JPH10293936A - Optical information recording/reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce luminous flux vignetting by arranging a deflection prism in an optical path from the objective lens to an information recording medium surface, thereby shortening the distance between a light source and an objective lens. SOLUTION: A deflection prism 27 is arranged in an optical path from an objective lens to an information recording medium surface, and the deflection prism 27 is formed to be smaller than that of a conventional example. A luminous flux made incident on the deflection prism is in a converged state, and here since luminous flux shading is prevented and neither objective lens nor AT/AF actuators exist between the deflection prism 27 and an optical card C, compared with a conventional optical head, a distance from the deflection prism 27 and the information recording medium surface is shorter. Then, a distance from the deflection prism 27 to the information recording medium surface is appropriately decided by the focusing point of the objective lens. Also, since the distance between an optical element 20 as a light source and the objective lens is shorter, a luminous flux from the light source is efficiently used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of detecting reflected light from an optical recording medium with a photodetector and performing auto-tracking and / or auto-focus control.
The present invention relates to an optical information recording / reproducing apparatus for recording and / or reproducing information.

[0002]

2. Description of the Related Art Various types of information recording media for recording and reproducing information using light, such as a disk, a card, and a tape, have been known. Among them, for example, a card-shaped optical information recording medium (hereinafter, referred to as an optical card) is a portable and relatively large-capacity information recording medium that cannot be erased and rewritten at present. Therefore, applications in fields where this property is advantageous are expected.

FIG. 10 is a schematic plan view of an optical card.
Here, in the optical recording area C1, as shown in an enlarged manner, an information track Ta for recording information and a light spot during information recording / reproduction are controlled so as not to deviate from a predetermined information track. Auto tracking (hereinafter A
A plurality of tracking tracks Tb, which are guides for T), are arranged in parallel.

Further, a home position HP is provided as a reference position for accessing the information track, and the information track Ta is given a track number in order from the one closer to the home position. Access to the target information track is performed by a seek operation of moving the light spot in a direction perpendicular to a large number of tracks arranged in parallel, and by scanning the information track with the light spot.

When information is actually recorded / reproduced, auto focus (hereinafter referred to as AF) control is performed so that a light spot is focused on a recording surface of an optical card. These AT and AF controls are general techniques that have been frequently used in optical information recording / reproducing apparatuses.

FIG. 11 is a block diagram showing a conventional optical card information recording / reproducing apparatus. Reference numeral 1 denotes an optical card information recording / reproducing apparatus (hereinafter referred to as a drive), and 2 denotes a CPU which is a higher-level control apparatus. It is. Drive 1 is CPU2
The recording and reproduction are executed based on the instruction issued from. Here, the configuration of the drive 1 will be described. Reference numeral 8 denotes a drive 1 for driving the optical card C via a transport mechanism (not shown).
It is a motor to be introduced into the inside or discharged outside the drive 1. A sensor 7 is provided near the card insertion slot 6. When the sensor 7 detects that the optical card C has been inserted, the optical card C is transported to a predetermined position as described above.

Reference numeral 21 denotes an irradiation optical system including a light source, which irradiates a light beam from the irradiation optical system onto the optical card C in spots during recording and reproduction. Here, the light spot and the optical card C relatively move back and forth to scan the light spot on the information track. Reference numeral 34 denotes a photodetector for receiving the reflected light of the light spot applied to the optical card C, and the recorded information is reproduced based on the detection signal.

Reference numeral 13 denotes an AF actuator for driving a part of the irradiation optical system 21 to move the light spot in the Z direction, that is, in a direction perpendicular to the card surface, to perform AF control. An AT actuator for performing AT control by driving a part of the irradiation optical system 21 to move the light spot in the X direction, that is, the direction orthogonal to both the Y direction and the Z direction.

