JP2001143305A - Optical pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical pickup device capable of correctly monitoring light source light without being influenced by return light, without increasing, the device scale and moreover, without being required for high assembling positional precision. SOLUTION: The number of parts for obtaining monitor light is reduced by detecting light source light emitted from a light source 21 (or 22) and reflected by the part of the surface 28a of an objective lens 30 side of a wavelength synthesizing prism 28 as monitor light Pm by a monitor light receiving element 35 (or 36). At this time, since the light source light reflected by the part of the surface 28a of the objective lens 30 side of the wavelength syntesizing prism 28 is converged by an optical element such as a coupling lens 25 (or 27) and is detected by the monitor light receiving element 35 (or 36), the return light made incident on a signal detection light receiving element 31 (or 32) is controlled and a function for correctly detecting signals is maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording system comprising a plurality of light sources which emit light having different wavelengths in order to correspond to optical recording media having different application wavelengths, for example, a CD disk and a DVD disk. The present invention relates to an optical pickup device that performs a reproducing, recording, or erasing operation on a medium.

[0002]

2. Description of the Related Art In recent years, in addition to CD-based disks as optical recording media, DVD-based disks of even higher density and large capacity have been put into practical use. As a light source in the optical pickup device, a wavelength of 7 in the case of a CD-based disc is used.
A semiconductor laser that emits a light source light of about 80 nm is used, whereas a DVD-based disc has a shorter wavelength in order to cope with a higher density.
Semiconductor lasers that emit light of about m are used. In this case, in configuring an optical pickup device that can be shared by one CD-type disc and one DVD-type disc,
It is necessary to provide an optical element for synthesizing all the light sources having different wavelengths so that the light can be emitted toward the objective lens side, and it is generally used that the optical element uses a wavelength combining prism.

FIG. 5 shows a proposal example of such an optical pickup device. The operation of the optical pickup device when a DVD disk is used as the optical recording medium 1 will be described. In this case, a semiconductor laser 2 that emits light at a wavelength of 660 nm is used. The light source light emitted from the semiconductor laser 2 almost passes through the hologram element 3, is converted into a substantially parallel light by the coupling lens 4, enters the wavelength combining prism 5, and has a beam combining surface of 45 ° depending on the wavelength. The light 6 is reflected by 90 ° and is incident on the objective lens 7 to be condensed and radiated on the DVD disk as the optical recording medium 1. The irradiation light is reflected by the DVD-based disc to become signal light, again enters the wavelength synthesizing prism 5 through the objective lens 7, is reflected by the beam synthesizing surface 6, and again enters the coupling lens 4. The light is incident on the hologram element 3 while being collected. The light is separated from the light source light by the hologram element 3 and is incident on the signal detection light-receiving element 8 to detect a recording signal, a servo signal and the like. Here, the signal detection light-receiving element 8 is mounted on the same substrate 9 as the semiconductor laser 2.

[0004] The operation in the case where, for example, a CD disk is used as the optical recording medium 1 will be described. In this case, the semiconductor laser 1 which emits light of a wavelength of 780 nm
0 is used. The light source light emitted from the semiconductor laser 10 disposed in a direction different from the semiconductor laser 2 by 90 °, for example, almost passes through the hologram element 11, is converted into substantially parallel light by the coupling lens 12, and is transmitted to the wavelength synthesizing prism 5. The light enters the objective lens 7 through the beam combining surface 6 of 45 ° depending on the wavelength thereof, and is condensed and irradiated on the CD disk as the optical recording medium 1. This irradiation light is reflected by a CD-based disc to become signal light,
The light again enters the wavelength synthesizing prism 5 through the objective lens 7,
After passing through the beam combining surface 6, the coupling lens 12
Hologram element 1 while being condensed by being incident on
Incident on 1. The light is separated from the light source light by the hologram element 11 and is incident on the signal detection light-receiving element 13, where the recording signal
Servo signals and the like are detected. Here, the signal detection light-receiving element 13 is mounted on the same substrate 14 as the semiconductor laser 10.

