JPH06174496A - Optical encoder - Google Patents

Abstract

PURPOSE:To provide a small optical encoder easily mounted on a vehicle. CONSTITUTION:An encoder is constituted of a body 1 forming a frame and a cover 2, and a shielding plate 7 having a slit train 9 is rotatably supported by their through holes 1b, 2a. Printed wires of the preset pattern are directly applied on the inner face 1a of the body 1. A light emitting element and a light receiving element 3 are arranged across the shielding plate 7 to face the slit train 9. The light emitting element and the light receiving element 3 are connected with an FPC 13, and the light receiving element 3 and the FPC 13 are connected to the printed wires.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical encoder, and more particularly to an optical encoder incorporating a printed circuit, which is suitable for use in a place where an accommodation space is extremely limited.

[0002]

2. Description of the Related Art A position detection sensor or an acceleration sensor for an automobile has a built-in printed circuit on which sensor elements and electronic parts are mounted.

It is well known that, for example, an optical encoder (hereinafter, simply referred to as an encoder) can be used as a position detection sensor to detect a rotation angle and a rotation direction of a rotating body. This encoder is a slit array consisting of a light emitting element (generally a photodiode) and a light receiving element (generally a phototransistor) housed in a resin holder, and a large number of slits regularly arranged in the rotation direction. And a light shielding plate disposed between the optical axes of the light receiving element and the light emitting element.

The light emitting element and the light receiving element are connected and fixed on a substrate made of epoxy resin reinforced with glass fiber, and the substrate is further fixed to a case, that is, a resin case. On the other hand, the light shielding plate is rotatably held with respect to the housing. As an example of the encoder, a detection device suitable for detecting a steering angle of an automobile is disclosed in Japanese Patent Laid-Open No. 3-125.
It is described in Japanese Patent Publication No. 920.

[0005]

The conventional encoder has the following problems. In the conventional encoder, the substrate, the light emitting element, the light receiving element, the holder of the light receiving and emitting element, and the light shielding plate are arranged in one direction (axial direction) in the housing. It is determined by the dimensions of the components and the clearance between each component.

For example, when the encoder is used for detecting a steering angle of an automobile, it is desirable to dispose the encoder around the steering wheel axis of the automobile. However, there is a problem in that the arrangement space around the axis of the steering wheel is extremely narrow, and if the axial dimension of the encoder is large, the degree of freedom in layout is reduced.

If the axial dimension of the encoder, that is, the thickness is large, the encoder is not limited to the one used for detecting the steering angle,
Generally, for vehicles, the degree of freedom of layout is reduced, and thus the applications are limited.

Further, as the resin used as the material of the substrate, so-called engineering plastics (PPS, LCP, PEI, etc.) having excellent heat resistance in consideration of soldering resistance are used. The surface of engineering plastic is inert and has excellent chemical resistance.
Prior to plating for printed wiring, the use of a strong acid is indispensable for etching performed to improve the adhesion of the plating.

Therefore, in order to avoid the corrosion due to the strong acid, the connector terminal inserted and fixed in the board is inserted in the board after etching and connected and fixed to the printed circuit by soldering or wire bonding. As a result, there is a problem that this soldering or wire bonding work is a separate process and is complicated.

Further, not only the encoder but also the in-vehicle control device and the detection device are used in a place where vibration is large, and therefore, the sensor element connected to the circuit pattern and the lead wires of the peripheral electronic parts (hereinafter, simply referred to as lead wires). Must be securely connected with solder so as not to come off easily due to vibration or the like. The same applies when connecting the connector terminals to the circuit pattern with solder.

However, in general, the leads and the connector terminals are in contact with the circuit pattern only within a very limited range of their tips, so that care must be taken in soldering.

Further, since the number of each component, that is, the number of parts is large, it takes time and effort to assemble and adjust the position of each part,
There was a problem that productivity was hindered.

An object of the present invention is to solve the above problems,
The circuit pattern and components can be connected securely and easily, and the number of components can be reduced.By using the printed circuit and printed circuit unit to shorten the dimension in the axial direction, it is possible to improve the flexibility of the layout when mounted on the vehicle. At the same time, it is to provide an optical encoder that can improve productivity by reducing the number of parts.