The optical head 20 includes the above-described irradiation optical system 21,
The configuration includes a photodetector 34, an AF actuator 13, and an AT actuator 14. The symbol 3 is RO
M, MPU with built-in RAM, controls various parts such as the card feed motor 8 and the like,
Communication and control of data with PU2 are performed. Reference numeral 10 denotes an AF actuator 13, A based on the detection signal of the photodetector.
An AT / AF control circuit for driving the T actuator 14 to perform AF control and AT control. Further, reference numeral 4
Is a modulation / demodulation circuit for reproducing the detection signal of the photodetector and demodulating the reproduction signal to reproduce the original recording data. Reference numeral 5 denotes the intensity of the light source (not shown); A light source drive circuit that modulates and controls according to output, and records information by light modulation on an information track.

FIG. 12 is a schematic plan view of the optical head 20. In the figure, reference numeral 40 denotes an optical element having a light source and a photodetector. The divergent light beam having an elliptical shape emitted from the light device enters a polarization hologram 41, is divided into a zero-order light beam and a diffracted light beam, and thereafter, The light enters the objective lens 29 via the 波長 wavelength plate 28 and the deflection prism 27. Here, the light flux from the light source is converged, and is imaged as a light spot at an appropriate position on the optical card C.

The light irradiated on the optical card C is reflected here, and is again reflected by the objective lens 29, the deflecting prism 27, 1 /
The light reaches the polarization hologram 41 via the four-wavelength plate 28. The light beam reflected from the optical card C is transmitted to the polarization hologram 4
1 is projected onto the photodetectors of the optical element 40, respectively. Then, based on the output of the photodetector, the objective lens 2
An appropriate current is applied to the AF actuator 13 and the AT actuator 14 that drive the actuator 9. As a result, the objective lens 29 moves two-dimensionally in the X and Z directions indicated by arrows in the drawing, and AF control by the astigmatism method and AT control by the three-beam method are performed. Then, the optical head 20 and the optical card C are moved in a direction perpendicular to the information track and the tracking track.
In, information is recorded / reproduced by relatively moving in the X direction indicated by an arrow in the drawing, which is a direction perpendicular to the paper surface, and in the Y direction, which is a parallel direction.

[0012]

SUMMARY OF THE INVENTION A conventional optical head 20
As described above, the objective lens 29 and the AT / AF actuator are disposed below the deflection prism 27.
For this reason, the height of the apparatus is limited by the deflection prism, the objective lens, the movable range of the objective lens in the AF direction, and the focal length of the objective lens, and it has been difficult to reduce the thickness of the apparatus. Further, in the conventional example which is a finite optical system and the distance from the light source to the objective lens is long, the distance between the light source and the objective lens is zero.
The relationship between the next light beam and the objective lens is as shown in FIG.

As is apparent from the figure, the zero-order light beam irradiated to the area other than the effective diameter of the objective lens 29 is vignetted here, so that the light cannot be used efficiently. As a means for avoiding this, it is conceivable to increase the effective diameter of the optical component. However, at present, it is necessary to increase the output of the light source so as to obtain a desired optical power on the medium surface without increasing the effective diameter, which leads to an increase in the size of the apparatus.

For this reason, a light source having a large rated output must be used, which causes an increase in cost. Further, in the conventional example, when the objective lens moves in the AT / AF direction, the vignetting of the light flux on the objective lens incident surface changes,
The light quantity of the light spot changes. For this reason, when moving in the AT direction, an AT offset occurs due to the difference in vignetting of the AT light beam, and when moving in the AF direction, the reproduced signal due to the zero-order light spot becomes unstable. turn into.

The present invention has been made based on the above circumstances, and an object of the present invention is to provide an optical information recording / reproducing apparatus which has a relatively thin optical information recording / reproducing apparatus with a reduced height. To provide.

Another object of the present invention is as follows.
At the same time, by reducing the amount of vignetting of the luminous flux emitted from the light source, it is possible to use a light source with a small rated output,
An object of the present invention is to provide an optical information recording / reproducing apparatus which is relatively inexpensive and can perform stable reproduction.

