JPS6288919A - Pulse encoder - Google Patents

Abstract

PURPOSE:To eliminate the influence of an external noise by shielding a wiring pattern for a signal which is formed on the intermediate layer of a photoelectric transducer array by shield patterns formed on both surfaces of the wiring pattern. CONSTITUTION:The photoelectric transducer array 3 is formed by laminating the 1st layer having a shield pattern 312 formed on the surface of an insulating plate 311, the 2nd layer having a wiring pattern 322 for a signal formed on the surface of an insulating plate 321, the 3rd layer having wiring for a signal formed on the reverse surface of the insulating plate 311, and the 4th layer having a shield pattern 342 formed on the reverse surface of an insulating plate 341. Consequently, the patterns 322 and 332 formed on the intermediate layer of the element 3 are sandwiched between patterns 312 and 342 formed on the top and reverse surfaces. Therefore, the patterns 322 and 332 are shielded completely by the patterns 312 and 342 to eliminate the influence of an external noise completely.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a pulse encoder, and in particular, detects the rotation angle, rotation speed, etc. of a servo motor to determine the position of a robot's arm,
This invention relates to noise countermeasures in a pulse encoder that reads movement or table feed of machine tools such as NG.

[Conventional technology]

Conventionally, this type of pulse encoder includes a light emitting part such as a light emitting diode, a photoelectric conversion element array having a photoelectric conversion element such as a PN type photodiode that receives light from the light emitting part, and a photoelectric conversion element array from the light emitting part to the photoelectric conversion element array. A rotating code plate and a fixed code plate having a signal pattern that transmits or blocks light transmitted to the frame, a fixed slit stand to which the fixed code plate and the photoelectric conversion element array are fixed, and a casing to which the fixed slit stand is fixed. , and a printed board on which a signal processing circuit (a comparator, a line driver, etc.) to which an output signal from the photoelectric conversion element array is input through a connection line is formed.

FIG. 5 shows an enlarged plan view of the photoelectric conversion element array in such a conventional pulse encoder. Figure).

As shown in FIG. 5, a predetermined number (for example, three) of photoelectric conversion elements (for example, PN type photodiodes) 70 are provided on the front side of the insulating substrate 71, and from these photoelectric conversion elements 70, The output signal is transmitted directly through a signal wiring pattern 72 formed on the surface (see FIG. 5 (al)), or through a through hole 74 formed in the insulating substrate 71 and the back surface of the insulating substrate 71. A signal processing circuit formed on the printed board is led to a signal terminal 73 through a signal wiring pattern 72 (see FIG. 5 (bl)) formed on the board, and is further passed through a predetermined connection line from the terminal 73. Note that 75 is a screw hole for fixing the photoelectric conversion element array to a fixed slit stand.

By the way, in this type of pulse encoder, the output signal from the photoelectric conversion element is on the order of several hundred mV at most, so the signal from the photoelectric conversion element to the amplifier (e.g., comparator) on the printed board is particularly prone to noise. Therefore, the external output signal of the pulse encoder is not correct, which often causes malfunctions, which has been a problem.

By the way, the main reason why such noise is likely to be absorbed into the output signal output from the photoelectric conversion element is that the fixed slit base that fixes the photoelectric conversion element array is made of metal (usually the housing to which the fixed slit base is fixed) made of the same metal)
Therefore, high-frequency noise from the power supply circuit to the motor, especially the amplifier connected to the supply circuit, comes into contact with the motor case, one end of the motor case, and the bearing that supports the rotating shaft of the motor. The noise is transmitted through the casing attached to the casing to the fixed slit slot stand fixed to the casing, and ultimately the fixed slit slit stand becomes the noise source.

However, the overall noise resistance of this type of optical pulse encoder is mainly determined by the noise resistance between the photoelectric conversion element and the comparator on the print i (see FIG. 6). This is because the signal after the comparator is at a logic level, whereas the signal before the comparator is a weak analog voltage as described above.

Therefore, improving the noise resistance of this path will improve the noise resistance of the entire encoder.
As a conventional measure to reduce such noise, for example, as shown in FIG. 6, a signal processing circuit (composed of a comparator 52, a line driver 53, etc. ) (mainly the input circuit of the comparator 52) is connected with a two-capacitor, and the capacitor absorbs the noise contained in the output signal from the photoelectric conversion element array 3.

However, such a capacitor absorbs the normal output signal along with the noise, for example when the motor is rotating at high speed or when the signal pattern slit formed on the rotation code plate is fine. When the frequency of the output signal becomes high, such as when the frequency of the output signal is high (in other words, when the number of pulses is large), the distortion of the output signal becomes noticeable due to the influence of the capacitor, and there is a risk that a correct signal may not be obtained as a rectangular wave signal on the comparator output side. There was a problem that there was a problem.

Furthermore, even if the fixed slit stand itself is made of an insulating material instead of being made of metal, the electric field due to cough high-frequency noise will pass through the insulating material to the photoelectric conversion element array, in almost the same way as if it were made of metal. There is a problem in that the noise is formed on the side, and a sufficient effect cannot be obtained as a countermeasure for this type of noise reduction.

