JPH0198169A - Track retrieval device - Google Patents

Abstract

PURPOSE:To attain stable track retrieval by detecting the speed of a means shifting a light converging means and correcting the discrete value of a counting means counting that optical beams have crossed tracks. CONSTITUTION:A track difference between a retrieval start track and an objective track is preset in the counting circuit 21 through a micro computer 24. The discrete value of the circuit 21 is reduced corresponding to the detection output of an edge detection circuit 20 which is detected whenever the optical beams by an optical head 100 in the light converging means cross the tracks in accordance with the shift of a transfer base 2 in the shifting means. An inhibition signal from an inhibition circuit 25 is added in a time T including a time when the optical beams pass through an address part, and the circuit 21 stops counting. The computer 24 fetches the speed V of the base 2 passing through an A/D converter 23, counts the number of optical beam crossing tracks by an expression N=(VXT)/P (P is a track pitch) and corrects the discrete value of the circuit 21. Consequently, the tracks can stably be retrieved by the number of accurate crossing tracks without the erroneous detection and the lack of the track crossing signals due to the influence of the bits of the address part.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an optical recording and reproducing device for optically recording and reproducing information, and particularly relates to an optical recording and reproducing device for optically recording and reproducing information, and in particular for recording and reproducing information using an optical beam laser on a disk for recording and reproducing signals. The present invention relates to a truck search device that moves from truck to truck.

Conventional optical recording and reproducing devices include, for example, optically recording and
Information carrier (
A light beam generated from a light source such as a semiconductor laser is convergently irradiated onto the disk (hereinafter referred to as a disk) using a converging lens.
When reproducing a signal, it uses a relatively weak constant light intensity to read the signal from the reflected light from the Deinuk, and when recording a signal, it modulates the intensity of the light beam depending on the signal to be recorded to write the signal. There is.

In such an optical recording/reproducing device, focus control is performed so that the light beam is always in a substantially predetermined convergence state on the recording material film, and control is performed so that the light beam is always correctly scanned on a predetermined track. Tracking control is being performed. Furthermore, in order to move the light beam to an arbitrary track on the disk, track search control is performed in which the entire optical system, including the light source and the converging lens, is moved in the disk radial direction by a linear motor or the like.

Various types of track search control have been proposed, but
One of them is to count the track crossing signals, detect the current position of the light beam from the number of tracks that the light beam has crossed from the track search control start track, and adjust the moving means such as a linear motor accordingly. There is a groove counting method that performs search control by moving in the radial direction.

FIG. 2 shows a tracking error signal and a track crossing signal when the light beam crosses the track in the radial direction.

The tracking error signal is determined by the wavelength λ of the light beam and the track having an uneven structure with an optical depth of approximately λ/8.
It is well known that it can be removed using the push-pull method, as in the example below, and its explanation will be omitted. FIG. 2C shows a binary signal of the tracking error signal, and FIG. 2D shows its rising edge detection signal.

As is clear from the relationship shown in FIG. 2, the rising edge detection signal shown in FIG. 2D is a track crossing signal generated when the light beam crosses the center of the track. Therefore, the value of this signal counted from the start of the track search control represents the current position of the light beam.

Problems to be Solved by the Invention On the other hand, address portions for identifying each track are formed in the tracks depending on the presence or absence of pits having an uneven structure, as shown in FIG. FIG. 4 shows a tracking error signal when the light beam traverses the address section. In the part of the address part where pits exist, a tracking error signal similar to that of a track is generated, but in the part without pits,
No tracking error signal is generated, and the tracking error signal when the light beam crosses the address area is modulated by the presence or absence of pits. This has the problem that the current position of the light beam is incorrect during track search control, resulting in a failure in track search.