[0014]

Means for Solving the Problems The present invention for solving the above problems and achieving the object has the following features (1) to (5). (1) A light shielding plate having a slit array is rotatably accommodated,
A resin casing in which printed wiring of a predetermined pattern is directly applied along the inner surface thereof, and a light emitting element and a light receiving element which are arranged to face the slit row of the light shielding plate and are connected to the printed wiring. A point equipped with. (2) A recess for holding an electronic component and a groove that is formed continuously with the recess and that supports the lead of the electronic component in the longitudinal direction are integrally formed when the housing is molded, and the print is provided. A part of the wiring forms a land that covers the groove. (3) A convex sensor holder portion is integrally formed in the casing when the casing is molded, and the light emitting element and the light receiving element are fixed to the sensor holder portion. (4) A point for external connection, which is subjected to corrosion-resistant plating treatment and integrally molded with the casing, and the printed wiring is directly applied so as to cover an end face of the terminal. (5) The housing has a seated hole for inserting a terminal for external connection, the printed wiring is provided so as to cover the surface of the seat of the seated hole, and the terminal is It is soldered to the printed wiring covering the seat.

[0015]

The operation of the present invention having the above characteristics (1) to (5) is as follows. (A) ... In the present invention having the feature (1), since the printed wiring is directly applied to the housing, it is not necessary to provide a printed board separately from the housing as in the conventional case. Therefore, the dimension of the encoder in the axial direction is reduced, and the encoder can be made thinner. (B) Since the lead of the component can be housed in the groove in the present invention having the feature (2), the lead of the component can be reliably fixed to the printed wiring by filling the groove with solder. (C) ... In the present invention having the feature (3), since the sensor holder portion is formed as a part of the housing, it becomes easy to align the sensor when mounting it on the housing, and the positional accuracy can be improved. . (D) In the present invention having the feature (4), since the terminal is covered with the corrosion-resistant plating layer, the terminal is etched even when printed wiring is performed with the terminal mounted in the housing. It is not subject to corrosion. (E) In the present invention having the feature (5), the terminal can be supported by the solder by filling the seat of the terminal insertion hole with the solder.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings. 1 to 3 are views showing an encoder incorporating a transmissive optical sensor according to a first embodiment of the present invention, FIG. 1 is an exploded view of the encoder, and FIG. 2 is a state in which the encoder is assembled. FIG. 3 is a cross-sectional view, and FIG. 3 is a cross-sectional view of essential parts showing an arrangement state of light emitting and receiving elements. 1 to 3, the same reference numerals indicate the same or equivalent parts.

First, in FIG. 1, the encoder has a casing formed by a body 1 and a cover 2 which are injection molded. A printed wiring (not shown) having a predetermined pattern is provided on the inner surface 1a of the body 1. Further, the protruding portion 4 that forms a frame for holding the phototransistor 3 for receiving light, that is, the convex sensor holder portion is molded integrally with the body 1. A side surface of the phototransistor 3 for light reception is surrounded by a protrusion 4, and a bottom portion of the phototransistor 3 is fixed to the body 1 with an adhesive.

The printed wiring provided on the inner surface of the body 1a is performed by a known processing method including a circuit imaging step by masking and an etching step.

As described above, in this embodiment, since the printed wiring is directly applied to the body 1, the phototransistor 3 is directly fixed to the body 1 without the substrate. Therefore, since the substrate can be omitted, not only the encoder can be downsized, but also the step of attaching the substrate to the body 1 and the step of fixing the phototransistor 3 to the substrate can be omitted.

The phototransistors 3 are provided in a set of two in order to obtain two pulse signals having different phases, that is, A-phase and B-phase pulses used for identifying the rotating direction of the rotating body ( Only one lead 3b is shown). A fixing plate 5 having a slit 5a is provided to fix the phototransistor 3 at a predetermined position surrounded by the protrusion 4 and at the same time limit the width of a light beam to be received. The leads 3a and 3b of the phototransistor 3 are connected to the printed wiring (not shown).

Further, the inner surface 1a of the body is provided with a reflection type photo interrupter 6 for generating a Z-phase pulse, that is, a signal indicating a reference position of rotation, that is, an element in which a light emitting / receiving element is integrally housed. The photo interrupter 6 is connected to the printed wiring (not shown) by so-called surface mounting without using leads.

The through hole 1b at the center of the body 1 is a bearing that rotatably holds a hub 8 formed by insert molding with a light shielding plate 7 formed with a slit array 9 composed of a plurality of slits for pulse generation. Be part of the department. Hook portions 8a and 8b are formed in the inner diameter direction of the hub 8 so as to engage with a detected rotating body (not shown) inserted in the hub 8.

