JPH08124206A - Optical pickup, light receiving element therefor and light spot diameter adjusting method therefor - Google Patents

Abstract

PURPOSE: To reduce the size and cost of an optical pickup while enhancing the performance by adjusting the diameter of light spot, as desired, without requiring any light receiving element for exclusive use. CONSTITUTION: A light receiving element 10 is shifted relatively to a light spot such that one of a pair of light spots is projected to a gap part between light receiving parts on the light receiving element 10. A first gap region A1 larger than a desired diameter of light spot and a second gas region A2 smaller than the desired diameter of light spot are provided at the gap part of the light receiving element 10. A spot lens is shifted in the direction of optical axis such that the presence and absence of photoelectric conversion signal from each light receiving part satisfy a predetermined combination thus adjusting the diameter of light spot as desired. Subsequently, the relative position is reset such that the light spot is projected substantially to the center of each light receiving part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting a light spot diameter of an optical pickup incorporated in a disc reproducing apparatus such as a CD or MD, a light receiving element of the optical pickup, and an optical pickup.

[0002]

2. Description of the Related Art First, an example of an optical system in an optical pickup will be described with reference to FIG. 2 which is an explanatory view of the present invention. This optical pickup is provided with a hologram laser unit 1 for emitting a laser beam, and from this unit 1, three lasers of a main beam and two sub-beams are provided by a grading (diffraction grating) provided on the emitting surface. Light is emitted.

These laser lights are collimated by the collimator lens 2 and are focused on the disk by the objective lens 5. Then, each reflected light from the disk follows an optical path opposite to that described above, is split by a beam splitter 3 provided midway, and one of the separated light beams passes through a collimator lens 2 and is a hologram laser unit. It is incident on the light receiving element in 1. The photoelectric conversion signal from the light receiving element causes the objective lens 5 to move in the optical axis direction so that the focal point when the light is focused through the objective lens 5 follows a position error in the optical axis direction of the disc and a surface wobbling. The focus control is driven to.

On the other hand, the other light beam split by the beam splitter 3 is the Wollaston prism 6,
It is separated into light beams that form a pair of S component and P component having polarization characteristics. Then, these 6 light beams separated by 3 pairs are guided to the light receiving element 10 via the 45 ° mirror 7, the spot lens 8 and the reflection mirror 9.

FIG. 9 shows the shape of a light receiving portion in a conventional light receiving element 10 'which receives the separated light as described above. As shown in the figure, in the conventional light receiving element 10 ', six light receiving portions are formed symmetrically with respect to the center line Xc' so as to correspond to a total of six separated lights, each of which has a rectangular shape. Has been done. In the figure, the separated light group of the S component is incident on the light receiving unit group on the right side, and the separated light group of the P component is incident on the light receiving unit group on the left side.

That is, the main spot MS _S in the separated light component of the S component is provided substantially in the center of the main light receiving portion Ra ', and the sub-spots SS _S1 and SS _S2 are provided above and below the main light receiving portion Ra', respectively. respectively incident on each central portion of the light receiving portion Rb '· Rc', at the same time, the main spot MS _P main light receiving portion La in the separation optical group P component ', the sub-spots SS _P1 ·
SS _P2 is incident on each central portion of the light receiving portions Lb ′ and Lc ′.

Then, each of the light receiving sections outputs a photoelectric conversion signal of a level corresponding to each incident light quantity, and based on these signals, a pit signal of a disk, a magneto-optical signal, an ADIP (Address In Pregroove on Recordable D) signal.
isc) signal and tracking error signal are obtained.

The right main light receiving portion Ra 'is divided into _two light receiving portions Ra ₁ ' and Ra 2'at the center of the dividing line along the Y direction, and the left main light receiving portion La 'is , The light receiving portion La ₁ ′ and La ₂ ′ are divided at the center by a dividing line along the X direction. Light receiving parts Ra ₁ 'and Ra ₂ ' and La ₁ 'and L
By setting the photoelectric conversion signals from a ₂ 'to be equal to each other, the initial adjustment is performed so that the respective light spots are incident on the substantially central positions of the respective light receiving portions.

[0009]

However, in the optical pickup including the above-mentioned conventional light receiving element 10 ',
For example, due to the error in the radius of curvature and thickness error of the spot lens, the position error in the optical axis direction, and the dispersion of the condensing state due to the position error in the optical axis direction of the light receiving element 10 ′,
The diameter of the light spot focused on each light receiving unit varies from device to device. As a result, as shown in FIG. 10, for example, there is a case where the light spot is assembled in a state where the diameter of the light spot is larger than that of each light receiving portion. In such a case, the main spot MS _S and the sub-spots SS _S1 and SS _S2 , or the main spot MS
_P and the sub-spots SS _P1 and SS _P2 interfere with each other,
There is a problem that stable reproduction operation cannot be maintained because the signal quality of the magneto-optical signal or ADIP signal is deteriorated.

On the other hand, contrary to the above, when the light spot diameter is too small with respect to the light receiving portion, the movement of the light spot becomes sensitive to changes in the surrounding environment, and in this case also, it becomes difficult to maintain the performance of the optical pickup. The problem arises.

By the way, Japanese Patent Laid-Open No. 63-29323 discloses "a light receiving element for adjusting an optical axis and an optical axis adjusting device" for adjusting the emitting direction of laser light. In the device, a light receiving element is arranged in a predetermined direction, and a light receiving section obtained by dividing a circle into four parts is provided in this light receiving element, and the outputs of these light receiving sections are adjusted to be at the same level. As a result, the optical axis of the laser light is aligned with the center of the light receiving element.

In such a structure, the spot diameter of the laser beam is smaller than the circular light receiving portion as a whole. Therefore, in order to adjust the spot diameter in advance, the circular light receiving portion is used. Further, a light receiving section for adjusting the spot diameter is provided surrounding the. The spot diameter is adjusted on the basis of the signal output from each of the circular light receiving portions where no laser light is incident on the light receiving portion.

