JPS62126376A - Reflection type optical coupling element - Google Patents

Abstract

PURPOSE:To accurately detect the position of an object, by arranging two or more of light receiving elements around the light emitting element on a substrate and providing light blocking bodies between the light emitting element and the light receiving elements while protecting the whole by a film. CONSTITUTION:One light emitting element 2 and light receiving elements 3a, 3b provided around said light emitting element 2 are arranged on a substrate 1 and light blocking bodies 5a, 5b are implanted between the light emitting element 2 and the light receiving elements 3a, 3b and the whole is covered with a film 4 for the purpose of protection. The direct light from the light emitting element 2 to the light receiving elements 3a, 3b and the reflected light from the surface of film are blocked by the light blocking bodies 5a, 5b. By this method, only the reflected light from an article to be measured is received as a signal component and the position of the article to be measured can be accurately detected. This device is suitable as the automatic focusing system of a camera.

Description

Detailed Description of the Invention [Technical Field of the Invention] This invention provides a light emitting element and at least two light receiving elements disposed on a substrate, and the light from the light emitting element reflected by an object is transmitted to the light receiving element. The present invention relates to a reflective optical coupling element that receives light with an element and detects the position of an object based on the difference between the light beams received.

[Technical background of the invention and its problems] An example of a conventional reflective optical coupling device is shown in FIGS. 7 and 8.

In this conventional element, an LED (Li
A light emitting element 2 such as a light emitting device (light emitting device) is arranged, two light receiving elements 3a, 3b are arranged on both sides of the light emitting element 2, and a protective film 4 of epoxy resin or the like is placed over the light emitting element 2 and the light receiving elements 3a, 3b. I try to coat it.

This reflective optical coupling element is used to detect the position of an object facing the element. That is, if the optical coupling element is fixed at a predetermined position and a reflective object such as a mirror is fixed to an object that moves parallel to the element, the light emitted from the light emitting element of the optical coupling element will be After being reflected by a mirror fixed to the object, the light is incident on light receiving elements 3a and 3b provided on both sides of the light emitting element. At this time, the optical cover of the light incident on each of the light receiving elements 3 a * 3 b changes in accordance with the change in the position of the mirror, that is, the position of the object. Therefore, the position of the object can be detected by taking the difference between the amounts of incident light on the light receiving elements 3a+3b.

Such an optical coupling element is used, for example, to detect the position of an objective lens provided in an optical head of an optical disk device.

By the way, in the conventional optical coupling device used for detecting the position of an object, some of the light emitted from the light emitting element 2 is directly transmitted to the light receiving element 3a # due to the non-directivity of the light emitting element 2.
The amount of light incident on 3b or reflected on the surface of the protective film 40 and then incident on the light receiving elements 3a and 3b is quite large.
For this reason, a large bias is caused in the signal components reflected by the object and incident on the light receiving elements 3a and 3b. Particularly when this optical coupling element is used to detect the position of the objective lens of the optical head, minute movements of the object must be detected with high precision; Compared to the amount of change in the signal component according to
As a result, signal processing such as signal amplification and differential processing becomes extremely difficult, resulting in the drawback that a signal component corresponding to the position of an object cannot be extracted accurately and precisely.

Furthermore, when such a conventional optical coupling element is used to detect the position of the objective lens of the optical head of the original disk device, it is difficult to accurately detect the position of the objective lens due to the reasons mentioned above, and therefore access is difficult. However, movement in the tracking direction occurs, causing track misalignment, and signal processing takes time, which hinders high-speed access.

[Purpose of the invention]

This invention was made in view of the above circumstances.

To provide a reflective optical coupling element capable of extracting a signal without bias by blocking direct incident light from a light emitting element to a light receiving element or light incident on a light receiving element due to reflection on the surface of a protective film. With the goal.

[Summary of the invention]

Therefore, in the present invention, the above-mentioned object is achieved by providing a light shielding body that blocks light from the light emitting element between the light emitting element and the light receiving element composed of at least two parts.

[Embodiments of the invention]

FIGS. 1 and 2 show an embodiment of a reflective optical coupling device according to the present invention.

