JPS5917765B2 - Single pulse generation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a single pulse generation method, and more particularly, to a single pulse generation method used mainly in an incremental code plate type AD converter and the like.

More specifically, it is equipped with a code plate with a code displayed on its surface and a detector for detecting the code, and as the two move relative to each other, the code plate is scanned by the detector to detect a predetermined code. The present invention relates to a single pulse generation method that is capable of generating a stable single pulse regardless of the above-mentioned moving speed in a device that simultaneously outputs a single pulse. A code plate type AD converter is known as one of the devices that converts the displacement of an object into a digital signal.

Two types of code plate type AD converters are known: an incremental type and an absolute type.
In particular, the former incremental type code plate type AD converter is also called an incremental type encoder 15, and when the measured object is displaced, it generates a number of pulses corresponding to the amount of displacement, a pulse indicating the direction of this displacement, and a reference for the displacement. The device 20 is configured to output pulses indicating the position and use these pulses to detect the position of the object to be measured from the reference point. FIG. 1 shows an example of this incremental encoder, and particularly shows the basic configuration of an incremental type rotary encoder.

As shown in the figure, the rotary encoder consists of a disc-shaped No. 25 plate A, a light source B and a slit plate C that face each other with this in between.
and a photoelectric conversion element D provided behind this slit plate C. The code plate A is configured to be rotatable together with an axis E, and this axis E rotates in response to the displacement of an object to be measured (not shown). Two annular light-shielding bands F and G are provided concentrically on the surface of the No. 30 plate A. In the outer light-shielding band FK, a large number of translucent slits H... are arranged radially at equal intervals υ, and in the inner light-shielding body G,
A similar translucent slit 1 is provided at only one location 35
ing. The slit plate C has three slits J2 and L. The slits J correspond to the translucent slits H and C on the code plate A, and the slit L corresponds to the translucent slit 1. Further, the light source B1 is for illuminating the outer light shielding zone F, and the light source B2 is for illuminating the inner light shielding body G. The photoelectric conversion elements Dl and D2 are for receiving the light beams passing through the slits K and J, respectively, and the photoelectric conversion element D3 is for receiving the light beams passing through the slit L. In the above configuration, when the code plate A rotates with the displacement of the object to be measured (not shown), each photoelectric conversion element Dl, D2,
A voltage having a waveform as shown in FIG. 2 is output from D3.

2. Waveforms shown by solid lines and broken lines in FIG. 1 indicate the output voltages of the photoelectric conversion elements D1 and D2, respectively, and as shown, these two voltages are output with a phase shift of 90 degrees electrical angle from each other.

FIG. 2 shows the output voltage of the photoelectric conversion element D3, and this signal is used as an index of the reference position. In order to detect the rotational direction of the code plate A from the output voltage obtained above, a waveform shaping circuit such as a Schmitt trigger circuit is connected to the output side of the photoelectric conversion elements D1 and D2, and a waveform shaping circuit such as a Schmitt trigger circuit is connected to the output side of the photoelectric conversion elements D1 and D2. Each signal is converted into a square wave as shown in FIG. However,
This incremental rotary encoder is
As the rotational speed of the code plate increases, that is, as the displacement speed of the object to be measured increases, the single pulse signal (indicated by V in FIG. 2) for indicating the reference position becomes more accurate. There is a problem that the detection accuracy of the displacement of the object to be measured decreases significantly because the single pulse signal itself is no longer displayed or the single pulse signal itself is no longer output.

FIGS. 3 to 5 are diagrams for explaining this. Figures 3 and 4 show an example in which only the single pulse generation mechanism used in a conventional encoder is taken out, and Figure 5 shows the example shown in Figure 3 or 4.
FIG. 6 is an explanatory diagram of the signal processing circuit for the signals generated as shown in the figure. As shown in FIG. 3, a light source a and a light sensor b are placed facing each other, and a fixed slit c is placed in the optical path between them.
and a rotating glass d are interposed.

