JP7156687B2 - optical encoder - Google Patents

Description

The present invention relates to optical encoders that use light to change electrical output signals.

Conventionally, a rotating body used in an optical encoder, such as the rotating body (11) shown in FIG. The scale portion (14) is formed by alternately arranging the portions (15a) and the non-reflecting portions (15b) in a circumferential manner, and the optical sensor (16) detects the state of reflection of the light irradiated to the scale portion (14), Thus, it is configured to detect the state of rotation of the rotating body (11).

The reflecting portion (15a) and the non-reflecting portion (15b) are formed on the rotating body (11) by forming the scale portion (14) by depositing a metal material such as aluminum on the lower surface of the disk (13). , by photo-etching the lower surface of the scale portion (14).

Conventionally, the method of forming the reflecting portion and the non-reflecting portion is not limited to the above method, but a method of attaching a metal plate to the lower surface of the rotating body that serves as a reflecting surface, or forming a metal layer by plating, and then etching these. And so on.

JP-A-07-209023

However, as described above, in order to form the reflective portion and the non-reflective portion on the reflective surface of the rotating body, the work of forming a metal layer or metal plate on the reflective surface and etching it is complicated. In addition, the manufacturing equipment has become large-scaled, leading to an increase in manufacturing costs.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical encoder which is easy to manufacture and which can obtain an accurate signal.

The present invention provides a rotating body rotatably supported about a rotating shaft and provided with a light reflecting surface, a light emitting element emitting light toward the light reflecting surface of the rotating body, and a light reflecting body of the rotating body. a light-receiving element for receiving light reflected by a surface; and a circuit board arranged below the rotating body and having the light-emitting element and the light-receiving element installed on the upper surface of the rotating body. a high reflection portion and a low reflection portion for reflecting the light received from the light emitting element are formed on the light reflection surface of the light receiving element, and the amount of light received by the light receiving element is adjusted to In the optical encoder for detecting the rotation state of the rotating body according to the above, the high reflecting portion is formed by exposing the surface of the synthetic resin itself constituting the rotating body, and the low reflecting portion is formed by exposing the light reflecting surface. A shaft portion is formed on the upper surface of the circuit board by printing, a shaft portion is provided upright from the upper surface of the circuit board, a bearing portion composed of a concave portion is provided on the light reflecting surface of the rotating body, and the bearing portion of the rotating body is erected from the circuit board. The shaft is rotatably inserted so that the upper surface of the shaft is brought into contact with the bottom surface of the bearing .
According to the present invention, the high reflective portion is formed by the exposed surface of the synthetic resin itself, which is the rotating body, and the low reflective portion is formed by printing. The high reflection portion and the low reflection portion can be easily formed simply by using a material (color) that is easy to reflect and forming the low reflection portion by printing. In addition, equipment used for printing can be cheaper than equipment used for vapor deposition, etching, and the like. For these reasons, the manufacturing cost can be reduced.
In the present invention, the high reflection portion and the low reflection portion are alternately formed on a circumference, and the high reflection portion includes low reflection portions positioned on both sides of the high reflection portion and low reflection portions positioned on both sides of the high reflection portion. The outer circumference is surrounded by a low-reflection outer ring portion surrounding the outer circumference side of the portion and a low-reflection inner ring portion surrounding the inner circumference side of the high reflection portion.
In addition to the above characteristics, the present invention has a bottom portion located on the lower surface side of the circuit board and a side wall portion erected so as to surround the periphery of the circuit board. and a cover covering the housing portion of the case and formed with a bearing portion having a through hole in the center, wherein the rotating body has the light reflecting surface as the lower surface. and a knob projecting from the upper surface of the main body, and the knob of the rotating body is inserted into the bearing of the cover and rotatably supported.

In addition to the above characteristics, the present invention is characterized in that the brightness of the synthetic resin material forming the rotating body is higher than the brightness of the ink printed to form the low reflection portion.
According to the present invention, it is possible to increase the difference between the amount of reflected light reflected by the high-reflection portion and the amount of reflected light reflected by the low-reflection portion, so that a reliable (accurate) ON/OFF signal can be obtained. .

