JPH0612678A - Optical pickup device - Google Patents

Abstract

PURPOSE:To make luminous flux incident on an information recording medium in a proper state. CONSTITUTION:A laser beam L emitted from a semiconductor laser 1 is made parallel luminous flux by a collimate lens 2 and after the parallel luminous flux is made to have a circular cross-section by a beam shaping prism 3, it is projected on an optical disk D through a objective lens 5 as a light spot. The collimate lens 2 is moved in the direction of the optical axis of the lens by an electromagnetic coil 13 being a lens actuator and the collimate lens is position-corrected and the light spot on the optical disk D is maintained in a prescribed setting state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup device for recording, reproducing or erasing information by irradiating a light spot on an information recording medium such as an optical disc or a magneto-optical disc.

[0002]

2. Description of the Related Art FIG. 12 is a block diagram of an example of an optical system in a conventional optical pickup device, in which 1 is a semiconductor laser (L
D), 2 is a collimating lens (CL) that makes the laser beam L emitted from the LD 1 a parallel light beam, 3 is a beam shaping prism that makes the parallel light beam from the CL 2 substantially circular, 4 is a beam splitter (BS), and 5 is BS4. The parallel light flux that has passed through
An objective lens for focusing as a light spot on the optical disc D for recording, reproducing and erasing information as is well known, 6
Is a condenser lens for condensing the reflected light R reflected by the optical disc D and the BS 4, and 7 is a light receiving element for receiving the reflected light R via an analyzer 8 and detecting various signals as is known. (PD).

As shown in FIG. 13, the laser beam L emitted from the LD1 has different emission angles in the vertical and horizontal directions, and has an elliptical cross section after being made into a parallel light flux by CL2. When the parallel light flux having the elliptical cross section is narrowed down on the optical disc by the objective lens, the light spot shape is also elliptical.

When the major axis of the light spot is in the information track direction, the jitter becomes worse, and when the major axis is in the direction perpendicular to the information track, crosstalk occurs from the adjacent information track. .

Therefore, in order to solve the above problems, beam shaping is generally performed.

In the above example, the parallel light flux having an elliptical cross section emitted from CL2 is refracted by the beam shaping prism 3 to be a parallel light flux having a circular cross section.

The principle of beam shaping will be described with reference to FIG. That is, the light beam having the width D _i is transmitted by the beam shaping prism 3
It is refracted by and becomes a light beam with a width D ₀ . If the incident angle to the beam shaping prism 3 is θ _i and the exit angle is θ ₀ , the beam shaping magnification K is

[0008]

## EQU1 ## K = D ₀ / D _i = cos θ ₀ / cos θ _i . The magnification K is set so that the cross-sectional shape of the light flux becomes circular in the vertical and horizontal directions.

FIG. 15 is a block diagram of another example of an optical system in a conventional optical pickup device, which has the same configuration and operation as the example of FIG. 12 except that a beam shaping prism is not shown.

[0010]

In the above-mentioned prior art, since the LD changes the wavelength at the time of light emission due to changes in the ambient temperature and the light emission output, as shown in FIG. The refraction angle θ ₀ changes θ ′. As a result, in the optical system of FIG.
The incident angle of the parallel light beam on the lens changes, and aberration occurs, which causes deterioration of jitter. Further, the angle of the reflected light R from the optical disc D also changes, which changes the incident position of the light beam on the PD 7. An offset occurs in the detection signal.

Further, in the optical system shown in FIGS. 12 and 15, even if the positional relationship between LD1 and CL2 changes due to temperature changes, changes over time, etc., signal detection is adversely affected.

That is, as shown in FIG. 17 (a), LD1
And CL2 deviate from the set position in the optical axis direction (direction of arrow A), the light flux emitted from CL2 is not a parallel light flux,
Focus or diverge. As a result, spherical aberration occurs in the light spot condensed by the objective lens 5, the emission spot cannot be sufficiently narrowed, and the incident position of the light beam on the PD 7 changes. An offset occurs in the detection signal.

As shown in FIG. 17 (b), LD1 and CL2
When and are deviated from the set position in a direction orthogonal to the optical axis (direction of arrow B), the light flux emitted from CL2 has an inclination with respect to the optical axis of CL2 and is obliquely incident on the objective lens 5. become. As a result, coma and astigmatism occur in the light spot focused by the objective lens 5, and in this case too, the light spot cannot be sufficiently narrowed or the incident position of the light flux on the PD 7 changes, and the detection signal is offset. Occurs.

