JPS58211335A - Optical recording and reproducing device - Google Patents

Abstract

PURPOSE:To realize a thin and miniature structure for an optical recording/reproducing device, by attaching an objective lens to a bobbin which is wound around in common with the 1st and 2nd driving coils that contribute to the control of both tracking and focusing directions. CONSTITUTION:The Z and X axis directions correspond to the focusing and tracking directions, respctively. The 1st driving coil 250 and the 2nd driving coil 260 which contribute to the control of tracking and focusing directions respectively are wound in common around a bobbin 27. A lens cell 500 holding an objective lens is pressed into a hollow part at the center of the bobbin 27. The bobbin 27 is fixed to plate springs 28 and 29 which can freely oscillate in both X and Y axis directions.

Description

[Detailed description of the invention] The present invention relates to an optical record reproduction device.

The optical recording device according to the present invention is a focusing and tracking control device used in a so-called optical disk information writing and reproducing device that optically writes or reads signals recorded on a disk such as an optical video disk or the like in a non-contact manner. Applicable as a light-duty device.

In the case of a non-contact laser type, as shown in Fig. 1, the disc 1 does not have the so-called grooves of a record, but has bits 2 which form microscopic indentations in the shape of a disc dotted in the circumferential direction. For example, the depth of this bit 2 is only 0.1 μm.

This value corresponds to a percentage of the wavelength of the laser beam scanning this signal track. When this bit 2 is scanned with a laser beam, the light reflected from the bit part becomes out of phase with the light waves reflected from other parts, and they cancel each other out, causing urine and rebeam to Modulation 2 is applied depending on the presence or absence of .

By detecting this and reproducing the signal, images and sounds of seedlings and
'Everything is recorded as changes in bit length and spacing. Note that the dimension 1 straight in the figure is a diagrammatic illustration of a specific example.

'l'ft to such a disc-shaped body! ? When writing, or when regenerating the written information, the 0 element does not fall off the track number Th (
Q-) Tracking control that controls the control and focusing control that controls the source so that it stays completely in focus on the disc? ! IJ f wholesale will be an important issue.

Therefore, an optical recording/reproducing apparatus according to the prior art including each of the control means described above will be introduced, and then the present invention will be explained.

In FIG. 2, a potential beam Lb such as a laser beam incident from the direction of the arrow is reflected by an actuator 6 for tracking control, and is focused by an objective lens 5 attached to an actuator 4 for focus song control. The signal surface 1rKe of the disk 1 is focused as a small spot.

The original beam Lb is intensity-modulated and reflected at the signal surface 1f,
The optical path is followed in the opposite direction, and an information signal is detected by a signal detection system (not shown). This detected signal is also obtained by demodulating the necessary video or audio signal.

Here, since the disk 1 is normally eccentric or warped, the focus of the original beam by the objective lens 5 is always on the signal plane 1fO,
) In order to keep the signal track 1 on top, the above-mentioned tracking gain control and focusing/focusing control are necessary.

The focus actuator 4 has a configuration similar to the voice coil driving portion of a speaker.

Reference numeral 6 indicates a magnetic circuit, and reference numeral 7 indicates a voice coil.

Since the operating principle of the voice coil driving portion of the speaker is well known, the configuration and operation will be explained very simply.

The magnetic circuit 6 is composed of a permanent magnet and soft iron, and a gap is provided in a certain part of the voice coil 7, and a strong magnetic flux exists in this gap in a direction orthogonal to the coil wire of the voice coil 7. The voice coil 7 is supported by an elastic member 8 and can be freely displaced in the vertical direction in FIG. 2, that is, in the optical axis direction, within the above-mentioned space. Voice coil 7 has E7.1. The objective lens 5 is
are coupled, and displacement of the voice coil 7 displaces the objective lens 5. When the voice coil 7 is supplied with a hot current proportional to the no-A-cush deviation signal detected by a 7m-cush deviation detection system (not shown), the interaction between this low current and the magnetic flux (Fleming's According to the law], the voice coil 7 is positioned in the '#:, llll11 direction (JE, including the page direction) and the focus is maintained.

Next, the actuator for tracking control uses a so-called vibrating mirror type. That is, magnets 12 and 13 are attached to both ends of the mirror 11, which is attached to the base via an elastic body 9 such as a comb so as to be able to vibrate freely. The magnets 12 and 13 are repelled and attracted by the current flowing through the coin L14, and as a result, the mirror 11 vibrates with the elastic body 9 as a fulcrum, and the original beam Lb
changes the power of incidence on the objective lens 5.