Therefore, it is conceivable that the light receiving element of the optical pickup is further provided with a light receiving portion for adjusting the spot diameter as described above, and the light spot diameter is adjusted in advance by this. However, in the structure in which the light receiving portion for adjusting the light spot diameter is provided in the light receiving element as described above, the element structure becomes large, so that it becomes impossible to sufficiently reduce the size and the manufacturing cost becomes high. .

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to make it possible to stably perform a reproducing operation of a disc, and to perform the work necessary for that purpose. An object of the present invention is to provide an optical spot diameter adjusting method for an optical pickup, a light receiving element for the optical pickup, and an optical pickup that can be easily performed and can be downsized and manufactured at low cost.

[0015]

In order to achieve the above object, the optical spot diameter adjusting method for an optical pickup according to claim 1 of the present invention divides and produces a pair of optical spots from the reflected light from the disc. Light spot dividing means, a light receiving element having a light receiving portion for receiving each light spot and outputting a photoelectric conversion signal according to the amount of received light, and a light spot diameter changing means for changing the light spot diameter at each light receiving portion. And a light receiving element orthogonal to the optical axis of the light spot so that one of the paired light spots is irradiated to the gap between the light receiving portions. The light spot diameter is changed so that the diameter of the light spot becomes a desired size based on the correspondence relationship between the photoelectric conversion signal from each light receiving portion and the size of the gap portion at this time. Adjust by means, after which the relative position of the light receiving element of the optical spot with respect to the optical axis, is characterized in that each light spot is set so as to be irradiated on substantially the center of each light receiving portion.

According to a second aspect of the present invention, there is provided a method for adjusting a light spot diameter of an optical pickup according to the first aspect, wherein the light spot diameter changing means divides a pair of light spots generated by the light spot dividing means. It consists of a spot lens that focuses on each light-receiving part of the light-receiving element and an adjusting mechanism that moves this spot lens in the optical axis direction.One of the paired light spots is irradiated to the gap between the light-receiving parts. As described above, after moving the light receiving element in the direction orthogonal to the optical axis of the light spot, the adjustment mechanism is operated to adjust the light spot diameter.

A light receiving element of an optical pickup according to a third aspect of the present invention includes a light receiving section which receives a pair of light spots divided from the reflected light on the disk and outputs a photoelectric conversion signal corresponding to each received light amount. A light receiving element of an optical pickup, characterized in that a size of a gap portion between the light receiving portions is set according to a desired diameter of a light spot to be received.

A light receiving element of an optical pickup according to a fourth aspect of the invention is provided with a light receiving portion for receiving a pair of divided light spots from the reflected light on the disk and outputting a photoelectric conversion signal according to the received light amount. A light receiving element of an optical pickup, wherein a first gap region larger by a predetermined size and a second gap region smaller by a predetermined size than a desired diameter of a light spot to be received are provided in a gap portion between the light receiving units. It is characterized by being.

A light receiving element of an optical pickup according to a fifth aspect is the light receiving element according to the fourth aspect, wherein two pairs of light receiving portions for respectively receiving at least two pairs of light spots are provided.
One of the pairs of light receiving portions is formed as the first gap region, while the other pair of light receiving portions is formed as the second gap region.

A light receiving element of an optical pickup according to a sixth aspect is the light receiving element according to the third, fourth or fifth aspect, wherein at least one of the pair of light receiving portions is a light receiving portion of a divided pair of light spots. It is characterized in that it is set to be smaller than the interval at the incident position on.

According to a seventh aspect of the present invention, there is provided an optical pickup comprising a substrate having the light receiving element according to any one of the third to sixth aspects.
The light receiving element is movably provided on the pickup base so that the light receiving element can be displaced in a direction orthogonal to the optical axis, and a pair of light spots split from the reflected light from the disc are focused on the respective light receiving portions of the light receiving element. It is characterized in that the spot lens is provided on the pickup base so as to be movable in the optical axis direction.

[0022]

According to the optical spot diameter adjusting method of the optical pickup of the first aspect, first, the light receiving element is moved relatively in the direction orthogonal to the light spot, and one of the paired light spots is in each light receiving portion. An operation is performed to position it in the gap portion between them. In this state, when the diameter of the light spot is smaller than the size of the gap portion, the photoelectric conversion signal is not output from the light receiving portion, and when it is larger than the size of the gap portion, the photoelectric conversion signal of the level corresponding to the diameter is output. become.

Therefore, it is possible to determine the size of the light spot diameter with respect to the preset size of the gap portion based on the presence or absence of the photoelectric conversion signal and the output level. By operating, the diameter of the light spot can be set to a desired size.

After the above setting, the relative position of the light receiving element with respect to the light spot is returned so that each light spot is irradiated substantially in the center of the light receiving portion. It is possible to suppress deterioration of signal quality due to fluctuations and maintain stable reproduction operation.

Moreover, in the above, since it is not necessary to separately provide a light receiving portion dedicated to the adjustment of the light spot diameter, it is possible to make the shape of the light receiving element smaller, thereby making the entire apparatus smaller and manufacturing cost higher. The cost can be reduced.

In the optical spot diameter adjusting method of the optical pickup according to the second aspect, in order to position one of the paired light spots in the gap between the light receiving portions, first, the light receiving element is set to the optical axis of the light spot. The laser beam is moved in a direction orthogonal to the direction, and the subsequent change of the light spot diameter is performed by moving the spot lens in the optical axis direction. Therefore, the light receiving element is adjusted only by causing reciprocal movement in the direction orthogonal to the optical axis of the light spot.

On the other hand, for example, in the configuration in which the light spot diameter is also changed by moving the light receiving element in the optical axis direction, the light receiving element is accurately moved in the biaxial directions of the optical axis direction and the direction orthogonal to the optical axis. A mechanism for holding the guide is required. However, in the above, since the position of the light receiving element in the optical axis direction is not changed, the guide holding structure can be simplified,
Therefore, also by this, the entire apparatus can be made more compact.

In the light receiving element of the optical pickup according to claim 3, the size of the gap between the light receiving parts is set in accordance with the desired diameter of the light spot to be received. According to the spot adjustment method, first, the light receiving element was relatively moved in the direction orthogonal to the optical axis of the light spot so that one of the paired light spots was irradiated to the gap between the light receiving portions. After that, in the operation process of narrowing the light spot diameter by the light spot diameter changing means, or in the reverse operation process, the light spot diameter is set to a desired diameter by setting the output of each light receiving unit to a point near zero. can do.