The rotating glass d rotates along with the axis e, and is covered with a light-shielding material g in an annular shape as shown in the figure, except for the portion at the origin f. The optical sensor b is a photoelectric converter that causes a photocurrent to flow and generates a voltage when it receives light. With this structure, when the rotating glass d is rotated, light passes through only when the slit c and the origin f overlap, and a voltage is generated from the optical sensor b. Figure 4 is the third
The rotation shown in the figure is simply a substitute for linear motion. That is, a fixed slit j is placed in the optical path between the light source h and the optical sensor i, and a glass k that moves in a straight line from side to side on the plane of the paper and whose entire surface is covered with a light-shielding material m except for the origin ' is placed. intervene. Glass k moves left and right to origin 2 and slit j
Only when the two overlap, light passes through and a voltage is generated from the optical sensor i. In FIG. 5, for example, the output signal from the optical sensor b in FIG. 3 is input to the positive input terminal 0 of the comparison amplifier n.
Furthermore, when separately supplied comparison voltages are input to the negative input terminal q, the voltage at the output terminal p becomes higher only when the voltage at the positive input terminal 0 is higher than the voltage at the negative input terminal q (hereinafter Conversely, the voltage becomes low only when the voltage at the positive input terminal 0 is lower than the voltage at the negative input terminal q (hereinafter referred to as being L).

Although the positive feedback circuit r is generally used for stabilizing the comparison operation, it is not essentially related to the present invention and will therefore be omitted from the following description. A conventional single pulse generator configured with such a single pulse generator and a processing circuit has extremely poor frequency characteristics as described below.

For example, if the abscissa s is the rotating glass d in Figure 3,
The rotation angle is taken as the rotation angle, and the ordinate t is taken as the voltage.

Curves U, v, and w indicate the input voltage to the positive input terminal 0 in FIG. 5, and straight lines X, y indicate the input voltage to the negative input terminal q. If the rotation of the rotating glass d is slow enough and the frequency characteristics of the optical sensor b are sufficiently good, the input voltage to the positive input terminal 0 will be proportional to the luminous flux incident on the optical sensor b, as shown by the curve u, and there will be no response delay. , the amplitude is large and the voltage waveform is symmetrical as shown in the figure.

However, as the rotation speed of the rotating glass d increases, the light incident on the optical sensor b becomes instantaneous.
The input voltage to the positive input terminal 0 decreases, the response speed is delayed, and the peak moves to the right as a whole. The output voltage of the ambient light sensor b is normally O volts while the light is blocked. Therefore,
As the rotational speed increases, as shown in the figure, the input voltage to the positive input terminal 0 becomes lower as shown by curves v and w, and approaches O volts. Therefore, if the comparison voltage to the negative input terminal q is set like a straight line x, the comparison amplifier n
If the rotation speed is slow as shown by curves U and v, the output voltage of the optical sensor will be higher than the comparison voltage, so it will operate and output a square wave with a predetermined voltage, but if the rotation speed is fast as shown in curve w. In this state, the output voltage of the optical sensor does not reach the comparison voltage, so it does not operate, and therefore the desired square wave cannot be obtained, resulting in a so-called overrun state. However, if the reference voltage to the negative input terminal q is lowered as shown by the straight line y, no overrun will occur even if the input voltage to the positive input terminal 0 is in a state as shown by the curve w. However, when the reference voltage is lowered in this way, the following problems occur. (
1) Since the input voltage level required to operate the comparison amplifier n is low, the S/N ratio is poor and malfunctions are likely to occur.

(2) The duration for which the output voltage of the output terminal p becomes H varies depending on the relative speed between the rotating glass and the slit, but
The maximum duration is from the starting point B to the ending point r.

This is significantly longer than the ideal H signal duration from the starting point z to the ending point d, and in particular, the delay of the ending point r from the ending point α is significant. Even if the comparison amplifier operates and an H signal is obtained, the reference position cannot be accurately detected with a signal whose end point is delayed in this way. Therefore, if the input voltage to the negative input terminal q is set low, it becomes necessary to adjust the time of the output pulses, etc. (3) The later the end point r is delayed, the more the comparison voltage and the signal voltage cross in parallel, and the SN ratio in the vicinity of the end point r deteriorates significantly. As explained above, in the conventional single pulse generation mechanism, as the displacement speed of the object to be measured increases, the accuracy of the output single pulse decreases significantly and the output state of the pulse becomes unstable.

In fact, in conventional incremental encoders, the pulses generated in response to the amount of displacement of the object to be measured are
Although it has a response capability of about 0.000 KHz, it can only respond to a single pulse indicating a reference point up to 90 KHz, and as a result, conventional encoders can only be used at low speeds of 90 KHz or less.