[0017]

In order to achieve the above object, according to the present invention, a light beam radiated from a light source is radiated as a light spot on an optical information recording medium surface by an objective lens, and reflected from the medium surface. A light beam is detected by a photodetector, and the information recording medium is scanned by the light spot while performing AT or (and) AF control based on a detection signal of the photodetector, and information of the information recording medium is read. In an optical information recording / reproducing apparatus for performing recording and / or reproducing, an optical path from the objective lens to the information recording medium surface is irradiated with a light beam from the light source substantially perpendicularly to the information recording medium surface. A light deflecting means is provided.

Further, according to the present invention, in the above-described optical information recording / reproducing apparatus according to the present invention, AT control means is arranged in an optical path from the objective lens to the information recording medium surface. Note that, in this embodiment, the AT control means includes: an optical element in which the optical axes of the incident light beam and the outgoing light beam are substantially parallel; a turntable on which the optical element is arranged; Actuator. Here, the optical element is a parallel plate. Further, the AT control means includes a first optical prism, a second optical prism, a turntable on which the first and second optical prisms are arranged, and an actuator for rotating the turntable. It may be configured.

Further, in the present invention, by arranging the light deflecting means between the objective lens and the recording medium, it is possible to achieve a reduction in the thickness of the apparatus, and to reduce the vignetting of light at the objective lens, thereby improving the light utilization efficiency. And a system with a small change in the amount of light emitted from the objective lens can be achieved. In such a system, by fixing the objective lens and arranging the drive system between the objective lens and the recording medium, the change in the amount of emitted light can be made zero, and a more effective system can be achieved.

That is, in the above-described optical information recording / reproducing apparatus according to the present invention, an optical path length control means for controlling an optical path length is provided in an optical path from the objective lens to the information recording medium surface. In this embodiment, the optical path length control means includes an optical prism and an actuator for driving the optical prism. Further, the optical path length control means may include a first optical prism, an actuator for driving the optical prism, and a second optical prism fixedly arranged. Further, the optical path length control means may be constituted by a first optical prism, a second optical prism, and an actuator for integrally driving the first optical prism and the second optical prism. .

Further, the optical path length control means includes a first optical prism, an actuator for driving the first optical prism, a second optical prism, and a drive for driving the second optical prism. And the actuator of the above.

Here, the incident optical axis entering the optical path control means and the exit optical axis emitted from the optical path length control means are substantially parallel. Further, a moving direction of the optical prism by the driving unit is a direction substantially parallel to the information recording medium surface and a direction parallel to one side of the optical prism within the substantially parallel surface. .

The angle formed between the light incident surface and the light emitting surface of the first optical prism is substantially the same as the angle formed between the light incident surface and the light emitting surface of the second optical prism.
In the optical prism, the light incident surface and the light exit surface are non-parallel. Further, the optical prism is a triangular prism. Further, the AF control is performed by changing an optical path length by the optical path length control means based on a detection signal of the photodetector.

Here, the optical axis of the light entering the first optical prism and the optical axis of the light emerging from the second optical prism are substantially parallel to each other. The angle formed between the light incident surface and the light emitting surface of the first optical prism is substantially the same as the angle formed between the light incident surface and the light emitting surface of the second optical prism. Further, the optical prism is a triangular prism.

In the present invention, as an embodiment thereof, the AT control means may comprise a variable apex angle prism and an actuator for changing the apex angle of the prism. Here, the variable apex angle prism has a function of the light deflecting unit. In the variable apex angle prism, a first surface transmits a light beam and a second surface reflects the light beam. Further, the first surface of the variable apex prism reflects a light beam.

The AT control is performed by rotating the turntable based on the output of the photodetector. The AT control is performed by changing the apex angle of the variable apex angle prism based on the output of the photodetector.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic plan view of an optical head used in an optical information recording / reproducing apparatus according to an embodiment of the present invention. The same parts as those in FIG. The description here is omitted. As is clear from the figure, the optical head of the present invention shown in FIG. 1 and the conventional optical head shown in FIG. 12 have no difference in the constituting members, and only the arrangement of the deflecting prism 27 is different. That is, the optical head used in the optical information recording / reproducing apparatus according to the embodiment of the present invention has the deflecting prism 27 disposed in the optical path from the objective lens to the information recording medium surface. In addition, compared with the conventional example,
Although the deflection prism 27 is made smaller, the deflection prism 2
Since the light beam incident on 7 is in a converged state, the light beam does not vignet here.

