JPS63102044A - Optical head - Google Patents

Abstract

PURPOSE:To record and reproduce information with an optical recording medium fixed by providing a rotary table with the 1st and 2nd 90 deg. mirrors aligning optical axes between a head unit and an optical processing part, sliding the head unit, and tracking and feeding the head. CONSTITUTION:For reproducing recorded information, an objective lens 11 receives and converges reflected light from a laser beam that is converged and projected on the recording surface of an optical card 37. The converged coming-back laser beam is supplied to the optical processing part 25 through the 90 deg. mirrors 18 and 23. A beam splitter 3 in the optical processing part 25 isolates the coming-back laser beam through a lambda/4 plate 31. The coming-back laser beam isolated in such a way is supplied to an optical sensor 35 through a convex lens 32 and a cylindrical lens 33, and converted into an electrical signal, after which it is taken out to the outside through a slip ring and a brush unit. Thus,with the optical recording medium fixed, information can be recorded and reproduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical head for recording and reproducing information on and from an optical recording medium such as an optical disk and an optical card, and particularly relates to an optical head that records and reproduces information on and from an optical recording medium such as an optical disk and an optical card. The present invention relates to an optical head for recording and reproducing information.

[Prior art]

Optical recording media such as optical discs and optical cards have an optical recording layer on the surface of a substrate, and when recording information,
Recording is performed by irradiating the optical recording layer with a laser beam modulated by recording information from an optical head so as to converge on the optical recording layer, thereby causing changes such as deformation or discoloration to the optical recording layer. Furthermore, when reproducing recorded information, the optical recording layer is irradiated with a relatively weak laser beam from an optical head, and a change in the reflected light is detected. In this case, the recording and reproducing laser beams must be moved at a relatively constant speed on the trunk provided on the surface of the optical recording layer.

For this reason, in conventional optical information recording and reproducing devices such as compact disc players and video disc players, an optical disc is provided with a ring-shaped track, and the optical disc is rotated while maintaining its center. Information is recorded and recorded information is reproduced by irradiating the rotating optical disk with a laser beam from an optical head that moves in the radial direction.

[Problem that the invention seeks to solve]

However, in the optical information recording/reproducing apparatus having the above configuration, both the optical recording medium and the optical head must be mechanically driven, which results in a complicated and expensive mechanism.

In addition, when an optical card is used as an optical recording medium, the optical card has a rectangular shape that is approximately the same as a credit card or a banking card, and has a linear track only in a part of its longitudinal direction. Tracking control is performed by linearly reciprocating the optical card and moving the optical head in a direction perpendicular to this reciprocating movement. Therefore, in this case as well, both the optical card as an optical recording medium and the optical head are driven.

Furthermore, in order to significantly increase the recording capacity of an optical card, it is necessary to make the recording area donut-shaped or fan-shaped, but when using the optical head described above, it is possible to rotate a rectangular optical card. It becomes necessary to do so. However, unlike the case of an optical disk, this optical card does not have a center hole, so it is extremely difficult to drive the optical card in rotation while positioning it with high precision.

The present invention was made to solve this problem, and allows information to be recorded and reproduced in a fixed position on an optical recording medium having a ring-shaped (including spiral-shaped) or fan-shaped track. The purpose is to provide an optical head.

[Means for solving problems]

The optical head according to the present invention includes an objective lens mounted on a rotary table rotated by a motor, a focus control mechanism for moving the objective lens in the axial direction of the rotary table, and a focus control mechanism that moves the optical axis of the objective lens in the direction of the rotation center of the rotary table. Tracking feed is performed by a slide mechanism that guides a head unit having a first 90° mirror on the rotary table in the radial direction thereof, and a second 90° mirror is provided on the axis of the rotary table.
By providing a ° mirror and guiding the optical axis from the first 90° mirror in the direction of the rotation axis of the rotary table, the optical axis of the objective lens can be guided to the optical processing section provided inside the rotary table. It is configured to align with the optical axis.

[Effect]

In the optical head configured in this way, the first optical head unit connects the optical axis between the head unit and the optical processing section. The second 90° mirror is provided on the rotary table, and the head unit is slid in the radial direction of the rotary table to perform tracking feed, making the optical head rotatable. Since information can be recorded and reproduced from ring-shaped or fan-shaped tracks provided on the optical recording medium while the optical recording medium remains fixed, the overall configuration is simplified.

[Example]

6- FIG. 1 is a perspective view showing an embodiment of the optical head according to the present invention, and FIG. 2 is a cross-sectional view of the optical head shown in FIG. 1 taken along line 1--n. In the figure, reference numeral 1 denotes a brushless motor mounted on the surface of a base plate 2 with the output shaft facing upward, and includes a disc-shaped stator 1a and a brushless motor 1 coaxially superimposed on the stator 1a. The rotor 1b is composed of a disc-shaped rotor 1b. 3 is a rotary cylinder fixed to the output shaft of the brushless motor 1; 4 is a rotary table; a cylindrical part 5 coaxially fixed to the upper end surface of the rotary cylinder 3; It is constituted by a disk portion 6 which is fixed in place. Brackets 7a and 7b are fixed to the peripheral edge portion of the surface of the disc portion 5 and to the portions facing each other across the center of rotation thereof, and the bracket 7a.