Therefore, in view of the above-mentioned problems encountered with conventional incremental encoders, the present inventor conducted intensive research to solve the problems and came up with the present invention.
The object of the present invention is to provide a code plate that moves in conjunction with the displacement of an object to be measured and has a code attached to its surface, and a code detector that is stationary with respect to the code plate; Accordingly, in a device that scans the code plate with the detector and generates a single pulse at the same time as detecting a predetermined code,
The present invention provides a single pulse generation method that can always generate a stable single pulse regardless of the displacement speed of the object to be measured.

In particular, in order to achieve the above object, the present invention is configured such that the output voltage from the sign detector is constant regardless of the displacement speed of the object to be measured, and a speed compensation voltage is superimposed on the output voltage. By doing so, the rise and fall characteristics of the output voltage waveform are improved, and this is converted using a waveform shaping circuit to provide a single pulse generation method in which a stable square wave pulse signal is obtained. It is something.

Another object of the present invention is that a stable single pulse can be generated regardless of the displacement speed of the object to be measured.
If this is adopted for detecting the reference position of an incremental encoder, the displacement detection accuracy of this type of encoder at high speeds will be greatly improved, and it will be used for various applications that require high-precision positioning even during high-speed motion. The present invention provides a single pulse generation method that can configure an incremental encoder suitable for automatic control equipment.

A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIGS. 7 and 8 show two examples of the mechanism of the pulse generator in the single pulse generator according to the present invention.

FIG. 7 shows a type in which the code plate makes a linear movement in relation to the displacement of an object to be measured (not shown), and FIG. 8 shows a type in which the code plate makes a rotational movement in response to the same displacement. The code plate 7 shown in FIG. 7 is made of a glass plate having an elongated rectangular shape as shown, and two code bands 7a and 7b extending in the longitudinal direction are formed on its surface. Light shielding parts 8 and 9 are arranged in each of these code bands 7a and 7b as follows. For the upper code band 7a, light shielding parts 8 are provided at both ends except for the center part, and for the lower code band 7b, the light transmitting parts 8a on the code band 7a are provided.
A light-shielding portion 9 having a length approximately equal to the interval is disposed at a position slightly shifted to the right in the figure with respect to the light-transmitting portion 8a. Light sources 1 and 2 and slit plates 5 and 6 are provided at opposite positions with the code plate 7 in between, and optical sensors 3 and 4 are provided behind the slit plates 5 and 6. There is. The optical sensor 3 having the above configuration is for receiving the light beam from the light source 1 passing through the code band 7a and the slit plate 5.
The optical sensor 4 is for receiving the light beam from the light source 2 that passes through the code band 7b and the slit plate 6. FIG. 8 shows another embodiment using a disk-shaped code plate 16, and in the illustrated example, the disk-shaped code plate 16 is rotatable together with the shaft 17.
, and two annular code bands 16a and 16b are arranged concentrically along the circumference of the surface. On each code band, there are approximately semi-arc shaped light shielding parts 18 and 19 as shown in the figure.
are arranged so that their starting and ending points are slightly offset in the circumferential direction and face each other. Light sources 10 and 11 and slit plates 14 and 15 are located at opposing positions with the code plate 16 in between.
Further, behind the slit plates 14 and 15, optical sensors 12 and 13 are provided. The optical sensor 12 is for receiving the light beam from the light source 10 that passes through the annular code band 16a and the slit plate 14, and the optical sensor 13 is for receiving the light beam from the light source 10 that passes through the annular code band 16b and the slit plate 15.
It is for receiving light rays from 1. Since the voltage waveforms output from the pulse generators in FIGS. 7 and 8 described above are completely the same, the following description will be made according to FIG. 7.

FIG. 9 is a graph showing the relationship between the output voltage of the optical sensor 3 and the position of the code plate 7. The horizontal axis 20 is the code plate 7 in FIG.
The vertical axis 21 indicates the moving distance from right to left, and the vertical axis 21 indicates the voltage. A solid line 22 and broken lines 23 and 24 indicate the output voltage of the optical sensor 3, respectively. When the moving speed of the code plate 7 is relatively slow, the output voltage of the optical sensor 3 is proportional to the incident light flux, as shown by a solid line 22. However, as the moving speed increases, the transition timings for both rising and falling edges shift as shown by broken lines 23 and 24. However, since the areas of the light-shielding part and the light-transmitting part on the code plate 7 are both large, the duration of the H state and the L
The duration of both states is relatively long, and the decrease in amplitude, that is, the decrease in the height of the mountain, as seen in FIG. 6 is not observed. FIG. 10 shows a signal processing circuit for converting the voltage output from the optical sensors 3 and 4 shown in FIG. 7 into a single pulse.

