JP2006073080A - Optical integrated unit and optical pickup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical integrated unit capable of reducing the size and the costs of a device and simplifying the wiring design of a substrate more, and an optical pickup device. <P>SOLUTION: A first light receiving element 17 for receiving an outward light reflected by a polarizing separation means 15 is disposed in a stem block 25a on a stem 25 provided with a semiconductor laser element 13, and the first light receiving element 17 is connected to an external circuit by an electrode pin 26 on the backside of the stem 25 as in connecting the semiconductor laser element 13 to the external circuit. Thus, the optical integrated unit 101 and the optical pickup device 12 are miniaturized to simplify wiring design. As components such as a light receiving element only stems or electrode pins are made unnecessary, low costs are expected. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical integrated unit and an optical pickup device.

  As an optical recording medium capable of recording or reproducing information, a CD (Compact Disc) in which information is recorded and reproduced by light having a wavelength of 780 nm is widely used. Recently, a DVD (Digital Versatile Disc) capable of recording more information than a CD has been used as the recording capacity of an optical recording medium increases. Information recording and reproduction with respect to a DVD is performed with light having a wavelength of 630 to 690 nm, which is shorter than the wavelength used for a CD.

  Information reproduction on the optical recording medium is performed by an optical pickup device that irradiates and reflects fine pits existing on the optical recording medium and reflects the change in the amount of reflected light as recording information. The recording of information on the optical recording medium by the optical pickup device is performed by irradiating a track groove formed of lands and grooves existing on the optical recording medium with laser light to generate pits. The optical pickup device includes, for example, a semiconductor laser element that is a light source that emits laser light, a three-beam generating diffraction element that diffracts laser light emitted from the semiconductor laser element into three beams, and light provided at a predetermined angle. Integrated unit including light separating means for transmitting or reflecting light, a light receiving element for detecting light reflected from the optical recording medium, and a diffraction element for diffracting reflected light from the optical recording medium toward the light detecting light receiving element And a condensing unit including a collimating lens that changes incident light into parallel light and an objective lens that condenses light on the information recording surface of the optical recording medium. In particular, when recording information on an optical recording medium, it is necessary to make the light emitted from the objective lens larger than that during reproduction. Therefore, it is necessary to increase the output of the semiconductor laser element and increase the optical reciprocating efficiency of the optical system. .

  The optical pickup device is usually provided with a monitor light receiving element for monitoring the amount of light emitted from the light source in order to stabilize the output from the light source to a desired value, and is detected by the monitor light receiving element. The light output of the light source is controlled by an APC (Auto Power Control) circuit in accordance with the signal to be transmitted.

  The optical pickup apparatus having such a configuration is mounted on a mobile optical information recording / reproducing apparatus such as a notebook personal computer and is widely used. Therefore, downsizing is an essential development issue.

  As a conventional technique for responding to such a problem, an integrated optical element having a structure in which reflected light from an optical recording medium is not fed back to the semiconductor laser element is mounted in order to increase the efficiency of optical round-trip use. An optical integrated unit and an optical pickup device in which a monitor light receiving element for detecting a part is integrated with the integrated optical element have been proposed (for example, see Patent Document 1).

  FIG. 10 is a schematic cross-sectional view showing a simplified configuration of the optical integrated unit 1 of Patent Document 1. As shown in FIG. The optical integrated unit 1 includes a semiconductor laser element 2 that emits laser light, a diffraction unit 3 that includes first and second diffraction elements 3a and 3b, a reflection unit 4 that includes polarization separation means 4a and reflection means 4b, and a semiconductor. A first light-receiving element 5 that is a monitor light-receiving element that detects part of the light emitted from the laser element 2, and a second light-receiving element 6 that is a light-detecting light-receiving element that detects reflected light from the optical recording medium; including. Note that the optical pickup device disclosed in Patent Document 1 includes an optical integrated unit 1 and a collimator lens and an objective lens (not shown).

The semiconductor laser element 2 is provided in the stem block 7a on the stem 7, and emits red light having a wavelength of 650 nm when the optical recording medium is a DVD, for example. The stem block 7a is provided with a second light receiving element 6 for detecting reflected light from the optical recording medium, and a cap 9 is provided on the stem 7 so as to cover the stem block 7a. In the cap 9, an opening 9a is formed in an upper portion of the stem block 7a, and the diffraction unit 3 is provided so as to seal the opening 9a. The first diffractive element 3a is provided on the surface of the diffractive unit 3 facing the semiconductor laser element 2, and branches the light emitted from the semiconductor laser element 2 into three beams of zero-order diffracted light and ± first-order diffracted light. A reflection unit 4 is provided on the side of the diffraction unit 3 opposite to the side facing the semiconductor laser element 2. The reflection unit 4 is provided with a polarization separation unit 4 a and a reflection unit 4 b in the direction of the optical axis 11 that is orthogonal to the optical axis 10 of the light emitted from the semiconductor laser element 2. As the polarization separation means 4a, a polarization beam splitter that transmits only P-polarized light and reflects S-polarized light is used. Further, the reflection unit 4 is provided with a first light receiving element 5 which is a monitor light receiving element in an integrated manner with the reflection unit 4 in a direction in which the light emitted from the semiconductor laser element 2 is reflected by the polarization separation means 4 a and travels. . The semiconductor laser element 2 is electrically connected to the electrode pins 8 by a gold wire, and is not shown in the figure with an FPC (Flexible Print).
Circuit) It is connected to an external circuit through electrical wiring such as a substrate.

  The light emitted from the semiconductor laser element 2 passes through the first diffraction element 3a, and a part of the light is reflected by the polarization separating means 4a. The remaining light is transmitted through the polarization separating means 4a and emitted from the reflection unit 4, and is condensed on the optical recording medium by a condensing means (not shown). The light condensed on the optical recording medium is reflected by the optical recording medium, passes through the condensing means again, and enters the reflection unit 4. The light incident on the reflection unit 4 is reflected by the polarization separation means 4a. This reflected light is further reflected by the reflecting means 4b, passes through the second diffraction element 3b, and enters the second light receiving element 6 which is a light detecting light receiving element. On the other hand, a part of the light emitted from the semiconductor laser element 2 and transmitted through the first diffractive element 3a and reflected by the polarization separating means 4a is received by the first light receiving element 5 which is a light receiving element for monitoring. Based on this, an output detection signal of the semiconductor laser element 2 is obtained.