According to this embodiment, the objective lens 29 and the AT / AF actuator are not provided between the deflecting prism 27 and the optical card C.
The distance from the deflection prism 27 to the information recording medium surface can be reduced.

In this embodiment, the thickness of the objective lens 29 is reduced by the thickness and the focal length. In addition,
The distance from the deflection prism 27 to the surface of the information recording medium can be appropriately determined by the focal length of the objective lens 29. Also, the optical element 40 as a light source and the objective lens 29
Since the distance from the light source becomes short, vignetting of the light beam is reduced, and the light beam from the light source can be used efficiently. Further, since the luminous flux vignetting is reduced, the rate of change in the amount of light of the light spot generated when the objective lens moves in the AT / AF direction becomes smaller than in the conventional example, so that a relatively stable reproduction signal can be obtained. it can.

(Embodiment 2) Hereinafter, a second embodiment of the present invention will be described in detail with reference to the drawings. What is shown here is different from Embodiment 1 described above,
An objective lens is fixedly arranged, and AF control means is provided in an optical path from the objective lens to the medium surface. FIG. 2 is a schematic plan view of an optical head used in the optical information recording / reproducing apparatus according to the embodiment of the present invention, and FIG. 3 is a schematic top view of a part of the optical head used in the embodiment of the present invention. Therefore, a description will be given below in comparison with a conventional configuration (see FIG. 14).

In FIG. 1, reference numerals 51 and 52 denote wedge prisms, and reference numeral 60 denotes a piezo element which is an AF actuator. The wedge prisms 51 and 52 are shown in FIG.
Are arranged so that they have the same apex angle α and their oblique sides are substantially parallel. That is, the wedge-shaped prisms 51 and 52 have the same angle between the surface on which the light beam is incident and the surface on which the light beam is emitted, and both have the angle α, and the optical axis of the light beam incident on the wedge-shaped prism 51, The optical axis of the light beam emitted from the wedge-shaped prism 52 is substantially parallel.

The wedge-shaped prism 51 can be linearly moved by the AF actuator 60 in a direction parallel to the optical card C and in a direction parallel to the side B, as indicated by an arrow in the drawing. Configuration. Also, the movement of the wedge prism 51 changes the optical path length of the convergent light beam from the objective lens 29, and changes the focus position as shown in FIG. 4, so that the AF control is performed.

Next, the operation of the optical information recording / reproducing apparatus according to the second embodiment will be described. The divergent light beam emitted from the optical element 40 including the light source and the photodetector enters the polarization hologram 41, is divided into a zero-order light beam and a diffracted light beam, and then, via the quarter-wave plate 28,
The light enters the objective lens 29. Here, the zero-order light beam and the diffracted light beam converge, and the wedge-shaped prisms 51 and 5
2. An image is formed as an optical spot at an appropriate position on the optical card C via the deflection prism 27.

That is, the optical head used in the optical information recording / reproducing apparatus according to the embodiment of the present invention includes wedge-shaped prisms 51 and 52, an AF actuator 60, The deflecting prism 27 is arranged, and the light irradiated on the optical card C is reflected here, and again, the deflecting prism 27, the wedge-shaped prisms 51 and 52, the objective lens 29, 1/4
The light reaches the polarization hologram 41 via the wave plate 28.
The light beams reflected from the optical card C are respectively projected on the photodetectors of the optical element 40 by the polarizing hologram 41.

Then, based on the output of the photodetector, an appropriate current is applied to the AF actuator 60 for driving the wedge-shaped prism 51, and AF control by the astigmatism method is performed. The optical head 50 and the optical card C are in a direction perpendicular to the information track and the tracking track.
The information is recorded / reproduced by relatively moving in the X direction indicated by an arrow in the drawing and in the Y direction which is a parallel direction.