The input terminal 25 is connected to the optical sensor 3, the input terminal 26 is connected to the optical sensor 4, and the input terminals 27 and 28 are connected to a separately supplied comparison voltage generator. Compare the signals from these amplifiers 29a
, 29b, it is determined whether the light beams from the light sources 1 and 2 are blocked by the code plate 7, and the AND circuit 31 converts the light beams into a single pulse. The speed compensation feedback circuits 30a and 30b output a pulse voltage that rises when the output voltage of the comparator amplifiers 29a and 29b becomes H and disappears after a certain period of time, and sends the rise of the voltage at the input terminal 25 to the comparison input terminal 28. Also, the rise of the voltage at the input terminal 26 is fed back to the comparison input terminal 27, respectively.
For example, the transmission circuit is as shown in FIGS. 20 and 21. Figure 20 shows a transfer circuit in which when a step input voltage is applied between the left terminals, an output voltage is obtained between the right terminals that rises after a certain time delay and decays with a certain time constant. 21 shows a transmission circuit in which when a step input voltage is applied between the left terminals, a pulse voltage having differential and integral characteristics is obtained between the right terminals. The capacitor 36 is for differentiation, the capacitor 37 is for integration, the diode 38 is for transmitting only the rising edge of the input signal, and the resistor 39 is for charging the capacitor 37.
The resistor 40 discharges the capacitor 36, and the resistor 41 discharges the capacitor 37. Also, logical product circuit 3
1 is shown in FIG. 22. FIG. 11 is a graph showing the operating state of the circuit of FIG. 10 with respect to FIG. 7. FIG. The abscissa 42 indicates the distance moved to the left of the code plate 7 in FIG. 7, and the ordinate 43 indicates the voltage at each terminal. Curve 44 is input terminal 25
The curve 45 represents the voltage at the input terminal 26, and the curve 46 represents the voltage at the input terminal 26.
represents the voltage at the output terminal 32 of the comparator amplifier 29a, as shown by the curve 47
is the voltage at the output terminal 33 of the comparator amplifier 29b according to the curve 4.
8 represents the output voltage of the AND circuit 31, a curve 49 represents the voltage at the input terminal 34 of the comparison amplifier 29a, and a curve 50 represents the voltage at the input terminal 35 of the comparison amplifier 29b. The straight line portion of the curve 49 indicates the voltage at the comparison input terminal 27, and the mountain portion 51 indicates the voltage from the output terminal 33 to the speed compensation feedback circuit 30b.
The figure shows a mountain formed by superimposing the voltages fed back through the .

Similarly, the straight line portion of the curve 50 indicates the voltage at the comparison input terminal 28, and the peak portion 52 indicates a peak formed by superimposing the voltages fed back from the output terminal 32 via the speed compensation feedback circuit 30a. In FIG. 7, moving the code plate 7 from left to right corresponds to following the abscissa 42 from right to left in FIG. 11, that is, in the opposite direction of the arrow.

In this case, the peak portion 51 of the curve 49 disappears, and the peak portion 51 of the broken line
3 appears. Similarly, the peak portion 52 of the curve 50 disappears, and a dashed line peak 54 appears. In this way, the curve 48 rises in a stepwise manner in relation to the rise of the input terminal 25, and the curve 48 falls in a stepwise manner in relation to the fall of the input terminal 26. This is because when the curve 48 rises, the speed compensation feedback circuit operates and the voltage at the negative input terminal 35 momentarily increases, thereby bringing forward the timing of the fall of the curve 48. In Fig. 11, between the curves 44 and 45 indicating the position signal of the code plate 7, ``A'' indicates the start of transition, and ``A'' indicates the end of the transition.
When moving from left to right, conversely, I is the end of the transition and mouth is the beginning of the transition). Furthermore, the mountain portion 52 (or 53
) is the speed compensation pulse signal. Like FIG. 10, FIG. 12 shows a signal processing circuit.