  In such an optical integrated unit, the first light receiving element 5 which is a light receiving element for monitoring is integrally provided in the reflection unit 4 of the optical integrated unit 1 as the polarization separating means, and the problem of the installation space of the optical member is solved. Therefore, it is said that downsizing can be realized.

  However, the light receiving element for monitoring included in the conventional optical integrated unit includes at least a Si photodiode and a semiconductor wafer chip to which an electrode is bonded, and the electrode is connected to the electrode pin of the light receiving element stem or the lead frame by a gold wire or the like. It is connected and molded by translucent epoxy resin or the like. Therefore, if the size of the monitor light receiving element stem and the electrode pin is taken into account, the monitor light receiving element has a larger outer dimension than the reflection unit. Therefore, even if the monitor light receiving element is integrated with the reflection unit, Miniaturization of the optical integrated unit cannot be realized. Furthermore, since a part such as a stem and a lead frame dedicated to the light receiving element for monitor detection is required, there is a problem that the cost is increased.

  Further, the elements other than the light receiving element for monitoring in the normal optical integrated unit and the external circuit are connected through electrode pins provided on the back side of the stem. However, since only the stem electrode for the monitor light receiving element is separated and independent, electrical connection between the monitor light receiving element and the external circuit must be made by a connecting member different from the electrode pin, and it is connected to the optical integrated unit. There is a problem that the design of a wiring board such as an FPC board becomes complicated.

JP 2003-132583 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide an optical integrated unit and an optical pickup device that can reduce the size and cost of the device and can further simplify the wiring design of the substrate.

The present invention relates to an optical integrated unit that emits light toward an optical recording medium on which information is recorded or reproduced by light and receives reflected light from the optical recording medium.
At least a light source that emits light;
A light separating means for separating the outward light emitted from the light source and the backward light emitted from the light source and reflected by the optical recording medium;
First reflecting means for further reflecting the outward light reflected by the light separating means;
A first light receiving element that receives forward light reflected by the first reflecting means,
The first reflecting means and the first light receiving element so that the traveling direction of the forward light incident on the first light receiving element is opposite or close to the traveling direction of the forward light emitted from the light source. Is an optical integrated unit.

In the present invention, the first reflecting means and the first light receiving element are:
The optical integrated unit is characterized in that the incident light of the outward light incident on the first light receiving element is arranged so as to have an inclination angle.

  Further, in the invention, the first reflecting means is provided so as to reflect only a part of the light emitted from the light source and reflected by the light separating means toward the first reflecting means. Is a unit.

In the present invention, a shielding member that shields outgoing light is provided between the light separating means and the first reflecting means or between the first reflecting means and the first light receiving element,
The shielding member is an optical integrated unit in which an opening that transmits a part of forward light is formed.

  Further, the present invention is the optical integrated unit characterized in that the first reflecting means has a reflecting surface, and the reflectance on the reflecting surface is different depending on the position in the reflecting surface.

In the present invention, the reflecting surface of the first reflecting means is
The optical integrated unit is characterized in that the reflectance is reduced in one direction from one end of the reflecting surface away from the light separating means to the other end near the light separating means.

  In the invention, it is preferable that the first reflecting means has a reflecting surface, and the reflectance of the reflecting surface is highest near the center of the reflecting surface and becomes low when separated from the center. It is an optical integrated unit.

  The present invention is also an optical integrated unit characterized in that a first diffractive means for diffracting the forward light is provided in the optical path of the forward light between the first reflecting means and the first light receiving element. .

In the present invention, the light receiving surface of the first light receiving element is:
The optical integrated unit is located closer to the optical recording medium with respect to the light emitting surface of the light source.

The present invention also provides a second light receiving element for receiving the return light reflected from the optical recording medium, the second light receiving provided on a plane parallel to a plane perpendicular to the optical axis of the forward light provided with the light source. Elements,
A second reflecting means for reflecting the return light reflected from the optical recording medium toward the second light receiving element;
A second diffracting means provided between the second reflecting means and the second light receiving element and diffracting the light reflected by the second reflecting means toward the second light receiving element;
The light separation means is
The integrated optical unit is provided so as to reflect the return light reflected by the optical recording medium toward the second reflecting means.

The present invention also includes third diffracting means for diffracting the light reflected from the optical recording medium toward the first light receiving element,
The optical integrated unit is characterized in that the second diffracting means and the third diffracting means are provided in the same member.

Moreover, this invention is equipped with the optical integrated unit as described in any one of the above,
A condensing unit arranged between the optical integrated unit and the optical recording medium and condensing the light emitted from the optical integrated unit on the optical recording medium;
An optical pickup device comprising a quarter wave plate disposed between the optical integrated unit and the light collecting means.

  According to the present invention, the first light receiving element that receives the outward light reflected by the light separating means is configured such that the outward light emitted from the light source is reflected by the light separating means and the reflecting means and emitted from the light source. It is provided so as to be incident from the opposite direction with respect to the traveling direction of the forward light immediately after. Therefore, since the connection between the light receiving element and the external circuit can be made from the electrode pins provided on the back side of the stem in the same manner as the connection between the light source and the external circuit, the size can be reduced and the wiring design can be simplified. Further, since parts such as a stem and electrode pins dedicated to the first light receiving element are not required, cost reduction can be expected.

  According to the invention, the first light receiving element is arranged such that the incident direction of the forward light incident on the light receiving element has an inclination angle. Therefore, it is possible to prevent the outward light slightly reflected by the light receiving element from entering the light emitting surface of the light source again, and improve the light output control accuracy of the light source.

  According to the invention, the first reflecting means is provided so as to reflect only a part of the light emitted from the light source and reflected by the light separating means toward the reflecting means. It is possible to prevent the light from entering the light source and improve the accuracy of the light output control of the light source. In addition, since the irradiation area of the light incident on the first light receiving element can be reduced, the light receiving segment of the light receiving element can be reduced, and the apparatus can be further reduced by downsizing the light receiving element. At the same time, the response speed of the light receiving element is increased, and high-speed recording on the optical recording medium is possible.