In this way, an optical pickup device capable of sharing the light source light having the wavelength of 660 nm and the light source light having the wavelength of 780 nm is provided.

Here, also in such an optical pickup device, as in the case of the optical pickup device for single-wavelength light, power control of the light source light of each light source (semiconductor lasers 2 and 10) is important. It is necessary to monitor the intensity fluctuation by some means and control it to an appropriate intensity. In this case, there is a backward light detection method in which a light emitting amount detection photodiode for receiving light emitted backward from the semiconductor laser is built in. However, due to the problem of control accuracy, the light is actually directed toward the optical recording medium. Outgoing forward light (direct light)
In many cases, a method of monitoring a part of is used.

With respect to such a direct light monitoring method, for example, as a monitoring method for the semiconductor laser 2 when using a DVD-type disc, a reflector (not shown) is attached to the hologram element 3 and emitted from the semiconductor laser 2. As shown by a dotted line in FIG. 5, the light from the light source is reflected by this reflector, turned back to the semiconductor laser 2 side, and received by the monitoring light receiving element 15 mounted on the same substrate 9 for monitoring. There is something. The same applies to the monitoring method for the semiconductor laser 10 when using a CD disc.
The light is received by the monitoring light receiving element 16 for monitoring.

[0008]

However, in the case of such a monitor system, the position of the reflector is provided closer to the semiconductor lasers 2 and 10 than the coupling lenses 3 and 12, and the light source incident on the reflector is provided. Since the light is divergent light and the monitor light reflected by the reflector is also divergent light, the light spreads and enters not only the monitoring light receiving elements 15 and 16 but also the signal detection light receiving elements 8 and 13. There is a problem that it is detected as a part of the signal light.

To solve this problem, the hologram elements 3 and 1
There is a device in which a reflection hologram having a light collecting function is provided in place of the reflection plate for 1. This is because the outer periphery of the light source light not used for signal light is reflected by a reflection hologram.
The monitor light receiving elements 15, 1 are reflected and condensed.
6 is to be detected. When a reflection hologram is used, the monitor light at the time of detection is focused,
The problem of the return light to the signal detection light receiving elements 8 and 13 can be solved. However, in this case, the relative position between the signal light spot and the monitor light spot is determined by the optical path of the light source light. For example, the semiconductor lasers 2 and 10 used for the light source are required to have high assembly position accuracy. I will.

Therefore, the present invention does not increase the size of the apparatus and does not require high assembling position accuracy.
An object of the present invention is to provide an optical pickup device capable of accurately monitoring light source light without being affected by return light.

[0011]

According to the first aspect of the present invention,
A plurality of light sources which are selectively driven to emit light sources having different wavelengths, a wavelength synthesizing prism for synthesizing the light source light emitted from these light sources toward the optical recording medium as irradiation light, and a wavelength synthesizing prism. In an optical pickup device including an objective lens for condensing the irradiation light having passed through the prism on the optical recording medium, and a signal detection light receiving element for receiving light reflected from the optical recording medium, The light source light reflected by one surface of the wavelength synthesizing prism is received as monitor light by a monitoring light receiving element, and the light source light of the corresponding light source is monitored.

Therefore, by obtaining monitor light using the wavelength synthesizing prism for synthesizing the light source lights emitted from at least two light sources, the number of components for obtaining monitor light can be reduced. Simplification and cost reduction can be achieved. In addition, since monitor light is generated on an optical path between an optical element such as a coupling lens and an optical recording medium, when monitor light is detected by the monitor light receiving element,
Since the light is substantially parallel light or convergent light, return light incident on the signal detection light receiving element can be suppressed, and the function of accurately detecting a signal can be maintained. Furthermore, it is also possible to reduce a high assembling position accuracy required for the light source due to the relative position between the signal light spot and the monitor light spot being determined by the optical path of the light source light.

According to a second aspect of the present invention, in the optical pickup device of the first aspect, the light receiving element for monitoring includes:
The light source light reflected by the surface of the wavelength combining prism on the side of the objective lens is received as monitor light.