In this circuit, the return location of the speed compensation signal is the comparison voltage input terminal side in FIG.
In the figure, the input terminal side from the optical sensor has been changed. As shown in FIG. 12, the input terminal 55 is connected to the optical sensor 3, the input terminal 56 is connected to the optical sensor 4, and the input terminal 57
, 58 are connected to a separately supplied comparison voltage generator.

The input voltages to these terminals are compared with amplifiers 29a and 29b.
The step voltage input to the output terminals 59 and 60 is input to the AND circuit 31 and converted into a single pulse. The rising voltage of the output terminal 59 is controlled by the speed compensation feedback circuit 3.
0a to the negative input terminal 62 of the comparator amplifier 29b, and the rising voltage of the output terminal 60 to the speed compensation feedback circuit 30b.
is fed back to the negative input terminal 61 of the ratio amplifier 29a.

FIG. 13 shows the operating state of each part of the above circuit. 13th
In the figure, the abscissa 65 indicates the moving distance of the code plate 7 from right to left in FIG. 7, and the ordinate 66 indicates the voltage at each terminal.

Curve 67 is the voltage at input terminal 55, curve 68 is the voltage at human power terminal 56, curve 69 is the voltage at output terminal 59, and curve 70 is the voltage at input terminal 55.
is the voltage at the output terminal 60, the curve 71 is the output voltage of the AND circuit 31, the curve 72 is the voltage fed back to the terminal 62 via the feedback circuit 30a, and the curve 73 is fed back to the terminal 61 via the feedback circuit 30b. Voltage, curve 74 is curve 67 and curve 7
3 is superimposed, and the voltage at the input terminal 61 is the curve 75.
is a superimposition of the curve 68 and the curve 72, and the input terminal 6
2 voltage is shown. As is clear from a comparison of curve 75 and curve 68, because curve 75 rises earlier, curve 71 falls earlier. Moving the code plate 7 from left to right in FIG. 7 corresponds to following the Yokoza Bridge 65 from right to left in FIG. 13.

In that case, the peak 78 of the curve 72 disappears and a dashed peak 80 appears. Also, the peak 79 of the curve 73 disappears, and a broken line peak 81 appears. Therefore, the voltage at input terminal 61 is curve 76 instead of curve 74, and the voltage at input terminal 62 is curve 76.
5 becomes a curve 77 instead. In Figure 13, curves 6T and 68 indicate the beginning of the transition and the end of the transition (when the code plate 7 moves from left to right,
Conversely, A is the end of the transition and Mou is the beginning of the transition).

Moreover, the peak 78 (or peak 81) of the curve 72 corresponds to the speed compensation pulse signal. In the circuits shown in Figures 7 to 13, determining whether light is passing through or being blocked is by comparing the output voltage of the optical sensor with a separately supplied comparison voltage. It was done by doing.

However, in Fig. 14, a comparison voltage is not used, and when one of the paired optical systems passes light, the other system blocks the light, so that both comparator amplifiers are operated in a push-pull manner. It is. As shown in FIG. 14, the light source 8
2, 83, 84, 85 and optical sensors 86, 87, 88, 8
9,' fixed slit plates 90, 91, 92, 9
3, light shielding portions 96 and 97 are disposed on the surface as shown in the figure, and a code plate 94 that rotates together with the shaft 95 is interposed. light source 8
2. Light shielding part 96, fixed slit plate 90, optical sensor 86
The light 5 source 83, the light shielding portion 96, the fixed slit 91, and the optical sensor 87 constitute a second optical system. The light source 84, the light shielding part 97, the fixed slit plate 92, and the optical sensor 88 constitute a third optical system, and the light source 85, the light shielding part 97, the fixed slit plate 93, and the optical sensor 89 constitute a fourth optical system. Configure the system. In each of the above optical systems, the first optical system and the second optical system form a pair, and when one system passes light, the other system is configured to block the light. Similarly, the third optical system and the fourth optical system are configured as a pair. Figure 15 shows
This figure shows a situation where the first optical system and the second optical system form a pair.

In FIG. 15, the abscissa 98 indicates the rotation angle of the shaft 95, and the ordinate 99 indicates the voltage. Curves 100 and 102 are optical sensor 8
6, and curves 101 and 103 show the output voltages of the optical sensor 87. When the rotation speed of the shaft 95 is slow, the output voltage of the optical sensor becomes curves 100 and 101 shown by the solid line, and when the rotation speed is fast, the output voltage from the optical sensor becomes like the curves 102 and 1 shown by the broken line.
03, the output signal has a delayed transition timing. A circuit shown in FIG. 10 is used as the signal processing circuit.