As described above, conventionally, both tracking and focusing are controlled by separate actuators, and these actuators are stacked in the optical axis direction. For this reason, in the conventional optical Y-ball rectification device configured with the actuator 6.4, the size in the optical axis direction is
(Only the sum of the dimensions of both actuators is necessary, and there is a demand for smaller devices in a general sense and thinner devices in a technical sense.) It is.

Here, the request for thinning in the technical sense mentioned above simply means shortening the optical path length between the objective lens and the receiving element, thereby increasing the detection limit of the light receiving element. Get the effect of being able to do something.

For example, in the focus detection method shown in FIG.
Wave plate, reference numeral 16 is a deflection beam splitter, reference numeral 17 is a focus detection prism, reference numerals 18a and 18b are light receiving elements,
Reference numeral 19 indicates a coupling lens, and reference numeral 20 indicates a laser diode. In this example, a focus error is detected based on the difference in the amount of light between the two light receiving elements 18a and 18b that are opposite to each other with respect to the optical axis. Assuming that the disc 1 is now in the focused position, the reflected light flux is reflected as parallel light to the light receiving elements 18a and 18b as shown in FIG. In contrast, if the disk 1 were to move away from the objective lens 5 further than the focal position shown in FIG.
18b, and when it approaches the focus position shown in FIG. 5, the reflected light beam is as shown in FIG.
Focuses on the t+11 side of i sb. In each of these cases, when the disk 1 tends to move away from the objective lens 5 from the in-focus position shown in FIG. 6 (see FIG. 4), the light beams on the left and right sides of the original axis are received by the "yfS elements 18a, 18b K. When the VC maintains the same positional relationship but tends to approach the opposite direction (see Figure 5), the light fluxes on the left and right sides of the optical axis are reversed compared to the example in Figure 4, and the light receiving element ""a1181 )
It becomes impossible to detect a focus error at each angle difference that the lens receives.

Therefore, in order to detect the focus error ((), the light receiving element 18
There must be a focal position of the Kf beam behind points a and 18b. Assuming that δ is the deflection of the disc 1 in the optical axis direction that satisfies such conditions, that is, the detection limit of the light receiving elements 18a and 18b, δ is derived from the following equation.

2 2 (I!-f) In the end, the smaller the equal optical path length/the smaller the value, the larger δ can be, and the detection limit of the light-receiving element can be increased.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an optical recording/reproducing device that can be made thinner and smaller.

The present invention will be explained in detail below.

First, the basic content of the present invention will be explained with reference to FIG.

In the figure, assuming a donut-shaped gap having a center axis 0-0 in the X-axis force direction, a magnetic flux generating means, which will be described later, is provided with a reference numeral 21 in an arbitrary virtual cross section in the radial direction of the gap.
, 22, 23, 24 are formed. Among these magnetic circuits, the magnetic paths of the components extending in the radial direction of the virtual circle centered on the central axis 0-0, for example, the magnetic paths 21a, 23a, 24a of the portion corresponding to the reference numeral 22a in the magnetic circuit 22. The first drive coil 25 is provided so as to intersect with the center axis 0-0 force direction. As can be seen from the figure, the first drive coil 25 intersects the magnetic path 21a in two axial directions, and
The magnetic path 232L opposite to a also intersects in the X-axis force direction.

Furthermore, each of the magnetic paths 21a, 22a, 23a, 24a
A second drive coil 26 is provided 5K to intersect with the VC in the circumferential direction of an imaginary circle centered on the central axis o-ay.

The first drive coil 25 and the second drive coil 26 are commonly wound around one bobbin K (not shown in FIG. 6), as will be described later. however,
It is assumed that each coil is capable of independently bending the electric current.

Now, assuming that the magnetic fields in the valley magnetic paths 21a, 22a, 23a, and 24a are directed radially outward around the central axis, the first drive coil 25 is energized clockwise. Sometimes, according to Fleming's law, the first drive coil 25 is integrally formed with a second drive coil 26.
At the same time, it is moved in the direction of the arrow X.

If the direction of the current is reversed, the object will be moved in the opposite direction to the arrow X.

Furthermore, if the second drive coil 26 is energized in the counterclockwise direction, the second drive coil 26 is moved in the direction of arrow 2 together with the first drive coil 25 according to Fleming's law. If the direction of the current is reversed, it will move in the opposite direction to the indicator y.

Based on this principle, the above 1. If the objective lens is mounted on the center of a bobbin around which the ringing coil 25 and the second drive coil 26 are commonly wound, and the bobbin is supported on a stationary member via an appropriate movable support means, An optical recording/reproducing device according to the present invention can be obtained. In that case, the X-axis force direction corresponds to the focus song direction, and the X-axis force direction corresponds to the tracking direction. In this configuration, the first drive coil 25 that contributes to control in the tracking direction and the second drive coil 26 that contributes to control in the focusing direction can be configured in a superimposed manner. It is possible to satisfy the demand for thinning, which is the objective of the above, and it is also possible to achieve miniaturization.