An object of the present invention is to provide an optical pickup device capable of correcting so that a light beam can be properly incident on an information recording medium.

[0015]

In order to achieve the above object, light emitted from a semiconductor laser is made into a parallel light flux by a collimating lens, and the cross-sectional shape of the parallel light flux is made substantially circular by a beam shaping prism. In an optical pickup device for recording, reproducing, or erasing information by converging a light spot on an information recording medium by an objective lens, the first means of the present invention is to record, reproduce, or change the position of the collimator lens. Alternatively, it is characterized in that means for correcting in the lens optical axis direction during the erasing operation is provided.

A second means is to record the position of the collimator lens in the above optical pickup device.
It is characterized in that it is provided with means for correcting in a direction orthogonal to the lens optical axis during reproduction or erasing.

A third means is to record the position of the collimator lens in the above optical pickup device.
It is characterized in that it is provided with means for correcting the direction of the lens optical axis and the direction orthogonal to the lens optical axis during reproduction or erasing.

A fourth means is the above-mentioned first, second, and third means, in which the position is corrected by the light flux reflected by a beam splitter installed between the beam shaping prism and the objective lens. It is characterized in that it is performed based on the output of the light receiving element that receives light.

A fifth means is characterized in that, in the above-mentioned fourth means, a condenser lens for condensing a light beam on the light receiving element is provided between the beam splitter and the light receiving element.

A sixth means is characterized in that, in the above-mentioned fifth means, the light receiving surface of the light receiving element is installed at a substantially condensing point of the light flux.

A seventh means is the above-mentioned fourth, fifth and sixth means, in which the light receiving surface of the light receiving element is divided into at least two surfaces, and the position is corrected based on the output difference of each surface. It is characterized by performing.

An eighth means is the above-mentioned fourth, fifth, sixth and seventh means, wherein the emitted light amount of the semiconductor laser is detected by the output of the light receiving element and the semiconductor laser of the semiconductor laser is detected based on the detection signal. It is characterized by performing output control.

Further, the light emitted from the semiconductor laser is converted into a parallel light flux by a collimator lens, and the parallel light flux is focused as a light spot on an information recording medium by an objective lens to record, reproduce or erase information. In the ninth means of the present invention, a lens actuator for moving the collimator lens in the lens optical axis direction is provided, and the lens actuator is provided with a semiconductor laser.

A tenth means is characterized in that, in the above optical pickup device, a lens actuator for moving the collimator lens in a direction orthogonal to the lens optical axis is provided, and the semiconductor laser is provided in the lens actuator. And

An eleventh means is provided with a lens actuator for moving the collimator lens in the lens optical axis direction and in a direction orthogonal to the lens optical axis in the above optical pickup device, and the semiconductor laser is provided in the lens actuator. It is characterized by that.

The twelfth means is the ninth, tenth, and the above-mentioned
The means of 11 is characterized in that the collimator lens can be held at an arbitrary position by a lens actuator.

A thirteenth means, in the above twelfth means, holds the position by using an output of a light receiving element for receiving a light beam reflected by a beam splitter installed between the collimating lens and the objective lens. It is characterized by performing based on.

A fourteenth means is characterized in that, in the above-mentioned thirteenth means, a condenser lens for condensing a light beam on the light receiving element is provided between the beam splitter and the light receiving element.

A fifteenth means is characterized in that, in the fourteenth means, the light receiving surface of the light receiving element is installed at a non-focusing point of the light beam.

The sixteenth means is the thirteenth, fourteenth, and fourteenth aspects described above.
In the fifteenth means, the light receiving surface of the light receiving element is divided into at least two surfaces, and the position is held based on the output difference of each surface.

The seventeenth means is the above thirteenth, fourteenth, and thirteenth means.
The fifteenth and sixteenth means is characterized in that the amount of light emitted from the semiconductor laser is detected by the output of the light receiving element, and the output of the semiconductor laser is controlled based on the detection signal.

[0032]

According to the first, second and third means, the position of the collimator lens can be corrected in at least one of the lens optical axis direction and the direction orthogonal to the lens optical axis. Wavelength fluctuation and temperature
It is possible to eliminate the variation of the emission angle of the beam shaping prism or the astigmatism of the emitted light beam, which is caused by the displacement of the semiconductor laser due to the change over time.