[Problems to be Solved by the Invention] The present invention has been made in view of the problems that the present invention faces. Based on the idea of forming a predetermined shield pattern on the back surface and forming a signal wiring pattern in the intermediate layer sandwiched between the shield patterns, noise contained in the output signal from the photoelectric conversion element array can be effectively reduced. It was designed to reduce this to .

[Means for solving problems]

In order to solve the above problems, the present invention includes a light emitting part, a photoelectric conversion element array that receives light from the light emitting part, and a signal that transmits or blocks the light sent from the light emitting part to the photoelectric conversion element array. A rotating code plate and a fixed code plate having a pattern, a fixed slit stand to which the fixed code plate and the photoelectric conversion element array are fixed, a casing to which the fixed slit stand is fixed, and an output signal from the photoelectric conversion element array. In a pulse encoder equipped with a printed circuit board on which a signal processing circuit is formed, the signal is input through a connecting line.
The photoelectric conversion element array is provided with photoelectric conversion elements on its surface, and a predetermined seal pattern is formed on the front and back surfaces excluding the photoelectric conversion element arrangement part and the signal wiring lead-out part, and the seal pattern is Provided is a pulse encoder characterized in that a signal wiring pattern is formed in an intermediate layer sandwiched between the two layers.

[For production]

According to the above configuration, in the photoelectric conversion element array,
The signal wiring pattern from the photoelectric conversion element to the signal derivation terminal is almost completely shielded by the shield patterns formed on both the front and back surfaces of the photoelectric conversion element array, so that the output signal from the photoelectric conversion element is It is no longer affected by the high frequency noise and the like, and the noise contained in the output signal from the photoelectric conversion element is effectively reduced.

〔Example〕

An embodiment of the pulse encoder according to the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing the overall configuration of a pulse encoder as an embodiment of the present invention.

First, in FIG. 1(a), reference numeral 1 denotes a casing (flange) that comes into contact with one end of the motor case, and a bearing that supports the rotating shaft 11 of the motor is mounted inside the casing. One end of the shaft 11 protrudes from the upper surface of the housing as shown in FIG.
) 4 are adhesively fixed.

Further, on the housing 1, a fixed slit base 2 is provided at its notch 23.
It is fixed by a set screw (indicated by reference numeral 25 in FIG. 3) which is inserted through FIG. 1 (see C1). Note that usually
The fixed slit base is made of the same metal as the housing,
It can also be made of an insulator.

22 is a fixed code plate adhesively fixed on the protrusion 24 (see FIG. 1(C)) provided on the fixed slit table 2, and 3 is a photoelectric conversion element provided in the fixed slit table 2. The array is fixed onto the fixed slit base 2, for example by means of a set screw (indicated by reference numeral 35 in FIGS. 2 and 3) via an insulating spacer 21.

Reference numeral 5 denotes a printed board, which is attached to the housing 1 by spacers 61 and 62 (two boards are shown in FIG. 1), and on the printed board 5 are light emitting diodes 5
1 is attached, and the light emitted from the light emitting diode 51 passes through the rotating code plate 4 and the fixed code plate 22 and is received by the photoelectric conversion element array 3, and the resulting output signal from the photoelectric conversion element is transmitted to the connection line. 52 and is supplied to a signal processing circuit (comparator, line driver, etc.) formed on the printed board 5. Note that 64 is a cover that covers the entire pulse encoder section, and is fixed to the interval bolt 62 with bolts 63. Also 6
5 is a cable connected to the signal processing circuit on the printed board 5 from the outside.

The configuration of the photoelectric conversion element array 3, which is a feature of the present invention, will be explained below. FIG. 1 (bl is a longitudinal cross-sectional view of the photoelectric conversion element array 3. In the diagram shown, the photoelectric conversion element array 3 is made of an insulating plate 311 made of glass, epoxy resin, etc. A first layer in which a shield pattern (metal layer) 312 is formed on the surface (excluding the photoelectric conversion element arrangement part and the signal wiring lead-out part as described later), and the signal wiring pattern 322 is formed on the surface of the insulating plate 321. The second layer to be formed, the third layer in which a signal wiring pattern 332 is formed on the back side of an insulating plate 331, and the fourth layer in which a shield pattern 342 is formed on the back side of an insulating plate 341 are superposed. As a result, signal wiring patterns 322, 3 formed in the intermediate layer of the photoelectric conversion element array 3
32 is sandwiched between shield patterns 312 and 342 formed on the front surface (top surface) and the back surface (bottom surface).

FIG. 4 shows in detail an example of a plan view of each layer constituting the photoelectric conversion element array 3. FIG. 4(a) is a top view of the first layer, and FIG. Top view, Figure 4 fc
) shows a bottom view of the third layer, and FIG. 4 (dl shows a bottom view of the fourth layer).