In the embodiment shown in FIGS. 1 and 2, a light emitting element 2, such as an LED, is provided approximately at the center of a substrate 1 whose glass surface is coated with a chemical coating, and two light receiving elements 3m are placed on both sides of the light emitting element 2. , 3b are arranged.

In this embodiment, a light shielding plate 5 is provided between the light emitting element 2 and the light receiving elements 3a*3b.

5b, and a protective film 4 made of epoxy resin or the like is placed over these.
I try to coat it. Here, the light shielding body 5
a,5bG'! Is it made of an insulator such as glass stick?
Alternatively, if it is made of a conductor such as stainless steel, its surface is coated with an insulating coating, or an insulating material is provided throughout the portions that come into contact with other components, that is, the light receiving element 3ae3b and the substrate 1. Further, each surface of the light shielding body 5at5b on the light emitting element 2 side is polished with high precision, thereby preventing diffuse reflection of light. The board 1 is a printed wiring board 1), and electrical connections are made to connect the light emitting elements 2 and light receiving elements 3 a e 3 b on the board.

According to this embodiment, from the light emitting element 2 to the light receiving element 3a*
It is possible to appropriately prevent direct incidence to the light receiving element 3b and incidence to the light receiving element 3s*3b due to reflection on the surface of the epoxy 4, thereby making it possible to extract a high quality signal free of bias.

Next, FIG. 3 shows another embodiment of the present invention. Figure 3b)
a (b) * (c) e (d) are respectively plan views, and in each of these examples, four light receiving elements 3 a + 3 b a 3 e and 3 d are arranged around the light emitting element 2. and an object X placed opposite to the optical coupling element.
It is now possible to perform position detection in two directions: the direction and the Y direction. That is, in these embodiment elements, the difference value (Gac - Gy
), and also detects the position of the object in the X direction based on the difference value (Gab
'cd) to detect the position of the object in the Y direction. In each of these embodiments, a light shielding body 5 is provided between the light emitting element 2 and the light receiving elements 31 to 3d, thereby blocking light leaking from the light emitting element 2 to the light receiving elements 31 to 3d.

Next, a case will be described in which the embodiment shown in FIG. 3(a) is applied to detecting the position of an objective lens in an optical pickup portion of an optical disk device.

First, the principle of signal detection in an optical disk device will be explained according to FIG.

In FIG. 4, rectangular holes (pits) are arranged concentrically or spirally on the surface of a disk-shaped disk 100, and 1 and 0 are distinguished by the presence or absence of these pits.

A laser beam emitted from a semiconductor laser 11 passes through a collimator lens 12 and a half prism 13 in sequence, and is then focused onto an information storage medium (disc) 10 by an objective lens 14 .

Further, the laser beam reflected from the disk 10 passes through the objective lens 14 again and is returned to the half prism 13. The laser beam reflected by this half prism 13 passes through a condensing lens 15 and a cylindrical lens 16 in sequence, and is irradiated onto a photodetector 17. The light density signal converted into an electric signal by the photodetector 17 is then sent out as a signal for information reproduction via a demodulation circuit and a signal processing circuit (not shown). That is, in the optical disk device, when light is irradiated onto the pit by the objective lens 14, the light that hits the edge of the pit is diffusely reflected or diffused, and the amount of light is smaller than that of the light that is specularly reflected from a flat area outside the pit. decreases. This light amount difference is converted into an electrical signal by the photodetector 17, and information is reproduced.

Next, the objective lens driving bag [20 includes the g
FIGS. 5 and 6 show an arrangement in which the embodiment shown in FIG. 3 (,) is provided to detect the position of the objective lens 14 in the tracking direction and the focus lens direction.

As shown in FIGS. 5 and 6, the objective lens 14 is held by a holding frame 21, which is attached to the other ends of a pair of parallel plate springs 22, 22, one end of which is fixed. Therefore, the objective lens 14 is movable in its radial direction, that is, in the tracking direction, as shown by arrow A.