According to the fourth means, the parallel light beam is split by the beam splitter between the beam shaping prism and the objective lens, and the optical change of the light beam is detected by the light receiving element. The signals relating to the variation of the output angle and the astigmatism are accurately detected.

According to the fifth means, the light can be efficiently used by condensing the light flux on the light receiving element by the condenser lens, and the light receiving element can be downsized.

According to the sixth means, a light receiving element is installed at a substantially condensing point of the condensing lens, whereby highly sensitive signal detection for detecting a change in a small condensing spot is performed.

According to the seventh means, by dividing the light receiving surface of the light receiving element, it is possible to accurately detect the signal based on the difference in the outputs of the light receiving surfaces.

According to the eighth means, the amount of light emitted from the semiconductor laser, that is, the output state can be detected from the output of the light receiving element, so that the output of the semiconductor laser can be controlled based on the output.

Further, according to the ninth, tenth and eleventh means,
Since the position of the collimator lens can be adjusted with respect to the semiconductor laser in at least one of the lens optical axis direction and the direction orthogonal to the lens optical axis by the lens actuator, parallel adjustment of parallel light flux and emission angle adjustment are facilitated. Done.

According to the twelfth means, since the collimator lens can be held at an arbitrary position by the lens actuator, screwing of the lens, which is complicated and requires delicate work, becomes unnecessary.

According to the thirteenth means, the beam splitter between the collimator lens and the objective lens splits the parallel light flux, and the optical change of the light flux is detected by the light receiving element. A relative positional deviation with respect to the laser is detected, and the positional deviation is corrected and the corrected position is held by this detection signal.

According to the fourteenth means, the light flux can be efficiently used by condensing the light flux on the light receiving element by the condenser lens, and the light receiving element can be downsized.

According to the fifteenth means, by installing the light receiving element at the non-light-converging point of the condenser lens, a signal can be detected by a large light-converging spot and the position of the light-receiving element can be easily adjusted.

According to the sixteenth means, by dividing the light receiving surface of the light receiving element, it is possible to accurately detect the signal based on the difference between the outputs of the light receiving surfaces.

According to the seventeenth means, the amount of emitted light of the semiconductor laser, that is, the output state can be detected from the output of the light receiving element, so that the output of the semiconductor laser can be controlled based on the output.

[0045]

Embodiments of the present invention will be described below with reference to the drawings. The members corresponding to those described with reference to FIGS. 12 and 15 are designated by the same reference numerals, and detailed description thereof will be omitted.

FIG. 1 is a block diagram of a first embodiment of the present invention, in which 10 is a beam splitter (BS) installed between the beam shaping prism 3 and the objective lens 5, and 11 is a light beam from the BS 10. A light receiving element composed of a plurality of (two in the figure) photoelectric conversion elements that receive light through the optical lens 12, 13 is a direction (arrow A direction) orthogonal to the lens optical axis of the collimator lens (CL) 2. Lens driving electromagnetic coil, 14 and 15 are operational amplifiers (difference) and operational amplifiers (sum) connected to the light receiving element 11, and 16 is the electromagnetic coils receiving signals from the operational amplifier (difference) 14. CL controller for driving 13
The semiconductor laser 17 receives the signal from the operational amplifier (sum) 15.
The LD power control unit controls the power of the (LD) 1.

Next, the operation of the above first embodiment will be described.

The laser beam L emitted from LD1 is CL
The beam is shaped into a parallel beam by 2 and is beam-shaped by the beam shaping prism 3 to have a circular cross section, and then is split by the BS 10 into a beam L ₁ transmitted in the direction of the objective lens 5 and a beam L ₂ reflected. The transmitted light beam L ₁ is focused as an optical spot on the optical disc D, which is an information recording medium, by the objective lens 5. On the other hand, the reflected light flux L ₂ is condensed by the condenser lens 12 on the light receiving element 11.

By the light spot on the optical disc D, information is recorded, reproduced, and recorded on the optical disc D in a known manner.
Various signals are detected by erasing and detecting the optical change of the reflected light R from the optical disc D by the PD 7.

2A to 2C show the light receiving state of the light receiving element 11.
(Hatched line is an irradiation spot S). When the wavelength of the laser beam L emitted from the LD 1 changes, the refraction angle at the beam shaping prism 3 changes, and as shown by the broken line in FIG. The optical axis is tilted, and the irradiation spot S on the light receiving element 11 changes from the reference irradiation position (initial state) of FIG. 2B to the irradiation position of FIG. 2A or 2C.