According to the present invention, an optical encoder can be easily manufactured, and an accurate signal can be obtained from the reflecting portions (high reflecting portion and low reflecting portion).

1 is a perspective view of an optical encoder 1; FIG. 2 is an exploded perspective view of the encoder 1; FIG. FIG. 2 is a schematic cross-sectional view taken along line AA of FIG. 1; 3 is a perspective view showing a circuit board 30; FIG. 4 is a perspective view of the rotating body 60 as seen from below; FIG. 6 is a side cross-sectional view of the rotating body 60. FIG. 4 is a bottom view of the rotating body 60. FIG. FIG. 4 is a schematic explanatory diagram showing the relationship between a photosensor 33 (or 35), a high reflection portion 615a, and a low reflection portion 615b;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view of an optical encoder (hereinafter simply referred to as "encoder") 1 according to one embodiment of the present invention, FIG. 2 is an exploded perspective view of the encoder 1, and FIG. 3 is a schematic sectional view taken along line AA of FIG. be. As shown in these figures, the encoder 1 comprises a case 10 housing a circuit board 30, a rotor 60, and a cover 80. As shown in FIG. In the following description, "up" refers to the direction in which the rotating body 60 is viewed from the circuit board 30, and "down" refers to the opposite direction.

FIG. 4 is a perspective view showing the circuit board 30. FIG. As shown in the figure, the circuit board 30 has a hard and substantially rectangular insulating substrate 31. A positioning hole 313 is formed through the center of this insulating substrate 31, and a plurality of (this Four through holes 315 are provided in the example. Two photosensors (light emitting/receiving elements) 33 and 35 and a signal processing circuit 37 are installed at predetermined positions on an upper surface (hereinafter referred to as “upper surface”) 311 of the insulating substrate 31 . One ends of a plurality of (six in this example) terminal plates 39 are in parallel contact with the upper surface near one side.

The two photosensors 33 and 35 are reflective photosensors (photoreflectors) of the same type, and have light emitting elements 331 and 351 and light receiving elements 333 and 353, respectively. When the light emitted from the light emitting element 331 is received by the light receiving element 333, an output voltage is generated. Similarly, when light emitted from the light emitting element 351 is received by the light receiving element 353, an output voltage is generated.

A signal processing circuit 37 receives the output signals from the photo sensors 33 and 35, converts these input signals (electrical signals) into rectangular electric signals (on/off signals), and amplifies the current value. This is the output circuit (waveform shaping circuit). This signal processing circuit can be configured by an IC circuit or other various semiconductor circuits. In this example, when the voltage value of the input waveform of the signals from the photosensors 33 and 35 exceeds a predetermined value, the switch is turned on, and when it falls below the predetermined value, the switch is turned off and a switching circuit is provided to amplify the current value. is doing. Since this switching circuit performs current amplification of the output signal, a more accurate output signal can be obtained. An output signal from the signal processing circuit 37 is led out to a connection pattern (not shown) provided in parallel on one side of the circuit board 30, and electrically connected to each terminal plate 39 abutting thereon.

As shown in FIGS. 2 and 3, the case 10 is formed by molding synthetic resin into a box shape with an open top. A rectangular recessed storage portion 11 is formed on the upper surface side of the case 10 . The upper surface of the circuit board 30 insert-molded in the case 10 is exposed on the bottom surface of the housing portion 11, and a circular columnar shaft portion forming a part of the case 10 is provided at the center of the upper surface of the circuit board 30. 13 are erected. A circular through hole 14 is formed in the center of the shaft portion 13 . In other words, the case 10 includes a substantially rectangular bottom portion 15, a side wall portion 17 extending upright around the bottom portion 15, and an axis projecting from the center of the bottom portion 15 through the circuit board 30 to the upper surface side thereof. From one side wall portion 17 of the case 10, tip end portions of six terminal plates 39 protrude outward. The portion of each terminal plate 39 that abuts on the circuit board 30 is fixed by the synthetic resin forming the case 10, and maintains a good connection state with each connection pattern of the circuit board 30. FIG. Small protruding positioning portions 19 protrude from the upper surfaces of the two corners of the side wall portion 17 .

