JPH07311055A - Absolute-value encoder - Google Patents

Abstract

PURPOSE:To provide sufficient rigidity to resist vibration and impact and to enable miniaturization by using rotating plates each of which comprises a metallic plate on the surface of which a pattern showing predetermined codes is formed. CONSTITUTION:Each of rotating plates 2 mounted on a rotating shaft 1 is formed by printing a Gray-code pattern 8 on a glossy metallic plate 7 such as a nickel plate using a black paste. The sum of the absorptivity, the reflectivity and the transmittance of the pattern 8 is 1, in which case the transmittance is 0 while the sum of the absorptivity and the reflectivity is 1. Since the pattern 8 has an absorptivity of approximately 1, its reflectivity becomes 0 and the light of light-emitting elements provided to a pair of reflection optical sensors 3 is absorbed and does not impinge on light sensing elements, and the output becomes 0. The unprinted metallic part of each rotating plate 2 has a reflectivity of approximately 1 and therefore an absorptivity of 0, and the light of the light-emitting elements is entirely inputted to the light sensing elements, and the output becomes 1. In this case, the use of the metallic plates 7 enables the rigid rotating plates 2 to be manufactured, and the use of the sensors 3 each comprising the light emitting and sensing elements made in pairs eliminates the need for a holding plate and can provide a miniaturized form by reducing the length along the direction of the shaft 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an angle sensor unit used at the control end of machine tools, FA equipment, automobiles and the like.

[0002]

2. Description of the Related Art An example of the structure of a conventional absolute value encoder is shown in FIG.
Shown in. The conventional absolute encoder is the rotary shaft 1 of the rotating body.
And a glass rotary plate 11 provided with a gray code pattern 12 by vapor deposition of chrome, etc.
The rotary plate 11 is provided so as to face the rotary plate 11 in the axial direction and has a glass fixed plate 15 having a plurality of windows formed by vapor deposition of chromium, and the light emitting element 13 is provided on the rotary plate 11 side and the light is received on the opposite side. The element 16 is arranged so as to sandwich the rotating plate 11 and the fixed plate 15, the output from the light receiving element 16 is converted into an electric signal by the signal processing circuit 17, and the absolute value of the rotation angle of the rotating shaft 1 is converted into a gray code signal. It is configured to be ejected. In this structure, when the transparent portions of the rotary plate 11 and the fixed plate 15 are aligned with each other, the light emitted from the light emitting element 13 passes through the rotary plate 11 and the fixed plate 15 and is input to the light receiving element 16. On the other hand, when the transparent portions of the rotating plate 11 or the fixed plate 15 do not match, the light emitted from the light emitting element 13 is reflected by the chrome portion deposited on the glass and is not input to the light receiving element 16. At this time, "on" and "off" of light are converted into electric signals and output.

[0003]

In the absolute value encoder according to the prior art shown in FIG. 5, the rotary plate and the fixed plate provided with a gray code pattern are formed by vapor-depositing chrome on glass and chemically etching it. The target code pattern was provided by. This manufacturing method is vapor deposition of chromium,
In addition, a process that requires precision such as etching is required,
Moreover, since glass is fragile, it must be handled with extreme caution. Furthermore, it is difficult to machine glass, and it is not possible to expect high-precision machining. The inner diameter hole has to be rough, and it is necessary to attach the core to the rotary shaft and then pull out the core. It is vulnerable to shocks, and the structure in which the light receiving element and the light emitting element sandwich the rotating plate and the fixed plate causes a problem that the axial dimension becomes large.

[0004]

The present invention uses a rotating plate in which a predetermined code pattern is formed by printing a black paste on the surface of a metal plate, and a light emitting element and a light receiving element are paired to form a reflection type light. By using a sensor, it is possible to provide a compact absolute value encoder that is resistant to vibration and shock at low cost.

[0005]

According to the present invention, since the metal plate is used as the rotating plate and the pattern of the predetermined code is formed on the metal plate by printing the black paste, the process is very simple, and the rotating plate which is robust and inexpensive can be manufactured. . Also, since a metal plate is used, high-precision machining is easy, so the centering work when attaching to the rotating shaft is simple. Further, in the present invention, since the reflection type optical sensor in which the light emitting element and the light receiving element are paired is adopted, the fixing plate is not required, and the reflection type optical sensor can be provided on one side of the rotating plate. The absolute value encoder that is robust, compact, and inexpensive can be configured by the effects of shortening the length of the and reducing the size.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention is shown in FIG. 1 and will be specifically described. FIG. 1 is a structural diagram showing the present invention. Rotation axis 1,
A rotary plate 2 having a gray code pattern attached to the rotary shaft 2, a reflection type optical sensor 3, a reflection type optical sensor 3
And a circuit board 4 in which an output signal processing circuit is incorporated, an encoder cover 5, and a lead 6 for taking out an output to the outside. FIG. 2 shows a plan view of the rotary plate 2 of the present invention.
The rotary plate 2 is formed by printing a gray code pattern 8 with a black paste on a relatively glossy metal plate 7 such as a nickel plate or a stainless plate. The metal plate 7 is formed at low cost by using a plate punched by a press or the like, and can be fixed to the rotary shaft with high precision.