Therefore, the number of components for obtaining the monitor light can be reduced by detecting, as monitor light, the light source light reflected by the surface portion of the wavelength combining prism on the objective lens side. Cost reduction can be achieved. Also, the light reflected from the surface of the wavelength combining prism on the objective lens side is converged by an optical element such as a coupling lens and detected by a monitor light receiving element, so that return light incident on the signal detecting light receiving element. Can be suppressed, and the function of accurately detecting a signal can be maintained.

According to a third aspect of the present invention, in the optical pickup device of the second aspect, the signal detection light receiving element and the monitor light receiving element corresponding to each of the light sources are provided on the same substrate.

Accordingly, by providing the signal detection light receiving element and the monitor light receiving element corresponding to each light source on the same substrate, the number of components can be reduced, and the assembly can be simplified.
Cost reduction can be achieved.

According to a fourth aspect of the present invention, in the optical pickup device of the second aspect, each of the light sources, the signal detection light receiving element corresponding to the light source, and the monitor light receiving element are provided on the same substrate. I have.

Therefore, by providing each light source and the signal detection light receiving element and the monitor light receiving element corresponding to the light source on the same substrate, the number of parts can be further reduced, and the assembly is simplified and the cost is reduced. Can be achieved.

According to a fifth aspect of the present invention, in the optical pickup device of the first aspect, the light receiving element for monitoring includes:
Light source light reflected by the surface portion on the light source side in the wavelength combining prism is received as monitor light.

Therefore, the number of components for obtaining the monitor light can be reduced by detecting the reflected light reflected by the surface portion of the wavelength combining prism on the light source side as the monitor light, thereby simplifying the assembly and reducing the number of components. Cost can be reduced. In addition, since the light is reflected by the surface portion on the light source side of the wavelength synthesizing prism or is converged by an optical element such as a coupling lens and detected by the monitor light receiving element, it is incident on the signal detection light receiving element. It is possible to suppress the returning light, and maintain the function of accurately detecting the signal.

According to a sixth aspect of the present invention, in the optical pickup device of the fifth aspect, an incident angle of the light source light from each of the light sources to a surface portion on the light source side in the wavelength combining prism is 45 ° or less. The signal detection light receiving element and the monitor light receiving element corresponding to each of the light sources are provided on the same substrate.

Accordingly, the angle of incidence of the light source light from each light source on the surface portion on the light source side in the wavelength synthesizing prism is 4
Since the monitor light is 5 ° or less and the monitor light is reflected on the light source side, the number of parts can be reduced by providing the signal detection light receiving element and the monitor light light receiving element corresponding to each light source on the same substrate. In addition, the assembly can be simplified and the cost can be reduced.

According to a seventh aspect of the present invention, in the optical pickup device according to the fifth aspect, an incident angle of each light source light from each of the light sources to a surface portion on the light source side in the wavelength combining prism is 45 ° or less. Each of the light sources, the signal detection light-receiving element corresponding to the light source, and the monitoring light-receiving element are provided on the same substrate.

Accordingly, the angle of incidence of the light source light from each light source on the surface portion on the light source side in the wavelength synthesizing prism is 4
Since the monitor light is reflected at the light source side at 5 ° or less, the signal detection light receiving element corresponding to the light source and the monitor light receiving element are provided together with each light source on the same substrate to further reduce the number of components. Therefore, the assembly can be simplified and the cost can be reduced.

[0025]

FIG. 1 shows a first embodiment of the present invention.
It will be described based on. The two-light-source optical pickup device according to the present embodiment corresponds to the first to fourth aspects of the present invention.

