JPS6135361A - Rotating speed detector - Google Patents

Abstract

PURPOSE:To obtain a DC voltage less in pulsation and short in transient response time by selecting the DC output voltage among plural frequency-voltage converters according to the rotating speed of a rotating body. CONSTITUTION:A pulse signal converting circuit 12 inputs two-phase pulse signals EP1 and EP2 from a rotation detector 1 and outputs pulse signals EP31- EP34 which have specific mutually different multiplication frequency and pulse widths. Then, they are converted into DC voltages + or -E04-+ or -E04 by frequency- voltage converters 11a-11d and switch signals EP60-EP63 are obtained from a switch signal generating circuit according to the levels of the DC voltages to conrol an output switch circuit 15, thereby selecting and outputting one of DC output voltages of the converters 11a-11d according to the rotating speed of the rotating body. Thus, a DC voltage obtained by converting a pulse signal having a low frequency and a short pulse width when the rotating body rotates fast or a DC voltage obtained by converting a pulse signal having a high frequency and a short pulse width in slow rotation are selected to obtain the DC output voltage which has less pulsation and a short transient response time.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a rotation speed detector, particularly a rotation speed detector using a rotation detector that outputs a two-phase pulse signal with a frequency proportional to the rotation speed of a rotating body. It is interlayered.

[Prior art 1] Fig. 7 shows an example of a conventional rotation speed detector using an optical encoder as a rotation detector, and Figs. 8 and 9 show signal waveforms at various parts in Fig. 7. It is.

In FIG. 7, the rotation detector 1 has an encoder plate 3 fixed to an input shaft 2 mechanically connected to a rotating body (not shown), and the encoder plate 3 has a number of slits 4 around its circumference. They are arranged at regular intervals in the direction. A light emitter and a light receiver (not shown) are arranged opposite to each other with an encoder plate 3 in between, corresponding to the arrangement of the slits 4, and the light generated from the emitter is transmitted to the encoder plate 3 as the encoder plate 3 rotates. The light passes intermittently and is irradiated onto the receiver. As a result, the light receiver outputs a pulse signal with a frequency proportional to the rotational speed of the rotating body. The rotation detector 1 has a signal conversion circuit 5, and the pulse signal output from the light receiver is converted into two-phase pulse signals Fpl and Fρ2 by the signal conversion circuit 5 and output.

The double multiplier circuit 6 is constituted by an exclusive OR circuit, and receives the two-phase pulse signal El)1. E112 is input, and a pulse signal Er13 having twice the frequency of the pulse signal Ep1 is input.
Output.

The pulse width conversion circuit 7 is composed of a well-known monostable multivibrator that operates on the rising and falling edges of an input signal, and receives the pulse signal Ep3 from the doubling circuit 6 as an input, and converts the pulse width twice as much as the pulse signal Ep3. Frequency (period T
) outputs a pulse signal El)4 having a predetermined pulse width Δt.

The rotational direction determination circuit 8 is a circuit for determining the rotational direction of the rotating body, and receives the two-phase pulse signal Ep1. Ep2 is input, and the two-phase pulse signal Ep1
．． By utilizing the characteristic that the phase lead/lag state of Fp2 differs depending on the rotation direction of the rotating body, the rotation direction discrimination signal Pf
, Pr. These signals have different levels depending on the direction of rotation of the rotating body. When rotating clockwise, the signal pf is high level and the signal pr is low level. When rotating in one direction counterclockwise, the signal P[ is low level and the signal pr is high level. The level is amazing.

AND circuits 9 and 10 receive the pulse signal Fp4 from the pulse width conversion circuit 7 and the direction discrimination signals Pf and Pr from the rotation direction discrimination circuit 8, respectively, and pulse when the direction discrimination signal Pf (or Pr) is at a high level. Signal E
Output p4.

Frequency-voltage converter (hereinafter referred to as F/V converter)
11 inputs the pulse signal Ep4 from the AND circuit 9 or 10, and generates a DC voltage +Et(1( or -Etg).

Next, the operation of the above-mentioned rotational speed detector will be explained with reference to FIGS. 8 and 9.