  According to the invention, the shielding member for shielding the forward light is provided between the light separating means and the first reflecting means, or between the first reflecting means and the first light receiving element, and the shielding member is provided. Since an opening for transmitting a part of the outward light is formed, it is possible to prevent the reflected outward light from entering the light source and to improve the accuracy of light output control of the light source. In addition, since the irradiation area of the light incident on the first light receiving element can be reduced, the light receiving segment of the light receiving element can be reduced, and the apparatus can be further reduced by downsizing the light receiving element. At the same time, the response speed of the light receiving element is increased, and high-speed recording on the optical recording medium becomes possible.

  According to the invention, the first reflecting means has a reflecting surface, and the reflectance on the reflecting surface is different depending on the position in the reflecting surface, so that the light source of the first light receiving element is used. It is possible to increase the amount of incident light at a far portion and reduce the amount of light incident on a portion close to the light source of the first light receiving element. Therefore, it is possible to prevent the reflected forward light from entering the light source and improve the light output control accuracy of the light source.

  According to the invention, the reflection surface of the first reflection means has a reflectance that decreases in one direction from one end of the reflection surface away from the light separation means toward the other end near the light separation means. Therefore, it is possible to prevent the reflected outward light from entering the light source, and to improve the accuracy of the light output control of the light source.

  According to the present invention, the first reflecting means has a reflecting surface, and the reflectance of the reflecting surface is the highest near the center of the reflecting surface and is lowered when it is separated from the center of the reflecting surface. Therefore, it is possible to prevent the outward light from entering the light source, and to improve the accuracy of the light output control of the light source.

  According to the invention, the diffractive means for diffracting the forward light is provided in the optical path of the forward light between the first reflecting means and the first light receiving element, and the radiation angle of the light transmitted by the diffractive means is set. Since the light can be made small, the light can be stably incident on the first light receiving element, the reflected forward light can be prevented from entering the light source, and the light output control accuracy of the light source can be improved. Can be improved. Further, since the irradiation area of the light incident on the light receiving element can be reduced, the light receiving segment of the light receiving element can be reduced, and the device can be further reduced by downsizing the light receiving element. The response speed of the light receiving element is increased, and high-speed recording on the optical recording medium becomes possible.

  According to the invention, when the light receiving surface of the first light receiving element is positioned closer to the optical recording medium with respect to the light emitting surface of the light source, the distance between the first reflecting means and the first light receiving element is shortened. . The shorter the distance from the reflecting means, the smaller the light irradiation area to the light receiving element, so that the forward light reflected by the reflecting means can be prevented from entering the light source, and the light output control accuracy of the light source can be improved. it can. In addition, since the irradiation area of the light incident on the first light receiving element can be reduced, the light receiving segment of the light receiving element can be reduced, the light receiving element can be further downsized, and The response speed is increased, and high-speed recording on an optical recording medium is possible.

  According to the invention, the second light receiving element for receiving the reflected light from the optical recording medium is provided on a plane parallel to the plane perpendicular to the optical axis of the forward light, and the second light receiving element and the external circuit are provided. Since the connection can be made from the back side of the stem by the electrode pins in the same manner as the connection between the light source and the external circuit, the apparatus can be miniaturized and the wiring design can be simplified.

  Further, according to the present invention, the first diffracting means for diffracting the forward light and the second diffracting means for diffracting the return light are provided in the same member. Since it can be simplified, the cost can be reduced.

  According to the invention, the optical pickup device can be downsized by using the optical integrated unit described in any one of the above in the optical pickup device.

  FIG. 1 is a schematic cross-sectional view showing a simplified configuration of an optical integrated unit 101 according to an embodiment of the present invention. FIG. 2 is a simplified configuration of an optical pickup device 12 including the optical integrated unit 101 shown in FIG. It is a schematic sectional drawing shown.

  The optical integrated unit 101 includes a semiconductor laser element 13 serving as a light source that emits light toward the optical recording medium 21, a first light receiving element 17 that is a light receiving element that receives forward light reflected by the reflecting means, and an optical recording. A second light receiving element 20 that is a second light receiving element that receives the return light reflected from the medium 21, and a diffractive means that is provided in the optical path of the forward light between the reflecting means and the light receiving element and diffracts the forward light. Diffracting unit 28 including first diffracting means 14 and second diffracting means 19 which is diffracting means for diffracting the return path light reflected from optical recording medium 21, forward path light emitted from semiconductor laser element 13, and light source Polarization separating means 15 that is a light separating means for separating the return light emitted from the optical recording medium 21 and reflected by the optical recording medium 21, and the reflecting means for further reflecting the forward light reflected by the polarization separating means 15 And a reflection unit 29 comprises a second reflecting means 18 is another reflecting means for reflecting a return light reflected from a certain first reflecting means 16 and the optical recording medium 21 to the second light receiving element 20.

  Here, the XYZ triaxial directions shown in FIGS. 1 and 2 will be described. The Z-axis direction is defined as a direction that coincides with the direction of the optical axis 55 of the light emitted from the semiconductor laser element 13. The X-axis direction is one of XY two axes representing two-dimensional plane coordinates, which are plane coordinates orthogonal to the Z-axis. This X-axis direction is defined as the first light receiving element 17 and the first light receiving element 17 in the optical integrated unit 101. It is defined as a direction that coincides with the arrangement direction of the two light receiving elements 20. The Y-axis direction is the remaining one axis representing two-dimensional plane coordinates that are plane coordinates orthogonal to the Z axis, and is defined as a direction orthogonal to the previous X axis direction.

  The semiconductor laser element 13 emits red light having a wavelength of 650 nm for DVD, for example. The semiconductor laser element 13 is mounted on a stem block 25 a on the stem 25.

  The first light receiving element 17 is a light receiving element for monitor detection that receives light and converts it into an electrical signal. The first light receiving element 17 receives a part of the forward light emitted from the semiconductor laser element 13 and monitors the light output. The detected light output of the semiconductor laser element 13 is input to an APC circuit which is a power controller (not shown) in response to the light detection output, and the APC circuit is configured so that the amount of light emitted from the semiconductor laser element 13 becomes a predetermined amount. The drive current of the semiconductor laser element 13 is controlled. Since the relationship between the drive current of the semiconductor laser element 13 and the optical output characteristics changes depending on the environmental temperature, aging, etc., monitoring the output of the semiconductor laser element 13 and controlling the output to stabilize the recording of information / Essential for regeneration.