The output of the optical sensor 86 is connected to the input terminal 25, the output of the optical sensor 87 is connected to the input terminal 27, the output of the optical sensor 88 is connected to the input terminal 26, and the output of the optical sensor 89 is connected to the input terminal 28. FIG. 16 shows the operating state of each part with respect to FIG. 10 and FIG. 14.

In FIG. 16, the abscissa 105 corresponds to the axis 95 in FIG.
The ordinate 106 indicates the voltage when the rotation angle is rotated in the direction of the arrow 104. Curve 107 represents the voltage at input terminal 25, curve 108 represents the voltage at input terminal 27, curve 109 represents the voltage at input terminal 26, curve 110 represents the voltage at input terminal 28, curve 111 represents the voltage at output terminal 32, curve 112
is the voltage of the output terminal 33, and the curve 113 is the voltage of the AND circuit 31.
The curve 114 represents the feedback voltage fed back from the output terminal 33 to the input terminal 34 via the speed compensation feedback circuit 30b, and the curve 115 represents the feedback voltage fed back from the output terminal 32 to the input terminal 35 via the speed compensation feedback circuit 30a. A curve 116 is a superimposition of curves 108 and 114, and a curve 117 is a superimposition of the voltage at the input terminal 34, and a curve 117 is a superimposition of curves 114 and 114.
and a curve 115, respectively indicating the voltage at the input terminal 35. The peak 120 of the curve 117 rises earlier than the curve 110, thereby causing the curve 113 to fall earlier.

In FIG. 14, rotating axis 95 in the opposite direction to arrow 104 corresponds to following abscissa 105 from right to left in FIG. 16.

In this case, the peak 121 of the curve 114 disappears,
Mountain 122 appears. Also, the peak 123 of the curve 115 disappears and the peak 124 appears. Therefore, the voltage at input terminal 34 is curve 118 instead of curve 116, and the voltage at input terminal 34 is curve 118 instead of curve 116.
5 becomes a curve 119 instead of a curve 117.

In this case, the peak 125 of the curve 118 causes the curve 113 to fall earlier. direction, curve 1 in Figure 16
07,109} indicates the beginning of the transition, and the opening indicates the end of the transition.

(When the circumferential shaft 95 rotates in the opposite direction to the arrow 104, these are reversed, and the end of the transition is the transition end, and the mouth is the beginning of the transition.) Furthermore, the peak 123 of the curve 115 (or the curve 11
The number 4 122) is a speed compensation pulse signal. In the embodiments shown in FIGS. 7 to 16, the generation timing of the speed compensation feedback voltage was synchronized with the rising timing of the single pulse.

However, in FIG. 17, this synchronization is performed with another signal unrelated to the single pulse. As shown in FIG. 17, light sources 126, 127, 128 and optical sensors 129, 1
Fixed slits 132, 133, 1 between
34, and a code plate 136 having light shielding portions 137, 138, and 139 on its surface.

The light source 126, the light shielding portion 137, the fixed slit 132, and the optical sensor 129 constitute a fifth optical system, and the light source 1
27, the light shielding portion 138, the fixed slit 133, and the optical sensor 130 constitute a sixth optical system, and the light source 128, the light shielding portion 139, the fixed slit 134, and the optical sensor 131 constitute a seventh optical system. In the fifth optical system and the sixth optical system, light passes through and is blocked in steps, but in the seventh optical system, light passes through and is blocked in steps.
In this optical system, the light shielding portion 139 has a lattice shape representing a scale, so that light passes through and shields periodically. FIG. 18 shows the processing circuit of FIG. 17.

The output voltage of the optical sensor 129 is input to the input terminal 140, the output voltage of the optical sensor 130 is input to the input terminal 141, and the output voltage of the optical sensor 130 is input to the input terminal 140.
2, the output voltage of the optical sensor 131 is input to the input terminal 143, 1.
A separately supplied comparison voltage generator is connected to 44 and 145, respectively.

These input signals are compared to amplifiers 29a, 29b, 29c.
input to determine the state of blocking light from each optical system.