In order to manufacture the case 10, the circuit board 30 and the terminal board 39 are placed in a mold having a cavity shaped like the case 10. are in contact with each connection pattern (not shown). In this state, molten synthetic resin is injected into the cavity, and after the synthetic resin has solidified, the mold is removed to complete the case 10 in which the circuit board 30 and the terminal plate 39 are insert-molded. At this time, the shaft portion 13 and the bottom portion 15 of the case 10 are connected through four through holes 315 provided in the circuit board 30 . Moreover, the hole 14 is formed so as to penetrate through the upper and lower surfaces of the bottom portion 15 of the case 10 through the positioning hole 313 of the circuit board 30. The reason for this is as follows. That is, as described above, when the circuit board 30 and the like are accommodated in the mold, the circuit board 30 is positioned by inserting positioning projections (not shown) protruding from the mold into the positioning holes 313 of the circuit board 30. For example, Even if the orientation of the circuit board 30 in the mold at that time is such that the horizontal circuit board 30 shown in FIG. (so that the circuit board 30 does not come off from the positioning projection), the positioning projection that penetrates the inside of the mold cavity (that is, the hole 14 becomes a through hole) is provided.

5 is a perspective view of the rotating body 60 as seen from below, FIG. 6 is a side cross-sectional view of the rotating body 60 (a cross-sectional view at a position rotated 90 degrees from the cross section of FIG. 3), and FIG. 7 is a rotating body. 60 is a bottom view of 60. FIG. As shown in these figures and FIGS. 1 to 3, the rotating body 60 is made of synthetic resin (polycarbonate resin in this example), and includes a disk-shaped main body 61 and a circular body protruding from the center of the upper surface of the main body 61. It is formed integrally with a columnar knob (shaft) 63 . The color of the synthetic resin forming the rotor 60 is white, that is, the synthetic resin is colored to easily reflect light. A lower surface of the body portion 61 serves as a light reflecting surface 62 . The main body portion 61 has an outer diameter dimension to be accommodated in the accommodating portion 11 of the case 10 . At the center of the light reflecting surface 62 on the lower surface of the body portion 61, a bearing portion 611 having a circular concave portion is formed. A circular reflecting portion 615 is formed at a position surrounding the bearing portion 611 of the light reflecting surface 62 .

The reflecting portion 615 is configured by forming a plurality of sets of high reflecting portions 615a and low reflecting portions 615b continuously and alternately at equal intervals in an endless manner. reflective track surface). The low reflection portion 615b is formed by printing black paint on the surface of the light reflecting surface 62. As shown in FIG. The highly reflective portion 615a is formed by exposing the surface of the white synthetic resin itself. That is, the reflecting portion 615 includes a high reflecting portion 615a formed by the color (white) of the synthetic resin itself forming the rotating body 60, and a low reflecting portion 615a formed by printing black printing ink (paint) on the surface thereof. It is configured by alternately forming the reflective portions 615b. Both the high reflection portion 615a and the low reflection portion 615b are sector-shaped, and the left and right sides of the high reflection portion 615a and the low reflection portion 615b are arranged on a line radially extending from the rotation axis L1 of the rotating body 60 (see FIGS. 6 and 7). It is formed so that the sides are positioned. The low reflection portion 615b further has an outer ring portion (outer connecting portion) 615bx that connects its outer periphery in a ring shape, and an inner ring portion (inner connecting portion) 615by that connects its inner periphery in a ring shape. That is, the high reflection portion 615a is surrounded by the low reflection portion 615b, the outer ring portion 615x, and the inner ring portion 615y located on both sides thereof.