In the light receiving element of the optical pickup according to claim 4, in the gap portion between the light receiving portions, a first gap region larger by a predetermined dimension and a second gap smaller by a predetermined dimension than a desired diameter of the light spot. Since the area is provided, the light spot diameter is changed after moving the light receiving element relative to the light spot so that one of the paired light spots is irradiated to the gap between the light receiving portions. The optical spot whose diameter has been changed by the means is moved between the first gap region and the second gap region, and no photoelectric conversion signal is output in the first gap region, and a photoelectric conversion signal is output in the second gap region. By confirming that is output, it is possible to determine that the light spot at this time is set within a predetermined range centered around the desired diameter.

In this case, the above determination can be made depending on the presence / absence of the photoelectric conversion signal. Therefore, for example, the adjustment work can be performed more quickly than the determination based on whether the output level of the photoelectric conversion signal is within a predetermined range. You can

In the light receiving element of the optical pickup according to a fifth aspect, one of the two light receiving portions is formed between the light receiving portions as the first gap region, and the other light receiving portion is formed as the second gap region. Therefore, after moving the light receiving element relative to the light spot so that one of the paired light spots is irradiated to the gap between the light receiving portions,
While the optical spot diameter changing unit adjusts the optical spot diameter so that the photoelectric conversion signal is not output in the first gap area and the photoelectric conversion signal is output in the second gap area, the optical spot is moved to the first gap area. Since it is not necessary to move between the second gap region and the second gap region, the adjustment operation of the light spot diameter becomes easy.

In the light receiving element of the optical pickup according to the sixth aspect, at least one of the pair of light receiving portions is smaller than the interval between the divided light spots, so that one of the light spots is a gap portion between the light receiving portions. When the light spot is moved relative to the light receiving element so that
The other light spot is located outside the light receiving portion, and the other light spot does not affect the output state of the photoelectric conversion signal.

Therefore, when the light spot diameter is adjusted by moving one light spot to the gap portion, it is not necessary to separately provide a shield or the like so that the other light spot does not enter the light receiving portion. The structure is simplified and the device can be downsized.

In the optical pickup according to the seventh aspect, since the light receiving element and the spot lens provided on the optical path of the incident light to the light receiving element are movably provided on the pickup base, respectively. By the method of adjusting the light spot diameter according to the first aspect, the diameter of the light spot incident on the light receiving element can be appropriately adjusted as necessary. For this reason, at the time of manufacturing and assembling the device, further, for example, after the maintenance and inspection work in the case where the transmittance of the laser emission source and other optical system components built in the optical pickup is impaired, By appropriately performing the adjustment work, the diameter of the light spot incident on the light receiving element can be appropriately maintained, and thus good reproduction performance can be maintained.

[0035]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following will describe one embodiment of the present invention with reference to FIGS.

First, the structure of the optical system of the optical pickup according to the present embodiment will be described with reference to FIG.

As shown in the figure, this optical system comprises a hologram laser unit 1 for emitting a laser beam. Laser light is emitted from the hologram laser unit 1 in a substantially horizontal direction (X direction). Along this emission direction, a collimator lens 2 that makes the emitted light from the hologram laser unit 1 parallel light, a beam splitter 3 described below, and a direction in which the optical path of the emitted light is directed upward (Y direction).
The rising mirror 4 for changing the angle by 90 ° is sequentially provided. Further, an objective lens 5 is provided above the raising mirror 4.
Is arranged, and the emitted light is focused on the surface of a disc (not shown) located above the objective lens 5 through the objective lens 5.

The beam splitter 3 has a direction toward the hologram laser unit 1 through the collimating lens 2 and a direction (Z direction) orthogonal to this direction with respect to the reflected light which is reflected by the disk and follows the above optical path in reverse. It has a function of dividing the reflected light into two directions. Further, a Wollaston prism 6 as a light spot dividing means and a 45 ° mirror 7 are sequentially arranged at a position adjacent to the beam splitter 3 in the Z direction.

The Wollaston prism 6 has a function of separating the light incident on the Wollaston prism 6 from the beam splitter 3 into an S component and a P component having polarization characteristics. The Wollaston prism 6 generates a pair of separated lights that are separated from each other in the X direction. This pair of separated lights is 90 ° in the direction along the X direction by the 45 ° mirror 7.
The spot lens 8 is changed on this optical path.
And a reflection mirror 9 are arranged. This reflection mirror 9
Thus, the optical path of the separated light is changed again by 90 ° in the direction along the Z direction, and the light receiving element 10 is arranged on the changed optical path. The configuration of the light receiving element 10 will be described in detail later.

The spot lens 8 has a function of condensing the separated light on the light receiving element 10. The spot lens 8 can be moved in the optical axis direction by an adjusting mechanism described later, as shown in FIG. And
According to the position in the optical axis direction, the spot diameter of the separated light focused on the light receiving element 10 changes as indicated by the solid line and the chain double-dashed line in FIG.

The hologram laser unit 1 includes
In addition to the semiconductor laser 1a, a light receiving element 1b for focus error detection is built in, and a hologram element 1c is attached to the emitting surface of the laser light. The hologram element 1c is provided with a grading (diffraction grating) for generating three beams on the semiconductor laser 1a side surface, and the reflected light from the disk 11 for focus error detection on the opposite side surface. Holograms for diffracting toward the light receiving element 1c are formed respectively.

From the hologram laser unit 1, three laser beams are emitted as described above. Three reflected lights from the disk 11 are guided to the Wollaston prism 6 for each of these beams. As a result, in the Wollaston prism 6, there are three pairs of separated lights, a total of 6 pairs.
Individually generated light receiving elements 10 through the spot lens 8.
Each is focused on the top.