Now, assume that the rotating body is rotating clockwise at a rotational speed N. In this case, the pulse signal Ell outputted from the signal conversion circuit 5 has a phase lead of 90 degrees with respect to the pulse signal Ep2, and the period To of the pulse signal Ep1 is inversely proportional to the rotation speed N. Note that during counterclockwise rotation, the pulse signal El)1 is delayed in phase by 90 degrees with respect to the pulse signal Ep2. These pulse signals Ep1.
Ep2 is multiplied by 2 of the pulse signal Ep1 by the doubling circuit 6.
The pulse signal ED3 is converted into a pulse signal El)3 with twice the frequency, and the pulse width conversion circuit 7 converts the pulse signal ED3 into a pulse signal with a period T(
1/2 of the period of pulse signal Ep3), pulse width T
It is converted into a pulse signal Ep4 and output. Further, the two-phase pulse signal El)1 from the signal conversion circuit 5 is also supplied. El)2 is input to the rotational direction determination circuit 8 to determine the rotational direction of the rotating body, and when rotating clockwise, a high level direction determination signal Pf and a low level direction determination signal pr are output, respectively.

Then, the pulse signal Ep4 and the direction determination signal Pf
is input to the AND circuit 9, and the pulse signal Ep4 and the direction discrimination signal pr are inputted to the AND circuit 10. When the rotating body rotates clockwise, the pulse signal EI'14 is output only from the AND circuit 9, and the counterclockwise direction is When rotating in one direction, only the AND circuit 10 outputs the pulse signal Ep4. The pulse signal E114 from the AND circuit 9 or 10 is input to different input terminals of the F/V converter 11, and the F
/V converter 11 outputs a DC voltage proportional to ΔT/T (+Eta when rotating clockwise, -Et(1) when rotating counterclockwise. As seen in FIG. When rotating at low speed, ΔT/T becomes small, so the DC voltage E t (11) becomes small, and when rotating at high speed, ΔT/T becomes large, so the DC voltage E t (12
becomes larger.

By the way, the frequency f of the DC voltage Etl) outputted from the F/V converter 11 and the frequency f of the pulse signal El)4 inputted to the F/V converter 11 is calculated by the following formula %f=1/T=2・N ...(
2) However, Kl and 2 are constants.

From the above equations (1) and (2), F/V converter 1
The DC voltage Etg output from 1 is expressed by the following equation.

E t(] = K 1 ・K2 ・ΔT−N ・
...(3) In order for the above equation (3) to hold true, the following inequality must be satisfied.

(ΔT/T)<1 (4) Therefore, when setting 6 pulse widths of the pulse signal E 1114, the pulse period at the maximum rotational speed N max (at this time, the pulse period is the minimum ΔT* 0.9X T m
It is set by the formula of tn.

Therefore, for example, the detection range of the rotational speed N can be set to 1 to 1 oor.
pm, ΔT/at the maximum and maximum rotational speeds
T has the following values.

ΔT/T at maximum rotational speed = 0.9 ΔT/T at minimum rotational speed = 0.9xlO-3 [Problem to be solved by the invention] As is clear from the equation L, at the minimum rotational speed It is clear that the pulse width of the pulse signal Eo4 with respect to the period T is quite small.

Therefore, in the conventional rotational speed detector, the pulsating voltage included in the DC voltage Ft() is large at low rotational speeds, and if you try to reduce this pulsating voltage with a low-pass filter with a low cutoff frequency, the output The disadvantage is that the voltage transient response time becomes long.For this reason, when such a rotation speed detector was conventionally used in a motor speed control system, the detection output voltage had large pulsations at low rotation speeds, making it difficult to achieve a smooth response. There was a problem in that it was difficult to perform low speed control.

In addition, in conventional rotational speed detectors, if an optical encoder with an increased number of output pulses per rotation is used, it is possible to reduce the pulsating voltage included in the DC voltage Ft(+) and improve the transient response time. However, such an optical encoder is expensive and generates a two-phase pulse signal El)1 during high-speed rotation. Since the frequency of F112 becomes high, there is a problem in that there is a limit to its high speed rotation.

Is the purpose of this invention low speed rotation? It is an object of the present invention to provide a rotation speed detector capable of obtaining a DC output voltage with little pulsation voltage and short transient response time from A degree to high rotation speed.