First, as a plurality of light sources, a semiconductor laser 21 that emits light source light having a wavelength of 660 nm and a semiconductor laser 22 that emits light source light having a wavelength of 780 nm are provided so that their emission directions are substantially orthogonal to each other. The semiconductor laser 21 is a light source when a DVD disk is used as the optical recording medium 23. A hologram element 24 for separating the light source light and the signal light is provided on the emission optical axis, and the divergent light is made into a parallel light. A coupling lens 25 is provided. The semiconductor laser 22 is a CD as the optical recording medium 23.
A hologram element 26 for separating the source light from the signal light, and a coupling lens 2 for converting the divergent light into parallel light
7 are provided. And these semiconductor lasers 2
A cubic wavelength synthesizing prism 28 for synthesizing any of the light sources as irradiation light to the optical recording medium 23 side is provided at a position where the light sources 1 and 22 are both incident. This wavelength combining prism 28 has a wavelength 66
It exhibits reflection characteristics with respect to light of 0 nm, and has a wavelength of 780 nm.
Has a 45 ° tilted beam combining surface 29 whose optical characteristics are set so as to exhibit transmission characteristics with respect to the light. Thereby, the light source light from the semiconductor laser 21 is reflected by the beam combining surface 29, and the light source light from the semiconductor laser 22 is set to pass through the beam combining surface 29. On the optical path between the wavelength combining prism 28 and the optical recording medium 23, an objective lens 30 for condensing the irradiation light on the optical recording medium 23 is provided.

A signal detecting light receiving element 31 is provided at a position where the signal light separated by the hologram element 24 is received. Similarly, the signal detection light-receiving element 32 is located at a position where the signal light separated by the hologram element 26 is received.
Are arranged. The signal detection light receiving element 31 is mounted on the same substrate 33 as the corresponding semiconductor laser 21, and the signal detection light receiving element 32 is mounted on the same substrate 34 as the corresponding semiconductor laser 22.

Here, in the present embodiment, the wavelength combining prism 28 is obliquely arranged so that the surface 28a on the objective lens 30 side is not orthogonal to the optical axis of the source light (irradiation light) but has an angle θ. (The wavelength combining prism 28 itself may not be disposed obliquely, and only the surface 28a may be configured to have an inclination of the angle θ). As a result, part of the light source light (irradiation light) traveling toward the objective lens 30 in the wavelength combining prism 28 is reflected by the surface 28a as shown by the broken line in FIG. 1, and is reflected in the present embodiment. This component is used as monitor light Pm for detecting fluctuations in light source light intensity. On the semiconductor laser 21 side,
A monitor light receiving element 35 is provided at a position where the monitor light receiving element 35 can receive the monitor light Pm reflected by the surface 28a, reflected by the beam combining surface 29, and passed through the coupling lens 25 again. The monitor light receiving element 35 is mounted on the same substrate 33 as the semiconductor laser 21 and the signal detection light receiving element 31. On the semiconductor laser 22 side, a monitor light receiving element 36 is provided at a position where it can receive the monitor light Pm reflected by the surface 28a, transmitted through the beam combining surface 29, and passed through the coupling lens 27 again. The monitor light receiving element 36 is mounted on the same substrate 34 as the semiconductor laser 22 and the signal detection light receiving element 32.

In such a configuration, for example, a case where a DVD disk is used as the optical recording medium 23 will be described. Wavelength 66 emitted from semiconductor laser 21
The light source light of 0 nm is divergent light. The divergent light passes through the hologram element 24, becomes substantially parallel light by the coupling lens 25, enters the wavelength combining prism 28, and is reflected by the beam combining surface 29. Here, the wavelength combining prism 28 of the present embodiment is
a is inclined by an angle θ with respect to the optical axis of the irradiation light reflected by the beam combining surface 29, and most of the irradiation light passes through the surface 28 a, exits to the objective lens 30 side, and is collected on the optical recording medium 23. Light, but some of the light is
Is reflected by the optical recording medium 23 and becomes the monitor light Pm.
Is reflected by the beam combining surface 29 along a path different from the signal light Ps reflected by the beam.

