that is, in the direction perpendicular to the direction of the information track 3 (FIG. 3). An optical head 8 that moves along a rod 16, a drive motor 10 that is provided to transport the belt 9 in the direction of arrow A-A, and an optical head pulse drive motor 11 that moves the optical head 8 as described above. It is equipped with the following. A male screw is formed on the rotating shaft of the pulse motor 11, and the male screw and a female screw fixedly provided on the optical head 8 engage with each other in response to a drive pulse sent from a motor control circuit (not shown). The rotating shaft rotates and screws the optical head 8.

On the other hand, the protruding piece 12 of the shuttlecock is engaged with the belt 9, and as the belt 9 rotates, the shuttle 7 is caused to reciprocate in the direction of arrow A--A.

Further, the shuttle 7 is provided with an opening window 13, so that the recording area portion of the optical card 1 mounted on the shuttle 7 is exposed to the optical head 8.

FIG. 5 is a perspective view showing details of the optical head portion of the device.

In FIG. 5, 27 is a semiconductor laser (LD) that is a light source.
, 28 is a collimator lens, 29 is a light beam shaping prism, 30 is a diffraction grating for splitting the beam, 20 is a beam splitter, 25 is a reflection prism, 26 is an objective lens, 2
1 is an astigmatism condensing lens system, and 22 to 24 are photodetectors.

The light beam emitted from the semiconductor laser 27 becomes a diverging light beam and enters the collimator lens 28, where it is converted into a parallel light beam. The parallel light beam is shaped into a predetermined light intensity distribution by a light beam shaping prism, and then enters the diffraction grating 30, where it is divided into three effective light beams (0th-order diffracted light and ±1st-order diffracted light). be divided.

These three light beams are then split into a beam splitter 20
It is reflected by the reflection prism 25, enters the objective lens 26, and is converged by passing through this, resulting in 3° minute light beam spots St (+1st-order diffracted light) on the optical card i. ), 52
(corresponding to the O-th order new party), and S3 (corresponding to the -1st order diffracted light).

The light beam spots S1 and S3 are located on adjacent tracking tracks T, and the light beam spot S2 is located on the information track 3 between the tracking tracks.

P indicates the information bit recorded by the light beam spot.

Thus, the reflected light from the light beam spot formed on the optical card passes through the objective lens 26 and is made substantially parallel.
The light is reflected by the reflection prism 25, further reflected by the beam splitter 20, and focused by the condenser lens system 21, and enters the photodetectors 22, 23, and 24.

FIG. 6 is a diagram showing the configuration of the photodetectors 22 to 24,
Ru. The photodetector 23 is a four-part photodetector.

The optical card 1 mounted in the optical recording/reproducing apparatus configured as described above is moved relative to the optical head 8 by the reciprocating movement of the shuttle 7 in the direction of arrow A--A. Information bits corresponding to the information signal are recorded along the information track 3 by the light beam emitted from the optical head 8, and the recorded information is read.

On the other hand, in order to perform predetermined recording and reproduction by moving the optical head 8 from one information track to another, the optical head 8 must be moved along the guide rod 16 to the desired information track. This becomes possible.

A second conventional example of a head feeding mechanism is shown in a schematic cross-sectional view and a plan view, respectively, in FIGS. 7A and 7B. Here, the optical head 100 is guided in a direction perpendicular to the tracking track T by two guide bars 101 and 102 fixed to frames 114 and 115, respectively. A linear motor is used as a drive source for moving the optical head 100. This linear motor consists of coils 106 and 110 fixed on both sides of the optical head 100 and magnets 104 and 10.
8, magnetic shunt group yoke 103.107, coil 106,1
The center yoke 10 is arranged so as to penetrate through the center yokes 10 and 10, respectively.
It consists of 5°109. Magnetic shunt yoke 103°107
are fixed to the frames 114 and 115, and the frame 11
4.115 is placed at a predetermined position on a chassis (not shown) via a vibration isolating member or the like. Here, the coils 106, 11
0 from a control circuit not shown, the coils 106, 110 and magnets 104, 1
An electromagnetic force is applied between
“Moved in the direction.