Below, further explanation will be given based on specific examples.

In FIG. 7, the reference numeral 250 is the first drive coil corresponding to the first drive coil 25 in the description of Ail, and the reference numeral 260 is the second drive coil corresponding to the fJ2 drive coil 26VC. It is a coil. Also, code 2
7 indicates these first drive coil 250 and second drive coil 2
60 shows a bobbin commonly wound.

The center of the bobbin has a cylindrical hollow space, and a lens cell 500 holding an objective lens is press-fitted into the hollow space. In this way, the bobbin 27, which is equipped with the itA moving coil 2501, the second drive coil 260, the lens cell 500, etc., has its upper end and lower end fixed to the leaf springs 28 and 29, which serve as supporting means, respectively. , 29 are each partially fixed to a main body case 60 (see FIG. 8), which is an immovable member. In addition to the lens cell 500,
It is also possible to integrally incorporate components such as a semiconductor laser and a light receiving element into the bobbin as shown in FIG. 6 in Section 11.

Next, with reference to FIG. 8, the manner in which the leaf springs 28 and 29 are attached to the main body case 60 will be described.

First, the shape of the upper plate spring 28 is such that the U-shaped strip plates 28a and 28a' have edges in the Z-axis direction, and the free ends of 28a' are opposite to each other in the x-axis direction. The upper edges facing each other in the X-axis direction have a cross-linked shape with saw-shaped plate portions 28b. A circular hole 28c formed in the center of the plate is for positioning the lens cell 500 through the lens. At the opposing free ends of each of the strips 28a, 28a', there are provided side plates 280a, 2 from the inside, respectively.
After 80a' is bonded, it is further fitted into the grooves 29Da', 290 of the T-shaped intermediate support members 29a, 29a' and fixed by bonding. In addition, the backing plates 280a, 280a
The small holes 281a and 281a' formed at the center of the intermediate support members 29a and 29a' are positioning means for the recesses 291a and 291a' formed at the center of the intermediate support members 29a and 29a' in the X-axis direction. Positioning is done by the pin that is inserted.

Each intermediate support member 29a, 29a' is an edge of the upper part body 61 of the main body case 30, and a Y
They are fastened with screws 53a and 33a''l (respectively) in grooves 32a and 32a' having an increased diameter of one dimension cut out on a line in the axial direction.

Next, regarding the lower leaf spring 29Vc, the above-mentioned upper leaf spring 28
It is made up of exactly the same shape. A ring-shaped flange 65 is fitted into the inner diameter of the lower cylinder 34 VC of the main body case 60. After fitting, the lower cylinder 34 VC of the main body case 60 is attached to the fillet part of the flange 65 while being adhesively fixed. , a groove portion 3 facing the groove portions 290a, 290a'
The punched spring 29 is adhesively fixed to 6a and 361L'. Note that the hole 37a formed in the flange 65.

67a' and the holes 381a formed in the backing plates 380a and 380a'.

381a' are for positioning.

In this way, the plate springs 28, 29 have roots 28b, 29, respectively.
b at regular intervals? They are added to face each other in the X-axis direction, and are swingable in the Z-axis direction as well as swingable in the X-axis direction. 4 of the upper edge of the upper cylinder 31 and the leaf spring 28
Four notches 39, 40 corresponding to the four corners
, 41 and 42 are each formed as a relief against the deflection of the punched spring 28 in the X-axis direction. flange 65
Four notches 39' and 40' formed on the edge of
, 41', and 42' were also provided by the master's intention, so each of these notches is the same as the above notch S.
9, 40, 41.42, respectively, in a matching relationship in the X-axis direction.

Next, the attachment state of the bobbin 27 to the leaf springs 28 and 29 will be explained. Referring to FIG. 10, lens cell 5
The upper end edge of 00 is integrally formed with a pressing ring 46 that is press-fitted, and the lens cell 500 is formed at the center of the bobbin 27 after sequentially inserting the rubber ring 44 and the hole 28c'f of the leaf spring 28. It is press-fitted into the hollow part 270. Therefore, the bobbin 27 is connected to the lens cell 5007.
It is attached to the leaf spring 28 in such a manner that it is sandwiched between the leaf spring 28 and the comb washer 44 through the comb.