A step voltage is output to the output terminal 151 for the fifth optical system, and a step voltage is output to the output terminal 152 for the sixth optical system, and a single pulse voltage is output to the output terminal 150 by the AND circuit 31. be done. Regarding the seventh optical system,
A pulse train signal is output to the output terminal 153. In order to synchronize both the rising and falling points of the voltage at the output terminal 153, a logic NOT circuit 146, a monostable oscillation circuit 147, and an OR circuit 148 are connected to the output terminal 153 as shown. The logic NOT circuit 146 is a circuit in which when the input signal is H (...high level), the output signal becomes L (low level), and when the input signal is L (low level), the output signal becomes H (...high level). The monostable oscillation circuit 147 is a circuit that generates a pulse only once for a short time at the rising edge of an input signal. An explanation of the OR circuit 148 is shown in FIG. As described above, among the synchronizing pulse trains obtained at the terminal 154, the one whose single pulse output voltage at the terminal 150 is in the feedback state of H is selected by the AND circuit 31, and a trigger pulse is obtained at the terminal 155. This trigger pulse is converted into waveform shaping circuit 1.
49, the synchronizing pulse 156 continues to some extent, and the AND circuit 31 selects whether to feed it back to the input terminal 157 of the comparison amplifier 29a or the input terminal 158 of the comparison amplifier 29b, and performs speed compensation feedback. circuit 30
Return via. FIG. 19 is an explanatory diagram of the operation of each part of the circuit of FIG. 18.

The abscissa 161 indicates the moving distance from the right to the left of the code plate 136 in FIG. 17, and the ordinate 162 indicates the voltage. curve 16
3 represents the voltage at input terminal 140, and curve 164 represents the voltage at input terminal 1.
41, and curve 165 represents the voltage at input terminal 142.
Curve 166 represents the voltage at output terminal 151, curve 167 represents the voltage at output terminal 152, curve 168 represents the single pulse voltage at output terminal 150, curve 169 represents the voltage at output terminal 153, and curve 170 represents the synchronized pulse train at terminal 154. Curve 171 represents the trigger pulse voltage at terminal 155, curve 17
2 represents the synchronous pulse voltage of the terminal 156, and a curve 173 represents the synchronous pulse voltage of the circuit 160 that feeds back the synchronous pulse 156 to the input terminal 158 via the speed compensation feedback circuit 30 when the voltage of the output terminal 153 is H (high level). The curve 174 is a superimposition of the curve 164 and the curve 173, and shows the voltage input to the input terminal 158 of the comparator amplifier 29b.

As is clear from the illustrated example above, the peak 180 of the curve 174
D causes the voltage applied to the input terminal 158 to rise earlier, thereby causing the curve 168 to fall earlier.
) In FIG. 17, when the code plate 136 moves from left to right, this corresponds to following the abscissa 161 in FIG. 19 from right to left.

In this case, peak 176 of curve 172 disappears and peak 177 appears. Since the curve 169 is L with respect to the peak 177, the AND circuit 31 operates based on the output of the logic NOT circuit 146. Therefore, the synchronization pulse at terminal 156 is fed back to input terminal 157 via speed compensation feedback circuit 30 and circuit 159. At this time, the transition of the voltage at the input terminal 158 is as shown in the curve 164, but not as shown in the curve 174. Moreover, the voltage transition of the input terminal 157 is as shown by the curve 175,
It does not look like curve 163. In the above embodiment, as is clear from the figure, the peak 181 of the curve 175 accelerates the fall of the curve 168.

}, In curves 163 and 164 in FIG. 19, ``A'' indicates the start of transition, and ``A'' indicates the end of transition.

← When the code plate 136 moves from left to right, the mouth is the transition start point, and A is the transition end point. ) Further, the peak 178 (or 179) of the curve 173 is a speed compensation pulse signal. In the above embodiment, for example, even if the arrangement of the light-shielding part 9 and the light-transmitting part 9a of the code band 7b in FIG. 7 is reversed, and H and L of the curve 45 in FIG. 11 are reversed, , the object of the present invention can be achieved by simply replacing the input terminals shown in FIG.