In order to form the reflecting portion 615, a printing ink having a brightness lower than the brightness of the synthetic resin forming the rotating body 60, specifically, the black printing ink (paint) is applied onto the light reflecting surface 62 as described above. This is done by printing (applying) and coloring the low reflection portion 615b, the outer ring portion 615bx, and the inner ring portion 615by. In this example, printing is performed by pad printing.

Further, according to this rotating body 60, instead of the protruding shaft for supporting the lower side of this rotating body 60, a concave portion serving as the bearing portion 611 is provided, so that there is no portion protruding from the light reflecting surface 62. . Therefore, the above-described printing work on the light reflecting surface 62 can be easily performed. Note that the upper side of the rotating body 60 is pivotally supported by a knob portion 63 .

The cover 80 is made of a metal plate and is connected to a pair of opposite sides of the cover main body 81, which is substantially rectangular and has a shape that covers the storage part 11 of the case 10, and which is substantially perpendicular to the cover main body 81. , and side portions 83, 83 that are bent downward. A cylindrical bearing portion 811 is formed in the center of the cover body portion 81, and the center thereof serves as a through hole. Further, in the vicinity of the two corners of the cover main body 81, a positioning portion 813 consisting of a small hole into which the positioning portion 19 of the case 10 is inserted is formed. At the center portion of the lower side of each side surface portion 83, another member mounting portion 831 is formed which protrudes downward. is formed.

Next, in order to assemble this encoder 1, the body portion 61 of the rotating body 60 is housed in the housing portion 11 of the case 10. As shown in FIG. At this time, the shaft portion 13 of the case 10 is inserted into the bearing portion 611 of the rotating body 60 to rotatably support the rotating body 60 . The distance between the light emitting elements 331 and 351 and the light receiving elements 333 and 353 is set as a predetermined distance. That is, by the shaft portion 13 of the case 10 and the bearing portion 611 of the rotating body 60, the rotating operation of the rotating body 60, the accurate setting of the separation distance between the light emitting elements 331 and 351 and the light receiving elements 333 and 353, and the reflecting portion 615, at the same time.

Next, the cover main body portion 81 of the cover 80 is put on the upper surface of the case 10 housing the main body portion 61 of the rotating body 60 to close the housing portion 11 of the case 10 . At this time, the knob portion 63 of the rotating body 60 is simultaneously inserted into the bearing portion 811 of the cover 80 to rotatably support the rotating body 60 . Then, by bending the case mounting portions 833 of the cover 80 toward the lower surface of the case 10, the cover 80 is fixed to the case 10, and the encoder 1 shown in FIG. 1 is completed. The above assembly procedure is only an example, and it goes without saying that other various different assembly procedures may be used for assembly.

In the encoder 1 configured as described above, first, a voltage is applied to one of the terminal plates 39 to activate the electric circuit on the circuit board 30 . Here, FIG. 8 is a schematic explanatory diagram showing the relationship between one of the two photosensors 33 (or 35), the high reflection portion 615a, and the low reflection portion 615b. For convenience of illustration, the rotation direction E of the rotor 60 and the arrangement direction of the pair of light emitting element 331 (or 351) and light receiving element 333 (or 353) provided in the photosensor 33 (or 35) are shown to be the same. However, the two directions are actually perpendicular to each other. As shown in the figure, light is emitted from the light-emitting element 331 (or 351) of the photosensor 33 (or 35) to the reflecting portion 615 (615a, 615b) on the lower surface of the rotating body 60, and the irradiated portion becomes the high reflecting portion. In the case of 615a, most of the light is reflected and received by the light receiving element 333 (or 353) of the photosensor 33 (or 35). Therefore, the light is not received by the light receiving element 333 (or 353) of the photosensor 33 (or 35). Therefore, when the rotor 60 rotates, the output signal from the photosensor 33 (or 35) changes according to the light receiving state of the light receiving element 333 (or 353). Specifically, an on/off signal corresponding to the difference in the reflection state between the high reflection portion 615a and the low reflection portion 615b is obtained.