Means for Solving Problem U] In order to achieve the above object, the present invention uses a rotation detector that outputs a two-phase pulse signal with a frequency proportional to the rotational speed of a rotating body. In the rotational speed detector that outputs a DC voltage proportional to the rotational speed of the rotating body based on the above, the two-phase pulse signals have different predetermined multiplication frequencies and each have the same or different predetermined pulse widths. A pulse signal conversion circuit that converts into a plurality of types of pulse signals, a plurality of frequency-voltage converters that convert and output each pulse signal from the pulse signal conversion circuit into a DC voltage, and a predetermined plurality of frequency-voltage converters. a switching signal generating circuit that receives DC output voltages from the device and outputs a predetermined switching signal according to the magnitude of each DC output voltage; It is characterized by comprising an output switching circuit that selectively outputs a DC output voltage from one of the plurality of frequency-voltage converters.

[Operation of the Invention] In the rotation speed detector of the present invention, a two-phase pulse signal outputted from the rotation detector is added to a pulse signal conversion circuit, and a two-phase pulse signal having n different predetermined multiplication frequencies and each having the same or Converts into multiple types of pulse signals having different predetermined pulse widths, and converts each pulse signal to a frequency of -
In addition to the voltage converter, it converts to DC voltage. Then, a switching signal is obtained from the switching signal generation circuit based on the magnitude of a predetermined number of the DC voltages, and the output switching circuit is controlled by the switching signal, so that the plurality of frequencies -
Selectively outputs the DC output voltage from one of the voltage converters.

In this way, among the plurality of types of pulse signals from the pulse signal conversion circuit, when the rotating body rotates at high speed, a DC voltage is selected and outputted by converting a pulse signal having a relatively low frequency and a relatively short pulse width, When the rotating body rotates at a low speed, a DC voltage obtained by converting a pulse signal having a relatively high frequency and a relatively long pulse width is selectively output. As a result, a DC output voltage with low pulsating voltage and short transient response time can be obtained from low to high rotational speeds.

[Example 1] Hereinafter, the present invention will be described in detail with reference to FIGS. 1 to 6.

FIG. 1 shows an embodiment of a rotational speed detector according to the present invention, and in this figure, the same parts as those of the conventional example shown in FIG.

In FIG. 1, the pulse signal conversion circuit 12 converts the two-phase pulse signal Fp1. It is configured to input Fr12 and output a plurality of pulse signals Ep31 to E1)34 having different predetermined multiplication frequencies and pulse widths.

FIG. 2 shows an example of the configuration of the pulse signal conversion circuit 12, and FIG. 3 shows signal waveforms of each part of the pulse signal conversion circuit 12. In FIG. 2, the pulse signal conversion circuit 12 of this embodiment includes disjunctive OR circuits 12a and 12b each functioning as a frequency multiplier, a resistor 12C, a capacitor 12d, and a D-type flip-flop functioning as a frequency divider. It consists of a circuit 12e and monostable multivibrators 12f to 12i, each of which performs a pulse width conversion function. This pulse signal conversion circuit 12 receives two-phase pulse signals E pl and Ep2 as shown in FIG. 3 as input, and receives ΔTl, ΔT2 .
ΔT3. Four pulse signals F with a pulse width of ΔT4
Output p31 to E p34.

The AND circuit group 13 is the two AND circuits 9 in FIG.
. Then, the pulse signal conversion circuit 12
The pulse signals E p31 to E p34 from the rotation direction discriminating circuit 8 and the direction discrimination signals pf and pr from the rotation direction discrimination circuit 8 are respectively input, and the above pulse signals E p31 to E p34 are input as they are, respectively, according to the rotation direction of the rotating body. Repulse signal E p41 to E 11 from output end with different signal waveform
44 or E1151 to E1154.