  The second light receiving element 20 is provided with a plurality of light receiving segments (not shown). The reflected light from the optical recording medium 21 is received by each light receiving segment, and the received light amount is converted into a current to detect the reflected light. Get. The detection signal is processed by an external circuit (not shown), and focus servo control and tracking servo control are simultaneously performed by generating a focus error signal and a tracking error signal, thereby reproducing an RF signal as an information signal from an optical recording medium or optically. Information signals are recorded on the recording medium. The first light receiving element 17 and the second light receiving element 20 are mounted on the stem block 25 a and are arranged in a direction symmetric with respect to the optical axis 55 emitted from the semiconductor laser element 13. Each of the semiconductor laser element 13, the first light receiving element 17, and the second light receiving element 20 has an electrode (not shown), and the electrode and the electrode pin 26 are connected by a gold wire so that the APC circuit and the servo signal described above are connected. Electrical connection with external circuits such as a processing circuit and a reproduction signal processing circuit is possible.

  A cap 27 is placed on the stem 25 so as to cover the stem block 25a and an inner lead pin (not shown) of the metal pin 26 connected to the gold wire. An opening is formed in the cap 27 so that light emitted from the semiconductor laser element 13 and light incident on the first and second light receiving elements 17 and 20 can pass therethrough. The diffraction unit 28 is provided so as to seal the opening provided in the cap 27. The diffraction unit 28 is provided with first diffraction means 14 and second diffraction means 19. The first diffracting means 14 is provided at a position where light emitted from the semiconductor laser element 13 is incident on the surface of the diffraction unit 28 facing the semiconductor laser element 13. The first diffracting means 14 is a diffraction grating, and diffracts and splits the light emitted from the semiconductor laser element 13 into three beams of 0th order diffracted light and ± 1st order diffracted light. The light diffracted into three beams is used to detect a tracking error signal that detects a change in the amount of reflected light caused by a relative position shift between the irradiation position of the three beams on the optical recording medium 21 and the track formed on the optical recording medium 21. Used. The second diffracting means 19 is provided at a position close to the second light receiving element 20 on the surface of the diffractive unit 28 opposite to the side facing the semiconductor laser element 13. The second diffracting means 19 is a diffractive element that divides the reflected light from the optical recording medium 21 into a plurality of beams and reflects the divided beams onto the plurality of light receiving segments of the second light receiving element 20.

  A reflection unit 29 is provided in contact with the surface of the diffraction unit 28 opposite to the side facing the semiconductor laser element 13. The reflection unit 29 is provided with the first reflection means 16, the polarization separation means 15, and the second reflection means 18 side by side in a direction orthogonal to the axis 55 of the light emitted from the semiconductor laser element 13.

  The polarization separation means 15 is a first reflection means 16 provided in parallel with the polarization separation means 15 in the direction substantially orthogonal to the axis 55 of the outgoing light with respect to the outgoing light emitted from the semiconductor laser element 13. The polarized light in a direction different from the polarized light is transmitted toward the optical recording medium 21. The reflected light reflected by the optical recording medium 21 and incident on the polarization separating means 15 is reflected to the second reflecting means 18 provided in a direction perpendicular to the axis 55 of the reflected light and aligned with the polarization separating means 15. It is arranged to let you. As the polarization separating means 15, for example, a polarization beam splitter having a characteristic of transmitting almost 100% of the P-polarized light of the outgoing light emitted from the semiconductor laser element 13 and reflecting almost 100% of the S-polarized light is used. If the light intensity on the optical recording medium 21 and the light intensity incident on the second light receiving element 20 are within a range that allows stable reproduction or recording, the polarization separating means 15 is a polarization beam splitter or the like. Without being limited to the separation optical member, it may be a light separation means such as a half mirror capable of selecting a desired transmittance and reflectance.

  As described above, the first reflecting means 16 is disposed in the reflecting unit 29 in the direction in which the forward light emitted from the semiconductor laser element 13 is reflected by the polarization separating means 15 and faces the polarization separating means 15. The reflection film 16a is provided so as to have an inclination of 45 degrees with respect to the optical axis of the reflected light of the forward path light by the polarization separation means 15. In order to adjust the position of the incident light on the second light receiving element 20 with high accuracy, it is preferable that the polarization separating means 15 and the second reflecting means 18 are integrated, but the incident light on the first light receiving element 17 is integrated. Since the position adjustment does not need to be performed as strictly as the incident light position adjustment accuracy to the second light receiving element 20, the polarization separating means 15 and the first reflecting means 16 are integrated as shown in FIG. There is no need. The reflective film 16a of the first reflecting means 16 has a desired reflectance. For example, FIG. 3 is a diagram showing the reflectance distribution of the reflective film 16a used in the first reflecting means 16 of the optical integrated unit 101 of the present invention. The distance in the X direction between one end and the other end of the reflective film 16a is shown, and the vertical axis shows the reflectance of the reflective film.

  The reflectance of the reflective film 16a having the reflectance distribution shown in FIG. 3 is constant from one end to the other end of the reflective film 16a, and the photoelectric conversion rate of the first light receiving element 17 and the current required for the APC circuit at the subsequent stage are If it is within the allowable value, it is not necessary that the reflectance is 100%, and the reflectance may be partially transmitted.

  4 and 5 are diagrams showing the reflectance distribution of the reflective film 16a used in the first reflecting means 16 of the optical integrated unit 101 of the present invention. The reflective film 16a in FIG. 3 is merely an example, and as shown in FIG. 4, for example, the reflectance is high only in a predetermined region near the optical axis 56 on the reflective film 16a, and the reflectance is small in other regions. As shown in FIG. 5, it may be a reflectance distribution in which the reflectance is uniformly reduced in the + X direction in the reflective film 16a. In the reflectance distribution of FIG. 4, the intensity distribution of light incident on the reflective film 16a is the highest in the vicinity of the optical axis 56, and becomes lower as the distance from the optical axis 56 increases. Therefore, only the light near the intensity distribution center of the incident light is used. In addition, since the light at the edge portion with low intensity is not used, it is possible to prevent the reflected light from entering the semiconductor laser element 13. The reflectance distribution of FIG. 4 is merely an example, and for example, it is not necessary to have a symmetrical shape about the center of the optical axis 56, and it is sufficient that the reflectance is set to be lower as it is closer to the semiconductor laser element 13. Similarly, in the reflectance distribution of FIG. 5, the intensity distribution of the light reflected by the reflecting film 16a becomes smaller as it is closer to the semiconductor laser element 13, and the reflectance of the reflecting film 16a is decreased as shown in FIG. If the reflectance distribution is 0%, it can be prevented from entering the semiconductor laser element 13. The reflectance distribution in FIG. 5 is merely an example, and the reflectance distribution may be curved, or may have a partially constant reflectance as shown in FIG.