2A shows the state when the wavelength becomes shorter and FIG. 2C shows the state when the wavelength becomes longer. In this embodiment, the light receiving surface of the light receiving element 11 is divided into two. , C so that the output difference (α−β) between the light receiving surfaces α and β becomes zero in the state of FIG. 2 (b).
By controlling the position of L2 in the direction of arrow A, the emission angle of the beam shaping prism 3 can be made constant at all times.

Specifically, the respective light receiving surfaces α and β of the light receiving element 11
The output difference of 1 is taken by the operational amplifier (difference) 14, and the CL controller 16 that receives the output difference signal drives the electromagnetic coil 13 to move CL 2 in the direction of arrow A.

Further, by taking the output sum of the light receiving element 11 by the operational amplifier (sum) 15, it is possible to detect the change in the amount of light emitted from the LD 1, that is, the output state. Output control is performed.

FIG. 3 is a block diagram of the second embodiment of the present invention. In the second embodiment, the light receiving surface of the light receiving element 20 is divided into four as will be described later, and the CL control section 21. It differs from the first embodiment in that the position of CL2 is controlled by the electromagnetic coil 22 in the lens optical axis direction (arrow B direction).

In the second embodiment described above, when the LD1 is displaced in the direction of arrow B due to temperature change and time change,
The parallelism of the parallel light flux after exiting CL2 changes. As a result, the light beam emitted from the beam shaping prism 3 has astigmatism, and thus the light beam L ₂ reflected by BS10 also has astigmatism, and the shape of the irradiation spot S on the light receiving element 20 changes. That is, the light receiving element 20 shown in FIGS.
As shown in the explanatory diagram of the light receiving state (the hatched portion is the irradiation spot S), the circular reference irradiation shape (initial state) of FIG.
It changes to the elliptical irradiation shape of (a) or FIG. 4 (c).

FIG. 4A shows the state when the LD1 is far from the CL2, and FIG. 4C shows the state when the LD1 is close to the CL2. In the second embodiment, the light receiving element 20 Since the light receiving surface is divided into four (α, β, γ, δ), the light receiving surfaces (α and γ, β and δ) facing each other as shown in the explanatory view of the signal detection system shown in FIG. The output signal obtained by subtracting the output sum of is output to the CL control unit 21 as a CL control signal.

Based on the CL control signal, the electromagnetic coil
By driving 22 to move CL2 in the direction of arrow B, an irradiation spot without astigmatism can always be obtained.
Further, by taking the total sum of the outputs of the light receiving elements 20 by the operational amplifier (sum) 15, the output control of the LD1 is performed in the same manner as in the first embodiment.

FIG. 6 is an explanatory view of a signal detecting system of the third embodiment of the present invention. In this third embodiment, the CL2 is orthogonal to the lens optical axis as in the first embodiment. And the position is controllable in two directions, that is, the lens optical axis direction as in the second embodiment.

In FIG. 6, the light receiving surface is divided into four parts α, β, γ, δ and is obtained by subtracting the output sums from the light receiving surfaces (α and γ, β and δ) facing each other in the light receiving element 25. The obtained output signal is used as a control signal in the direction of the lens optical axis of CL2, and a signal change due to the movement of the irradiation spot S is obtained from the output difference between the light receiving surfaces β and δ to obtain a signal in the direction orthogonal to the lens optical axis of CL2. By using the control signal, CL in the above two directions
2 position control can be performed. Further, the output control of the LD can be performed from the total output of the light receiving elements 25 as in the first embodiment.

FIG. 7 is a block diagram of the fourth embodiment of the present invention, in which reference numeral 30 is a B arranged between the CL 2 and the objective lens 5.
S and 31 are light receiving elements composed of a plurality of (two in the figure are shown) photoelectric conversion elements that receive the light flux from the BS 30 through a condenser lens 32, and 33 is CL2 in the lens optical axis direction (arrow A direction). )
To the electromagnetic coil for holding CL2 at the moved position, and 34 and 35 are operational amplifiers connected to the light receiving element 31.
(Difference) and operational amplifier (sum), 36 is a CL control unit for driving the electromagnetic coil 33 by receiving a signal from the operational amplifier (difference) 34, and 37 is a signal from the operational amplifier (sum) 35 LD power control unit for controlling the power of the semiconductor laser (LD) 1, 38 is an actuator housing for the electromagnetic coil 33 which is a lens actuator, and LD is provided on the bottom.
1 is fixed.