After being reflected by the beam combining surface 29, the signal light Ps is condensed by the coupling lens 25 and is incident on the hologram element 24, is separated from the light source light, is incident on the signal detection light receiving element 31, and is incident on the signal detection light receiving element 31. Ps is detected. On the other hand, the monitor light Pm is reflected by the beam combining surface 29, is then condensed by the coupling lens 25, enters the monitor light receiving element 35, and detects the monitor light Pm. More specifically, assuming that the focal length of the coupling lens 25 is f, the monitor light receiving element 35 condenses the light at a position shifted by f × tan 2θ from the emission point of the semiconductor laser 21. Further, if the monitor light passes through the diffraction grating portion of the hologram element 24, it can be focused further away. Thus, the monitor light receiving element 35 can directly detect (monitor) the light source light emitted forward from the semiconductor laser 21.

Thus, the monitor light Pm based on the direct light
Since the number of components for obtaining the signal can be reduced and the light is condensed by the coupling lens 25, the influence of the return light on the signal detection light-receiving element 31 can be suppressed, and the assembly accuracy can be simplified. it can. Further, by returning the monitor light Pm to the side of the semiconductor laser 21, the signal detection light receiving element 31, the monitor light receiving element 35, and the semiconductor laser 21 itself are mounted on the same substrate 33. And the assemblability can be improved.

Such an operation is achieved by the optical recording medium 23 as C
The same applies to the semiconductor laser 22 when a D disk is used. The light source light having a wavelength of 780 nm emitted from the semiconductor laser 22 is divergent light. The divergent light is transmitted through the hologram element 26, becomes substantially parallel light by the coupling lens 27, enters the wavelength combining prism 28, and transmits through the beam combining surface 29. Here, the wavelength synthesis prism 28 of the present embodiment is
8a is inclined by an angle θ with respect to the optical axis of the irradiation light passing through the beam combining surface 29, and most of the irradiation light passes through the surface 28a and is emitted to the objective lens 30 side and condensed on the optical recording medium 23. However, part of the light is reflected by the surface 28a as shown by the broken line to become monitor light Pm, and passes through the beam combining surface 29 along a path different from the signal light Ps reflected by the optical recording medium 23. .

After passing through the beam combining surface 29, the signal light Ps is condensed by the coupling lens 27 and is incident on the hologram element 26, is separated from the light source light, is incident on the signal detection light receiving element 32, and the signal light is transmitted. Is detected. On the other hand, the monitor light Pm passes through the beam combining surface 29, is then condensed by the coupling lens 27, enters the monitor light receiving element 36, and detects the monitor light. More specifically, assuming that the focal length of the coupling lens 27 is f, the monitor light receiving element 36 is fxtan2θ from the emission point of the semiconductor laser 22.
Focus on the shifted position. Further, if the monitor light Pm passes through the diffraction grating portion of the hologram element 26, it can be focused further away. Thus, the monitor light receiving element 36 can directly detect (monitor) the light source light emitted forward from the semiconductor laser 22.

Thus, the monitor light Pm based on the direct light
Since the number of components for obtaining the signal can be reduced and the light is condensed by the coupling lens 27, the influence of the return light on the signal detection light-receiving element 32 can be suppressed, and the assembly accuracy can be simplified. it can. Further, by returning the monitor light Pm to the semiconductor laser 22, the signal detection light receiving element 32, the monitor light receiving element 36, and the semiconductor laser 22 itself are mounted on the same substrate 34. And the assemblability can be improved.

As described above, the operation is basically the same regardless of whether a DVD-based disc or a CD-based disc is used. Therefore, in the following embodiments, the configuration and operation of the CD-based disc will be described. Omitted, DVD
The configuration and operation of only the system disk will be described.

A second embodiment of the present invention will be described with reference to FIG. The same or corresponding portions as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted (the same applies to the following embodiments).

