JPS62109241A - light head - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an optical head, and more particularly to an optical head that moves to the right in the direction of 8 degrees for information transfer.

[The day before the invention]

In the J3 optical disk device that records and reproduces information using an optical head, a light beam is irradiated onto a metal film formed on the surface of a rotating disk, and when recording information, the irradiation power of the light beam is modulated by 1 degree. , the information on the above metal film “
By forming grooves (pits) corresponding to 1" or "0" and irradiating the metal film with a weak light beam during playback, changes in reflected light due to the presence or absence of bits are detected.
Recognize information.

FIG. 2 is a diagram showing a schematic configuration of a conventional optical head.
10 is a body that supports all the components of the optical head; 11
is a semiconductor radar which is a light source, 12 is a collimator lens,
13 is a polarizing beam splitter, 14 is a quarter wavelength plate,
15 is an objective lens, 16 is an actuator for driving the objective lens 15 two-dimensionally, and 17 is an optical disk. Further, 18 degrees 19 and 20 detect the positional deviation between the focal position of the objective lens 15 and the recording/reproducing surface of the optical disc 17, detect the track deviation between the disc 17 and the lens focal point, and further detect the positional deviation from the optical disc 17. This is an example of an optical system that detects the presence or absence of a signal based on the strength of the repulsion 1" This method is widely used in disk devices and the like.

A signal from the photodetector 20 is output as an information signal 21. Separate signals from the photodetector 20 are supplied as a focus deviation signal 22 and a track deviation signal 23 to an actuator control circuit 24, where they are converted into two control signals and actuator drive. The signal is supplied to the circuit 25. A control signal from the actuator drive circuit 25 is supplied to the actuator 16, which displaces the objective lens 15 in the vertical direction relative to the optical disc 17 so as to eliminate focus deviation, and also displaces the objective lens 15 so as to eliminate track f. 15 in a direction parallel to the f-isk surface.

Incidentally, it is known to move the secondary head in the radial direction of the disk 17 in order to record information at a desired position on the disk 1- or to reproduce information, but compared to a magnetic disk device, it is difficult to do so. Since the weight of the head is large, the above-mentioned ◇ positioning operation requires a large amount of time.

One possible solution to this problem is to arrange multiple optical heads on the same disk and divide and allocate the area of the disk for each optical head, but this would require a huge amount of equipment. Moreover, it also has the drawback of increasing costs, and so far only one optical head per device is known. Therefore, information transfer is also performed by only one optical head, and although it has the characteristics of high recording density and large storage capacity compared to magnetic disk devices, it has the disadvantage of slow information transfer speed.

As a conventional example, as described in Japanese Patent Application Laid-Open No. 57-191841, there is an example having multiple light sources, but monitoring is performed at the same time as recording, and information is extracted from multiple parts of the recording medium at the same time. This point was not taken into account.

(Object of the Invention) An object of the present invention is to provide an optical head with a short positioning time and a high information transfer speed.

[Summary of the invention]

In order to achieve the above object, the present invention has a conventional optical head having only one objective lens for one light source (semiconductor radar), but has a plurality of objective lenses, and each optical head has a plurality of objective lenses. The objective lens is capable of recording and reproducing information, and in particular, when reproducing information, it is characterized in that information can be simultaneously output for several h1 of the objective lenses.

[Embodiments of the invention]

Hereinafter, an embodiment of the F1 invention will be explained.

FIG. 1 is a diagram showing the configuration of an embodiment of an optical head according to the present invention. In the figure, the same components as in FIG. 2 are designated by the same reference numerals. Also, of the same components as in Figure 2,
The subscript "a" is added to the side of the optical component, and the subscript "a" is added to the side of the second optical component.

In this embodiment, two sets of components except the semiconductor laser 1111 and the collimator lens 2 are assembled into the same radiation body 30. Furthermore, half wavelength plates 31a and 31b
7 cutuators 32a and 32b are provided for arbitrarily inserting the light beam emitted from the semiconductor laser 11 into the optical path and withdrawing it from the optical path.