On the other hand, on the cover 2 side, a pair of photodiodes 10 are arranged as light emitting elements at positions corresponding to the phototransistors 3 for receiving light. As with the phototransistor 3, the photodiode 10 is also provided with a fixing plate 11 having a slit 11a. And
The fixing plate 11 allows the photodiode 1 to be positioned at a predetermined position defined by the protrusion 12 or the convex sensor holder portion.
0 is retained. The leads (not shown) of the photodiode 10 are connected to the wiring printed on the flexible sheet (FPC) 13. The FPC 13 is connected to a printed wiring (not shown) on the body 1 side.

The cover 2 is also formed with a through hole 2a for supporting the hub 8 of the light shielding plate 7 in the same manner as the body 1.

The body 1 and the cover 2 are engaged with each other when they are combined and integrated, and hook portions (snap fits) 14a and 14b are held so that the elastic state of the materials of each of them holds the fixed state. Are formed.

A bolt hole 15a is formed on the outer periphery of the cover 2.
Is formed, and the encoder is fixed by bolting the flange 15 to a predetermined position.

Next, the assembled state of the body 1 and the cover 2 will be described with reference to FIGS. In FIG. 2, the body 1 and the cover 2 are the snap fits 14a, 1
Enclosed housing 100 is formed by engaging 4b. The hub 8 of the light shielding plate 7 is held by the bearing portions formed in the housing 100, that is, the through holes 1b and 2a of the body 1 and the cover 2, and part of the hub 8 and the light shielding plate 7 include the body 1 and the cover 2. From inside of the housing 100 to the inside of the housing 100.

The photodiode 10 and the phototransistor 3 are sandwiched by the light shielding plate 7 protruding inside the housing 100.
And are located (see FIG. 3).

The body 1 is provided with a coupler 17 into which a terminal 16 for external connection is press fitted. One end of the terminal 16 is soldered to the printed wiring of the FPC 13 to supply power and a signal to the light emitting element of the photodiode 10 and the photo interrupter 6 from the outside, and the signal of the light receiving element of the photo transistor 3 and the photo interrupter 6. Used for taking out.

The terminal 16 is press-fitted into the coupler 17 so that F
It is not limited to soldering to the PC 13, but may be integrally molded (insert mold) with the body 1 as described later with reference to FIG. Also, a means for ensuring the soldering of the terminal 16 will be described later with reference to FIG.

Since the body 1 is required to have a certain degree of heat resistance in order to solder components to the printed wiring, polyetherimide is suitable as the material. On the other hand, since the cover 2 is not required to have heat resistance, polybutylene terephthalate (PBT) can be used, for example.

Next, referring to FIGS. 4 and 5, the second embodiment of the present invention will be described.
An example will be described. FIG. 4 is a sectional view of an encoder showing a second embodiment, and FIG. 5 is a view showing a body of the encoder shown in FIG. 4 and a light shielding plate housed therein. 4 and 5, the same reference numerals as those in FIGS. 1 to 3 indicate the same or equivalent portions.

The second embodiment is an example in which a reflection type photo interrupter is used as an optical sensor for obtaining A-phase and B-phase pulses and Z-phase pulses. In this embodiment, the photo interrupters 18 and 19 for obtaining the A phase and B phase pulses and the photo interrupter 6 for obtaining the Z phase pulse are all surface-mounted on the printed wiring formed on the inner surface 1a of the body 1. Has been done.

The body 1 has the same structure as in the first embodiment.
Although the protrusion 4 for holding the phototransistor is formed, the protrusion 4 may have a shape capable of holding the photointerrupter.

In the case of using a reflection type photo interrupter or a transmission type photo interrupter, the pattern of the printed wiring may be made common.

In the second embodiment, the cover combined with the body 1 does not have the FPC 13,
The front view is omitted because it is the same as the cover 2 of the first embodiment except that the photodiode 10 and its fixing plate 11 are not provided.

With the above structure, when the photo interrupter is a transmissive type, when the light emitted from the light emitting element, that is, the photodiode passes through the slit array 9, the light receiving element, that is, the phototransistor detects the light, and the slit. The phototransistor does not detect light when column 9 is not passed.

On the contrary, when the photo interrupter is of a reflection type, when the light emitted from the photodiode passes through the slit row 9, the phototransistor does not detect the light and passes through the slit row 9. If not, the light is reflected by the light shielding plate 7 and detected by the phototransistor.

In the case of a reflection type photo interrupter, the light shielding plate 7 may have a glossy surface or the cover 2 of the cover 2 so that the reflected light can be surely detected when the light does not pass through the slit array 9. The inner surface may be formed in a dark tone surface that does not reflect light.