The F/V converter 11a receives the pulse signal E1)41 or E1)51 from the AND circuit group 13 at different input terminals, and generates a DC voltage E01 or E01 proportional to the pulse width of the input pulse signal and inversely proportional to the pulse period. - Output Eol. Similarly, the F/v converter 11b receives the pulse signal @ E p42 or E p52 and converts the DC voltage EO2
or -EO2, and the F/V converter 11c receives the pulse signal Ep43 or E1153 and outputs the DC voltage EO.
3 or -FO3, and also F/V': ] inverter 1
1d receives the pulse signal E 1144 or E 1154 and outputs the DC voltage EO4 or -EO4. These F
The frequency-to-voltage conversion ratio of the /V converter is set to a predetermined ratio.

The switching signal generation circuit 14 is connected to the F/V converter 11a.
DC voltage from ~11C EOI~EO3 or -E01~
- EO3 are compared with respective predetermined voltages, and different switching signals E 1160 are generated depending on the respective absolute values of the DC voltages.
~E I) Output one of 63.

FIG. 4 shows an example of the configuration of the voltage comparison circuit that constitutes the switching signal generation circuit 14.
is constructed by installing three sets of such voltage comparison circuits. This voltage comparison circuit includes operational amplifiers 14a, 14b, an AND circuit 14G, a NOT circuit 14d1, and resistors 148 to 14.
diodes 14m, 14n, etc. are connected as shown in the figure. This voltage comparator circuit uses DC voltage EO
1 (or -Eol) as input, resistor 14C1, 14h
and the reference voltage 1mo+Ebl, -Fbl divided by the resistors 14i and 14k, and the DC voltage E01 (or -
EOl). Figure 5 (△) is the DC voltage E
01 (or -Eol) and the respective output voltages E14a and E14b of the operational amplifiers @14a and 14b. As is clear from the figure, when the input voltage E01 (or -Eol) is smaller than the reference voltage (-Ebl), the output voltage E14a is at a high level and the output voltage E14a is at a high level.
14b becomes low level, and the output voltage E14a is in the range from the reference voltage (-Ebl) to the reference voltage (+Ebl).
, E14b both become high level, and the reference voltage (-+
4b1), the output voltage 14a becomes low level and the output voltage 14b becomes high level. Figure 5 (B
) shows the voltage level of each part when the DC voltage EO1 increases with time and becomes larger than the reference voltage +Ebl at time t1. As seen in the figure, when the DC voltage E01 is smaller than the reference voltage (+Ebl), a high level switching signal E1) 60 is sent from the AND circuit 14G.
is output, and when it is higher than the reference voltage (+Eb1), a high level switching signal E116 is output from the NOT circuit 14d.
1 is output. In addition, the DC voltage of EO2 and ±
EO3 is also added to a voltage comparison circuit similar to that shown in FIG. 4, and when each becomes larger than a predetermined reference voltage, a high level switching signal E11 is sent from the NOT circuit 14d.
62, E p63 is output. As described above, in this embodiment, the switching signals E 1160 to E
Any one of the switching signals 1163 will be output at high level.

The output switching circuit 15 is composed of a semiconductor analog switch circuit including contacts 15a to 15d, and is configured to perform various functions based on the high-level switching signal Ep60 (or Fl161, El)62, Eρ63) from the switching signal generating circuit 14. One of the DC voltages F01 to E04 (or -E01 to -E04) from the F/V converters 11a to 11d is selected and output.

In this embodiment, the contacts 158 to 15d are individually turned on in response to the high level of the switching signals E peo to E 1163, and the DC voltages EO1 to EO4 are individually selected and output. .

Next, the overall operation of the above embodiment will be explained.

First, the rotating body rotates clockwise at a rotation speed of Q −N 1 rpm.
We will explain the case where the motor rotates at a low speed.

In this case, from the rotation direction determination circuit 8 to the AND circuit group 13
A high-level direction discrimination signal Pf is inputted to the AND circuit group 13 to the F/V converters 11a to 11d, respectively, at the 4.2.1.1/217) multiplication frequency. ΔT
2. ΔT3. ΔT4 (However, ΔTl > ΔT2 > Δ
Pulse signal E041~ with a pulse width of T3>ΔT4)
ED44 is input individually. Then, the pulse period of each pulse signal Ep41 to E1144 is set to T and 2, respectively.
For T, 4T, and 8 units, each F/V converter 11a~
From 11d, ΔT1 /T, ΔT2 /2T, respectively.
ΔT3/4. DC voltage EO proportional to T, ΔT4/8T
1 to EO4 are output individually. Of these, DC voltage E
O1 to EO3 are input to the switching signal generating circuit 14, which outputs a high level switching signal Ep60 that turns on the contact 15a of the output switching circuit 15.