That is, in FIG. 10, only the input terminal 28 is changed to the optical sensor 4, and the input terminal 26 is changed to a separately supplied comparison voltage, and other than that, the other components remain the same as described above. The inversion of blocking and transmission of light in the code band 7b is canceled out by the inversion of the input polarity of the comparator amplifier 29b, and the output 33 is not inverted. The speed compensation feedback circuit 30a remains connected to the negative input of the comparator amplifier 29b, and its function remains unchanged. As is clear from the above, according to the present invention, a code plate provided with a code and a detector for detecting the code are provided, and the code is scanned by the detector as the two move relative to each other, and the code is scanned by the detector. In addition to the device that outputs a single pulse upon detection of
obtain two position signals that transition from one level to the other at different transition times, compare the signals with a reference signal of a predetermined level, and at the time of the comparison, adjust the reference signal according to the moving speed. By compensating for the level difference between the signal and each of the position signals, converting each of the two position signals into a predetermined step-like signal, and obtaining the logical product of the signals, the desired single pulse is output. Regardless of the moving speed, it is possible to output a rectangular pulse with an extremely stable transition period.

Further, according to the present invention, as in the conventional single pulse generator of this kind, a narrow light-transmitting part is provided on the code plate, and a pair of light emitter and light receiver are arranged to face each other with the code plate in between. We do not adopt any configuration in which a single pulse is generated by the light beam that reaches the instantaneous light receiver as the code plate moves, and the rising and falling points of the single pulse are determined by signals from separate optical systems. Therefore, even if the relative movement speed between the code plate and the detector increases, the voltage from the pulse generation source does not drop as in the conventional system.

Therefore, when waveform-shaping the voltage from the pulse generation source via the comparator circuit, there is no need to lower the reference voltage level, and therefore the S/N ratio can be significantly improved. Further, according to the present invention, the delay in the rise and fall of the output voltage from the pulse generation source, which occurs as the moving speed of the code plate increases, is reduced by instantaneously lowering the relative level of the reference of the comparator circuit at the time of rise. In addition, since it is configured to compensate by instantaneously increasing the relative level of the reference at the time of falling, it is possible to obtain an extremely stable square wave output signal at the transition period even when the code plate is moving at high speed. .

Furthermore, if the single pulse generation method according to the present invention is adopted in an incremental encoder, the falling timing of the reference pulse will not deviate even when the frequency increases, and positioning can be performed with extremely high precision from high speed to low speed. It is possible to construct an incremental encoder that obtains the following information.

For example, when reading a scale using an optical sensor, even if a conventional scale pulse train can be read at a high speed of about 300 KHz, only the reference pulse indicating the origin can be read at a high speed of 90 KHz.
However, according to the present invention, the origin pulse can also be read at high speed. Therefore, by dividing the scale into smaller units and at the same time making the origin pulse smaller, the accuracy of conventional incremental encoders can be dramatically improved, and various automatic controls that require high-precision positioning at high speeds can be used. It exhibits various features such as contributing to improving the performance of equipment, and is highly practical.

[Brief explanation of drawings]

Figures 1 to 2 are diagrams for explaining a conventional incremental encoder, Figures 3 to 6 are diagrams for explaining a conventional single pulse generator, and Figures 7 and 6 are diagrams for explaining a conventional single pulse generator. 8, 14, and 17 are explanatory diagrams of the pulse generation section of the single pulse generator according to the present invention, and FIGS. 10 and 12.
18 are explanatory diagrams of the processing circuit of the single pulse generator according to the present invention, FIGS. 20, 21, 22, and 23.
The figure is an explanatory diagram of the circuit symbol used in the processing circuit, Fig. 9,
FIG. 11, FIG. 13, FIG. 15, FIG. 16, and FIG. 19 are explanatory diagrams of the operation of the processing circuit.

Claims (1)

[Claims] 1 In a device that has a code plate and a detector, and that detects a predetermined code and generates it as a single pulse by scanning the code plate with the detector as the two move relative to each other, different pulses are generated as a result of the scanning. Two position signals that transition from one of two levels to the other at different transition times are obtained, and are generated between the start of transition of the first position signal and the end of transition of the second position signal, and at least A speed compensation pulse signal that continues until the transition period of the position signal and then disappears is obtained, and the previous position signal is compared with a reference signal of a predetermined level to convert the previous position signal into a predetermined step signal. Compare the position signal with a signal obtained by superimposing the speed compensation pulse signal on a reference signal of a predetermined level, convert the resulting position signal into a predetermined step signal, and obtain the logical product of these two step signals, A single pulse generation method characterized in that a rectangular pulse with a constant transition timing is output regardless of the moving speed.