In this embodiment, a reflection type wavelength combining prism 41 having a beam shaping function is used as the wavelength combining prism instead of the wavelength combining prism 28.
That is, instead of the wavelength synthesizing prism 28 formed by combining simple triangular prisms, a wavelength synthesizing prism 41 obtained by combining trapezoidal columnar prisms on a beam synthesizing surface 42 is used. The optical system includes a semiconductor laser 21 and a wavelength combining prism 41.
And the exit surface from the wavelength combining prism 41 to the objective lens 30 side is the same. That is,
The surface 41a is commonly used as an incidence surface for the semiconductor laser 21 and an emission surface for the objective lens 30. However, since the surface 41a is inclined by an angle θ with respect to the optical axis of irradiation light toward the objective lens 30, the surface 41a In the surface portion 41ao on the objective lens 30 side, the semiconductor laser 21
The part of the light source light emitted from the light source and incident on the wavelength synthesizing prism 41 and reflected on the beam synthesizing surface 42 is reflected to be used as monitor light Pm.

That is, the light source light emitted from the semiconductor laser 21 is transmitted through the hologram element 24, and then is made parallel by the coupling lens 25, and is converted into a parallel light.
And is reflected by the beam combining surface 42 and emitted to the objective lens 30 side. At this time, a part of the light is reflected by the surface portion 41ao, reflected again by the beam combining surface 42, returns to the coupling lens 25 side, forms an image on the monitor light receiving element 35 as monitor light Pm, and Used for detection of Pm.

As described above, the case where the reflection type wavelength synthesizing prism 41 having the beam shaping function is used as the wavelength synthesizing prism can be applied similarly to the case of the first embodiment.

A third embodiment of the present invention will be described with reference to FIG. The two-light-source optical pickup device of the present embodiment corresponds to claims 1 and 5 to 7.

The present embodiment is basically the same as the embodiment shown in FIG.
8, the surface 28b on the side of the semiconductor laser 21 is inclined by an angle θ such that the light source light from the semiconductor laser 21 is incident at an incident angle θ of 45 ° or less, and is emitted from the semiconductor laser 21 by the coupling lens 25. When the collimated light from the light source enters the wavelength combining prism 28 from the surface 28b, a part of the light is reflected by the surface 26b. Therefore, the reflected light is used as the monitor light Pm.

In such a configuration, for example, a case where a DVD disk is used as the optical recording medium 23 will be described. Wavelength 66 emitted from semiconductor laser 21
The light source light of 0 nm is divergent light. The divergent light passes through the hologram element 24, becomes substantially parallel light by the coupling lens 25, enters the wavelength combining prism 28, and is reflected by the beam combining surface 29. Here, the wavelength synthesizing prism 28 of the present embodiment is provided on the surface 2 on the semiconductor laser 21 side.
8b is inclined by an angle θ with respect to the optical axis of the light from the light source, and most of the light from the light source passes through the surface 28b, is emitted to the objective lens 30 side, and is collected on the optical recording medium 23. The light is reflected by the surface 28b to become the monitor light Pm as shown by the broken line, and passes through the beam combining surface 29 along a path different from the signal light Ps reflected by the optical recording medium 23.

The light is condensed by the coupling lens 25, passes through the hologram element 24, and is
5 and is incident. Assuming that the focal length of the coupling lens 25 is f, the monitor light receiving element 35 condenses the light at a position shifted by f × tan 2θ from the light emitting point of the semiconductor laser 21. Further, if the monitor light Pm passes through the diffraction grating portion of the hologram element 26, it can be focused further away. Thereby, the monitor light receiving element 36
Thus, the light source light emitted forward from the semiconductor laser 22 can be directly detected (monitored).

Thus, the monitor light Pm based on the direct light
Since the number of components for obtaining the signal can be reduced and the light is condensed by the coupling lens 25, the influence of the return light on the signal detection light-receiving element 31 can be suppressed, and the assembly accuracy can be simplified. it can. Furthermore, since the incident angle θ of the light source light with respect to the surface 28b is smaller than 45 ° and the reflected light = monitor light Pm is returned to the semiconductor laser 21 side, the signal detection light receiving element 31 and the monitor light receiving element Since the semiconductor laser 21 and the semiconductor laser 21 themselves are mounted on the same substrate 34, the number of components can be reduced, and the assemblability can be improved.

In the optical system for a CD disk, although not particularly shown, the surface 28c of the wavelength combining prism 28 is a surface portion on the semiconductor laser 22 side, and a part of the light source light from the semiconductor laser 22 is used as monitor light. The effect of reflecting light is shown.