Therefore, in the light receiving element 10, as shown in FIG. 4, six light receiving portions are formed in a rectangular shape so as to correspond to a total of six separated light beams separated by the Wollaston prism 6. It is formed by being divided into. That is,
Two light receiving unit groups are formed symmetrically with respect to the center line Xc along the Y direction. In the figure, the separated light group of S component is incident on the light receiving unit group on the right side, and the separated light group of P component is incident on the light receiving unit group on the left side.

The light receiving unit group on the right side is the main light receiving unit Ra.
And the light receiving parts Rb and Rc respectively arranged above and below it, and the left light receiving part group consists of the main light receiving part La and the light receiving parts Lb and Lc arranged above and below it.
The right main light receiving portion Ra is divided into _two light receiving portions Ra ₁ and Ra ₂ at the center thereof along a dividing line along the Y direction so that the spot position in the X direction can be detected. Further, the left main light receiving portion La is divided into _two light receiving portions La ₁ and La ₂ at the center thereof along a dividing line along the X direction so that the spot position in the Y direction can be detected.

The mounting position of the light receiving element 10 in the normal operation described later is set so that the separated light beams separated by the Wollaston prism 7 are incident on the respective light receiving portions of the light receiving element 10 having the above-described structure. . That is,
The main spot MS _S in the separated light group of S component is located at the substantially central portion of the main light receiving portion Ra, and the sub spots SS _S1 and SS _S2
Respectively enter the central portions of the light receiving portions Rb and Rc, and at the same time, the main spot MS _P in the separated light group of the P component is the main light receiving portion La and the sub-spots SS _P1 and SS _P2 are the light receiving portions L.
The mounting position of the light receiving element 10 is set so that the light is incident on each central portion of b · Lc.

As the separated lights are incident as described above, the light receiving portions Ra ₁ , Ra ₂ , Rb, Rc, La ₁ and L are received.
The photoelectric conversion signals E _Ra1 , E _Ra2 , E _Rb , E _Rc , E _La1 , E from a ₂ · Lb · Lc at the level according to the respective incident light amount.
_La2 , E _Lb, and E _Lc are output respectively.

In the light receiving element 10, X
The intervals between the respective light receiving portions located opposite to each other in the direction are set as follows based on the desired diameter D ₀ of the light spots respectively incident on these light receiving portions.

That is, there is a first gap between the main light receiving portions Ra and La.
The first gap region A ₁ is formed as the gap region A ₁ , and the dimension of the first gap region A _{1 in} the X direction, that is, the dimension L of the gap portion.
₁ is set to be larger than the desired light spot diameter D ₀ by a predetermined dimension ΔD. The second gap regions A ₂ and A ₂ are provided between the light receiving portions Rb and Lb and between the light receiving portions Rc and Lc.
The dimensions L ₂ and L ₂ of the gap portions of these regions A ₂ and A ₂ are set smaller than the desired light spot diameter D ₀ by a predetermined dimension ΔD.

Further, with respect to the distance Ls in the X direction between the center points of the respective light spots, the dimension Le in the X direction from the center line Xc to the left and right ends of each light receiving portion is set as follows. . For example, three light spots SS vertically aligned on the left side
_{When P1} / MS _P / SS _P2 are moved relative to the right direction from the position shown in the figure to be positioned on the center line Xc, three light spots SS ₁ / MS _S / SS _S2 vertically aligned on the right side are arranged. Is located on the right side of the right end of each of the right light receiving portions Rb, Ra, and Rc, and is set to Le <Ls so as not to enter the light receiving portions Rb, Ra, and Rc.

The above optical system and light receiving element 10 are shown in FIG.
It is incorporated in the pickup base 21 shown in FIG. That is, the hologram laser unit 1 is fixed to the right end side of the pickup base 21 in the figure with the laser light emission surface facing leftward, while the actuator that supports the objective lens 5 in the laser light emission direction. The unit 22 is built in. With this actuator unit 22, the objective lens 5 is moved in the Y direction (focusing direction) orthogonal to the paper surface and in the Z direction (the disk 1).
1), the servo control is performed so that the laser spot follows the track of the disk 11 as will be described later.

Although not shown, the collimator lens 2 and the beam splitter 3 are arranged on the back side of the drawing along the alternate long and short dash line connecting the hologram laser unit 1 and the objective lens 5. In addition, along the optical path of the reflected light separated by the beam splitter 3 along the Z direction,
The Wollaston prism 6 and the 45 ° mirror 7 are arranged, and the spot lens 8 is arranged on the optical path reflected by the 45 ° mirror 7 and traveling in the X direction.

Above the spot lens 8 (on the front side of the paper surface), a rod-shaped eccentric cam 2 extending in a direction orthogonal to the paper surface is formed.
4 is attached. The eccentric cam 24 is rotatably supported by fitting its upper end into a round hole 21b formed in the upper surface plate 21a of the pickup base 21. Therefore, the eccentric cam 24 can be rotated by inserting the tip of a driver or the like into the slit formed in the upper end surface thereof from above, and the function thereof will be described later.

The optical path along the spot lens 8 is further changed by 90 ° in the direction toward the Z direction by the reflecting mirror 9 as shown by the alternate long and short dash line in the figure. And
In this optical path direction, that is, on the side surface of the pickup base 21 located on the lower side in the drawing, the light receiving element substrate 23 is provided.
Are arranged on the light receiving element substrate 23.
0 is attached.

The light-receiving element substrate 23, as shown in FIG.
The upper and lower end surfaces are brought into contact with the upper surface plate 21a and the support frame 21c of the pickup base 21 to be vertically supported. In addition, in order to maintain this vertical assembled state, a leaf spring 25 hanging downward is provided on the end face of the top plate 21a.
Is provided. The above-mentioned assembled state is maintained by the spring force in the state where the lower end side of the leaf spring 25 contacts the surface of the light receiving element 10 from the front side of the drawing.

Then, the light receiving element substrate 23 and the support frame 2 are maintained in the above-mentioned vertical posture.
By inserting and pushing the tip of a driver into the gap between the left and right end faces of 1c, it becomes possible to slide in the left-right direction (X direction) in the figure by a predetermined distance. There is.

On the other hand, the spot lens 8 is fixed to the end surface of a cylindrical lens holder 26, as shown in FIG. The lens holder 26 is accommodated in a support cylinder 27 fixed in the pickup base 21 so as to be movable in the axial direction.