A lubricant such as grease may be applied to the contact surface between the hub 8 of the light shield plate 7 and the body 1 and the cover 2 so that the light shield plate 7 can rotate smoothly. Needless to say.

Next, the means for ensuring the electrical connection of the components connected to the printed wiring in this embodiment will be described. First, the fixing and connecting means of electronic components will be described with reference to FIGS.

FIG. 6 is a perspective view of an essential part showing the relationship between an electronic component such as a capacitor and a fixed recess formed in the body, and FIG. 7 is a sectional view of an essential part showing a state where the electronic part is mounted in the fixed recess. 8 is a sectional view taken along the line AA of FIG.

6 to 8, the fixing recess 21 provided in the body 1 has a U-shaped cross section for accommodating the rectangular groove 21a for accommodating the main body 20a of the electronic component 20 and the leg 20b of the electronic component 20. The groove 21b is formed.

A conductive layer 22 made of copper plating is provided in the groove 21b having a U-shaped cross section, and a land connected to another printed wiring is formed. The land, that is, the conductive layer 22 may be formed at least on the inner surface of the groove 21b having a U-shaped cross section, but may be protruded from the groove 21b as illustrated. In short, the land, that is, the conductive layer, can be made large so that the contact area with the leg 21b can be made large and the connection by the solder 23 can be ensured, and the connection with other printed wiring on the body 1 can be facilitated. 22 may be formed.

The rectangular groove 21a and the groove 21 having a U-shaped cross section
The depth of “b” is the depth of the main body 2 with the electronic component 20 mounted.
It is desirable to set the relationship such that the leg 20b horizontally projects from 0a and can be accommodated in the groove 21b. Also, the groove 21
Strictly speaking, b is not limited to the U-shaped cross section, but may be a substantially U-shaped one.

Next, the detailed structure of the connecting portion between the external connection terminal 16 and the body 1 will be described. 9 and 1
Reference numeral 0 is a sectional view of an essential part showing a state in which the terminal 16 is fixed to the body 1. In FIG. 9, a hole 24 into which the terminal 16 is inserted is formed in the body 1 to which the terminal 16 is fixed.
A conical or dish-shaped seat 25 is formed in a part of the hole 24. Then, a conductive layer 26 formed by copper plating is formed around the seat 25.

By forming the seat 25 as described above, the contact area between the solder 27 and the terminal 16 can be increased, so that the electrical connection is ensured.

Further, in FIG. 10, a connecting portion which can omit the step of soldering the terminal 16 to the body 1 is constructed. In the figure, the terminal 16 is fixed to the body 1 by insert molding. That is,
When molding the body 1, the terminal 16 is set in a molding die in advance, and then resin is injected into the molding die to integrally mold the terminal 16 and the body 1.

Print wiring is directly applied to this integrally molded product, and the conductive layer 28 is formed on the end surface of the terminal 16, so that the terminal 16 can be attached to the body 1 without soldering.
It can be fixed to and can be electrically connected to the printed wiring.

By the way, when the body 1 and the terminals 16 are integrally molded, they are subjected to the action of etching with a strong acid which is performed prior to plating for printed wiring. Therefore, in order to avoid corrosion due to this etching, an etching resistant treatment is performed beforehand. It is important to keep it. In particular,
The terminal 16 is plated with corrosion-resistant gold or rhodium.

As an anti-corrosion plating, according to the experiments of the present inventors, the etching resistance for a polyetherimide (sulfuric acid type) is excellent in anti-corrosion with a thickness of 0.5 μm or more by gold plating. was gotten. In addition, in order to improve the plating property with respect to iron, which is a material of the terminal, it is preferable to perform Ni plating with a film thickness of 5 to 10 μm as a base. By the above-described processing, it is possible to avoid the influence of etching by a strong acid which is performed as a pretreatment for plating for printed wiring.

[0052]

As is apparent from the above description, according to the present invention, the following effects can be obtained. (1) Since the printed wiring is directly formed on the inner surface of the housing, it is not necessary to separately provide a printed circuit board, and the axial dimension of the encoder can be reduced. As a result, the degree of freedom of layout for a vehicle or the like whose space is limited is increased. Further, since it is not necessary to separately provide a printed circuit board, the number of parts can be reduced and the size can be reduced, and the assembling process can be simplified to improve the productivity. (2) Since the sensor holder portion is formed as a part of the housing, it becomes easy to position the sensor when mounting the sensor on the housing, and the positional accuracy can be improved. (3) The electronic component can be reliably connected to the printed wiring, and the electronic component itself can be fixed securely. As a result, high reliability is obtained even when used in a vehicle that is easily affected by vibration. (4) The electrical connection of the external connection terminal to the printed wiring is ensured and the strength of fixing to the housing is improved. (5) Since the external terminals are covered with the corrosion resistant plating layer,
Even when printed wiring is provided in a state where the terminal is mounted on the housing, the terminal is not corroded by etching. Therefore, the terminal and the housing can be integrally molded, and the process can be simplified.