Means for Solving the Problems The present invention provides a converging means for converging and irradiating a light beam from a light source onto an information carrier having a track with an address section;
It has at least a moving means for moving the converging means in the radial direction of the information carrier, a detecting means for detecting that the light beam has crossed the track, and a counting means for counting the output of the detecting means, according to the soup stock of the counting means. A track retrieval device for moving an optical vinyl from one track to another is provided with a speed detecting means of a moving means, a counting inhibiting means, and a counting correction means for correcting the count value of the counting means according to the output of the speed detecting means. It is something that

Function: During a track search, the present invention calculates the track count when the light beam crosses the address section at least at the center of the track search in order to avoid erroneous counting by the counting means and counting failures that occur when the light beam crosses the address section. To provide a stable truck retrieval device that prohibits truck counting by a prohibiting means and corrects the count value of a counting means while prohibiting truck counting by a counting prohibiting means according to the output of a speed detecting means of a moving means. .

Example FIG. 1 is a diagram showing an embodiment according to the present invention.

Light source such as a semiconductor laser, optical head 1 such as a converging lens, etc.
oo are all mounted on a transfer table 2, and are driven by a coil motor 3 approximately in the radial direction of a disk 6 which is rotated by a disk motor 4. On the transfer table 2,
A speed sensor 6 is attached to detect the speed.

The speed sensor 6 is, for example, as shown in FIG.
and a magnet 8, and converts speed into voltage using electromagnetic force.

The output of the speed sensor 6 is amplified by an amplifier 9 and then sent to an adder 10. The point coil is added to the motor 3 via the drive circuit 11 to form a speed control system.

In addition, FIG. 6 shows an optical held 100 mounted on the transfer table 2.
The configuration diagram is shown below.

A light beam emitted from a light source 12 such as a semiconductor laser passes through a collimator lens 13 for collimating the light beam, is reflected by a polarizing beam splitter 14, passes through a Kλ plate 15, and is converged by a converging lens 1. , is irradiated onto the disk 5.

The reflected light from Deinuk 5 is transmitted through converging lenses 1 and 3Aλ plate 1
5 and a beam splitter 14, and enters a two-split photodetector 16. The dividing line of the two-split photodetector 16 is arranged in the longitudinal direction of the track on the light receiving surface.

The output signal of the two-split photodetector 16 is input to the differential amplifier 7. The output signal of the differential amplifier 17 configured in this way is a tracking error signal 1 as shown in FIG.
It is known that the number is 8.

The tracking error signal 18 is binarized by a binarization circuit 19 shown in FIG. 1, and inputted via an edge detection circuit 2o to a counting circuit 21 in which a count value can be preset. The count value of the counting circuit 21 is converted into an analog signal by the D/A converter 22 via the speed conversion circuit 26 and sent to the adding circuit 1.
o is input.

On the other hand, the signal of the speed sensor 6 amplified by the amplifier 9 is A
The signal is converted into a digital signal by the /D converter 23 and input to a microcomputer 24 (hereinafter referred to as microcomputer). Furthermore, the count value of the counting circuit 21 is input to the microcomputer 24, and the count value of the counting circuit 21 can be preset by the microcomputer 24.

In order to prohibit counting by the counting circuit 21, a prohibiting signal force ζ is input from the prohibiting circuit 26 to the counting circuit 21 and the microcomputer 24.

When performing a track search, the microcomputer 24 presets the track difference between the track search start track and the target track in the counting circuit 21 prior to the track search. The speed conversion circuit 26 is connected to a counting circuit 21 as shown in FIG. 7 in order to perform track searching smoothly.
The larger the count value, the larger the speed value.

The speed value output from the speed conversion circuit 26 is D/A converted and applied to the speed control system as a speed reference signal. Therefore, the further away from the target track, the faster the transfer table 2 carrying the optical components and the like moves, and the light beam moves along with it.

The reason why the speed value is constant when the counting frequency is larger than a predetermined value is to prevent non-linearity due to the limitation of the dynamic range of the speed control system.

The edge detection circuit 2o is configured to detect the rising edge of the tracking error signal binarized by the binarization circuit 19 and output a pulse of a predetermined width. It has already been mentioned above that the output signal of the circuit 20 is a track crossing signal.