Regarding the lower end of the bobbin 27, a metal Wannonya 45 hit is attached to the lower end surface, and a leaf spring 'IB metal washer is attached to the lower end surface.
45 Togomu Wano Shear 4 Sandwiched in a state,
A flange 47 attached from below is attached to the plate spring 29 by being press-fitted into the hollow portion 270. In addition,
The lower cylindrical body 34 also has cutouts 39' and 40' at the lower end edge.
, 41', 42' have a notch B9' at a position corresponding to the valley.
, 40 da, 41'', 42'' are formed.

The roofed cylindrical portion 2700 constituting the bobbin 27 has two
Two brim portions 2701 and 2702 are formed,
A second drive coil 260 is wound between the brim 2701 and 2702.

Parts of the flange portions 2701 and 2702 are cut out symmetrically with respect to an imaginary line passing through the center of the lens cell 500 and parallel to the Y-axis. Each notch has a code 48.
, 49, 50. 51 (see Figures 7 and 9).

The first drive coil 250 is wound using each of the above cutouts as guide means. Note that the bobbin is not limited to the cylindrical shape as in the illustrated example, but may also be prismatic.

Next, the magnetic flux generating means will be explained. In FIG. 1o, the inner yoke 52 is in a position similar to that of a flange with a flange, and the flange of the inner yoke 52 is in a position similar to that of the main body case 6.

The cylindrical portion of the bobbin 27 has entered into the inner cavity of the covered cylindrical portion 2700 of the bobbin 27.

On the other hand, a ring-shaped permanent magnet 56 is stacked on the flange portion of the inner yoke 52, and a ring-shaped outer yoke 54 is further stacked on top of the ring-shaped permanent magnet 56, and these are bonded and fixed to each other. The outer yoke 54 slightly overhangs in the inner radial direction, and a magnetic path that intersects the first drive coil 250 and the second drive coil 260 is formed between the cutout and the opposing inner yoke 52. Reference numeral 55 indicates the direction of the magnetic field.

By energizing the first drive coil 250, the bobbin 27 receives a force in the X-axis direction, and the plate springs 28.

Movement is achieved by displacement of each strip portion of 29. Furthermore, by energizing the second drive coil 260, the bobbin 27 receives force in the X-axis direction from the plate portions 28b of the plate springs 28 and 29.

Movement is achieved by displacement of 29b. During these movements, since the lens cell 500 is supported by leaf springs at two locations, the upper and lower, it is difficult for the lens cell 500 to tilt toward the optical axis.High precision movement is guaranteed.Tracking in the X-axis direction control direction,
If the X-axis direction is the focusing control direction, the first and second drive coils 250 and 250 are wound around the bobbin 27 in a superimposed manner, so that the device can be made thin. It becomes possible.

Note that the notches 48, 49, 50. formed in the collar portions 2701, 2702 of the bobbin 27. 51 requires a specific positional relationship with the leaf springs 28 and 29. In other words, each of the notches 48, 49, 50, 50 should face the part where the leaf springs 28, 29 are attached to the main body case. Therefore, holes for positioning are formed in the leaf spring and bobbin so that the positional relationship can be determined correctly during assembly.In the figure, holes formed in the leaf spring are shown. is designated by the symbol J, and a hole formed in the bobbin is designated by the symbol.Furthermore, the symbol 60 represents a cap.

[Brief explanation of drawings]

FIG. 1 is a partial perspective view of a disk, FIG. 2 is a configuration diagram of an optical recording filter explaining the prior art, and FIGS. 6 to 5 are optical path diagrams used to explain the present invention in detail. , Fig. 6 is a detailed basic configuration diagram of the present invention, Fig. 7 is a perspective view of the bobbin and its surroundings, Fig. 8 is an exploded perspective view of the main body case and leaf spring, etc., Fig. 9 10 is a sectional view taken along line AA in the same figure, FIG. 11 is a sectional view taken along line BB in FIG. 9, and FIG. 12 is a bottom view of FIG. 9. It is a diagram. 25, 250...first drive coil, 26,260...
・Second drive coil, 27...Bobbin, 28.29...
- Leaf spring, 52... Inner yoke, 53... Permanent magnet,
54...Outer yoke.

Claims (1)

[Scope of Claims] Assuming a Dawn-shaped void having a central axis in the Z-axis direction of the six orthogonal axes, a virtual circle centered on the central axis within a virtual cutting plane in the radial direction of this void. a first drive coil that interlinks the magnetic flux in the direction of the central axis; a bobbin that captures both the first drive coil and the second drive coil; an optical unit that is provided integrally with the bobbin and includes at least an objective lens; Move the bobbin in the central axis direction and on a plane perpendicular to the central axis direction. tb Please do not ask for support means that allow movement in the direction of the force and are supported on immovable members.'(!'
Special optical recording and reproducing equipment.