In the above-mentioned fourth embodiment, the light spot irradiation on the optical disc D by the laser beam emitted from the LD1 and the optical detection of various signals are the same as those described above.

FIGS. 8A to 8C show the light receiving state of the light receiving element 31.
It is an explanatory view of (irradiated spot S is an oblique line), and the light receiving element 31
Is divided into a central circular light-receiving surface α and an outer peripheral light-receiving surface β in the fourth embodiment, and FIG. 8 (b) shows that when light emitted from CL2 is parallel, FIG. 8C shows the state when the emitted light is divergent light, and FIG. 8C shows the state when the emitted light is focused light.

Accordingly, the output difference between the light-receiving surfaces α and β is taken by the operational amplifier (difference) 34, and is fed back to the CL control section 36 as a CL position control signal to drive the electromagnetic coil 33, whereby the initial adjustment position is set. Corresponding difference signal (output difference: α-β)
The position of CL2 in the direction of the optical axis of the lens with respect to LD1 is controlled with reference to, and CL2 can be held at the control position, and the light emitted from CL2 can always be maintained in a predetermined parallel state.

The output of the LD1 can be controlled from the total output of the light receiving elements 31 as in the first embodiment.

FIG. 9 is a block diagram of the fifth embodiment of the present invention. The difference between the fifth embodiment and the fourth embodiment is that the electromagnetic coil 40 makes CL2 orthogonal to the lens optical axis. The configuration is that the CL2 is moved in the direction (arrow B direction) and the CL2 is held at the moved position, and the light receiving element 41 described later.

FIGS. 10A to 10C show the light receiving state of the light receiving element 41.
It is an explanatory view of (irradiation spot S is hatched), and the light receiving element 41
Is divided into a pair of left and right light receiving surfaces α and β in the fifth embodiment, and FIG. 10 (b) shows that when the parallel light flux emitted from CL2 is parallel to the lens optical axis, FIG. , (B) are the states when the parallel light beam is tilted to the left or right with respect to the lens optical axis.

Accordingly, the output difference between the light receiving surfaces α and β is taken by the operational amplifier (difference) 34, and is fed back to the CL control unit 42 as a CL position control signal to drive the electromagnetic coil 40, so that the initial adjustment position is set. Position control in a direction orthogonal to the lens optical axis with respect to LD1 of CL2 with reference to the corresponding difference signal (α-β) is performed.

FIG. 11 is an explanatory view of a signal detection system of a sixth embodiment of the present invention. In this sixth embodiment, CL2 is set to LD1 with respect to the lens optical axis direction as in the fourth embodiment. When,
As in the fifth embodiment, the position can be controlled in two directions, that is, the direction orthogonal to the lens optical axis.

In FIG. 11, the light-receiving element 45 is divided into four parts, that is, two light receiving surfaces α and β on the circular light receiving surface in the center and two light receiving surfaces γ and δ on the outer light receiving surface. For the output from the surface,

[0070]

## EQU2 ## (α + β)-(γ + δ) is calculated, and the obtained difference signal (output difference) is used as a control signal in the lens optical axis direction.

[0071]

## EQU3 ## By calculating (α + γ)-(β + δ) and using the obtained difference signal as a control signal in the direction orthogonal to the lens optical axis, the position of the CL with respect to the LD in the two directions described above. You can control. Further, the output control of the LD can be performed from the total output of the light receiving elements 45 as in the first embodiment.

In each of the above-described embodiments, the light receiving elements 11, 20, 25, 31, 41, 45 are arranged at the substantially condensing points of the condenser lenses 12, 32.
If the light receiving surface is installed, the irradiation spot becomes small, the movement and deformation of the spot appear extremely, and the signal detection is performed with high sensitivity. On the contrary, if the light-receiving surface of the light-receiving element is installed at the non-light-converging point of the condenser lens, the irradiation spot becomes large and the position adjustment of the light-receiving element becomes easy.