An annular groove 26a is formed on the outer peripheral surface of the lens holder 26, and the engaging pin 24a provided at the lower end of the eccentric cam 24 is fitted into the annular groove 26a for assembly. The engagement pin 24a is provided at a position eccentric in the radial direction from the central axis of the eccentric cam 24, so that the eccentric cam 24 is rotated from the upper surface plate 21a side of the pickup base 21 as described above. As a result, the lens holder 26 is pushed together with the spot lens 8 in the optical axis direction. As a result, the optical path length between the spot lens 8 and the light receiving element 10 is changed, and accordingly, the spot diameter of the separated light focused on the light receiving element 10 is changed. Therefore, in this embodiment, the eccentric cam 24 and the lens holder 26 constitute an adjusting mechanism, and the adjusting mechanism and the spot lens 8 are also included.
This constitutes a light spot diameter changing means.

In the optical pickup having the above-mentioned structure, the normal operation when reproducing the recorded information on the disk 11,
The operation of adjusting the spot diameter of each separated light incident on the light receiving element 10 will be described in order.

First, during the above-mentioned normal operation, the light emitted from the semiconductor laser 1a in the hologram laser unit 1 is divided into three beams by the grading of the hologram element 1c. Of the three beams, the 0th-order diffracted light becomes parallel light by the collimator lens 2, is reflected by the rising mirror 4 and is guided to the objective lens 5, and the disc 11
The light is focused as a main spot and two sub-spots on a straight line along the track above.

The light reflected by the disk 11 passes through the objective lens 5 and the rising mirror 4, and then is passed through the beam splitter 3 to the Wollaston prism 6.
And a direction toward the collimator lens 2.

The light split in the direction toward the collimator lens 2 is diffracted by the hologram of the hologram element 1c, and the first-order diffracted light is detected by the focus error detection light receiving element 1b as a focus error signal. The actuator unit 22 is servo-controlled based on this detection signal. As a result, the objective lens 5 is designed so that the diameter of the light spot focused on the disk 11 is always constant.
Are driven in the optical axis direction.

On the other hand, the light split in the direction toward the Wollaston prism 6 is
At, a separated light group having an S component and a P component having polarization characteristics is formed. Each of the separated lights of the separated light group has a 45 ° mirror 7
Is guided to the spot lens 8 via the reflection mirror 9,
It is incident on the light receiving element 10.

As described above, in FIG. 4, the separated light group of the S component is incident on the light receiving unit group on the right side, and the separated light group of the P component is incident on the light receiving unit group on the left side. , And outputs a photoelectric conversion signal corresponding to each incident light amount. That is, in the separated light group of the S component, the main light receiving portion Ra according to the light quantity of the main spot MS _S.
The photoelectric conversion signals E _Ra1 and E _Ra2 are output from the light receiving portions Rb and R according to the light _amounts of the sub-spots SS _S1 and SS _S2.
The photoelectric conversion signals E _Rb and E _Rc are respectively output from c.
Similarly, in the P component separated light group, the light receiving portion La is selected according to the light amount of each of the main spots MS _P , SS _P1, and SS _P2.
・ Photoelectric conversion signals E _La1 , E _La2, and E _Lb from Lb and Lc
・ E _Lc is output respectively.

Based on the above signals, a pit signal, a magneto-optical signal, A
A DIP (Address In Pregroove on Recordable Disc) signal and a tracking error signal are obtained by the following calculation.

Pit signal = E _Ra1 + E _Ra2 + E _La1 + E _La2 magneto-optical signal = (E _Ra1 + E _Ra2 ) − (E _La1 + E _La2 ) ADIP signal = E _Ra1− E _Ra2 tracking error signal = (E _Rb + E _Lb ) − (E _Rc + E
_Lc ) In this way, by reading the pit signal, the magneto-optical signal, and the ADIP signal, the information recorded on the disk 11 is read. The ADIP signal is a wobble signal of the guide groove of the disk 11, and by this, the address of the disk 11 and the CLV control signal for a spindle motor (not shown) for rotationally driving the disk 11 are read.

On the other hand, the actuator unit 22 is servo-controlled on the basis of the above tracking error signal, whereby the objective lens 5 is driven in the tracking direction so that its focal point follows the track on the disk 11. To be done.

Next, the operation of adjusting the spot diameter of each separated light incident on the light receiving element 10 will be described. This operation is performed at the time of assembling the disc reproducing apparatus manufactured by incorporating the above optical pickup.

As described with reference to FIG. 6, the light receiving element substrate 23 can be slid in the X direction by a preset distance. Therefore, first, the tip of the driver is inserted into the gap between the light receiving element substrate 23 and the left and right end surfaces of the support frame 21b, and is slid from the normal operating position described above, for example, to the right in the drawing by a predetermined distance, Move it to the adjustment position.

At this adjustment position, each of the light spots incident on the central position of each light receiving portion of the light receiving element 10 has three vertical spots, as shown in FIG.
Each is located on the center line Xc.

In the figure, three kinds of light spots S1, S2 and S3 having different diameters are shown. That is, in the figure, the dashed circle is the light spot S1 when its diameter is larger than the gap portion size L ₁ in the above-mentioned first gap region A ₁ , and the dashed-dotted circle has its diameter. a light spot S2 of time smaller than the dimension L ₂ of the gap portion in the second gap region a _2. The solid line circle indicates the light spot S3 when the diameter is between L ₁ and L ₂ .

The sizes of these light spots are set according to the optical path length from the spot lens 8 to the light receiving element 10. That is, the size of the light spot is changed by moving the spot lens 8 in the optical axis direction.