According to this embodiment, the objective lens 29 and the AT / AF actuator are not provided between the deflecting prism 27 and the optical card C.
The distance from the deflecting prism 27 to the surface of the information recording medium can be reduced by the thickness and the focal length of the objective lens. Further, since the objective lens 29 is fixedly arranged, the distance from the light source to the objective lens does not change. As a result, a constant amount of light spot can always be irradiated, and a stable reproduction signal can be obtained.

In the second embodiment, the wedge prism 52 is fixedly arranged. However, the wedge prism 52 is also moved by an arrow in FIG. In the AF control, the wedge-shaped prisms may be moved in directions opposite to each other. In this case, the moving amount of the wedge-shaped prism can be halved compared to the above-described embodiment, and the optical path length can be changed more quickly. Further, the wedge-shaped prism 52 may be removed from the embodiment of the present invention, and a configuration as shown in FIG. 14 may be adopted. In this case, the number of parts is reduced, and downsizing of the optical head in the left-right direction on the paper can be achieved.

In the configuration shown in FIG. 14, the wedge-shaped prism 51 is in a plane parallel to the information recording medium surface and in a direction parallel to the side A by the AF actuator 60. Move in the indicated T direction. In this embodiment, a wedge-shaped prism is used.
A prism in which the light incident surface and the light exit surface are non-parallel can change the optical path length and can be used instead.

(Embodiment 3) Hereinafter, a third embodiment of the present invention will be described in detail with reference to the drawings. Here, unlike the first embodiment, the objective lens is fixedly arranged, and AF control means is provided in the optical path from the objective lens to the medium surface. FIG. 5 is a schematic plan view of an optical head used in an optical information recording / reproducing apparatus according to a third embodiment of the present invention. The same parts as those in FIG. Therefore, the description here is omitted. In FIG. 5, reference numerals 51 and 52
Is a wedge prism, 53 is a turntable, and 104 is an AT magnet. FIG. 6 is a schematic top view of a part of an optical head used in the third embodiment of the present invention. As shown in FIG. 6, the wedge-shaped prisms 51 and 52 have the same apex angle α, and are arranged on the turntable 53 such that their oblique sides are substantially parallel.

That is, the optical axis of the light beam entering the wedge prism 51 and the optical axis of the light beam emitted from the wedge prism 52 are substantially parallel. The turntable 53 is an AT
An AT actuator composed of an AT coil 102 and an AT magnet 104 is configured to be rotatable in the R direction indicated by an arrow in the drawing. Then, by the rotation of the turntable 53,
The light spot irradiated on the optical card can move to an appropriate position in the X direction indicated by an arrow in the drawing. In the third embodiment of the present invention, the information track and the tracking track on the optical card are arranged alternately in the X direction indicated by the arrow in the figure. AT control is performed by the rotation of.

Next, the operation of the optical information recording / reproducing apparatus according to the third embodiment of the present invention will be described. A divergent light beam emitted from an optical element 40 having a light source and a photodetector enters a polarizing hologram 41 and is divided into a zero-order light beam and a diffracted light beam. It is incident on 29. Here, the zero-order light beam and the diffracted light beam converge, and the wedge-shaped prisms 51 and 5
2. An image is formed as an optical spot at an appropriate position on the optical card C via the deflecting prism 27.

That is, the optical head used in the optical information recording / reproducing apparatus according to the third embodiment of the present invention includes wedge-shaped prisms 51 and 52, a rotating prism, in the optical path from the objective lens 29 to the information recording medium surface. The table 53, the AT actuator, and the deflecting prism 27 are arranged, and the light irradiated on the optical card C is reflected here and is again reflected on the deflecting prism 27, the wedge-shaped prisms 51 and 52, the objective lenses 29 and 1/4. After passing through the wave plate 28, the polarization hologram 4
Reach 1 The light beams reflected from the optical card C are respectively projected on the photodetectors of the optical element 40 by the polarizing hologram 41.