[0073]

As described above, according to the first, second and third means of the present invention, the collimator lens is arranged in at least one of the lens optical axis direction and the direction orthogonal to the lens optical axis. Since the position can be corrected in the above-mentioned manner, it is possible to eliminate the variation of the emission angle of the beam shaping prism or the astigmatism of the emitted light beam, which is caused by the variation of the wavelength of the semiconductor laser and the displacement of the semiconductor laser due to the temperature / time-dependent change. According to the method, a beam splitter between a beam shaping prism and an objective lens splits a parallel light beam, and an optical change of the light beam is detected by a light receiving element. The signal related to can be accurately detected, and according to the fifth means, the light flux can be condensed on the light receiving element by the condenser lens, so that the efficiency can be improved. The light can be used, and the light receiving element can be downsized. According to the sixth means, the light receiving element is installed at a substantially condensing point of the condensing lens to detect a change in a small condensing spot. According to the seventh means, it is possible to perform highly sensitive signal detection, and by dividing the light receiving surface of the light receiving element, it is possible to accurately perform signal detection based on the difference in output of each light receiving surface. According to the eighth means, the amount of light emitted from the semiconductor laser, that is, the output state can be detected from the output of the light receiving element, so that the output of the semiconductor laser can be controlled based on the output. , No.
According to the means of 11, the position of the collimator lens can be adjusted with respect to the semiconductor laser in at least one of the lens optical axis direction and the direction orthogonal to the lens optical axis by the lens actuator. And the emission angle can be easily adjusted, and according to the twelfth means, since the collimator lens can be held at an arbitrary position by the lens actuator, it is possible to eliminate the complicated and delicate work of tightening the lens screw. Again
According to the means of 13, the beam splitter between the collimator lens and the objective lens splits the parallel light flux, and the optical change of the light flux is detected by the light receiving element, so that the relative distance between the collimator lens and the semiconductor laser is increased. The positional deviation can be detected, the positional deviation can be corrected and the position after the correction can be held by this detection signal, and the 14th means allows the light beam to be efficiently condensed by condensing the light flux on the light receiving element by the condenser lens. Moreover, according to the fifteenth means, by installing the light receiving element at the non-focusing point of the focusing lens, the signal can be detected by a large focusing spot, and the light receiving element can be used. The position of the element can be easily adjusted, and according to the sixteenth means, by dividing the light receiving surface of the light receiving element, it is possible to accurately detect the signal based on the difference in the output of each light receiving surface. Further, according to the seventeenth means, since the emitted light amount of the semiconductor laser, that is, the output state can be detected from the output of the light receiving element, the output of the semiconductor laser can be controlled based on the output, and the information recording medium can be used. On the other hand, it is possible to provide an optical pickup device capable of performing correction so that a light beam can be incident in an appropriate state.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment of an optical pickup device of the present invention.

FIG. 2 is an explanatory diagram of a light receiving state in the light receiving element of the first embodiment.

FIG. 3 is a configuration diagram of a second embodiment of the present invention.

FIG. 4 is an explanatory diagram of a light receiving state in the light receiving element of the second embodiment.

FIG. 5 is an explanatory diagram of a signal detection system according to a second embodiment.

FIG. 6 is an explanatory diagram of a signal detection system according to a third embodiment of the present invention.

FIG. 7 is a configuration diagram of a fourth embodiment of the present invention.

FIG. 8 is an explanatory diagram of a light receiving state in the light receiving element of the fourth embodiment.

FIG. 9 is a configuration diagram of a fifth embodiment of the present invention.

FIG. 10 is an explanatory diagram of a light receiving state in the light receiving element of the fifth embodiment.

FIG. 11 is an explanatory diagram of a signal detection system according to a sixth embodiment of the present invention.

FIG. 12 is a configuration diagram of an example of an optical system in a conventional optical pickup device.

FIG. 13 is an explanatory diagram of a laser beam emission state.

FIG. 14 is an explanatory diagram of beam shaping.

FIG. 15 is a configuration diagram of another example of the optical system in the conventional optical pickup device.

FIG. 16 is an explanatory diagram of a change in refraction angle in the beam shaping prism.

FIG. 17 is an explanatory diagram of a change in luminous flux due to a relative position change between LD and CL.

[Explanation of symbols]

1 ... LD (semiconductor laser), 2 ... CL (collimate lens), 3 ... Beam shaping prism, 5 ... Objective lens,
7 ... PD (light receiving element), 10, 30 ... BS (beam splitter), 11, 20, 25, 31, 41, 45 ... Light receiving element, 12, 3
2 ... Condensing lens, 13, 22, 33, 40 ... Electromagnetic coil (lens actuator), 16, 21, 36, 42 ... CL control unit, 1
7, 37 ... LD power control section, D ... Optical disk (information recording medium).