Two slide shafts 8a and 8b are fixed between the two slide shafts 8a and 7b in parallel with each other such that the center of rotation of the disk portion 6 is located between the two slide shafts 8a and 13b. 9 is a slide shaft 3a.

The slider 8b is a slider that moves in the radial direction of the rotary table 4 while being guided by the slider 8b, and the slider shafts 8a, 8b and the slider 9 constitute a slide mechanism. 10 is a head unit placed on the slider 9. Here, the head unit 10 includes an objective lens holder 12 that holds an objective lens 11, and the objective lens holder 1, as shown in detail in FIG.
Two gimbal springs 13 are coaxially fixed to the bottom of the
a bobbin 14 held by a bobbin 14, a focus coil 15 wound around the bobbin 14, a pot-shaped yoke with a through hole in the center, and a ring-shaped focus magnet 17 fixed to the inner wall surface of the yoke 16. It is composed of. The focus coil 15 is located in the gap between the opposing surfaces of the center pole of the yoke 16 and the focus magnet 17 in the magnetic path configured by the yoke 16 and the focus magnet 17. The generated magnetic flux acts on the magnetic flux generated within the air gap to move the objective lens 11 in the vertical direction, that is, in the focus direction. In addition, the slider 9
is hollow inside, and a 90° mirror 18 is fixed directly below the objective lens 11.
The optical axis toward the rotary table 4 is bent by 90 degrees toward the rotation center of the rotary table 4.

Next, 19 is a weight for keeping rotational balance with the slider 9 and the head unit 10, and is adapted to slide while being guided by the slide shafts 3a and 13b. 20 is a pinion gear rotated by a motor (not shown), and 21 is a rank gear that meshes with the pinion gear 21, one end of which is fixed to the slider 9. A rack gear 22 meshes with the opposite side of the pinion gear 21 from the side where it meshes with the rank gear 20, and one end of the rack gear 22 is fixed to the weight 19. This pinion gear 21 and rack gears 21, 2
2 constitutes a feeding mechanism. Reference numeral 23 denotes a 90° mirror provided at the center of rotation of the disc 6, which allows the optical axis from the 90° mirror 18 to pass through the hole 24 provided at the center of rotation of the disc 6, and Guide it downward along the center axis of rotation.

Next, the interiors of the cylindrical portion 5 and the rotary tube 3 are hollow, and serve as housing portions for the optical processing portion 25 . As is generally known, the optical processing unit 25 includes a laser diode 26 that emits a laser beam upward along the rotation center, a collimator 27, and a beam correction lens 28 that makes the laser beam into a perfect circle. .29, a beam splinter 30, a λ/4 plate 31, a convex lens 32, a cylindrical lens 33, and an optical sensor 34.

In addition, 35 in FIG. 1 is a brush unit, 36 is a slip ring provided on the outer peripheral surface of the rotating cylinder 3,
It is used for power supply and signal extraction to the laser diode 26 and optical sensor 34.

In the optical head constructed in this way, FIG. 1 shows the optical recording surface of the optical card 37 shown in FIG. 3, for example.

While facing the hesode unit) 10 shown in Fig. 2,
The ring-shaped recording track 34 is positioned and fixed so that its center coincides with the rotation center of the rotary table 4. Next, when power is supplied to the brushless motor 1, the brushless motor 1 rotates, and the rotary cylinder 5 fixed to the rotation output shaft and the rotary table 4 fixed to the upper end of the rotary cylinder 5 are coaxial. , for example, in the direction shown by arrow A.

In this state, when an electric signal modulated by the recorded information is supplied to the laser diode 2 via the brush unit 35 and the slip ring 36, the laser diode 2 outputs laser light modulated by the recorded information. Become. This laser light then passes through the collimator 27 and beam correction lenses 28 and 29, thereby becoming a perfectly circular laser beam consisting of only parallel light. The laser beam subjected to such correction is passed through a beam splitter 30 and a λ/4 plate 3, and is then supplied to a 90° mirror 23, so that its optical path is deflected by 900° to the head unit 1.
Supplied to the 0 side. Here, inside the slider 9,
90° mirror 1 provided opposite to 900 mirror 23
8, and the laser beam reflected at the 90° mirror 23 is reflected again at the 90° mirror 18 and supplied to the objective lens 11 above.

The objective lens 11 converges the laser beam supplied from the 90' mirror 23 and irradiates it onto the surface of the optical recording layer of the optical card 37 shown in FIG. Record information by making changes.

In this case, since the rotary table 4 is rotating, optical recording can be performed on the tractor 34 according to the distance from the rotation center on the optical card 37 to the objective lens 11 at the current time. Here, when the disc 6 is rotated, the slider 9 and the hend unit 11 are located far from the center of rotation, resulting in an unbalanced rotation. 19, such an unbalance problem does not occur.

Next, when a focus control signal is supplied to the focus coil 15, a magnetic flux corresponding to the focus control signal is generated from the focus coil 15. The magnetic flux generated from this focus coil 15 is
The magnetic flux in the air gap in the focus magnetic path constituted by the yoke 16 and the focus magnet 17 acts to generate a vertical force according to the focus control signal. Focus control is performed by moving the objective lens holder 12 up and down.