By the way, in this embodiment, since the low reflection portion 615b, the outer ring portion 615bx, and the inner ring portion 615by are formed so as to surround the entire outer periphery of the high reflection portion 615a, a more accurate on/off signal can be obtained. That is, each high reflection portion 615a is isolated including its outer periphery and inner periphery by the black low reflection portion 615b, the outer ring portion 615bx, and the inner ring portion 615by. Therefore, even if part of the light emitted from the light emitting element 331 (or 351) of the photosensor 33 (or 35) is irradiated to a position corresponding to the outer ring portion 615bx or the inner ring portion 615by and reflected, the reflected light can be reduced, and the possibility of malfunction caused by the reflected light entering the light receiving element 333 (or 353) after being reflected by another member can be reliably prevented. From this, a more accurate on/off signal can be obtained.

Furthermore, both photosensors 33 and 35 are positioned on the same circumference around the rotation axis L1 of the rotating body 60, and are positioned to face the two photosensors 33 and 35, respectively. It is arranged so as to be slightly displaced in the circumferential direction with respect to the reflecting portion 615b). Therefore, when the rotating body 60 rotates, the timing at which one of the photosensors 33 passes through the high reflection portion 615a (or the low reflection portion 615b) at the position facing the other photosensor 35 is at the position at which the other photosensor 35 faces. The timing of passing through the high reflection portion 615a (or the low reflection portion 615b) is slightly shifted. This output signal is then output to the terminal board 39 . By using the output signal thus obtained, the rotational direction and rotational speed of the rotating body 60 can be measured by analyzing the pair of on-off waveforms that are out of phase.

In each of the above-described embodiments, an example of using a photosensor in which a light emitting element and a light receiving element are integrated has been described. good.

As described above, the encoder 1 emits light toward the rotating body 60 which is rotatably supported about the rotation axis L1 and has the light reflecting surface 62 and the light reflecting surface 62 of the rotating body 60. light emitting elements 331 and 351 and light receiving elements 333 and 353 for receiving light reflected by the light reflecting surface 62 of the rotating body 60, and the light emitting elements 331 and 353 are provided on the light reflecting surface 62 of the rotating body 60; A high reflection portion 615a and a low reflection portion 615b are formed to reflect the light received from 351, and the light reflected by these high reflection portion 615a and low reflection portion 615b is received by the light receiving elements 331 and 351 according to the amount of received light. The high reflection portion 615a is formed by exposing the surface of the synthetic resin itself constituting the rotation body 60, and the low reflection portion 615b is formed on the light reflecting surface 62. is formed by printing on In this way, the high-reflection portion 615a is formed by the exposed surface of the synthetic resin itself that forms the rotating body 60, and the low-reflecting portion 615b is formed by printing. The high reflection portion 615a and the low reflection portion 615b can be easily formed simply by using a material (color) that reflects easily and forming the low reflection portion 615b by printing. In addition, equipment used for printing can be cheaper than equipment used for vapor deposition, etching, and the like. For these reasons, the manufacturing cost can be reduced.

Furthermore, in the encoder 1, the brightness of the synthetic resin material forming the rotating body 60 is higher than the brightness of the ink printed to form the low-reflectance portion 615b, so the reflected light reflected by the high-reflection portion 615a and the amount of reflected light reflected by the low reflection portion 615b can be increased, and a reliable (accurate) ON/OFF signal can be obtained.