  The second reflecting means 18 provided in the reflecting unit 29 is provided on the side where the light reflected by the optical recording medium 21 is further reflected by the polarization separating means 15 and travels, and the incident light is reflected by the second light receiving element 20. It arrange | positions so that it may reflect in the direction of.

  The optical pickup device 12 including the optical integrated unit 101 includes an optical integrated unit 101, a quarter-wave plate 22 disposed between the optical integrated unit 101 and the optical recording medium 21, a collimator lens 23, and an actuator (not shown). And an objective lens 24 mounted on the vehicle.

  The optical recording medium 21 is, for example, a DVD, has a thin disk shape with a diameter of 12 cm, is formed by depositing aluminum on the surface of a polycarbonate substrate, and coating a protective layer of resin on the aluminum deposited layer. The

  The quarter wavelength plate 22 converts P-polarized light, which is linearly polarized light transmitted by the polarization separation element 15, out of the outgoing light emitted from the semiconductor laser element 13 into circularly polarized light, and is reflected by the optical recording medium 21. The circularly polarized light of the return path light is converted to S-polarized light that is linearly polarized light. The collimating lens 23 converts the forward light transmitted through the quarter wavelength plate 22 into parallel light. The objective lens 24 condenses the outward light emitted from the semiconductor laser element 13 on the information recording surface on the optical recording medium 21 to form a light spot on the information recording surface.

  Here, a manufacturing method of the optical integrated unit 101 and the optical pickup device 12 of the present invention having the above-described configuration will be described.

  First, the semiconductor laser element 13, the first light receiving element 17 and the second light receiving element 20 are directly die-bonded to the stem block 25 a on the stem 25. Subsequently, the electrode of each element and the electrode pin 26 are connected with a gold wire (not shown), and a cap 27 having an opening is placed on the stem 25. A diffraction unit 28 including a first diffractive means 14 and a second diffractive means 19 is provided thereon so as to seal the opening, and further, a polarized light separating means 15, a first reflecting means 16 and a second diffractive unit 28 are provided thereon. A reflection unit 29 including the reflection means 19 is provided. The plane on the stem block 25a where the first light receiving element 17 and the second light receiving element 20 are installed is a plane perpendicular to the optical axis 55 of the light emitted from the semiconductor laser element 13. In FIG. 1, the first light receiving element 17 and the second light receiving element are installed on the same plane on the stem block 25a, but the height in the Z-axis direction may be different without being limited thereto. In order to prevent the light reflected by the first reflecting means 16 from entering the semiconductor laser element 13, the light receiving surface 30 b of the first light receiving element 17 is compared with the light emitting surface 30 a of the semiconductor laser element 13. It is desirable to be close to the position. Further, a distance is provided as much as possible between the polarization separating means 15 and the first reflecting means 16, so that the emitted light from the semiconductor laser element 13 does not directly enter the first reflecting means 16, and the first reflecting means 16 The reflected forward light is arranged so as not to enter the semiconductor laser element 13.

  The diffraction unit 28 and the reflection unit 29 are allowed to move in the XY plane without being fixed to the cap 27. Such an optical integrated unit 101 is incorporated together with the quarter-wave plate 22, the collimating lens 23, and the objective lens 24, thereby forming the optical pickup device 12.

The optical pickup device 12 is operated so that the second light receiving element 17 that is a light detecting light receiving element can stably detect a focus error signal, a servo signal that is a tracking error signal, a reproduction signal that is an RF signal, and the like. The diffraction unit 28 and the reflection unit 29 are appropriately adjusted in position in the XY plane, and the diffraction unit 28 and the reflection unit 29 are fixed with an adhesive. Here, when the diffraction unit 28 and the reflection unit 29 change from a predetermined position, the amount of light incident on the first light receiving element 17 changes, and when controlled by the APC circuit, the drive current of the semiconductor laser element 13 also changes. Therefore, the electric signal output from the first light receiving element 17 also varies. In addition, when the amount of light incident on the first light receiving element 17 is small, the drive current of the semiconductor laser element 13 controlled by the APC circuit becomes extremely large, so that the light output exceeds the rating, and the semiconductor laser element 13 is output. May cause deterioration. Therefore, when the diffraction unit 28 and the reflection unit 29 are positioned and assembled, the ACC (Auto Current) is required until the diffraction unit 28 and the reflection unit 29 are bonded and fixed.
It is preferable to control the drive current of the semiconductor laser element 13 to a constant current by a control circuit. The above-described method is an example of the light output control of the semiconductor laser element 13 when adjusting the positions of the diffraction unit 28 and the reflection unit 29. For example, the light output control of the semiconductor laser element 13 by the APC circuit In addition to the first light receiving element 17, the light output control by the APC circuit may be performed by installing a monitoring light receiving element (not shown) and an APC circuit outside the integrated optical unit 101. If the reflectance of the reflection film 16a of the optical integrated unit is not 100%, the external light receiving element for monitoring is installed at a position to receive a partially transmitted light, so that the outward light of the semiconductor laser element 13 can be obtained. Can be monitored. As another method, a half mirror is installed between the optical integrated unit 101 and the quarter-wave plate 22 to reflect a part of the forward light emitted from the polarization separating means 15 and to reflect the reflected light. Even if it is installed in such a direction, it is possible to monitor the optical output of the forward light from the semiconductor laser element 13.

Hereinafter, operations of the optical integrated unit 101 and the optical pickup device 12 will be described.
The forward light emitted from the semiconductor laser element 13 passes through the first diffracting means 14, is diffracted and branched into zero-order diffracted light and ± first-order diffracted light, and enters the polarization separating means 15. Most of the polarization direction of the laser light emitted from the semiconductor laser element 13 is P-polarized light, but also includes some S-polarized light. The polarization separation means 15 transmits P-polarized light that occupies most of the laser light emitted from the semiconductor laser element 13 and reflects slightly contained S-polarized light.