FIG. 3 is a timing chart of the Gray code obtained from the rotary plate 2 and shows an example of 5 bits. The operation of the embodiment of the absolute value encoder according to the present invention shown in FIGS. 1 and 2 will be described. There are absorptivity, reflectivity, and transmissivity to indicate the optical properties of a substance, and the law of energy conservation shows that the relationship of absorptivity + reflectivity + transmissivity = 1 ……………… (1) Are known. When the metal plate 7 is used as the rotating plate 2, since the transmittance = 0 in the formula (1), the absorption ratio + the reflectance ratio = 1. In the metal rotary plate 2, a portion 8 where a predetermined code pattern is formed by printing a black paste has a maximum absorption rate of about "1".
Therefore, the reflectance is "0", and the light emitted from the light emitting element is absorbed and does not enter the light receiving element, so the output is "0". On the other hand, in the portion of the rotating plate 2 where the black paste is not printed, that is, in the metal portion, the reflectance is almost "1", so the absorptance is "0", and all the light emitted from the light emitting element is input to the light receiving element. The output becomes "1".

FIG. 4 shows a rotary plate 2 showing another embodiment of the present invention.
FIG. A metal rotating plate 7 is provided with a pattern 9 representing a predetermined code by etching or pressing, and the above formula (1) is also applied to this embodiment. Absorption rate + reflectance + transmittance = 1 (1 ), The portion 9 of the metallic rotary plate 7 from which the metal has been removed has a transmittance of 1 and a reflectance of 0, and the output is "
The metal part 7 has a reflectance of 1 and an output of "1" as described above. The absolute value encoder according to the present invention has a metal rotary plate having an absorptivity of 1 or a transmittance. = 1 portion and reflectance = 1 portion are provided to form a predetermined code pattern, and a desired output is obtained by using a reflection type optical sensor. Although the embodiment of the present invention shown in FIG. 4 has been described with an example of 5 bits, any number of bits of 5 bits or more is possible, and not only the absolute value encoder of Gray code but also the incremental type encoder can be applied. is there.

[0009]

Since the absolute value encoder according to the present invention is configured as described above, there is an effect that it is possible to provide a small-sized absolute value encoder which is strong against vibration and impact at low cost.

[Brief description of drawings]

FIG. 1 is a sectional view showing a structure of an absolute value encoder according to the present invention.

FIG. 2 is a plan view of an embodiment of a rotary plate of an absolute value encoder according to the present invention.

FIG. 3 is a timing chart showing the output of the absolute value encoder according to the present invention.

FIG. 4 is a plan view of another embodiment of the rotary plate of the absolute value encoder according to the present invention.

FIG. 5 is a cross-sectional view showing a structure of an absolute value encoder according to a conventional technique.

[Explanation of symbols]

 1: Rotation axis 2: Rotation plate 3: Reflection type optical sensor 4: Circuit board 5: Cover 6: Lead 7: Metal plate 8: Pattern formed by printing 9: Pattern formed by removal of metal 11: Glass rotation plate 12 : Chrome vapor deposition gray code pattern 13: Light emitting element 14: Chrome vapor deposition fixing plate pattern 15: Glass fixing plate 16: Light receiving element 17: Signal processing circuit G0 to G4: Gray code signal

Claims (2)

[Claims] 1. A rotary plate attached to a rotary shaft of a rotary body, on which a pattern representing a predetermined code is formed, and a reflection type in which a light emitting element and a light receiving element are arranged so as to face each other without forming a pair. An optical sensor and a conversion circuit for converting an ON / OFF signal of light into an electric machine signal and extracting the rotation angle of the rotary plate from the output of the optical sensor as a digital amount of an absolute value are provided. An absolute value encoder characterized in that a pattern representing a code on the surface of the member is formed by printing a black paste. 2. A reflection type light which is attached to a rotation shaft of a rotating body and on which a pattern representing a predetermined code is formed and a light emitting element and a light receiving element which are paired and are arranged so as to face the rotation plate. A sensor and a conversion circuit that converts an on / off signal of light into an electric signal and extracts the rotation angle of the rotary plate from the output of the optical sensor as a digital amount of an absolute value, and a pattern representing a code of the rotary plate is provided. An absolute value encoder formed by cutting a metal plate forming the rotary plate.