The edge detection circuit 2o outputs a pulse to the counting circuit 21 every time the track search is started, the transfer table 2 moves, and the light beam crosses the track.

The counting circuit 21 is configured to reduce the count value by 1 every time a pulse is input. Therefore, as the transfer table 2 and the light beam move toward the target address, the count value of the counting circuit decreases, and correspondingly, the moving speed of the transfer table and the light beam also decreases. When you reach it, the movement speed becomes 0,
End track search.

On the other hand, the prohibition circuit 26 transmits the prohibition signal to the counting circuit 2 for a time T including at least the period during which the light beam passes through the address section.
1. Output to the microcomputer 24. When the prohibition signal is input, the counting circuit 21 does not perform the above-described counting operation even if a pulse is input from the edge detection circuit 20. Further, when the prohibition signal is input, the microcomputer 24 converts the speed V of the transfer table 2 into A/D using the A/D converter 23 and imports it.
In addition, 1 is taken into the count value of the counting circuit 21, and from these values, the number N of tracks that the light beam crosses during the time T during which the prohibition signal is input is determined by the following formula. Set 2 to .

However, P is a track pitch and is a value predetermined by the disc.

The microcomputer 24 completes the above correction operation before cutting at time T.

After time T, when the light beam finishes crossing the address section and the prohibition signal from the prohibition circuit 26 is released, the counting circuit 21 restarts the counting operation, the light beam crosses the track, and the edge detection circuit 2o detects the PALNU. Each time it is output, the count value is subtracted by 1.

Therefore, even when the light beam crosses the address section, it is possible to perform a correct track search.

In this embodiment, as shown in FIG. 3, a so-called in-glue disk was described in which the center line of the pit in the address area coincides with the center line of the track, but as shown in FIG. The present invention can be similarly applied to so-called on-land disks in which the center lines of pits and the center lines of tracks are parallel and alternating, and produce similar effects.

Effects of the Invention By configuring as in the embodiment described above, even if the light beam passes through the address section and the track crossing signal is erroneously detected or lost due to the influence of the address section pits, the counting circuit can be activated based on the speed of the transfer table. By correcting the count value, it becomes possible to correctly detect the number of tracks that the light beam crosses, and it becomes possible to perform a stable track search.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of an embodiment of the present invention, Fig. 2 is an explanatory diagram of a tracking error signal and a track crossing signal when a light beam crosses a track, and Fig. 3 is a perspective view of the main part showing the structure of the address section. 4 is an explanatory diagram of a tracking error signal and a track crossing signal when a light beam crosses an address section, FIG. 6 is a configuration diagram of a speed sensor, and FIG. 6 is an optical component of an embodiment of the present invention, etc. FIG. 7 is a count value-speed value characteristic diagram of the speed converting circuit, and FIG. 8 is a main part oblique speed diagram showing the structure of the address section. 2...Transfer table, 25...Prohibition circuit, 2
6... Speed conversion circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Counting Direction

Claims (1)

[Claims] an information carrier having a track having a concentric or spiral uneven structure and an address section for identifying the track; a converging means for converging and irradiating a light beam generated from a light source onto the information carrier; a first detecting means for detecting that the information carrier has been crossed; a counting means for counting the output of the first detecting means; and a moving means for moving at least the converging means in a substantially radial direction of the information carrier. , when moving the light beam from track to track, the track search device moves the moving means in accordance with the output of the counting means, a second detection means for detecting the speed of the moving means, and a second detection means for detecting the speed of the moving means, and an operation of the counting means. A prohibiting means for prohibiting the counting means and a correcting means for correcting the count value of the counting means are provided, and when the light beam crosses at least the address section, the inhibiting means prohibits the operation of the counting means and the second detecting means The track search device is characterized in that the correction means corrects the count value of the counting means during the period in which the prohibition means is in operation, according to the output of the prohibition means.