Then, based on the output of the photodetector, an appropriate current is applied to an AT actuator (not shown) for driving the turntable 53, and the AT control by the three-beam method is performed. The optical head 50 and the optical card C relatively move in the X direction indicated by arrows in the drawing and the Y direction which is a direction parallel to the information track and the tracking track, and record / reproduce information. Is performed.

According to this embodiment, the objective lenses 29 and A are located between the deflecting prism 27 and the optical card C.
Since there is no T / AF actuator, the distance from the deflecting prism 27 to the surface of the information recording medium can be reduced by the thickness and the focal length of the objective lens as compared with the conventional optical head. Further, since the objective lens 29 is fixedly arranged, the distance from the light source to the objective lens does not change. As a result, it is possible to always irradiate a light spot with a constant light amount, and to obtain a stable reproduction signal.

In the embodiment of the present invention, the turntable 5
Although three wedge-shaped prisms 51 and 52, i.e., a pair of wedge-shaped prisms, are provided on the rotary table 53, one parallel flat plate may be provided on the turntable 53. In this case, the number of parts is reduced, and at the same time, the load on the AT actuator is reduced.
The weight and cost of the device can be reduced. Embodiment 4 Hereinafter, a fourth embodiment of the present invention will be described in detail with reference to the drawings. FIG. 7 is a schematic configuration diagram of an optical head used in an optical information recording / reproducing apparatus according to a fourth embodiment of the present invention. The same parts as those in FIGS. The description in is omitted. In FIG. 7, reference numeral 54 denotes a variable apex angle prism, which is a first prism to which a light beam from the objective lens 29 is irradiated.
The surface is a total reflection surface that totally reflects light, and a second surface facing the total reflection surface is fixed to the optical head housing. As shown in FIG. 8, the variable apex angle prism 54 expands and contracts a bellows-like holding frame by an actuator (not shown) to change the apex angle of the prism.
It is configured to be able to deflect light in the direction. In the fourth embodiment, the information track and the tracking track on the optical card are arranged alternately in the X direction indicated by the arrow in FIG. AT control is performed.

Next, the operation of the optical information recording / reproducing apparatus according to the fourth embodiment of the present invention will be described. The divergent light beam emitted from the optical element 40 including the light source and the photodetector enters the polarization hologram 41 and is divided into a zero-order light beam and a diffracted light beam. The light enters the objective lens 29. Here, the zero-order light beam and the diffracted light beam converge, and are imaged as an optical spot at an appropriate position on the optical card C via the variable apex angle prism 54. That is, the optical head used in the optical information recording / reproducing apparatus according to the fourth embodiment of the present invention has a variable apex angle prism 54 and an AT actuator arranged in the optical path from the objective lens 29 to the information recording medium surface. ing.

The light irradiated onto the optical card C is reflected here, and is again returned to the variable angle prism 54, the objective lens 29,
The light reaches the polarization hologram 41 via the 波長 wavelength plate 28. The light beam reflected from the optical card C is transmitted to the polarization hologram 4
1 is projected onto the photodetectors of the optical element 40, respectively. Then, based on the output of the photodetector, an appropriate current is applied to a T-actuator (not shown) for driving the variable apex angle prism 54, and AT control by the three-beam method is performed. Recording and reproduction of information are performed by the optical head 50 and the optical card C relatively moving in the X direction indicated by arrows in the figure and the Y direction which is parallel to the information track and the tracking track. .

In the fourth embodiment, the first surface of the variable apex angle prism 54 is a total reflection surface and the second surface is fixed to the optical head housing. However, as shown in FIG. The first surface may be a transmission surface, and the second surface may be a total reflection surface. In this case, by setting the surface to be fixed to the optical head housing as the first surface, the work of fixing the variable apex angle prism can be performed from the upper surface of the optical head, thereby facilitating the assembling work.