The light spot whose diameter is changed by the operation of moving the spot lens 8 is the light spot S1.
As shown in Table 1, which of the S2 and S3 is classified, each light receiving portion Ra ₁
It is possible to make the determination by combining the presence or absence of the output of the photoelectric conversion signal at La ₁ , La ₂ , Rb, Lb, Rc, and Lc. That is, in the case of the light spot S1 having a large diameter, outputs are obtained from all the above-mentioned light receiving portions, whereas in the case of the light spot S2 having a small diameter, no photoelectric conversion signal is outputted from all the above light receiving portions. . Then, in the case of the light spot S3 within the range of ± ΔD with respect to the desired light spot D ₀ , the light receiving portions Ra ₁ and La ₁ sandwiching the first gap region A ₁ are provided.
The photoelectric conversion signal is output from the light receiving portions Rb, Lb, Rc, and Lc that sandwich the second gap region A _{2 and} are not output from La ₂ .

When the light spots in one row (the left row in the figure) are positioned on the center line Xc as described above, as described above, the distance L between the center points of the respective light spots is L.
With respect to s, the dimension Le from the center line Xc to the left and right end portions of each light receiving portion is set to Le <Ls, so that the light spot row on the right side does not enter each light receiving portion, and therefore each light receiving portion The presence or absence of the output of the part depends on the size of the diameter of only the left light spot.

[0074]

[Table 1]

Therefore, each light receiving portion Ra ₁ , La ₁ , La ₂ , Rb
-While confirming the change in the output of the photoelectric conversion signal from Lb / Rc / Lc, the eccentric cam 24 is rotationally operated, thereby moving the lens holder 26 to which the spot lens 8 is attached in the axial direction. . Then, the adjustment operation is performed so that the combination of outputs corresponding to S3 in Table 1 is obtained. As a result of this operation, the light spot diameter of each separated light incident on the light receiving element 10 is set in the range of the desired diameter D ₀ ± ΔD.

After the operation of adjusting the light spot diameter is completed, the lens holder 26 is fixed in the support cylinder 27 with an adhesive, for example. Then, the light receiving element substrate 23 is set to X
Slide in the opposite direction to the above, and return to the normal operating position. It should be noted that the state in which the respective light spots are located at substantially the central positions of the respective light receiving portions by this return movement is as follows in the main light receiving portion Ra on the right side in FIG.
It can be confirmed that the respective outputs from the light receiving portions Ra ₁ and Ra ₂ which are divided into two parts on the left and right have the same level as each other. Further, at this time, in the main light-receiving portion La on the left side in the figure, by confirming that the respective outputs from the light-receiving portions La ₁ and La ₂ which are vertically divided into two are at the same level, the vertical direction ( It is also possible to confirm whether there is a deviation in the Y direction).

In this way, after the light receiving element substrate 23 is moved back to the normal operating position, the light receiving element substrate 23 is fixed to the pickup base 21 with, for example, an adhesive to complete the adjustment operation of the light spot diameter. .

As described above, in the above embodiment, when adjusting the diameter of the separated light incident on the light receiving element 10, one of the paired light spots is located in the gap between the light receiving portions. As described above, first, the light receiving element 10 is moved in the direction orthogonal to the optical axis direction of the light spot. Then, based on the correspondence relationship between the diameter of the light spot at this time and the photoelectric conversion output at the light receiving portion, the spot lens 8 is moved in the optical axis direction to set the light spot diameter to a desired size.
After performing such setting, an operation of returning the position of the light receiving element 10 with respect to the light spot is performed so that each light spot is irradiated to the substantially center of the light receiving portion.

By such an adjusting operation, the light spot diameter can be set to a desired diameter for each device.
Therefore, for example, the radius of curvature error of the spot lens 8, the thickness error, the position error in the optical axis direction, and the light receiving element 10
Even if the diameters of the light spots incident on the respective light receiving portions of the light receiving element 10 vary due to the position error in the optical axis direction and the like, by the above setting, the reproducing operation of the disc 11 can be performed more stably. become.

Moreover, in the above, it is not necessary to provide a dedicated light receiving portion for detecting the light spot diameter, and it is possible to carry out by changing the shape and arrangement of the conventional light receiving portion structure, so that a spot diameter adjusting function is provided. The device can be manufactured at a lower cost and can be downsized.

In the above embodiment, in order to position one of the paired light spots in the gap between the light receiving portions, first the light receiving element 10 is moved in the direction orthogonal to the optical axis of the light spot. The movement and subsequent change of the light spot diameter are performed by moving the spot lens 8 in the optical axis direction. Therefore, the light receiving element 10 causes only reciprocating motion in the direction orthogonal to the optical axis of the light spot,
Since it is not moved in the optical axis direction, a simple guide holding structure in the uniaxial direction can be provided and configured. Therefore, in the case where the light receiving element is also movable in the optical axis direction to change the light spot diameter, a complicated guide holding mechanism or the like is required, and the entire device can be made smaller.

Further, in the above embodiment, among the three pairs of light receiving portions, the first light receiving portion Ra / La is the first gap region A ₁ , the other light receiving portions Rb / Lb are the light receiving portions Rc / Lc.
Since the gap is formed as the second gap region A ₂ for each of the light receiving portions, the light receiving element 10 is moved after the light spot is relatively moved to these gap regions.
The light spot diameter setting operation can be performed while the camera is stationary, and the operation becomes easy.

Further, in the above embodiment, the X of the light receiving portion is
The width dimension in the direction is smaller than the interval between the divided light spots, and when one of the light spots is moved with respect to the light receiving element 10 so that the gap between the light receiving portions is irradiated, The light spot is located outside the light receiving portion.

For this reason, when one light spot is moved to the gap portion to adjust the light spot diameter, it is not necessary to separately provide a shield or the like so that the other light spot does not enter the light receiving portion. Also, the entire configuration is simplified and the device can be downsized.

It should be noted that one of the paired light spots is moved to the gap portion between the light receiving portions, and the diameter of the light spot is set based on the correspondence between the size of the gap portion and the photoelectric conversion signal from each light receiving portion. The above adjusting method is not limited to the shape of the light receiving portion in the light receiving element 10 of the above embodiment,
Other light receiving part shapes can be used.

For example, in the above embodiment, the desired light spot diameter D is set between the main light receiving portions Ra and La as described above.
_The second gap region A ₁ is formed as a first gap region A _{1 which} is larger than ₀ by a predetermined dimension ΔD, while the distance between the light receiving portions Rb and Lb and between the light receiving portions Rc and Lc is smaller than D ₀ by ΔD. was formed as a _2, but as shown in FIG. 8, contrary to the above, the main light receiving portion Ra · La between the second gap region a ₂ above, among and between the light receiving portion Rc · Lc light receiving unit Rb · Lb is It is also possible to determine and configure the shape of each light receiving portion so as to become the first gap region A ₁ .