Especially in this encoder 1, the shaft portion 13 of the case 10 projecting from the center of the upper surface of the circuit board 30 is rotatably supported by the concave bearing portion 611 provided at the center of the lower surface of the rotating body 60. The contact area is small, so it has a structure with little wear. At the same time, the upper surface of the shaft portion 13 abuts against the bottom surface of the bearing portion 611 to support the rotating body 60 in the vertical direction. can be Thereby, the light emitted from the light emitting portions 331 and 351 of the photosensors (light emitting elements) 33 and 35 is reflected by the reflecting portion 615 and received by the light receiving portions 333 and 353 of the photosensors (light receiving elements) 33 and 35. can be configured with high precision, and a high-precision output signal can be obtained.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the technical ideas described in the claims, specification and drawings. It is possible. Any shape, structure, or material that is not directly described in the specification and drawings is within the scope of the technical idea of the present invention as long as it produces the action and effect of the present invention. For example, in the above-described embodiment, the high-reflectance portion formed by the exposed surface of the synthetic resin of the rotating body itself is white, and the low-reflection portion formed by printing is black. Any color may be used as long as the color is high. For example, red, yellow, or the like may be used as the color of the high reflection portion, and dark gray, dark blue, or dark green may be used as the color of the low reflection portion. Further, in the above-described embodiment, the outer ring portion 615bx and the inner ring portion 615by are provided on the outer peripheral side and the inner peripheral side of the low reflection portion 615b. Further, the outer ring portion 615bx and the inner ring portion 615by may not have a shape in which a part thereof is cut, that is, a complete ring shape.

Moreover, the embodiments shown in the above description and each drawing can be combined with each other as long as there is no contradiction in the purpose, configuration, and the like. In addition, even if only a part of the above description and the contents of each drawing can be independent embodiments, the embodiment of the present invention is one embodiment in which the above description and each drawing are combined. is not limited to

1 encoder (optical encoder)
60 rotating body L1 rotating shaft 62 light reflecting surface 611 bearing portion 615 reflecting portion 615a high reflecting portion 615b low reflecting portion 30 circuit board 33, 35 photosensor 331, 351 light emitting element 333, 353 light receiving element

Claims (4)

a rotating body rotatably supported about a rotating shaft and provided with a light reflecting surface;
a light emitting element that emits light toward the light reflecting surface of the rotating body;
a light receiving element for receiving light reflected by the light reflecting surface of the rotating body;
a circuit board arranged below the rotating body and having the light-emitting element and the light-receiving element installed on its upper surface;
has
A high reflection portion and a low reflection portion are formed on the light reflection surface of the rotating body to reflect the light received from the light emitting element, and the light reflected by the high reflection portion and the low reflection portion is received by the light receiving element. In an optical encoder that detects the rotation state of the rotating body according to the amount of light received,
The highly reflective portion is formed by exposing the surface of the synthetic resin itself that constitutes the rotating body,
The low-reflection portion is formed by printing on the light-reflecting surface ,
A shaft portion is erected from the upper surface of the circuit board,
The light reflecting surface of the rotating body is provided with a bearing portion comprising a concave portion,
An optical encoder characterized in that a shaft portion erected from the circuit board is rotatably inserted into a bearing portion of the rotating body so that an upper surface of the shaft portion is brought into contact with a bottom surface of the bearing portion . An optical encoder according to claim 1, comprising:
The high reflection portion and the low reflection portion are alternately formed on the circumference,
The high reflection portion includes low reflection portions positioned on both sides of the high reflection portion, a low reflection outer ring portion surrounding the outer circumference of the high reflection portion, and a low reflection inner ring surrounding the inner circumference of the high reflection portion. An optical encoder characterized in that the outer circumference is surrounded by a portion. 3. The optical encoder according to claim 1 or 2,
a case having a bottom positioned on the lower surface side of the circuit board and a side wall part erected so as to surround the circuit board so as to form a storage part on the upper surface side of the circuit board;
a cover that covers the housing portion of the case and forms a bearing portion that has a through hole in the center;
has
The rotating body comprises a main body having a lower surface as the light reflecting surface, and a knob protruding from the upper surface of the main body,
An optical encoder, wherein the knob portion of the rotating body is inserted into a bearing portion of the cover so as to be rotatably supported. 4. The optical encoder according to claim 1, 2 or 3 ,
The optical encoder according to claim 1, wherein the brightness of the synthetic resin material forming the rotating body is higher than the brightness of the ink printed to form the low reflection portion.

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