[0049]

As described above, in the present invention, since the deflecting prism is disposed in the optical path from the objective lens to the surface of the information recording medium, the apparatus is thinner than a conventional apparatus using an optical head. Can be achieved. In addition, since the distance between the light source and the objective lens is short, luminous vignetting is reduced, and a light source with a small rated output can be used. Thereby, cost reduction of the light source can be achieved. Furthermore, even if the objective lens moves in the AT / AF direction, the rate of change in the light spot light amount is small and a relatively stable reproduction signal can be obtained even if the objective lens moves in the AT / AF direction.

Further, according to the present invention, in the optical path from the objective lens to the surface of the information recording medium, an optical path length control means for controlling the optical path length, and the light beam from the light source is applied substantially perpendicularly to the surface of the information recording medium. Since the light deflecting means for irradiating is provided, the distance from the light deflecting means to the surface of the information recording medium can be reduced, and the device can be made thinner. Further, by arranging the objective lens fixedly, the distance from the light source to the objective lens does not change, and as described above, the light amount of the light spot does not change due to the movement of the objective lens. Thereby, a more stable reproduction signal can be obtained.

Further, according to the present invention, in the optical path from the objective lens to the information recording medium surface, the AT control means and the light deflecting means for irradiating the light flux from the light source substantially perpendicularly to the information recording medium surface are provided. The distance from the light deflecting means to the information recording medium surface can be shortened, and the device can be made thinner. Furthermore, the fixed arrangement of the objective lens makes the distance from the light source to the objective lens invariable,
As described above, the light amount of the light spot does not change due to the movement of the objective lens. Thereby, a more stable reproduction signal can be obtained.

In particular, when a variable apex angle prism having the function of a light deflecting means is used, a rotating table, a mechanism for rotating and a light deflecting prism are not required, and the number of parts is reduced.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of an optical head of an optical information recording / reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic plan view of an optical head of an optical information recording / reproducing apparatus according to a second embodiment of the present invention.

FIG. 3 is a schematic top view of a part of an optical head according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a change in a focus position due to movement of a wedge-shaped prism.

FIG. 5 is a schematic configuration plan view of an optical head of an optical information recording / reproducing apparatus according to a third embodiment of the present invention.

FIG. 6 is a schematic top view of a part of an optical head according to a third embodiment.

FIG. 7 is a schematic plan view of an optical head of an optical information recording / reproducing apparatus according to a fourth embodiment of the present invention.

FIG. 8 is a diagram showing a change in a light deflection direction by a variable apex angle prism.

FIG. 9 is a diagram showing a method of attaching the variable apex angle prism to the optical head housing.

FIG. 10 is a schematic plan view of an optical card.

FIG. 11 is a block diagram showing a conventional optical card recording / reproducing apparatus.

FIG. 12 is a schematic plan view of a conventional optical head.

FIG. 13 is a diagram illustrating a relationship between a zero-order light beam and an objective lens on the entrance surface of the objective lens.

FIG. 14 is a diagram illustrating an example of an optical path length changing unit.

[Explanation of symbols]

 C Optical Card 20 Conventional Optical Head 40 Optical Element Including Light Source and Photodetector 27 Optical Deflection Prism 29 Objective Lens 51, 52 Wedge Prism 53 Rotating Table 54 Variable Vert Angle Prism 60 AF Actuator

Claims (25)