  The P-polarized light of the outgoing light emitted from the semiconductor laser element 13 and transmitted through the polarization separating means 15 is converted into circularly polarized light through the quarter-wave plate 22, converted into parallel light through the collimator lens 23, and then the objective lens. 24 is focused on the information recording surface of the optical recording medium 21. The light condensed on the optical recording medium 21 is reflected by the optical recording medium 21, passes through the objective lens 24 and the collimating lens 23, passes through the quarter wavelength plate 22, and is converted into S-polarized light.

  The return light reflected by the optical recording medium 21 and converted into S-polarized light by the quarter-wave plate 22 enters the polarization separating means 15. The light converted to S-polarized light is reflected toward the second reflecting means 18 by the polarization separating means 15, further reflected by the second reflecting means 18, and incident on the second diffracting means 19, and is diffracted into a plurality of lights. The The return light diffracted by the second diffracting means 19 into a plurality of lights enters the second light receiving element 20 and is converted into an electrical signal. With this electrical signal, a focus error signal and a tracking error signal are generated by a subsequent circuit (not shown), and information on the optical recording medium 21 is reproduced or recorded by performing focus servo control and tracking servo control.

  On the other hand, the S-polarized light of the forward path light reflected by the polarization separation unit 15 is further reflected by the first reflection unit 16 and received by the first light receiving element 17. The detection output of the outward light received by the first light receiving element 17 is given to the APC circuit, and the APC circuit controls the light output of the semiconductor laser element 13 based on the detection output.

  In the optical integrated unit 101 of the present embodiment, the first light receiving element 17 that is a light receiving element for monitoring is provided in a stem block 25a where the semiconductor laser element 13 is provided. Therefore, the connection between the first light receiving element 17 and the external circuit can be performed by the electrode pin 26 provided on the back side of the stem 25 in the same manner as the connection between the semiconductor laser element 13 and the external circuit. Therefore, since no external wiring and connection terminals for connecting the first light receiving element 17 to an external circuit are required, the apparatus can be reduced in size and the wiring design can be simplified. Moreover, the number of members can be reduced and cost reduction can be realized.

  Also, the optical pickup device 12 including the optical integrated unit 101 according to the present embodiment can be downsized.

  In the optical pickup device 12, when the light emitted from the semiconductor laser element 13 returns and enters the semiconductor laser element 13 as reflected light, noise is generated in the emitted light from the semiconductor laser element 13. In general, a semiconductor laser element is a resonator in which a light emitting surface and a reflective film on the back surface of the light emitting surface are provided, and the reflectance of the light emitting surface is lower than the reflectance of the back surface. The light generated inside is amplified, and laser light is emitted from the light emitting surface. As described above, since the reflectance of the light emitting surface of the semiconductor laser device is low, when the feedback light is incident on the light emitting surface, the feedback light is amplified inside the device and acts as noise, so that the operating characteristics fluctuate. It becomes difficult to control the light output accurately. Therefore, in order to improve the accuracy of light output control from the semiconductor laser element, it is necessary to design the reflected light so that it does not enter the semiconductor laser element.

  Here, as shown in FIG. 1, when the first light receiving element is installed on a plane perpendicular to the optical axis 55 of the light emitted from the semiconductor laser element 13, the first light receiving element 17 is diffracted more than the semiconductor laser element 13. The forward light reflected by the first reflecting means 16 is incident on the semiconductor laser element 13 by being arranged near the unit 28 and providing as much distance as possible between the polarization separating means 15 and the first reflecting means 16. Can be prevented.

  Furthermore, by using a reflective film having a reflectance distribution such that the reflectance on the reflecting surface varies depending on the position in the reflecting surface, the amount of light received in the region near the semiconductor laser element 13 of the first light receiving element 17 can be reduced. Since it can be made small, it is possible to prevent the outward light from entering the semiconductor laser element. In particular, as shown in FIG. 4, if the reflectance distribution is such that the reflectance is high only in the vicinity of the center of the reflective film 16a and does not reflect in a region away from the vicinity of the center, the light reflected by the reflective film 16a. In the vicinity of the center of the optical axis, which is the intersection of the shaft 57 and the light receiving surface 30b of the first light receiving element 17, the amount of received light is large. Incoming light can be prevented from entering.

  FIG. 6 is a schematic cross-sectional view showing a simplified configuration of the optical integrated unit 31 according to the second embodiment of the present invention. The optical integrated unit 31 of the present embodiment is similar to the optical integrated unit 101 of the first embodiment described above, and corresponding portions are denoted by the same reference numerals and description thereof is omitted.

  The optical integrated unit 31 of this embodiment is characterized in that the light receiving surface 30b of the first light receiving element 17 has an inclination angle with respect to a plane perpendicular to the optical axis 55 of the light emitted from the semiconductor laser element 13. And

  The light receiving surface 30b of the first light receiving element 17, the cap installation surface 28a of the diffraction unit 28, and the reflection unit installation surface 28b are provided with an antireflection film that prevents reflection and transmits light. However, even if there is an antireflection film, it is difficult to transmit 100% of light, and it is actually reflected slightly. Therefore, the light reflected by the light receiving surface 30 b of the first light receiving element 17 causes multiple reflection such that the light is further reflected by the cap installation surface 28 a of the diffraction unit 28. Further, due to the miniaturization of the optical integrated unit 101, there is a limit in installing the first reflecting means 16 and the polarized light separating means 15 apart from each other. Therefore, if the light receiving surface 30b of the first light receiving element 17 and the cap installation surface of the diffraction unit 28 are parallel, the light that is diverging light reflected by the first reflecting means 16 is small in the optical integrated unit. The multiple reflections are repeated as much as possible, and the light having repeated the multiple reflections easily enters the semiconductor laser element 13.

  Therefore, since the light receiving surface 30b of the first light receiving element is parallel to the stem installation surface, the optical axis 57 of the light reflected by the first reflecting means 16 on the installation surface 30e of the first light receiving element 17 of the stem block 25a. The optical axis 58 of the light reflected by the light receiving surface 30b of the first light receiving element 17 is tilted so as to slightly rotate counterclockwise in the XZ plane, so that multiple reflected light enters the semiconductor laser element 13. Can be prevented. Rotation of the installation surface 30e of the first light receiving element 17 on the stem block 25a in the XZ plane is an example. Although not shown, in addition to the rotation of the XZ plane, the rotation is also performed in the XY plane. In addition, it is possible to prevent the multiple reflected light from entering the semiconductor laser element 13.

  FIG. 7 is a schematic cross-sectional view showing a simplified configuration of the optical integrated unit 41 according to the third embodiment of the present invention. The optical integrated unit 41 according to the present embodiment is similar to the optical integrated unit 101 according to the first embodiment described above, and corresponding portions are denoted by the same reference numerals and description thereof is omitted.

  The optical integrated unit 41 of the present embodiment is characterized in that the first reflecting means 42 provided in the reflecting unit 43 is arranged so as to reflect only a part of the forward light reflected by the polarization separating means 15. .

  The first reflecting means 42 is disposed in the reflecting unit 43 in the direction in which the forward light emitted from the semiconductor laser element 13 is reflected by the polarization separating means 15 and travels. The first reflecting means 42 includes a reflecting film 42a having a desired reflectance, and the reflecting film 42a is formed having a reflectance distribution as shown in FIG. The first reflecting means 42 is disposed so as to reflect only the portion near the optical recording medium in the forward light reflected by the polarization separating means 15 toward the first light receiving element 17.

  Laser light emitted from the semiconductor laser element 13 passes through the first diffracting means 14 and enters the polarization separating means 15.

  The outgoing S-polarized light emitted from the semiconductor laser element 13 and incident on the polarization separation means 15 is reflected by the polarization separation means 15, and only the portion of the reflected light near the optical recording medium is incident on the first reflection means 32. Then, it is reflected and received by the first light receiving element 17. The remaining light is emitted from the reflection unit 43.

  Since the optical integrated unit 41 of the present embodiment is provided so as to reflect only a part of the light emitted from the semiconductor laser element 13 and reflected by the polarization separating means 15 to the first light receiving element 17, the reflected forward path The incident area of light with respect to the first light receiving element 17 is reduced, and the reflected forward light can be prevented from entering the semiconductor laser element 13.

  Further, since the incident area of the reflected forward light with respect to the first light receiving element 17 is reduced, the diameter of the light spot incident on the first light receiving element 17 is reduced, so that the light receiving segment of the first light receiving element 17 is reduced. Is possible. Therefore, since the size of the first light receiving element 17 can be reduced and the response speed can be increased, the entire apparatus can be downsized and high-speed recording onto the optical recording medium can be realized.

  In the optical integrated unit 41 of the present embodiment, the first reflecting means 42 is arranged so as to reflect only a part of the light reflected by the polarization separating means 15 and the reflected light is transmitted to the semiconductor laser element 13. The position near the diffraction unit 28 may be used as long as it is not incident. However, in that case, the reflection angle of the reflection film 42a is set so that the reflected light does not enter the semiconductor laser element 13 if the distance between the first reflection means 42 and the polarization separation means 15 is sufficiently long or close. It is necessary to install the first reflecting means 42 having a large.

  Further, when the light receiving surface 30b of the first light receiving element 17 is tilted like the optical integrated unit 31, further forward light is prevented from entering the semiconductor laser element 13, and the amount of incident light to the first light receiving element 17 is reduced. It can be stabilized.

  Even if the reflective film 42a having the reflectance distribution shown in FIG. 5 is used, it is possible to prevent the outward light from entering the semiconductor laser element 13 and to stabilize the light quantity of the incident light to the first light receiving element 17. Can do.

  FIG. 8 is a schematic cross-sectional view showing a simplified configuration of the optical integrated unit 51 according to the fourth embodiment of the present invention. The optical integrated unit 51 of this embodiment is similar to the optical integrated unit 101 of the above-described embodiment, and corresponding portions are denoted by the same reference numerals and description thereof is omitted.

  In the optical integrated unit 51 of the present embodiment, a shielding member 52 that shields outgoing light, and an opening 52a that is formed in the shielding member 52 and transmits part of the outgoing light, includes the first reflecting means 16 and the first light receiving unit. It is provided in the optical path of forward light between the element 17 and the element 17.

  The shielding member 52 is provided in the optical path of forward light between the first reflecting means 16 and the first light receiving element 17 on the side contacting the diffraction unit 28 of the reflecting unit 53. Further, the shielding member 52 has an opening 52 a that transmits only a part of the forward light near the optical axis center of the forward light reflected by the first reflecting means 16. The above structure is an example, and the opening 52a may be provided so as to be shifted from the center of the optical axis so that the light passing through the opening 52a is separated from the semiconductor laser element 13. Further, the position of the shielding member 52 may be installed on the joint surface 53 a between the polarization separating means 15 and the reflecting means 16. However, if the surface of the first reflecting means 16 that contacts the diffraction unit is a polished surface, the light reflected by the reflective film 16a is easily reflected by the shielding member 52 even if the shielding member 52 that is difficult to reflect is installed. It is better to leave it on the sand surface.

  The S-polarized light of the outgoing light emitted from the semiconductor laser element 13 and incident on the polarization separation means 15 is reflected by the polarization separation means 15 and further reflected by the first reflection means 16. A part of the light reflected by the first reflecting means 16 passes through the opening 52 a of the shielding member 52 and enters the first light receiving element 17.

  Thus, since the irradiation area of the light incident on the first light receiving element 17 can be reduced, the incidence of light on the semiconductor laser element 13 can be prevented. Furthermore, since the light receiving segment of the first light receiving element 17 can be reduced, the first light receiving element 17 can be further miniaturized and the response speed can be increased.

  Further, if the light receiving surface 30b of the first light receiving element 17 is tilted as in the optical integrated unit 31 of the second embodiment, it is possible to prevent the forward light from entering the semiconductor laser element 13 and to prevent the first light receiving. The amount of incident light on the element 17 can be stabilized.

  FIG. 9 is a schematic cross-sectional view showing a simplified configuration of the optical integrated unit 61 according to the fourth embodiment of the present invention. The optical integrated unit 61 of this embodiment is similar to the optical integrated unit 101 of the above-described embodiment, and corresponding portions are denoted by the same reference numerals and description thereof is omitted.

  The optical integrated unit 61 of this embodiment includes a third diffractive unit 62 that is provided in the optical path of the forward light between the first reflecting means 16 and the first light receiving element 17 and is a diffraction unit that diffracts the forward light. It is characterized by that.

  The third diffracting means 62 is provided on the surface of the diffractive unit 63 on the side to be joined with the reflecting unit 29 so as to diffract the light reflected by the first reflecting means 16. The third diffracting means 62 emits the incident light with the radiation angle of the third diffracting means being reduced.

  The S-polarized light of the outgoing light emitted from the semiconductor laser element 13 and incident on the polarization separation means 15 is reflected by the polarization separation means 15 and further reflected by the first reflection means 16. The light reflected by the first reflecting means 16 enters the third diffracting means 62. The third diffracting means 62 reduces the radiation angle of the incident light and makes it incident on the first light receiving element 17.

  Thus, since the irradiation area of the light incident on the first light receiving element 17 can be reduced, the incidence of light on the semiconductor laser element 13 can be prevented. Furthermore, since the light receiving segment of the first light receiving element 17 can be reduced, the first light receiving element 17 can be further miniaturized and the response speed can be increased.

  Further, if the light receiving surface 30b of the first light receiving element 17 is tilted like the optical integrated unit 31 of the second embodiment, the forward light is further prevented from entering the semiconductor laser element 13 and also to the first light receiving element 17. The amount of incident light can be stabilized.

  Further, the third diffracting means 62 is integrally provided in the diffraction unit 63 together with the first diffracting means 14 and the second diffracting means 19, so that the manufacturing process can be simplified and the cost can be reduced. Can be achieved.

It is a schematic sectional drawing which simplifies and shows the structure of the optical integrated unit 101 which is one Embodiment of this invention. It is a schematic sectional drawing which simplifies and shows the structure of the optical pick-up apparatus 12 provided with the optical integrated unit 101 shown in FIG. It is a figure which shows the reflectance distribution of the reflecting film 16a used for the 1st reflection means 16 of the optical integrated unit 101 of this invention. It is a figure which shows the reflectance distribution of the reflecting film 16a used suitably for the 1st reflection means 16 of the optical integrated unit 101 of this invention. It is a figure which shows the reflectance distribution of the reflecting film 16a used suitably for the 1st reflection means 16 of the optical integrated unit 101 of this invention. It is a schematic sectional drawing which simplifies and shows the structure of the optical integrated unit 31 which is the 2nd Embodiment of this invention. It is a schematic sectional drawing which simplifies and shows the structure of the optical integrated unit 41 which is the 3rd Embodiment of this invention. It is a schematic sectional drawing which simplifies and shows the structure of the optical integrated unit 51 which is the 4th Embodiment of this invention. It is a schematic sectional drawing which simplifies and shows the structure of the optical integrated unit 61 which is 5th Embodiment of this invention. It is a schematic sectional drawing which simplifies and shows the structure of the optical integrated unit 1 of patent document 1. FIG.

Explanation of symbols

31, 41, 51, 61, 101 Integrated optical unit 12 Optical pickup device 13 Semiconductor laser element 14 First diffracting means 15 Polarization separating means 16, 42 First reflecting means 17 First light receiving element 18 Second reflecting means 19 Second diffraction Element 20 Second light receiving element 21 Optical recording medium 22 1/4 wavelength plate 23 Collimating lens 24 Objective lens 25 Stem 26 Electrode pin 52 Shielding member 62 Third diffraction element

Claims (12)

In an optical integrated unit that emits light toward an optical recording medium on which information is recorded or reproduced by light and receives reflected light from the optical recording medium,
At least a light source that emits light;
A light separating means for separating the outward light emitted from the light source and the backward light emitted from the light source and reflected by the optical recording medium;
First reflecting means for further reflecting the outward light reflected by the light separating means;
A first light receiving element that receives forward light reflected by the first reflecting means,
The first reflecting means and the first light receiving element so that the traveling direction of the forward light incident on the first light receiving element is opposite or close to the traveling direction of the forward light emitted from the light source. An optical integrated unit, wherein: The first reflecting means and the first light receiving element are:
The optical integrated unit according to claim 1, wherein the forward light incident on the first light receiving element is arranged such that the incident direction has an inclination angle.   The first reflecting means is provided so as to reflect only a part of light emitted from the light source and reflected by the light separating means toward the first reflecting means. Optical integrated unit. Between the light separating means and the first reflecting means or between the first reflecting means and the first light receiving element, a shielding member that shields the forward light is provided,
The optical integrated unit according to claim 1, wherein the shielding member is formed with an opening that transmits a part of the forward light.   The first reflecting means has a reflecting surface, and is formed so that the reflectance on the reflecting surface varies depending on the position in the reflecting surface. Integrated optical unit. The reflecting surface of the first reflecting means is
6. The optical integrated unit according to claim 5, wherein the reflectance is reduced in one direction from one end of the reflecting surface away from the light separating means to the other end near the light separating means. .   6. The first reflecting means according to claim 5, wherein the first reflecting means has a reflecting surface, and the reflectance of the reflecting surface is highest in the vicinity of the center of the reflecting surface and becomes low when separated from the vicinity of the center. Optical integrated unit.   The first diffracting means for diffracting the outward light is provided in the optical path of the outward light between the first reflecting means and the first light receiving element. An optical integrated unit according to 1. The light receiving surface of the first light receiving element is
The optical integrated unit according to claim 1, wherein the optical integrated unit is located closer to the optical recording medium with respect to the light emitting surface of the light source. A second light receiving element for receiving the return light reflected from the optical recording medium, the second light receiving element provided in a plane parallel to a plane perpendicular to the optical axis of the forward light in which the light source is provided;
A second reflecting means for reflecting the return light reflected from the optical recording medium toward the second light receiving element;
A second diffracting means provided between the second reflecting means and the second light receiving element and diffracting the light reflected by the second reflecting means toward the second light receiving element;
The light separation means is
The optical integrated unit according to any one of claims 1 to 9, wherein the optical integrated unit is provided so as to reflect the return light reflected by the optical recording medium toward the second reflecting means. Including third diffracting means for diffracting light reflected from the optical recording medium toward the first light receiving element;
11. The optical integrated unit according to claim 10, wherein the second diffracting means and the third diffracting means are provided in the same member. An optical integrated unit according to any one of claims 1 to 11, comprising:
A condensing unit arranged between the optical integrated unit and the optical recording medium and condensing the light emitted from the optical integrated unit on the optical recording medium;
An optical pickup apparatus comprising a quarter wave plate disposed between the optical integrated unit and the light collecting means.

Images