JPS6273429A - Position detector for optical pickup - Google Patents

Abstract

PURPOSE:To form a position detector for an optical pickup obtaining position information of the pickup accurately with high accuracy by utilizing that a part of the laser light irradiated to a recordable optical disc is transmitted. CONSTITUTION:A laser light A transmitted through a center of an objective lens 17 is stopped (focus P1) to a disc 11 and a part of a laser light B transmitted through a peripheral part of the objective lens 17 is transmitted through the disc 11 and stopped (focus P2) to an optical sensor 15. Further, the focus P1 on the disc 11 and the focus P2 on the optical sensor 15 are positioned on the same axial line Y. In using a dual focus lens in this way, it is possible to detect the position with higher accuracy to the optical sensor 15. Further, a filter 18 having a light shut performance to a part of the objective lens 17 corresponding to a boundary BD of the curvatures and the filter 18 covers the objective lens 17 to prevent the laser light with different foci from being interfered mutually.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a device for recording or reproducing data on or from a disk as a recording medium using an optical pickup.
The present invention relates to an optical pickup position detection device that detects the position of a pickup using recording or reproduction laser light irradiated from the pickup onto a disk.

[Technical background of the invention]

Currently, in the field of audio equipment and video equipment, optical discs such as compact discs and video discs that can be rotated and optically played back using laser light are used. Here, on a video disc, one frame of an information signal is recorded every round, and the number of revolutions of the disc motor is constant no matter where the pickup is at the time of reproduction. On the other hand, in the case of compact discs, information signals are recorded using the CLV (constant linear velocity) method in order to increase the recording density, and during playback, the clock component of the read signal is extracted and the rotation of the disc motor is controlled by this. It's in control. Address data indicating the track position of the disk is recorded along with the main information signal on these disks.Based on this address data, the pickup position, that is, the laser beam irradiation position is detected, and the desired track is detected. Rank P! It is possible to perform a complete search, and it is also possible to control the rotation of the disk motor using the CLV method.

By the way, for playback-only optical discs like the one mentioned above,
In recent years, various types of recordable optical discs have been proposed. However, in such a disc, there are many cases where no synchronization signal or address data is recorded in an unrecorded state, or where no address data is recorded even in a recorded state. Therefore, when recording information signals on the disk or reproducing recorded information signals, it becomes difficult to control the rotation using the CLV method or to accurately search for a desired track position.

Incidentally, a disc in which a synchronization signal and track position information are recorded in advance on an unrecorded disc has also been proposed as a recording disc, but in this case, the format of the recording signal is limited and the price of the disc increases. It is difficult to adopt this method due to its drawbacks.

For this reason, when using a recordable disc, it is necessary to be able to detect the position of the pickup by some means.

In addition, the pickup position information is used as a control signal for delay circuits and band gain control circuits to obtain waveforms that accurately correspond to unit recording areas such as optical pits, even when the rotational speed of the disk is constant. .

Therefore, the following methods have been considered as pickup position presentation means. First, as an example, there is the one shown in FIG. 1 of Japanese Unexamined Patent Publication No. 55-48835. As shown in Fig. 4, a slider (3) is connected to an optical pickup (2) that is sent in the radial direction of the disk (1), and this slider (3) is moved in the radial direction of the disk. The resistor (4) is brought into contact with the resistor (4) extending from the
) is applied with a voltage of 1E, and a voltage V corresponding to the moving position of the pickup is extracted from the slider (3). In the figure, (5) shows the disk motor, and (6) shows the feed motor of the pickup (2).

In addition, another example is Japanese Patent Laid-Open No. 55-93536, No. 8
There is one shown in the figure. This is as shown in Figure 5 (the same parts as in Figure 4 are given the same reference numerals).
, a light emitting element (7) such as a phototransistor is provided on the pickup (2), and a plurality of light receiving elements (8) such as a photodiode are provided on one side facing the moving path of the light emitting element (7) that moves together with the pickup (3). The output of array l-1 is detected by a signal processing circuit (9) to obtain position data of the pickup (2).

[Problems with background technology]

However, in the conventional pickup position detection device as described above, although the scanning members such as the slider and the light emitting element move together with the pickup, they are not attached externally to the pickup. Therefore,
11. It is difficult to handle small movements such as when only the objective lens of the pickup moves. 11. However, there is a problem in that the irradiation position of the light cannot be detected accurately.

[Purpose of the invention]

The present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide an optical pickup position detection device that can obtain pickup position information accurately and with high precision.