[Claims] 1. A light beam irradiated from a light source is irradiated as a light spot on an optical information recording medium surface by an objective lens.
The light beam reflected from the medium surface is detected by a photodetector, and the information recording medium is scanned by the light spot while performing auto-tracking or (and / or) autofocus control based on a detection signal of the photodetector. In an optical information recording / reproducing apparatus for recording and / or reproducing information on / from an information recording medium, a light flux from the light source is substantially applied to the information recording medium surface in an optical path from the objective lens to the information recording medium surface. An optical information recording / reproducing apparatus, comprising a light deflecting means for irradiating vertically. 2. The optical information recording / reproducing apparatus according to claim 1, wherein an optical path length control means for controlling an optical path length is provided in the optical path. 3. The optical information recording / reproducing apparatus according to claim 1, wherein an automatic tracking control means is provided in the optical path. 4. An optical information recording / reproducing apparatus according to claim 2, wherein said optical path length control means comprises an optical prism and a driving means for driving said optical prism. 5. The optical path length control means includes a first optical prism, a second optical prism fixedly arranged, and a driving means for driving the first optical prism. The optical information recording / reproducing apparatus according to claim 2, wherein: 6. The optical path length control means includes a first optical prism, a second optical prism, and a driving means for integrally driving the first optical prism and the second optical prism. 3. The method according to claim 2, wherein
An optical information recording / reproducing apparatus according to claim 1. 7. The optical path length control means includes a first optical prism, a second optical prism, a first driving means for driving the first optical prism, and the second optical prism. 3. The optical information recording / reproducing apparatus according to claim 2, wherein the optical information recording / reproducing apparatus comprises a second driving unit for driving the optical information recording / reproducing apparatus. 8. An optical axis incident on the optical path length control means and an output optical axis emitted from the optical path length control means,
The optical information recording / reproducing apparatus according to any one of claims 5 to 7, wherein the optical information recording / reproducing apparatus is substantially parallel. 9. The moving direction of the optical prism by the driving means is in a plane substantially parallel to the information recording medium surface, and is parallel to one side of the optical prism in the substantially parallel plane. The direction is a direction.
8. The optical information recording / reproducing apparatus according to any one of items 7 to 7. 10. The light beam incident surface of the first optical prism and an angle formed by a light beam exit surface thereof are substantially the same as an angle formed by a light beam exit surface of the second optical prism. 8. The optical information recording / reproducing apparatus according to any one of items 7 to 7. 11. The optical information recording / reproducing apparatus according to claim 4, wherein the optical prism has an incident surface and an exit surface of a light beam that are not parallel to each other. 12. The optical information recording / reproducing apparatus according to claim 9, wherein the optical prism is a triangular prism. 13. The optical information according to claim 2, wherein the autofocus control is performed by changing an optical path length by the optical path length control means based on a detection signal of the photodetector. Recording and playback device. 14. The auto tracking control means,
An optical element in which the optical axes of the incident light beam and the outgoing light beam are substantially parallel,
4. The optical information recording / reproducing apparatus according to claim 3, further comprising: a turntable on which the optical element is arranged; and an actuator for rotating the turntable. 15. The optical information recording / reproducing apparatus according to claim 14, wherein the optical element is a parallel flat plate. 16. The automatic tracking control means,
It is characterized by comprising a first optical prism, a second optical prism, a turntable on which the first and second optical prisms are arranged, and an actuator for rotating the turntable. The optical information recording / reproducing device according to claim 3. 17. The optical system according to claim 16, wherein an incident optical axis entering the first optical prism and an emitting optical axis exiting from the second optical prism are substantially parallel. Optical information recording / reproducing device. 18. The light beam incident surface of the first optical prism and an angle formed by the light exit surface are substantially the same as the angle formed by the light incident surface and the light exit surface of the second optical prism. The optical information recording / reproducing apparatus according to any one of claims 16 to 17, wherein: 19. The optical information recording / reproducing apparatus according to claim 16, wherein said optical prism is a triangular prism. 20. The auto tracking control means,
4. The optical information recording / reproducing apparatus according to claim 3, comprising a variable apex angle prism and an actuator for changing the apex angle of the prism. 21. The optical information recording / reproducing apparatus according to claim 20, wherein the variable apex angle prism has a function of the light deflecting unit. 22. The optical information recording / reproducing apparatus according to claim 21, wherein the variable apex angle prism has a first surface transmitting a light beam and a second surface reflecting the light beam. 23. The optical information recording / reproducing apparatus according to claim 21, wherein the first surface of the variable apex angle prism reflects a light beam. 24. The optical information recording according to claim 14, wherein the auto-tracking control is performed by rotating the turntable based on an output of the photodetector. Playback device. 25. The auto-tracking control according to claim 20, wherein the auto-tracking control is performed by changing a vertex angle of the variable vertex angle prism based on an output of the photodetector.
24. The optical information recording / reproducing apparatus according to any one of claims to 23.