A fourth embodiment of the present invention will be described with reference to FIG. In this embodiment, a reflection type wavelength combining prism 41 having a beam shaping function is used as the wavelength combining prism instead of the wavelength combining prism 28 in the third embodiment. That is, instead of the wavelength synthesizing prism 28 formed by combining simple triangular prisms, a wavelength synthesizing prism 41 obtained by combining trapezoidal columnar prisms on the beam synthesizing surface 42 in the same manner as in the second embodiment is used. In the optical system for DVD-based discs, the plane of incidence from the semiconductor laser 21 to the wavelength combining prism 41 and the plane of emission from the wavelength combining prism 41 to the objective lens 30 are the same.
That is, although the surface 41a is shared as an incidence surface for the semiconductor laser 21 and an emission surface for the objective lens 30,
Since the surface 41a is inclined so that the light source light incident on the surface 41a from the semiconductor laser 21 has an incident angle θ, a part of the light source light incident on the surface portion 41ab on the semiconductor laser 21 side in the surface 41a. Is reflected by the surface 41b, and this reflected light is used as the monitor light Pm.

That is, the light source light emitted from the semiconductor laser 21 passes through the hologram element 24, and is converted into parallel light by the coupling lens 25, so that the wavelength combining prism 41
And is reflected by the beam combining surface 42 and emitted to the objective lens 30 side. On the other hand, when the light is incident on the surface 41b, a part of the light from the light source is reflected by the surface 41b to form an image on the monitor light receiving element 35 as a monitor light as a parallel light flux, and is used for detection of the monitor light Pm. In the case of the present embodiment, since the incident angle θ of the light source light is larger than 45 ° and does not return to the semiconductor laser 21 side, the signal detection light-receiving element 31
Are not mounted on the same substrate.

In any case, a reflection type wavelength combining prism 41 having a beam shaping function as a wavelength combining prism.
Is applicable in the same manner as in the third embodiment.

In these embodiments, the present invention is applied to an optical pickup device for processing two kinds of wavelength light.
The present invention can be similarly applied to an optical pickup device that handles light of a different wavelength or more.

[0050]

According to the first aspect of the present invention, the number of components for obtaining the monitor light is obtained by obtaining the monitor light using the wavelength synthesizing prism for synthesizing the light source lights emitted from at least two light sources. Can be reduced, so that the assembly can be simplified and the cost can be reduced. Further, since the monitor light is generated on the optical path between the optical element such as a coupling lens and the optical recording medium, when the monitor light is detected by the monitor light receiving element, it becomes substantially parallel light or convergent light. As a result, it is possible to suppress return light that enters the signal detection light receiving element, and to maintain the function of accurately detecting a signal. Furthermore, it is also possible to reduce a high assembling position accuracy required for the light source due to the relative position between the signal light spot and the monitor light spot being determined by the optical path of the light source light.

According to the second aspect of the present invention, in the optical pickup device according to the first aspect, the monitor light is detected by detecting, as monitor light, the light source light reflected by the surface portion of the wavelength combining prism on the objective lens side. Since the number of parts to be obtained can be reduced, assembly can be simplified and cost can be reduced. Also, the light reflected from the surface of the wavelength combining prism on the objective lens side is converged by an optical element such as a coupling lens and detected by a monitor light receiving element, so that return light incident on the signal detecting light receiving element. Can be suppressed, and the function of accurately detecting a signal can be maintained.

According to the third aspect of the present invention, in the optical pickup device according to the second aspect, the number of components can be reduced by providing the signal detection light receiving element and the monitor light receiving element corresponding to each light source on the same substrate. Therefore, the assembly can be simplified and the cost can be reduced.

According to the fourth aspect of the present invention, in the optical pickup device according to the second aspect, the signal detection light receiving element and the monitor light receiving element corresponding to each light source are provided on the same substrate together with each light source. The number of parts can be further reduced, so that assembly can be simplified and cost can be reduced.