First, as shown in FIG. A predetermined number (for example, three) of photoelectric conversion elements 310 are provided on the surface of the plate 311, and signals output from these photoelectric conversion elements 310 pass through through holes 315 formed in the insulating plate 311. A signal terminal 323 provided on the insulating plate 321 via a signal wiring 322 formed on the surface of the insulating plate 321 constituting the second eyebrow (for example, a signal terminal 323 provided on the first layer insulating plate 311) through holes 315 and 325 formed in the insulating plates 311 and 321, respectively, and the insulating plate 3 constituting the third layer.
The signal wiring 33 is formed on the back surface of the insulating plate 331 constituting the third layer through a through hole 335 formed in the third layer.
A signal terminal 333 provided on the insulating plate 331 via 2
(integrated with the signal terminals 313 and 323, for example, by soldering), and penetrates through the insulating plates 311, 321, 331, and 341 of each layer, and is integrated with the signal terminals 313 and 323, for example, by soldering. The signal is input to the signal processing circuit formed on the printed board 5 through a predetermined connection line 52.

Furthermore, as shown in FIG. 4 (al), the surface of the insulating plate 311 constituting the first layer includes a portion where the photoelectric conversion element 310 is arranged, a through hole 315 for guiding the output signal from the photoelectric conversion element 310, and A predetermined shield pattern 312 is formed in a portion excluding each forming portion of the signal terminal 313,
A ground terminal 314 connected to the shield pattern 312 is provided on the insulating plate 311 . This ground terminal (which penetrates the insulating plates of each layer and is integrated, for example, by soldering, as described later) is connected to the power Ov terminal formed on the printed board 5 through a predetermined connecting wire 52. be done.

Further, as shown in FIG. 4(d), on the back side of the insulating plate 341 constituting the fourth layer, there are through holes 31 of each layer.
5, 325, and 335, for example, by soldering, and the signal terminal 343, which is integrally connected to the signal terminals 313, 323, and 333 of each layer, by, for example, soldering. A predetermined shield pattern 342 is formed in the portion, and the insulating plate 341 is provided with a ground terminal 344 connected to the shield pattern 342. In addition, the earth terminal 3
Reference numeral 44 denotes each ground terminal 314, 32 provided so as to pass through each insulating plate 311, 321, and 331, respectively.
4 and 334, for example, by soldering. Furthermore, 316. 326.

Reference numerals 336 and 346 are tapped holes provided in the insulating plates of each layer, respectively, and the multilayered photoelectric conversion element is fixed by the setscrews 35 (see FIGS. 2 and 3) inserted into these screw holes. An array 3 is fixed to a fixed slit base 2.

In this way, the signal wiring patterns 322 and 332 formed in the intermediate layer of the photoelectric conversion element array 3 are almost completely shielded by the shield patterns (earth patterns) 312 and 342 formed on both the front and back surfaces. The influence of external noise on the output signal from the photoelectric conversion element can be almost completely blocked.

〔Effect of the invention〕

According to the present invention, noise contained in an output signal from a photoelectric conversion element can be effectively reduced, and the noise resistance of a pulse encoder can be significantly improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a schematic configuration of a pulse encoder as an embodiment of the present invention, FIG. 1(a) is a diagram showing the overall configuration, and FIG. b) is a longitudinal cross-sectional view of the photoelectric conversion element array, FIG. 1(C) is a plan view of the fixed slit base, and FIG. FIG. 3 is a side view showing the removed state; FIG. 3 is a plan view of the pulse encoder shown in FIG. 1, looking down from the rotary code plate; FIGS. Figure 1 is a plan view showing in detail the front or back side of each layer of the photoelectric conversion element array in the pulse encoder, and Figures 5 (al and b) are detailed views of the front and back sides of the photoelectric conversion element array in the conventional pulse encoder, respectively. 6 is a block diagram showing a signal transmission path in this type of optical pulse encoder. (Explanation of symbols) 1-- Housing (flange), 2-- Fixed slit Base, 22-- Fixed code plate, 3-- Photoelectric conversion element array, 311.321.331 .341... Insulating plate, 31
2, 342・-Shield pattern (earth pattern)
, 322, 332-- Signal wiring pattern, 4-
...One rotation code board, 5--One-printed board, 52--One connection line, 64--Cover, 71--Insulating board, 72--Signal wiring pattern. (Q) (c) Figure 1 Figure 3 Figure 4 (b) Deaf Figure 5 Figure 6

Claims (1)

[Claims] 1. A light emitting section, a photoelectric conversion element array that receives light from the light emitting section, and a rotation code having a signal pattern that transmits or blocks the light sent from the light emitting section to the photoelectric conversion element array. A board and a fixed code plate, a fixed slit stand to which the fixed code plate and the photoelectric conversion element array are fixed, a casing to which the fixed slit stand is fixed, and an output signal from the photoelectric conversion element array is input through a connecting line. In a pulse encoder equipped with a printed circuit board on which a signal processing circuit is formed, the photoelectric conversion element array is provided with photoelectric conversion elements on the surface thereof, and a part where the photoelectric conversion elements are arranged and a signal wiring lead-out part are removed. A pulse encoder characterized in that predetermined shield patterns are formed on the front and back surfaces, and a signal wiring pattern is formed in an intermediate layer sandwiched between the shield patterns.