Claims (17)

[Claims] 1. A light beam emitted from a semiconductor laser is made into a parallel light flux by a collimator lens, a cross-sectional shape of the parallel light flux is made substantially circular by a beam shaping prism, and the parallel light flux is focused as a light spot on an information recording medium by an objective lens. Thus, the optical pickup device for recording, reproducing, or erasing information is provided with means for correcting the position of the collimator lens in the lens optical axis direction during the recording, reproducing, or erasing operation. Optical pickup device. 2. The light emitted from the semiconductor laser is made into a parallel light flux by a collimator lens, the cross-sectional shape of this parallel light flux is made substantially circular by a beam shaping prism, and the parallel light flux is focused as a light spot on an information recording medium by an objective lens. An optical pickup device for recording, reproducing, or erasing information is provided with means for correcting the position of the collimator lens in the direction orthogonal to the lens optical axis during recording, reproducing, or erasing. An optical pickup device characterized by: 3. The light emitted from the semiconductor laser is made into a parallel light flux by a collimator lens, the cross-sectional shape of this parallel light flux is made substantially circular by a beam shaping prism, and the parallel light flux is focused as a light spot on an information recording medium by an objective lens. Then, in the optical pickup device for recording, reproducing, or erasing information, the position of the collimator lens is corrected to the lens optical axis direction and the direction orthogonal to the lens optical axis during recording, reproducing, or erasing. An optical pickup device comprising means. 4. The position correction is performed based on an output of a light receiving element that receives a light beam reflected by a beam splitter installed between the beam shaping prism and an objective lens. , 2 or 3 optical pickup device. 5. The optical pickup device according to claim 4, further comprising a condenser lens provided between the beam splitter and the light receiving element for condensing the light flux on the light receiving element. 6. The optical pickup according to claim 5, wherein the light-receiving surface of the light-receiving element is installed at a substantially condensing point of a light beam. 7. The optical pickup device according to claim 4, wherein the light receiving surface of the light receiving element is divided into at least two surfaces, and the position is corrected based on an output difference between the surfaces. 8. The output of the semiconductor laser is detected from the output of the light receiving element, and the output of the semiconductor laser is controlled based on the detection signal.
Or the optical pickup device of 7. 9. A light beam emitted from a semiconductor laser is converted into a parallel light beam by a collimator lens, and the parallel light beam is focused as a light spot on an information recording medium by an objective lens,
An optical pickup device for recording, reproducing, or erasing information, comprising a lens actuator for moving the collimating lens in the lens optical axis direction, and the semiconductor laser is provided on the lens actuator. 10. An optical pickup for recording, reproducing, or erasing information by collimating a light beam emitted from a semiconductor laser into a parallel light beam by a collimator lens and focusing the parallel light beam as a light spot on an information recording medium by an objective lens. An optical pickup device, comprising: a lens actuator that moves the collimator lens in a direction orthogonal to a lens optical axis, and the semiconductor laser is provided on the lens actuator. 11. An optical pickup for recording, reproducing, or erasing information by collimating a light beam emitted from a semiconductor laser into a parallel light beam by a collimator lens and focusing the parallel light beam as a light spot on an information recording medium by an objective lens. An optical pickup device, comprising: a lens actuator that moves the collimator lens in a lens optical axis direction and a direction orthogonal to the lens optical axis, and the semiconductor laser is provided in the lens actuator. 12. The optical pickup device according to claim 9, wherein the collimator lens can be held at an arbitrary position by the lens actuator. 13. The holding of the position is performed based on an output of a light receiving element that receives a light beam reflected by a beam splitter installed between the collimator lens and the objective lens. Optical pickup device. 14. The optical pickup device according to claim 13, further comprising a condenser lens provided between the beam splitter and the light receiving element for condensing the light flux on the light receiving element. 15. The optical pickup device according to claim 14, wherein a light receiving surface of the light receiving element is installed at a non-focusing point of a light beam. 16. The light receiving surface of the light receiving element is at least 2
16. The optical pickup device according to claim 13, wherein the optical pickup device is divided into surfaces and the position is held based on an output difference between the surfaces. 17. The output of the semiconductor laser is detected by the output of the light receiving element, and the output of the semiconductor laser is controlled based on the detection signal.
15 or 16 optical pickup device.