According to the fifth aspect of the present invention, in the optical pickup device according to the first aspect, the monitor light is detected by detecting, as monitor light, the reflected light reflected on the light source side surface of the wavelength combining prism. The number of parts to be obtained can be reduced, and the assembling can be simplified and the cost can be reduced. In addition, since the light is reflected by the surface portion on the light source side of the wavelength synthesizing prism or is converged by an optical element such as a coupling lens and detected by the monitor light receiving element, it is incident on the signal detection light receiving element. It is possible to suppress the returning light, and maintain the function of accurately detecting the signal.

According to a sixth aspect of the present invention, in the optical pickup device of the fifth aspect, the incident angles of the light from each light source to the light source side surface of the wavelength combining prism are each 45 ° or less, Since the monitor light is reflected on the light source side, the number of components can be reduced by providing the signal detection light receiving element corresponding to each light source and the monitor light receiving element on the same substrate, and the assembly can be simplified. Cost can be reduced.

According to a seventh aspect of the present invention, in the optical pickup device according to the fifth aspect, an incident angle of each light source light from each light source to a light source side surface portion of the wavelength combining prism is 45 ° or less, Since the monitor light is reflected on the light source side, the number of components can be further reduced by providing the signal detection light receiving element corresponding to the light source and the monitor light receiving element together with each light source on the same substrate. The attachment can be simplified and the cost can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a principle configuration diagram showing an optical pickup device according to a second embodiment of the present invention.

FIG. 3 is a principle configuration diagram showing an optical pickup device according to a third embodiment of the present invention.

FIG. 4 is a principle configuration diagram showing an optical pickup device according to a fourth embodiment of the present invention.

FIG. 5 is a diagram showing the principle of the configuration of a conventional optical pickup device.

[Explanation of symbols]

 21, 22 Light source 23 Optical recording medium 28 Wavelength combining prism 28a Object lens side surface 28b, 28c Light source side surface 30 Objective lens 31, 32 Signal detection light receiving element 33, 34 Substrate 35, 36 Monitor light receiving element 41 Wavelength combining prism 41ao Surface part on the objective lens side 41ab Surface part on the light source side

Claims (7)

[Claims] 1. A plurality of light sources which are selectively driven to emit light sources having different wavelengths, and a wavelength synthesizing prism for synthesizing the light source lights emitted from these light sources toward an optical recording medium as irradiation light. And an objective lens for condensing the irradiation light having passed through the wavelength synthesizing prism on the optical recording medium, and a signal detection light-receiving element for receiving light reflected from the optical recording medium. Light, wherein the light source light reflected by one surface of the wavelength synthesizing prism other than the irradiation light is received as monitor light by a monitoring light receiving element, and the light source light of the corresponding light source is monitored. Pickup device. 2. The optical pickup device according to claim 1, wherein the monitor light receiving element receives, as monitor light, light source light reflected by a surface portion of the wavelength combining prism on the objective lens side. 3. The optical pickup device according to claim 2, wherein the signal detection light receiving element and the monitor light receiving element corresponding to each of the light sources are provided on the same substrate. 4. The optical pickup device according to claim 2, wherein each of said light sources, said signal detecting light receiving element corresponding to said light source, and said monitoring light receiving element are provided on a same substrate. 5. The monitor light receiving element receives, as monitor light, light source light reflected by a surface portion of the wavelength combining prism on the light source side.
An optical pickup device as described in the above. 6. The signal detection light-receiving element and the monitor light corresponding to each of the light sources, wherein an incident angle of light from each of the light sources to a surface portion on the light source side of the wavelength synthesizing prism is 45 ° or less. 6. The optical pickup device according to claim 5, wherein the light receiving element is provided on the same substrate. 7. An incident angle of the light source light from each of the light sources to a surface portion on the light source side in the wavelength synthesizing prism is 45 ° or less, and each of the light sources and the signal detection light receiving element corresponding to the light source are provided. The optical pickup device according to claim 5, wherein the light receiving element for monitoring is provided on the same substrate.