Further, in the above embodiment, the first gap region A ₁ and the second gap region A ₂ are provided so as to correspond to the light receiving portions respectively receiving the three pairs of separated lights. Even if the light receiving element is provided with only the light receiving section,
It is also possible to form the opposite sides of each light receiving portion in a stepped manner and to provide a first gap region and a second gap region between these light receiving portions.

In this case, the light spot located in the gap portion is further moved between the first gap region and the second gap region in the direction orthogonal to the gap width direction, so that the first gap region is formed in the same manner as described above. Setting the light spot diameter within a predetermined range by setting that the photoelectric conversion signal is not output when positioned in the area and the photoelectric conversion signal is output when positioned in the second gap area. You can

The above-described light spot diameter adjusting method can also be applied to a light receiving element in which the size of the gap between the light receiving portions is set in accordance with the desired light spot diameter. In this case, after one of the paired light spots relatively moves so as to be irradiated to the gap between the light receiving portions,
The light spot diameter can be set to a desired diameter by setting the output of the light receiving unit to be near zero in the operation process of narrowing the light spot diameter or the reverse operation process.

Furthermore, the above light spot diameter adjusting method is
It can also be applied to a light receiving element in which a change in the output level of the photoelectric conversion signal with respect to a change in the light spot diameter is previously obtained, depending on the size of the gap portion and the desired light spot diameter.

That is, when the diameter of the light spot is smaller than the size of the gap portion, the photoelectric conversion signal is not output from the light receiving portion, and when it is larger than the size of the gap portion, the photoelectric conversion signal of a level corresponding to the diameter is received. Is output from.
That is, the signal level at this time corresponds to the ratio of the central irradiation area of the gap portion in the light spot to the outer irradiation area of the light receiving portion, and this ratio corresponds to the light spot diameter with respect to the size of the gap portion. As described above, the output level of the photoelectric conversion signal from the light receiving portion corresponds to the light spot diameter.

Therefore, this correspondence is obtained in advance,
The desired diameter can be set by operating so that the output level of the photoelectric conversion signal with respect to the desired light spot diameter can be obtained.

On the other hand, in the optical pickup of the above-described embodiment, the spot lens 8 is adjusted when the operation of adjusting the light spot diameter is performed at the assembly stage and the setting operation to the desired diameter is completed.
Although the position of the light receiving element substrate 23 and the light receiving element substrate 23 is fixed by an adhesive, a fixing structure such as a set screw may be used instead of the adhesive so that the fixing release state can be repeated.

In this case, the above-mentioned method for adjusting the light spot diameter allows the light spot diameter incident on the light receiving element to be appropriately adjusted as necessary, and therefore, at the time of manufacturing and assembling the apparatus, For example, after the maintenance and inspection work when the transmittance of the laser emission source or other optical system components built into the optical pickup has been impaired, the incident light is incident on the light receiving element by performing the above adjustment work appropriately. The appropriate light spot diameter is maintained, whereby good reproduction performance can be maintained.

[0095]

As described above, in the optical spot diameter adjusting method for an optical pickup according to the first aspect of the present invention, one of the paired optical spots is applied to the gap between the light receiving portions. , The light receiving element is relatively moved in a direction orthogonal to the optical axis of the light spot, and the diameter of the light spot is calculated based on the correspondence between the photoelectric conversion signal from each light receiving portion and the size of the gap portion at this time. Is adjusted to a desired size by the light spot diameter changing means, and thereafter, the relative position of the light receiving element with respect to the optical axis of the light spot is set so that each light spot is irradiated approximately in the center of the light receiving portion. This is the configuration.

As a result, the deterioration of the signal quality due to the fluctuation of the light spot diameter can be suppressed, the stable reproducing operation can be maintained, and the light spot can be formed without separately providing a light receiving element dedicated to the adjustment of the light spot diameter. Since the diameter can be adjusted to a desired value, there is an effect that the device can be downsized and the cost can be reduced.

According to a second aspect of the invention, there is provided a method for adjusting a light spot diameter of an optical pickup, wherein the light spot diameter changing means condenses a pair of light spots divided and generated by the light spot dividing means on each light receiving portion of the light receiving element. It consists of a spot lens and an adjusting mechanism that moves the spot lens in the optical axis direction.The light receiving element is set so that one of the paired light spots is irradiated to the gap between the light receiving portions. After moving in a direction orthogonal to the optical axis of, the adjustment mechanism is operated to adjust the light spot diameter.

Thus, in order to hold the position of the light receiving element in the optical axis direction after setting the light spot diameter to a desired diameter and further move it in the direction orthogonal to the optical axis, a complicated guide holding structure or the like is provided. It is not necessary and therefore also makes the overall construction simpler and the overall device more compact.

According to a third aspect of the present invention, there is provided a light receiving element of an optical pickup in which a size of a gap portion between the light receiving portions is set according to a desired diameter of a light spot to be received.

As a result, the light spot diameter can be set to a desired diameter by setting the output of each light receiving portion to a point near zero in the operation process of narrowing the light spot diameter or the reverse operation process. There is an effect that can be.

According to a fourth aspect of the present invention, in a light receiving element of an optical pickup, a first gap region that is larger than a desired diameter of a light spot to be received by a predetermined size and a second gap that is smaller by a predetermined size in a gap portion between the light receiving parts. A gap region is provided.

As a result, whether or not the light spot is set within a predetermined range centered around a desired diameter can be determined by the presence or absence of the photoelectric conversion signal from the light receiving section. There is an effect that the adjustment work can be performed more accurately and promptly than the judgment based on the confirmation as to whether or not the output level is within the predetermined range.

According to a fifth aspect of the present invention, there is provided a light receiving element for an optical pickup, wherein two pairs of light receiving portions for receiving at least two pairs of light spots are provided, and one pair of light receiving portions is formed as the first gap region. On the other hand, the other gap between the light receiving portions is formed as the second gap region.