Furthermore, when the half-wave plates 31a and 31b are removed from the optical path, the light emitted from the semiconductor laser 1f11 passes through the collimator lens 12, and then is deflected by the polarizing beam splitter 13a toward the objective lens 15a. Only the first optical component side indicated by the subscript a becomes operable. At this time, information is recorded only on the first optical component side, not indicated by the subscript a, by passing a current through the semiconductor laser 11, which is the light source, to provide enough power to record information on the optical disk 17. be able to.

On the other hand, a half beam is set so that the light passes through the polarizing beam splitter 13a when inserted into the optical path in advance.
A state in which the wavelength plate 31a and the half-wave plate 31b, which is provided in the optical path between the polarizing beam splitters 13a and 13b and which keeps the transmitted light in the original polarization direction, are inserted at the same time. In this case, the light that has passed through the 1/2 wavelength root 31b can be brought into a state in which only the second optical component shown in the subscript can be operated, Information can only be recorded by the department. These facts indicate that when recording information on one optical disc 17, either of the two sets of optical components indicated by subscripts a and b can be used freely, and the distance between these two sets of optical components is , by setting it to approximately half the width of the recording area in the radial direction (total track width) to be used on the optical disc 17.
It is clear that the time it takes to move the head in the track direction to record information can be reduced by up to half.

Furthermore, in order to reproduce information from the optical disc 17, the setting angle of the half-wave plate 31a with respect to the optical axis of the light transmitted through the collimator lens 12 is set in advance so that the light can also be deflected in the direction of the objective lens 15a. By doing so, it is possible to simultaneously obtain 15 pieces of information on two positions of the optical disc 17 from the photodetectors 20a and 20b, making it easy to transfer information)
! It becomes possible to double the amount of Maro.

On the other hand, even if the half-wave plates 31a and 31b are not used, it is possible to achieve the above-mentioned purpose.

The polarizing beam splitters 13a and 13b are half mirrors.
You should do it. This makes it possible to deflect the laser beam to both objective lenses 15a and 15b,
Each of the two sets of optical components becomes operational. However, when recording information, recording can be controlled by removing the autofocus servo on the unused side and intentionally causing defocus on the C side only.

Therefore, if the embodiment of the present invention is used, it is possible to shorten the time required to move to a desired track without increasing the size of the device or using a large number of heads, and the reproduction and transfer of information can be performed faster than the conventional two. This means you can do it twice as fast.

In J3, in the embodiment, there are two sets of optical components, but the number of sets is between 3 and 1.

〔Effect of the invention〕

As described above, according to the present invention, by mounting one light source, multiple types of objective lenses, and photodetectors in one body, objective lenses and photodetectors can be easily and compactly maintained at conventional transfer speeds. Information can be reproduced and transferred at a speed equal to the number of combinations of detectors, and the distance required to move Eh to the desired track position tPj is approximately the distance divided by the number of combinations of objective lenses and photodetectors. It has the advantage of being able to significantly shorten the head movement (14 intervals).

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention, and FIG. 2 is a diagram showing the configuration of an example of an optical disk device having a conventional optical head. 11... Semiconductor laser, 12... Collimator lens, 13a, 13b... Polarizing beam splitter, 14a
. 14b/quarter wavelength plate, 15a, 15b... One objective lens, 16a, 16b, 32a, 32b-actuator, 17... Optical disk, 20a, 20b... Photodetector, 31a, 31b... Half wavelength plate.

Claims (4)

[Claims] (1) A single light source, a plurality of objective lenses for converging and irradiating the light beam from the light source onto different positions on the optical disk, and a light beam that is reflected from the optical disk and passes through a plurality of separate optical paths. An optical head characterized by comprising a plurality of photodetectors that perform detection separately. (2) a plurality of half-wave plates; and an actuator for inserting or retracting the plurality of half-wave plates into an optical path between the single light source and the plurality of objective lenses; 2. An optical head according to claim 1, further comprising an optical path control means. (3) The distance between the plurality of objective lenses in the radial direction of the optical disc is selected to be approximately equal to the value obtained by dividing the recording area width of the optical disc by the number of objective lenses. The optical head according to item 1. (4) At the time of recording, means is provided for focusing only the light beam that has passed through one of the plurality of objective lenses onto the optical disk, and for defocusing the light beam that has passed through the other objective lenses. An optical head according to claim 1, characterized in that: