JPH0620297A - Optical pickup - Google Patents

Abstract

PURPOSE:To make it possible to secure members of optical system more easily and accurately to a housing by fixing the optical system members to a fixing board made of same material as the optical system member at predetermined positions thereof and then securing the fixing board to the housing at a predetermined position thereof. CONSTITUTION:A semiconductor laser 3 and a collimator lens 4 are disposed on the outside of a housing 1. A spot lens 8 and a fixing board 9 mounting Wollaston prism 5, a compound lens 6 and a half mirror 7 are disposed in the housing 1. Each of these optical system members is made of optical glass, for example. The prisms 5, 6 and the mirror 7 are secured onto the top surface of the fixing board 9 made of optical glass having same composition as the optical system members. The board 9 is bonded through adhesive to a fixing part la provided on the bottom surface of the housing 1. This constitution allows the optical system members to be handled just like a single member when they are secured to the housing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup used in an optical information recording / reproducing device such as an optical disk device.

[0002]

2. Description of the Related Art In recent years, optical discs, which are a type of information recording medium, have been used in many fields because they can record a large amount of information signals at high density. Therefore, it is attracting attention as an external recording medium such as an optical file or a computer.

In such an optical disc, an information signal is recorded, reproduced or erased in a non-contact manner by an optical pickup using a semiconductor laser, for example. The optical pickup is being made smaller, lighter and thinner so that it can be mounted on a small information recording / reproducing apparatus such as a laptop personal computer or a word processor.

As shown in FIG. 7, the conventional optical pickup 52 is a wall-mounted optical system of the optical pickup 52 at a predetermined position of a housing 51 made of a plastic molded product such as aluminum or polyphenylene sulfide (PPS). A Ton prism 5, a compound prism 6, a mirror 7 for guiding a laser beam to an objective lens (not shown), a spot lens 8 for signal detection, and the like are internally provided. Further, the semiconductor laser 3 as a light source and the collimator lens 4 are arranged at predetermined positions outside the housing 51. The optical members such as the Wollaston prism 5, the composite prism 6 and the mirror 7 are made of, for example, optical glass, and are directly attached to the protruding mounting portions 51a ... It is fixed by sticking it on. The mounting portions 51a ... Support one optical system member at at least three points in order to accurately fix each optical system member at a predetermined position of the housing 51. Further, on the bottom surface of the housing 51, positioning contact portions 51b ... Are provided in order to fix the above optical system members at a predetermined angle.

In order to fix each optical system member to the housing 51 with high precision, the mounting portions 51a ... And the contact portions 51b ... Are precisely machined into a complicated shape. In particular, when the optical system member is downsized in order to reduce the weight and size of the optical pickup, the mounting portions 51a ... And the contact portions 51b.

Next, as shown in FIG. 8, the conventional optical pickup 52 is a glass attached below the housing 51, which is a movable part, in order to detect the moving position of the housing 51 in the radial direction of the optical disc 45. A linear encoder composed of a movable scale 54 made of a metal and a detecting portion 55 attached to a fixed portion is used as the detecting means. The detector 55 is an LED (light emitting diode),
It is formed of two photodetectors and a fixed scale made of glass (neither is shown), and the moving scale 54 with graduations moves between the LED and the two photodetectors to move the two photodetectors. The output signal changes, and from this change amount, the housing 51
It is designed to recognize the moving position and speed of the.

[0007]

However, if the housing 51 is formed of a plastic molded product such as PPS in order to reduce the weight and size of the optical pickup, the plastic molded product is inferior in processing accuracy to aluminum. It is difficult to precisely machine the mounting portions 51a ... And the contact portions 51b ... into a complicated shape. Therefore,
In the above-mentioned conventional fixing method, if the weight and the size of the optical pickup are reduced, the housing 51 must be processed precisely, so that the optical pickup cannot be mass-produced and the optical system members are fixed to the housing 51 with high accuracy. Has the problem of becoming difficult.

Further, in the above-mentioned conventional fixing method, since each optical system member is directly stuck and fixed to the housing 51, the optical surface is distorted due to shrinkage of the adhesive when it is dried,
There is a problem that the position of the optical system member is displaced and the accuracy of the optical pickup is lowered. In particular, the smaller the size of the optical system member, the more serious the influence of the adhesive on the accuracy of the optical pickup. Furthermore, since the thermal expansion coefficient of the optical system member is different from that of the housing 51 and the adhesive, a difference in thermal expansion due to a temperature change causes the optical surface to be distorted, or the optical system member is misaligned to cause the accuracy of the optical pickup. It also has the problem of decreasing

In addition, the conventional detecting means for detecting the moving position of the housing 51 is required to mount the moving scale 54 of the heavy object on the housing 51 or to provide the fixing portion with the complicated and large detecting portion 55. There is a problem that it is difficult to reduce the size and weight of the optical pickup.

The present invention has been made in view of the above points, and in order to reduce the weight and size of an optical pickup, the optical system member and the detection means are downsized, and the housing is formed of a plastic molded product. Also aims to provide an optical pickup that does not cause a decrease in accuracy.

[0011]

In order to solve the above-mentioned problems, the optical pickup according to the first aspect of the present invention is an optical pickup including a housing in which an optical system member is fixed at a predetermined position. The optical system member is fixed to a predetermined position of a mounting board made of the same material as the optical system member, and the mounting board is fixed to a predetermined position of the housing.

In order to solve the above-mentioned problems, the optical pickup according to a second aspect of the present invention has a housing in which an optical system member is fixed at a predetermined position, and the housing in the radial direction of the optical recording medium. In the optical pickup having a detection means for detecting the moving position of the optical system member, the optical system member is fixed at a predetermined position of a mounting substrate formed of the same material as the optical system member, and the mounting substrate is A part of the light beam irradiated onto the optical recording medium is fixed to a predetermined position of the housing and is guided to the above detection means through the mounting substrate, and the detection means includes a light receiving element that receives the above light beam. It is characterized by being.

[0013]

According to the optical pickup of the first aspect, the optical system member is fixed to a predetermined position of the mounting substrate made of the same material as the optical system member, and the mounting substrate is fixed to the housing. Since the optical system member is fixed at the position of 1, the optical system member can be treated as one member when fixing the optical system member at a predetermined position of the housing. Therefore, when reducing the size and weight of the optical pickup, even if the housing is processed with the same level of processing accuracy as before, compared to the conventional fixing method in which each optical system member is directly fixed to the housing. The optical system member can be more easily and accurately fixed to the housing, and the accuracy of the optical pickup can be ensured.

Further, since the optical system member is fixed to the mounting substrate, the mounting position and angle of each optical system member are not affected by the variation in the processing accuracy of the housing. Moreover, the housing does not need to be processed into a complicated shape because it only fixes a flat mounting substrate. Therefore, the housing can be mass-produced and the manufacturing cost can be reduced.

Further, since the optical system member and the mounting substrate are made of the same material, they have the same coefficient of thermal expansion, and the optical surface is distorted or the optical system member is displaced due to expansion and contraction due to temperature change. There is no such thing. Further, for example, even if distortion occurs due to thermal expansion between the mounting substrate and the housing, it does not directly affect the optical surface of the optical system member. As a result, a compact and lightweight optical pickup can be obtained.

According to another aspect of the optical pickup of the present invention, the optical system member is fixed to a predetermined position of a mounting substrate made of the same material as the optical system member, and the mounting substrate is mounted on the housing. Since the optical pickup is fixed at a predetermined position, a compact and lightweight optical pickup can be obtained as in the optical pickup according to the first aspect.

Moreover, since a part of the light beam applied to the optical recording medium is guided to the above-mentioned detecting means through the mounting substrate, and the detecting means is provided with a light receiving element for receiving the above-mentioned light beam. By using an optical sensor or the like as the light receiving element, it is possible to recognize the moving position and speed of the housing in the radial direction of the optical recording medium from the light beam with which the detection means is irradiated. Therefore, since a simple and simple detecting means can be used, it is easy to reduce the size and weight of the optical pickup while ensuring the accuracy of the optical pickup.

[0018]

【Example】

[Embodiment 1] An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. For convenience of explanation, the same members as those shown in the drawings of the above-mentioned conventional example are designated by the same reference numerals.

As shown in FIG. 1, the optical pickup 2 of this embodiment is used in an optical disk device (not shown) having an optical disk or the like as an optical recording medium, and is made of, for example, a plastic molded product such as polyphenylene sulfide (PPS). A plurality of optical system members constituting the optical system of the optical pickup 2 are fixed to a housing (housing) 1 having an open upper surface. The housing 1 is a movable portion that can be moved back and forth by a driving means (not shown) such as a linear motor so as to be linearly moved in a radial direction of an optical disk (not shown). The information signal can be recorded and reproduced at any position up to the copy.

At a predetermined position outside the housing 1, a semiconductor laser 3 as a light source and a collimator lens 4 for collimating a laser beam (light beam) are arranged. Inside the housing 1, a Wollaston prism 5 which is a kind of a deflection prism, a compound prism 6 for refracting the laser light emitted from the semiconductor laser 3, and an optical path of the laser light are changed by 90 ° to make an objective lens. A mounting substrate 9 on which a mirror 7 (not shown) is mounted and a spot lens 8 for signal detection are arranged. Therefore, the laser light emitted from the semiconductor laser 3 enters the optical disc through the collimator lens 4, the Wollaston prism 5, the composite prism 6, the mirror 7, and the objective lens. Also,
The reflected light from the optical disk follows the above optical path in reverse, and the Wollaston prism 5 separates the emitted light and the reflected light,
A photodetector (not shown) provided in the fixed portion through the spot lens 8 housed in the lens holder 8a and a cylindrical lens (not shown) used for an astigmatism method for detecting a focus error. The information signal and the servo signal are detected from this light. Each of the above optical system members is made of, for example, optical glass.

The Wollaston prism 5, the composite prism 6 and the mirror 7 are placed at predetermined positions on the upper surface of the mounting substrate 9 made of optical glass having the same composition as those of the optical system members, for example, an adhesive for optical glass. It is attached and fixed with. Then, when fixing each of the above optical system members 5 to 7 to the mounting substrate 9, the mounting position and angle are adjusted by a mounting jig (not shown) so as to be mounted accurately. The upper surface and the lower surface of the mounting board 9 are formed in parallel planes. Further, the spot lens 8 is housed in the lens holder 8 a and fixed inside the side surface of the housing 1.

The above-mentioned mounting substrate 9 is fixed to the projecting mounting portions 1a provided on the bottom surface of the housing 1 by, for example, being adhered with an adhesive. The mounting portions 1a ... Support the lower surface of the mounting substrate 9 at at least three points in order to mount the mounting substrate 9 at a predetermined position of the housing 1 with high accuracy. Further, the bottom surface of the housing 1 is provided with contact portions 1b ... For positioning the mounting substrate 9.

Here, as shown in FIG. 2A, the case where the mirror 7 is attached to the housing 51 by using the conventional fixing method of directly attaching the optical system member to the housing will be considered. Or dust or the like adheres to the mounting portion 51a of the housing 51, or the projection 20 on the mounting portion 51a by a machining error or burrs are present, since short span S _a mounting portion 51a ... of the housing 51, the mirror 7 is predetermined It is inclined by θ _a more than the angle of. When the mirror 7 is tilted in this way, the laser light cannot be accurately incident on the optical disc, and the information signal and the servo signal cannot be detected from the reflected light from the optical disc.

However, in the optical pickup 2 of this embodiment, the mounting substrate 9 to which the mirror 7 is fixed is fixed to the housing 1. Therefore, as shown in FIG. The span S _b can be made sufficiently long, and even if the above-mentioned protrusion 20 is present on the mounting portion 1 a of the housing 1, the mirror 7 can only have an angle θ _b sufficiently smaller than the angle θ _a. I can't lean. In this way, since the mirror 7 hardly tilts even if the protrusions 20 are present, the laser light can be accurately incident on the optical disc, and the information signal and the servo signal can be detected from the reflected light from the optical disc. it can.

Therefore, as compared with the conventional fixing method in which the optical system member is directly attached to the housing, the span S _b of the mounting portions 1a of the housing 1 can be made sufficiently long, so that the optical pickup 2 is fixed. When reducing the size and weight, the mounting portion 1a of the housing 1 is processed with the same processing accuracy as the conventional one.
The precision of the optical pickup 2 can be sufficiently ensured even if the contact parts and the contact parts 1b are processed. The smaller the optical system member is, the more the angle θ _b and the angle θ _{a become.}
And the difference from the conventional fixing method becomes significant. Further, the housing 1 is suitable for mass production because it is not necessary to process the mounting portions 1a ... And the contact surfaces 1b ... into a complicated shape according to the optical system member, and is suitable for mass production, which reduces the manufacturing cost. It becomes possible.

Further, according to the above construction, the Wollaston prism 5, the compound prism 6 and the mirror 7 are fixed in advance at a predetermined position on the upper surface of the mounting substrate 9 which can be easily formed into a flat surface, and are formed as one member. Since it can be handled as described above, it is possible to more easily and accurately fix each optical system member as compared with the case where it is directly fixed to the housing 1. In particular, when a millimeter-order optical system member such as a micro prism is fixed, it can be fixed more easily and accurately. Further, since the optical system members are fixed to the mounting substrate 9, the mounting position and angle of each optical system member are not affected by variations in the processing accuracy of the housing 1.

Further, since the optical system member and the mounting substrate 9 are made of optical glass having the same composition, they have the same coefficient of thermal expansion, and the adhesive surface is peeled off due to expansion and contraction due to temperature change.
The optical surface is not distorted and the position of the optical system member is not displaced. Further, even if the mounting substrate 9 is distorted due to contraction of the adhesive that fixes the mounting substrate 9 to the housing 1, it does not directly affect the optical surface of the optical system member. As a result, a compact and lightweight optical pickup 2 can be obtained.

In this embodiment, the mounting substrate 9 is fixed to the housing 1 with an adhesive, but a fixing tool such as a screw or a pressing spring is used instead of the adhesive. 9 may be fixed to the housing 1. Also, instead of the Wollaston prism 5 and the compound prism 6, a beam splitter having the same function as these two optical system members may be used.

[Embodiment 2] Another embodiment of the present invention will be described below with reference to FIG.
For convenience of explanation, the same members as those shown in the drawings of the first embodiment will be designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 3, the optical pickup 22 of this embodiment is made of, for example, a plastic molded product such as PPS, and a plurality of optical systems of the optical pickup 2 are formed in a housing 21 having an open upper surface. The mounting substrate 23 to which the optical system member is fixed is mounted from the bottom surface side of the housing 21, and the upper surface of the mounting substrate 23 and the housing 21 are bonded and fixed with an adhesive. Other configurations are
This is the same as the first embodiment.

With the above structure, the optical pickup 2 is reduced in size and weight like the optical pickup 2 of the first embodiment.
2 is obtained. Moreover, the mounting substrate 23 is attached to the housing 21.
Since the mounting substrate 23 is mounted from the bottom side, it is not necessary to form the upper surface and the lower surface of the mounting substrate 23 in a plane and parallel, and only the upper surface may be formed in a plane. This makes it possible to reduce the manufacturing cost of the mounting substrate 23 while ensuring the accuracy of the optical pickup.

[Embodiment 3] The following description will discuss still another embodiment of the present invention with reference to FIG. For convenience of explanation, the same members as those shown in the drawings of the first embodiment will be designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 4, the optical pickup 25 of this embodiment has a lens holder 8 containing a spot lens 8.
A is fixed to the inside of the side surface of the housing 26 while being brought into contact with the mounting substrate 27 by the mounting spring 28. Other configurations are the same as those in the first embodiment.

When the reflected light from the optical disc is focused on the photodetector (not shown) by the spot lens 8, if an optical axis shift occurs, an information signal or a servo signal can be detected from the reflected light. Disappear. Therefore, the spot lens 8
Requires a guide surface for position adjustment, but as described above, the lens holder 8 containing the spot lens 8 is used.
a is brought into contact with the mounting substrate 27 by the mounting spring 28, and the upper surface of the mounting substrate 27 parallel to the optical axis is attached to the lens holder 8
Since it is used as the guide surface of the above, there is no fear that the optical axis of the reflected light will be displaced. Therefore, the optical pickup 26 configured as described above can ensure accuracy without separately providing the guide surface on the housing 26. Thereby, the first embodiment
Similar to the optical pickup 2 of 1, the optical pickup 25 can be downsized and reduced in weight.

[Fourth Embodiment] The following description will explain still another embodiment of the present invention with reference to FIG. For convenience of explanation, the same members as those shown in the drawings of the first embodiment will be designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 5, the optical pickup of this embodiment has a structure in which only the mirror 7 is fixed to the mounting substrate 32, and the mounting substrate 32 is fixed to the housing 31 which is a movable portion. The optical system members other than the mirror 7 are
It is fixed to a fixing portion (not shown) together with the photodetector and the like.
Other configurations are the same as those in the first embodiment.

Even when the mounting substrate 32 to which only the mirror 7 is fixed is fixed to the housing 31 as described above, the first embodiment
Similar to the housing 1 of the optical pickup 2 of FIG. 1, the span of the mounting portion of the housing 31 can be made sufficiently long. Therefore, when the size and weight of the optical pickup are reduced, the accuracy of the optical pickup can be ensured even if the housing 31 is processed with the same processing accuracy as the conventional one. As a result, a compact and lightweight optical pickup can be obtained as in the optical pickup 2 of the first embodiment.

[Fifth Embodiment] The following description will explain still another embodiment of the present invention with reference to FIG. For convenience of explanation, the same members as those shown in the drawings of the first embodiment will be designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 6, in the optical pickup 40 of this embodiment, instead of the Wollaston prism 5 and the compound prism 6, a beam splitter 42 having the same function as these two optical system members is attached to a mounting substrate 43. And the mounting substrate 43 is fixed to the housing 41. A position sensor (detection means) 46 is provided below the housing 41, which is a movable part.
The semiconductor beam 3 and the collimator lens 4 are arranged in parallel with the forward / backward movement direction of the. The position sensor 46 also serves as a speed sensor for the housing 41.

The position sensor 46 is the optical disc 45.
In order to detect the moving position and speed of the housing 41 in the radial direction of, the one-dimensional optical sensor (light receiving element) such as a semiconductor position detector is used, and is installed with the light receiving surface facing upward. . Then, based on the output signal from the position sensor 46, a control device (not shown) controls drive means (not shown) such as a linear motor,
The housing 41 is moved back and forth (coarse seek) in the radial direction of the optical disc 45. Other configurations are the same as those in the first embodiment.

A method of detecting the moving position of the housing 41 by the position sensor 46 in the above structure will be described. The laser beam A emitted from the semiconductor beam 3 is incident on the optical disc 45 through the beam splitter 42, the mirror 7 and the objective lens 44, but a part of the laser beam A is separated by the beam splitter 42 and is made of optical glass or the like. Board 4
It is led to the optical sensor of the position sensor 46 through 3. When the light receiving surface is irradiated with the laser light A ₁ , the optical sensor of the position sensor 46 generates an output voltage according to the irradiation position and outputs the output voltage to the control device. The control device recognizes the moving position and speed of the housing 41 from the change in the output voltage, performs speed feedback control of the driving means, and moves the housing 41 to a predetermined position. Thus, the information signal can be recorded and reproduced at any position from the inner peripheral portion to the outer peripheral portion of the optical disc 45.

In this way, the optical pickup 4 of this embodiment is
0 is the laser beam A ₁ split by the beam splitter 42
Is radiated to the optical sensor of the position sensor 46 disposed below the housing 41 through the mounting substrate 43, and the moving position and speed of the housing 41 can be recognized from the laser light A ₁ . Therefore, since the simple and simple position sensor 46 can be used, it is possible to obtain the optical pickup 40 that is downsized and lightweight while ensuring the accuracy of the optical pickup.

[0043]

As described above, in the optical pickup according to the first aspect of the present invention, the optical system member is fixed at a predetermined position of the mounting substrate made of the same material as that of the optical system member. The mounting board is fixed to a predetermined position of the housing.

As a result, when fixing the optical system member at a predetermined position of the housing, the optical system member can be handled as a single member, so that the optical pickup can be made smaller and lighter than before. Even if the housing is processed with the same degree of processing accuracy as the above, compared to the conventional fixing method in which each optical system member is directly fixed to the housing, the optical system member is more easily and accurately fixed to the housing. Therefore, the accuracy of the optical pickup can be sufficiently ensured. Further, since the optical system member is fixed to the mounting substrate, the mounting position and angle of each optical system member are not affected by variations in the processing accuracy of the housing.

Further, the housing does not need to be processed into a complicated shape because it only fixes the flat mounting substrate. Therefore, the housing can be mass-produced and the manufacturing cost can be reduced. In addition, since the optical system member and the mounting substrate are formed of the same material, they have the same coefficient of thermal expansion, and the optical surface is not distorted or the optical system member is displaced due to expansion and contraction due to temperature change. . Moreover, for example, even if distortion occurs due to thermal expansion between the mounting substrate and the housing,
It does not directly affect the optical surface of the optical system member. As a result, there is an effect that it is possible to obtain a compact and lightweight optical pickup.

Further, in the optical pickup of the second aspect of the invention, as described above, the optical system member is fixed at a predetermined position of the mounting substrate made of the same material as the optical system member, The mounting substrate is fixed to a predetermined position of the housing, and a part of the light beam applied to the optical recording medium is guided to the detecting means through the mounting substrate and the detecting means receives the light beam. It is a configuration provided with.

As a result, as in the case of the optical pickup according to the first aspect, there is an effect that it is possible to obtain a compact and lightweight optical pickup. Moreover, since a part of the light beam irradiated on the optical recording medium is guided to the above-mentioned detecting means through the mounting substrate, for example, by using an optical sensor or the like as the light receiving element, from the light beam irradiated on the detecting means, It is possible to recognize the moving position and speed of the housing in the radial direction of the optical recording medium. Therefore, since a simple and simple detecting means can be used, there is an effect that it is easy to reduce the size and weight of the optical pickup while ensuring the accuracy of the optical pickup.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing an optical pickup according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a difference in accuracy caused by a difference in a fixing method between the above optical pickup and a conventional optical pickup.

FIG. 3 is an exploded perspective view of essential parts showing an optical pickup according to another embodiment of the present invention.

FIG. 4 is an exploded perspective view of essential parts showing an optical pickup according to still another embodiment of the present invention.

FIG. 5 is an exploded perspective view of essential parts showing an optical pickup according to still another embodiment of the present invention.

FIG. 6 is a perspective view showing an optical pickup according to still another embodiment of the present invention.

FIG. 7 is an exploded perspective view showing a conventional optical pickup.

FIG. 8 is a perspective view showing a conventional optical pickup.

[Explanation of symbols]

 1 Housing (Housing) 1a Mounting part 1b Contact part 2 Optical pickup 3 Semiconductor laser 4 Collimator lens 5 Wollaston prism (optical system member) 6 Composite prism (optical system member) 7 Mirror (optical system member) 8 Spot lens (optical) System member) 8a lens holder 9 mounting substrate 42 beam splitter (optical system member) 46 position sensor (detection means)

Claims (2)

[Claims] 1. An optical pickup having an enclosure in which an optical system member is fixed at a predetermined position, wherein the optical system member is at a predetermined position of a mounting substrate made of the same material as the optical system member. The optical pickup is characterized in that the mounting substrate is fixed to a predetermined position of the housing. 2. An optical pickup comprising: a housing in which an optical system member is fixed at a predetermined position; and detection means for detecting a moving position of the housing in the radial direction of an optical recording medium. The member is fixed to a predetermined position of a mounting substrate made of the same material as this optical system member, the mounting substrate is fixed to a predetermined position of the housing, and the optical beam irradiated onto the optical recording medium is fixed. An optical pickup characterized in that a part thereof is guided to the above-mentioned detecting means through a mounting substrate, and the detecting means is provided with a light receiving element for receiving the above-mentioned light beam.