As a result, the light spot diameter changing means adjusts the light spot diameter so that the photoelectric conversion signal is not output in the first gap area and the photoelectric conversion signal is output in the second gap area. Since it is not necessary to move the spot between the first gap region and the second gap region, there is an effect that the operation of adjusting the light spot diameter becomes easier.

In the light receiving element of the optical pickup according to the sixth aspect, at least one of the pair of light receiving portions is set to be smaller than the interval between the incident positions of the divided light spots on each light receiving portion. It is a composition.

As a result, when one of the light spots is moved to the position of the gap between the light receiving portions, the other of the light spots does not enter the light receiving portion. Therefore, when adjusting the light spot diameter, Since it is not necessary to separately provide a shield or the like for the other light spot, the overall configuration is simplified and the device can be downsized.

According to a seventh aspect of the present invention, there is provided an optical pickup comprising the substrate having the light receiving element according to any one of the third to sixth aspects.
The light receiving element is movably provided on the pickup base so that the light receiving element can be displaced in a direction orthogonal to the optical axis, and a pair of light spots split from the reflected light from the disc are focused on the respective light receiving portions of the light receiving element. The spot lens is provided on the pickup base so as to be movable in the optical axis direction.

In this case, the diameter of the light spot incident on the light receiving element can be appropriately adjusted by the method of adjusting the diameter of the light spot according to the first aspect. Therefore, the diameter of the light spot incident on the light receiving element can be properly maintained by performing the above-mentioned adjustment work at the time of manufacturing and assembling the device, and further, for example, after the maintenance and inspection work and the like. The effect of being able to maintain.

[Brief description of drawings]

FIG. 1 is a front view showing a relationship between a light receiving portion in a light receiving element of an optical pickup according to an embodiment of the present invention and various light spot diameters.

FIG. 2 is a perspective view showing a configuration of an optical system in the optical pickup.

FIG. 3 is a plan view schematically illustrating a light collecting state on a light receiving element in the optical system.

FIG. 4 is a front view showing a configuration of a light receiving section in the above light receiving element.

FIG. 5 is a plan view of the optical pickup.

FIG. 6 is a side view of the optical pickup.

FIG. 7 is an enlarged cross-sectional view showing an arrangement structure of a spot lens built in the optical pickup.

FIG. 8 is a front view showing a configuration of a light receiving section in a light receiving element of an optical pickup according to another embodiment of the present invention.

FIG. 9 is a front view showing a configuration of a light receiving portion provided in a light receiving element of a conventional optical pickup.

10 is a front view showing a state where the conventional light receiving element shown in FIG. 9 is irradiated with a light spot having an excessively large diameter.

[Explanation of symbols]

6 Wollaston prism (light spot dividing means) 8 Spot lens (light spot diameter changing means) 10 Light receiving element 11 Disk 21 Pickup base 23 Light receiving element substrate 24 Eccentric cam (adjusting mechanism / light spot diameter changing means) 26 Lens holder (adjustment) Mechanism / light spot diameter changing means) Ra / La main light receiving portion Rb / Rc / Lb / Lc light receiving portion A ₁ first gap area A ₂ second gap area

Claims (7)

[Claims] 1. A light receiving device having a light spot dividing means for dividing and generating a pair of light spots from reflected light on a disc, and a light receiving portion for receiving each light spot and outputting a photoelectric conversion signal according to a received light amount. A method for adjusting a light spot diameter of an optical pickup, comprising: an element; and a light spot diameter changing means for changing a light spot diameter at each light receiving portion, wherein one of the paired light spots is a gap portion between the light receiving portions. The light receiving element is relatively moved in the direction orthogonal to the optical axis of the light spot so that the photoelectric conversion signal from each light receiving section and the size of the gap section are associated with each other. The diameter of the light spot is adjusted based on the light spot diameter changing means based on the light spot diameter changing means, and then the relative position of the light receiving element with respect to the optical axis of the light spot, Setting the light spot diameter adjusting method for an optical pickup, which comprises as irradiated crucible to the center. 2. A spot lens for condensing a pair of light spots divided and generated by the light spot dividing means on each light receiving portion of a light receiving element, and the light spot diameter changing means, and the spot lens. After moving the light-receiving element in the direction orthogonal to the optical axis of the light spot so that one of the paired light spots is radiated to the gap between the light-receiving parts. The method of adjusting the light spot diameter of an optical pickup according to claim 1, wherein the adjustment mechanism is operated to adjust the light spot diameter. 3. A light-receiving element of an optical pickup, comprising a light-receiving portion for receiving a pair of divided light spots from reflected light on a disk and outputting a photoelectric conversion signal according to the amount of light received, respectively. A light receiving element of an optical pickup, wherein a size of a gap portion between the light receiving portions is set according to a desired diameter of a light spot to be received. 4. A light-receiving element of an optical pickup, comprising a light-receiving portion for receiving a pair of divided light spots from reflected light on a disk and outputting a photoelectric conversion signal according to the amount of received light. An optical pickup characterized in that a gap portion between the light receiving portions is provided with a first gap region that is larger than a desired diameter of a light spot to be received by a predetermined size and a second gap region that is smaller than the desired size by a predetermined size. Light receiving element. 5. A pair of light receiving portions for respectively receiving at least two pairs of light spots are provided, and a space between the light receiving portions of one pair is formed as the first gap region, while a light receiving portion of the other pair is formed. 5. The light receiving element of the optical pickup according to claim 4, wherein is formed as the second gap region. 6. A light receiving portion which forms a pair, and at least one of the light receiving portions is set to be smaller than an interval between the incident positions of the divided light spots on each light receiving portion. Alternatively, the light receiving element of the optical pickup described in 5. 7. A substrate having the light receiving element according to claim 3 is movably provided on a pickup base so that the light receiving element can be displaced in a direction orthogonal to the optical axis, and is reflected by a disc. 2. An optical pickup, wherein a spot lens for condensing a pair of light spots split from light on each light receiving portion of the light receiving element is provided on a pickup base so as to be movable in the optical axis direction.