Further, the holding frame 21 is provided with a movable magnetic body 23, and a pair of yokes 24.2 surrounding the movable magnetic body 23 and cooperating with the movable magnetic body 23 are provided in the vicinity of the movable magnetic body 23.
4 and a pair of permanent magnets 25°25 are fixedly disposed. Also, the yoke 24.24 has a coil 26.26.
is wound. Then, by applying a current corresponding to the track deviation to the coils 26 and 26, the objective lens 1 is
4 is fixed such that it can be moved by a predetermined amount in the radial direction. This middle frame 27 has a pair of spiral springs 28.
The objective lens 14 is supported by an outer frame 29 via a lens 28e, so that the objective lens 14 can be freely displaced in the optical axis direction as shown by an arrow B. Further, a coil 31 is attached to the inner frame 27 via a U IJ ring 30, while a permanent magnet 32 and a yoke 33.3 are attached to the outer frame 29, which cooperate with the coil 31.
3 is installed. Then, by passing a current corresponding to the focus shift through the coil 31, the objective lens 14 is
can be moved by a predetermined amount in the direction of its optical axis.

By the way, the frame 40 of this objective lens driving device 20
In order to detect the position of the objective lens in the tracking direction A and the focus lens direction B, a portion 41 facing the mirror 42 fixed to the surface of the movable magnetic body 230 is removed, and this portion 41 is Figure 3 (al
The substrate 1 of the optical coupling device shown in FIG. As mentioned above, this optical coupling device is composed of a light emitting element 2, four light receiving elements 38 to 3d, a protective film 4 and a light shielding body 5, and the light emitted from one light emitting knob 2 is arranged on the surface of the coil. After being reflected by the mirror 42, the four light receiving elements 38 to 3
It will be incident on d. Since the movable magnetic body 23 is moved together with the objective lens 14 in the tracking direction A and the focusing direction B, the outputs of the four light receiving elements 3a to 3d are differentially processed in the manner described above. The position of the objective lens 14 in the dragging direction A and the focusing direction can be detected.

As described above, this optical coupling element is provided with the light shielding body 5, so that a high quality signal free of bias can be obtained from the outputs of the light receiving elements 38 to 3d, which allows accurate measurement of the objective lens. By being able to perform position detection and driving the moving mechanisms in the tracking and focusing directions based on the detection output, it becomes possible to perform stable and accurate tracking and focusing operations.

〔Effect of the invention〕

As explained above, according to the reflective optical coupling device according to the present invention, a light shielding body is provided between the light emitting device and the light receiving device, so that direct light from one light emitting device and the light from the sampled film surface are prevented. It is possible to reliably block reflected light from entering the light-receiving element, thereby suppressing the bias component appearing in the output signal of the light-receiving element, and making it possible to obtain a high-quality light-receiving output of only the signal component.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an embodiment of a reflective optical coupling device according to the present invention, FIG. 2 is a cross-sectional view of the same, and FIG. 3(a), T
b), (e) and (di-) are respectively plan views showing other embodiments of the present invention, FIG. 4 is a configuration diagram schematically showing an optical head of an optical disk device, and FIG. 5 is a plan view showing another embodiment of the present invention. 6 is a plan view showing an example of an objective lens driving device, FIG. 6 is a sectional view thereof, FIG. 7 is a plan view showing an example of a conventional reflective optical coupling element, and FIG. 8 is a sectional view thereof. ... Substrate, 2... Light emitting element, 3... Light receiving element,
4... Retaining film, 5... Light shielding body, 10... Information recording medium, 11... Laser, 12... Collimating lens, 13... Barf grism, 14... Objective lens,
15... Condensing lens, 16... Cylindrical lens, 17... Photodetector, 20... Objective lens drive device, 42... Mirror l, ·::, - Agent Patent attorney Kimura Hisashi Taka, ``Figure 2 Xx (Q) (b) X X (C
) (d) Figure 5 Figure 6 Figure 8

Claims (1)

[Claims] A light emitting element is disposed on a substrate, and at least two light receiving elements are disposed around the light emitting element on the substrate,
A reflective type in which the light-emitting element and the light-receiving element are coated with a predetermined protective film, and the position of the object is detected by receiving the light emitted from the light-emitting element and reflected by the object by the at least two light-receiving elements. 1. A reflective optical coupling device, which comprises a light shielding body that blocks light from the light emitting device between the light emitting device and the light receiving device.