Next, when the pinion gear 20 is rotated clockwise by a motor (not shown) in the state shown in FIG. 1, for example, the rack gears 21 and 22 are both pulled toward the pinion gear 20. Since the pulling directions of both rank gears 21 and 22 are opposite to each other, the slider 9 and the weight 19 move in opposite directions and are always balanced. Furthermore, by moving the head unit 1O together with the slider 9 in the direction of the rotation radius of the rotary table 4 in this balanced state, track feed and tracking control can be performed.

Next, when reproducing the recorded information, the objective lens 11 receives and converges the reflected light of the laser beam convergently irradiated onto the recording surface of the optical card 37, and the converged return laser beam is transmitted to the 90° mirrors 18 and 23. through the optical processing section 25
supply to. In the optical processing section 25, the return laser beam that passes through the λ/4 plate 3 and the sheet metal 1 is separated by a beam splitter 30. The returned laser beam separated in this way is supplied to the optical sensor 35 via the convex lens 32 and the cylindrical lens 33, where it is converted into an electrical signal, and then taken out to the outside via the slip ring 36 and the brush unit 35. It will be done. In other words, when using the optical head configured in this manner, information can be easily recorded and recorded information can be reproduced while the optical recording medium such as an optical card remains completely fixed.

In the above embodiment, only the case where an optical card having a ring-shaped track was used was explained.
The present invention is not limited thereto (for example, it goes without saying that it may be fan-shaped as a part of a ring-shaped trunk as shown in FIG. 4).

〔Effect of the invention〕

As described above, the optical head according to the present invention includes a first optical head that connects a head unit, an optical processing section, and an optical axis between the two. By providing a second 90° mirror on the rotary table and sliding the head unit in the radial direction of the rotary table to perform trunking feed,
Since the optical head is of a rotating type, it is possible to record and reproduce information on ring-shaped or fan-shaped tracks provided on the optical recording medium while the optical recording medium remains fixed. Since this can be done, the overall configuration is simplified. Furthermore, since the optical recording medium does not need to be rotated, it becomes easier to read optical recording media that are difficult to rotate, such as optical cards. Further, by forming the tracks of the optical card in a ring shape or a fan shape based on the center of rotation, various excellent effects such as the ease of greatly increasing the recording capacity can be obtained.

FIG. 1 is a perspective view showing an embodiment of an optical head according to the present invention, FIG. 2 is a sectional view of the optical head shown in FIG. 1, and FIGS. 3 and 4 are perspective views of an optical card. 1------
Brushless morph, 1 stator, 1--
-1 rotor, 3-1111 rotary tube, 4--1 rotary table, 5-----cylindrical section, 6-----disc section, 7 a, 7 b--bracket, 8 a
, 8 t+-1---Slide shaft, 9-11--Slider, 10-----Head unit, 1t--1 Objective lens, 12------
・1 objective lens holder, 13 --- gimbal handle, 1
4--1~--Bobbin, 15--Focus coil, 16-----Yoke, 17--Focus magnet, 18-1--90° mirror, 19
------1 weight, 20---- pinion gear,
21゜22～---m-rack gear, 23-111-
90° mirror, 24------ one hole, 25------
- Optical processing section, 26 ------- Laser diode, 27 ---- Collimator, 28. 29 - 111111 Beam correction lens, 30 ---- Beam splinter, 31 - ------ λ/4 plate, 32 --- one --- convex lens, 33 --- one cylindrical lens, 34 ---
- Optical sensor, 35 ------- Brush unit, 36
−−−−−Srisopring.

Applicant: NEC Home Electronics Figure 3 Figure 4 Procedural amendment (fan) February 16, 1988

Claims (2)

[Claims] (1) A rotary table rotated by a motor, a focus control mechanism that moves the objective lens in the axial direction of the rotary table, and a first 90° mirror that guides the optical axis of the objective lens toward the rotation center of the rotary table. a head unit having: a slide mechanism that guides the head unit in the radial direction on the rotary table; a feed mechanism that slides the head unit guided by the slide mechanism; and an axis of the rotary table. a second 90° mirror that guides the optical axis from the first 90° mirror in the direction of the rotational axis of the rotary table; and a second 90° mirror that is located within the rotary table and whose optical axis is the second 90° mirror. and an optical processing section aligned with the optical axis of the optical head. (2) A rotary table rotated by a motor, a focus control mechanism that moves the objective lens in the axial direction of the rotary table, and a first 90° mirror that guides the optical axis of the objective lens toward the rotation center of the rotary table. a head unit, a weight, a slide mechanism that guides the head unit and the weight in a radial direction on the rotary table, and a slide mechanism that guides the head unit and the weight in opposite directions to each other. a feeding mechanism for sliding movement; a second 90° mirror for guiding the optical axis from the first 90° mirror in the direction of the rotational axis of the rotary table in the axial center portion of the rotary table; and an optical processing section positioned so that its optical axis is aligned with the optical axis of the second 90° mirror.