In the above device, in order to control the moving speed or detect the moving amount of the optical head 100, a slit plate 112 in which slits are provided at a predetermined pitch in the moving direction of the optical head 100, and a light emitting diode fixed to the optical head 100 are provided. A transmission type optical sensor 113 made of a light receiving diode is provided.

These constitute a linear encoder. That is, when the optical head 100 moves, the optical sensor 113 outputs a pulse signal every time it crosses a slit, and by counting this signal, the position and speed of the optical head can be known.

[The problem that the invention is trying to solve, however,
In the example shown in FIG. 4, the shaft of the pulse motor 11 merely rotates by a desired angle according to the number of pulses applied to the pulse motor 11, and the substantial amount of movement of the optical head could not be detected. In addition, the example shown in FIG. 7 can compensate for the drawbacks of the example shown in FIG. 4, but the optical sensor 113 must be mounted on the optical head 100, which increases the weight of the optical head and makes high-speed movement difficult. There were some problems. Furthermore, it is necessary to form an electric signal line including circuits other than the electric circuits originally necessary for the optical head (for example, AT/AF circuit, LD drive circuit, etc.), making the configuration complicated. Also, contrary to FIG. 7, the slit plate 112 is connected to the optical head 100, and the optical sensor 1
If the optical head 13 is fixed to the frame, there is no need to mount an electric circuit for position detection on the optical head 100, but a new problem arises in that the optical head 100 itself becomes larger.

[Means for Solving the Problems] An object of the present invention is to solve the problems of the prior art described above, and to provide an optical head that can accurately detect the position of an optical head without increasing the weight or complicating the optical head. The purpose of the present invention is to provide a recording/playback device.

The above object of the present invention is to provide an optical head for recording and/or reproducing information by irradiating a light beam emitted from a light source onto an optical recording medium, and a means for moving the optical head with respect to the medium. This is achieved in an optical recording/reproducing device by providing means for extracting a portion of the light beam emitted from the light source to the outside of the optical head, and means for receiving the extracted light beam and detecting the position of the optical head. .

[Example] Embodiments of the present invention will be described in detail below with reference to the drawings.

FIGS. 1A and 1B are a schematic sectional view and a plan view, respectively, of an optical head transport mechanism showing an embodiment of the present invention. In these figures, the same members as in FIGS. 7A and 7B are designated by the same reference numerals, and detailed explanations will be omitted.

In the figure, 200 indicates optical recording/recording on the optical recording medium 1.
An optical head 201 for reproduction is provided in the optical head 200, and an imaging lens 2 condenses the light beam split by the beam splitter 20 onto the optical sensor 202.
02 is an optical sensor that receives the light beam focused by the imaging lens 201. As the optical sensor 202, a charge transfer device such as a CCD is most preferable, but any photo-electric conversion device can be used as long as the electrical output changes linearly depending on the irradiation position of the light beam. Also good. 203 holds the optical sensor 202 in a predetermined position, and the frames 114 and 115 or the magnetic shunt yoke 107
It is a plate fixed to.・Also, the optical sensor-2
The light receiving surface 02 is arranged substantially parallel to the moving direction of the optical head 200 so that the focus of the light beam condensed by the imaging lens 201 does not shift due to the movement of the optical head 200.

FIG. 2 is a perspective view showing the detailed configuration of the optical head 200. Here, the same members as in FIGS. 1 and 5 are given the same reference numerals, and detailed explanations will be omitted.

In the figure, El is a driver that drives an optical sensor (here, a CCD is used) 202. This driver E1 generates clock pulses that cause each element of the optical sensor 202 to be scanned.

At the same time, the driver E3 also outputs clock pulses to the microprocessor unit (MPU) E3.

E2 is a signal shaping circuit that performs predetermined processing on the output of the optical sensor 202 and then outputs it to the MPUE 3 as a digital signal. The MPUE 3 counts the clock pulses, compares the count number with the output of the signal shaping circuit E2, and stores the count number at the time when the output of the signal shaping circuit E2 is present.

Further, the MPUE 3 stores the pitch of each element of the CCD 202 in advance, and performs arithmetic processing based on the error element pitch and the count number. Then, as a result, it is determined whether the spot position is the desired position or not,
The determination result is output to the linear motor control circuit E4.