[Brief description of drawings]

FIG. 1 is an exploded view of an encoder showing a first embodiment.

FIG. 2 is a sectional view of the encoder according to the first embodiment in an assembled state.

FIG. 3 is a sectional view of an essential part of the encoder of the first embodiment.

FIG. 4 is a cross-sectional view of an assembled encoder of the second embodiment.

FIG. 5 is a front view showing the body of the encoder of the second embodiment.

FIG. 6 is a main part perspective view showing the relationship between an electronic component and a fixed recess formed in the body.

FIG. 7 is a cross-sectional view of essential parts showing a state where the electronic component is mounted in a fixed recess.

8 is a cross-sectional view taken along the line AA of FIG.

FIG. 9 is a main-portion cross-sectional view showing an example of a connecting portion between a terminal and a housing.

FIG. 10 is a main-portion cross-sectional view showing an example of a connecting portion between a terminal and a housing.

[Explanation of symbols]

1 ... Body, 2 ... Cover, 3 ... Phototransistor, 7 ... Light-shielding plate, 9 ... Slit row, 10 ... Photodiode, 13 ... FPC, 16 ... Terminal, 20 ...
Electronic parts, 21 ... Fixing recesses, 22, 26, 28 ... Conductive layer, 23, 27 ... Solder, 25 ... Seat

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masajiro Inoue, 1-4-1, Chuo, Wako-shi, Saitama Inside the Honda R & D Co., Ltd. (72) Inventor, Kazuhisa Yamamoto 1-4-1, Chuo, Wako, Saitama No. Stock Company Honda Technical Research Institute (72) Inventor Akihiro Iwasaki 1-4-1 Chuo, Wako City, Saitama Stock Company Honda Technical Research Institute (72) Inventor Masato Moriyama 1-4-1 Chuo, Wako City Saitama Prefecture No. Incorporated in Honda R & D Co., Ltd. (72) Inventor Hiroshi Furuumi 1-4-1 Chuo, Wako-shi, Saitama Incorporated in Honda R & D Co., Ltd. (72) In-house Mitsunori Kawashima 4-1-1, Wako, Saitama No. Incorporated in Honda R & D Co., Ltd. (72) Inventor Yoshitaka Katashima 4-1-1 Chuo, Wako, Saitama Incorporated in R & D Co., Ltd.

Claims (6)

[Claims] 1. A light-emitting element and a light-receiving element, a light-shielding plate which is arranged between optical axes of the light-emitting element and the light-receiving element, and has a slit array for generating a pulse train from the light-receiving element, the light-emitting element and the light-receiving element. In an optical encoder including a housing containing an element and a light shielding plate, the housing is formed by injection molding of resin, and a printed wiring of a predetermined pattern is directly provided along the inner surface of the housing. An optical encoder in which a plate is rotatably accommodated, and the light emitting element and the light receiving element are arranged so as to face a slit row of the light shielding plate and are connected to the printed wiring. 2. A recess for holding an electronic component and a groove which is formed continuously with the recess and supports a lead of the electronic component in a longitudinal direction are integrally formed when the casing is molded, and The optical encoder according to claim 1, wherein a part of the printed wiring forms a land that covers the groove. 3. A convex sensor holder portion is integrally formed in the casing when the casing is molded, and the light emitting element and the light receiving element are fixed to the sensor holder portion. The optical encoder according to claim 1. 4. A terminal for external connection, which has been subjected to corrosion-resistant plating treatment and is integrally molded with the housing, is provided, and the printed wiring is directly applied so as to cover an end face of the terminal. The optical encoder according to claim 1. 5. The housing has a seated hole for inserting a terminal for external connection, and the printed wiring is provided so as to cover the surface of the seat of the seated hole, and The optical encoder according to claim 1, wherein the terminal is soldered to a printed wiring that covers the seat. 6. The housing comprises a body and a cover, and the printed wiring is provided on at least one of the body and the cover.
The optical encoder according to any one of 1.