[Summary of the invention]

Therefore, the position detection device for an optical pickup of the present invention focuses on the fact that the above-mentioned recordable optical disk transmits a part of the irradiated laser light, and uses such a disk as an intervening device to detect the position of the optical pickup. An optical sensor section is provided on the side and along the moving path of the optical pickup, and a laser beam irradiated from the optical pickup is focused on a first focal point focused on the disk and a second focal point focused on the optical sensor section. The optical sensor section senses the laser beam having the second focal point that passes through the disk and is incident, and outputs a different signal depending on the optical sensing position. .

[Embodiments of the invention]

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

In Fig. 1, the disk αυ is irradiated and a part of the laser beam is transmitted through it; for example, tellurium carbon is deposited on the substrate, and about 30% of the laser beam is transmitted through the disk αυ. . And this disk συ
The disk motor 2 rotates at a predetermined rotational speed. On the other hand, the optical pickup @ is moved in the radial direction by a big amplifier feed motor d4) facing the information recording/reproducing surface of the disk dυ. Therefore, on the opposite side of the pickup (+3) with the disk 0υ in between, an optical sensor section is provided along the transfer path of the pickup (13). It is a sensor or PSD that senses the light incident from the pickup (13) via the disk I, and outputs a signal corresponding to the position of the light sensor to the signal processing circuit +l119.The output is sent to the optical sensor unit If it is an amorphous silicon sensor or a CCD element, it is a discrete signal, and the signal processing circuit αO generates a scan signal, and based on the signal from the optical sensor unit α9, the position is detected by processing such as holding the value of an internal counter. If you want to convert the position data obtained by the signal processing into an analog signal, you can add a digital-to-analog converter.Also, if the optical sensor section α9 is a PSD, its output will be an analog signal. In the signal processing circuit aQ, if output as a digital signal is desired, it converts it into an analog-to-digital signal and outputs it as position data.The optical sensor unit uSl is not limited to the above-mentioned one, but may also be an element having a similar function. If so, you can use it as appropriate.

Here, the objective lens αη built in the pickup Q3
A double focus lens as shown in Fig. 2 is used for this, and as shown in the same figure, the laser beam A that passes through the central part of the lens 1 of the lamp is focused on the disk 01). The laser beam B that passes through the outer circumferential portion of the objective lens 1I7) passes through the disk αυ and is focused on the optical sensor section (19) (focal point Pz
). Note that the focal point P on the disk +11) and the focal point P on the optical sensor section QF9 are positioned on the same axis Y. By using the bifocal lens in this manner, it becomes possible to cause the optical sensor section αω to perform position detection with higher accuracy. That is,
This is because if a general objective lens were used, all of the laser light would be focused on the disk, so it would be dispersed over a wide range at the time it entered the optical sensor, and many error components would be hidden. . In addition, in the bifocal method as described above, if the light transmittance of the disk αυ is low, the optical sensor section'
This is also effective for reducing the sensitivity of ts.

In addition, as shown in FIG.
[If a frame is installed and the objective lens is covered with this filter a ladle, laser beams with different focuses can be prevented from interfering with each other, which is more effective.

In this way, in this embodiment, since the position of the pickup 0 is detected using the recording or reproducing laser beam irradiated onto the disk housing, accurate position detection is possible. Bifocal objective lens (+7
) can perform position detection with higher accuracy than buttons. The position data thus obtained can be fully utilized for rotational control of the disk motor 0υ and search operation as described above.

〔Effect of the invention〕

As described above, the optical pink-up position detection device of the present invention is capable of detecting the position of the pickup accurately and with high precision.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a position detection device for an optical pickup according to the present invention, and FIGS. 2 and 3 show laser beam irradiation t'tr! in the same embodiment. I Figure 4 and Figure 5 are configuration diagrams showing the position detection device of a conventional optical pickup.
...Pickup, 14...Pickup feed mode 15...Light sensor section, 16...Signal processing circuit, 17
...Objective lens. Agent Patent Attorney Nori Ken Chika Yudo Uji Hiroshi 1st factor 2nd figure 3rd figure

Claims (1)

[Claims] an optical pickup for recording or reproducing, which is disposed so as to be movable in the radial direction of the disk, facing the information recording/reproducing surface of the disk at the rotated position, and an opposite side of the optical pickup with the disk interposed therebetween; and a photosensor section provided along the moving path of the optical pickup, which transmits a part of the laser beam irradiated to the disk, and the optical pickup detects information about the disk. The optical sensor section includes a built-in means for generating a laser beam having a first focal point focused on the recording/reproducing surface and a second focal point coaxial with the first focal point and focused on the optical sensor section. 1. A position detection device for an optical pickup, characterized in that the device senses laser light transmitted through the disk and outputs different signals depending on the light sensing position.