To explain the above operation in more detail, first
3 receives a clock signal from the driver E1, and counts the number of pulses.

Here, the MPUE 3 determines which pulse number of the clock signal manually input from the driver E1 corresponds to the pulse signal manually input from the signal shaping circuit E2, stores the pulse number, and uses this as the initial value. do. Next, the pulse number of the spot position at the time when the optical head 200 moves is detected by the above-mentioned procedure, and the difference in the number of pulses from the initial value is calculated to calculate the number of pulses of the movement of the optical head 200. do. Then, the MPUE 3 determines whether the calculated number of movement pulses is a predetermined number, and outputs the result to the linear motor control circuit E4. If there is a discrepancy in the number of pulses, the control circuit E4 drives the linear motor to
The optical head 200 is moved again. Along with this, the spot moves again, and the position servo of the optical head 200 is performed by repeating a servo loop in which the number of pulses is determined again.

In addition, in order to know how many mm the optical head 200 has moved from the initial position, it is necessary to use the above movement pulse number and the MPUE3 in advance.
What is necessary is to calculate the pitch of the light-receiving element 202a manually.

Furthermore, to detect the moving speed of the optical head 200, the MPUE 3 calculates how many pulses are output from the signal shaping circuit E2 per unit time, or how many seconds are the intervals between pulses. This is done by making a judgment. According to this result, MPUE3 outputs a control command to linear motor control circuit E4, and in response to this, linear motor control circuit E4 controls the linear motor.

Another possible use of the optical sensor 202 is to control the power of the 2D 27. In this case, the signal shaping circuit E2 compares whether the analog output value of the optical sensor 202 is within a predetermined value range. Then, as a result, the input terminal of D27 may be controlled by an LD driver (not shown) so that the error and signal become zero. Furthermore, it is also possible to determine whether the LD is out of order based on whether the output of the optical sensor 202 exceeds a predetermined output range for a predetermined period of time.

In the configuration shown in FIG. 2, two beams are split by a beam splitter 20 and directed toward the optical card 1 and the optical sensor 202, respectively.
It is desirable that the light quantity ratio of the two light beams is set so that the photodetectors 22 to 24 receiving the modulated light from the optical card 1 can obtain sufficient output. The reason for this is that there is no variation in optical power when the surplus light quantity bundled due to the structure of the optical head is used.

The present invention can be applied in various ways in addition to the embodiments described above. For example, the above-mentioned imaging lens 201 can be used as a cylindrical lens or an aperture in a car because it suffices to irradiate a light beam onto the optical sensor in the form of a spot or a slit. Further, the shape of the medium used in the apparatus of the present invention is not limited to a card shape, but may be any shape such as a disk shape or a tape shape.

[Effects of the Invention] As explained above, the optical recording and reproducing apparatus of the present invention includes a means for extracting a part of the light beam emitted from the light source to the outside of the optical head, and a means for receiving the extracted light beam to the optical head. By providing a means for detecting the position of Effects such as being able to serve both as a means for detecting the position of the optical head and as a sensor for controlling the power of the light source can be obtained.

FIG. 3 is a plan view of an optical card, and FIGS. 4 to 7 are schematic diagrams each showing an example of a conventional optical recording/reproducing device.

20...beam splitter, 200...optical head, 201...imaging lens, 202...light sensor

Claims (4)

[Claims] (1) Irradiating the optical recording medium with a light beam emitted from a light source,
In an optical recording/reproducing device comprising an optical head for recording and/or reproducing information and means for moving the optical head with respect to the medium, a part of the light beam emitted from the light source is directed outside the optical head. An optical recording/reproducing apparatus comprising: a means for extracting the light beam; and a means for detecting the position of the optical head by receiving the extracted light beam. (2) The optical recording/reproducing apparatus according to claim 1, wherein the speed of the optical head moving means is controlled by the output of the position detecting means. (3) The optical recording and reproducing apparatus according to claim 1, wherein the output of the light source is controlled by measuring the amount of light beam received by the position detecting means. (4) The optical recording and reproducing apparatus according to claim 1, wherein the light beam extraction means comprises a beam splitter arranged in an optical path from the light source to the medium.