As a result, the output switching circuit 15 selectively outputs the DC voltage EO1 obtained by F/V converting the pulse signal E p41 having a relatively long pulse width (ΔT1) and a relatively high frequency (period T).

Next, the rotating body moves clockwise faster than the above speed N1 to N2.
A case where the ROM is rotating at the rotational speed of the ROM will be explained.

In this case, similarly to the above, pulse signals El)4 are sent from the AND circuit group 13 to the F/V converters 11a to lld, respectively.
1 to Eρ44 are input individually, and the F/V converter 11
DC voltages EO1 to EO4 are individually output from a to 11d, respectively. Then, the DC type pressures EO1 to EO3 are input to the switching signal generating circuit 14, and a high level switching signal E 1161 that turns on the contact 15b of the output switching circuit 15 is outputted from the switching signal generating circuit. As a result, the output switching circuit 15 outputs a DC voltage E obtained by F/V converting the pulse signal E142 with a period of 2T and a pulse width of ΔT2.
O2 is selectively output.

Further, the rotating body moves clockwise to N2 to N3 or N3, respectively.
~N When rotating at a relatively high rotational speed of 4 rpm, similarly to the above, the switching signal generating circuit 14 generates a high-level switching signal E p62 or [ that turns on the contact 15c or 15d of the output switching circuit 15, respectively. a63
is output. As a result, the output switching circuit 15 selectively outputs the DC voltage EO3 or EO4 obtained by F/V converting the pulse signal E p43 or E p44, respectively.

On the other hand, when the rotating body rotates counterclockwise, a high-level direction discrimination signal pr is input from the rotation direction discrimination circuit 8 to the AND circuit group 13, and the AND circuit group 13 outputs a high-level direction discrimination signal pr to each F/V:l.
4.2 and 1.1/2 for inverters 11a to 11d, respectively.
At the multiplication frequency of ΔT1°ΔK2. ΔT3. Pulse signals E1151 to F054 having a pulse width of ΔT4 are individually input. In this case, F/V: ] converter 11a to 1
From 1d, ΔTl /T, ΔT2 /2T, Δ
T3/4T.

DC voltages -[01 to -EO4 proportional to ΔT4/8T are individually output. Hereinafter, as in the case of rotation in the above-mentioned direction, the DC voltage -EO1 to
-EO4 is selectively output.

As mentioned above, in this embodiment, the rotational speed is N3 to N4rp.
When I11 rotates at high speed, the frequency is relatively low (period 8
T>Pulse signal E p with relatively short pulse width (ΔT4)
DC voltage EO4 (or -E04) obtained by converting 34 to F/V
is selectively output, and during low speed rotation from 0 to N1 rpm, the frequency is relatively high (period IlI■) and the pulse width is relatively long (ΔTl).The DC voltage E01 (or - Fol) is selectively output. As a result, during low-speed rotation, the pulsating voltage included in the DC voltage E01 (or -Eol) becomes considerably smaller than in the conventional case. Therefore, this pulsating voltage can be sufficiently reduced by a low-pass filter with a relatively high cutoff frequency.
The transient response time of the output voltage can be shortened.

In the above embodiment, the output pulse signals Ep31 to E1)31+ from the pulse signal conversion circuit were made to have different frequencies and pulse widths, but these pulse signals were made to have different frequencies and different pulse widths. The widths may be the same.

Furthermore, although the above-described embodiments have shown a rotational speed detector in which the rotating direction of the rotating body is two directions, the present invention can also be applied to detecting the rotational speed in one direction. The direction determination circuit 8 and the AND circuit group 13 can be omitted.

[Effects of the Invention] As described above, the rotation speed detector of the present invention adds the two-phase pulse signals output from the rotation detector to the pulse signal conversion circuit, so that the two-phase pulse signals have different predetermined multiplication frequencies and the same frequency. Alternatively, the pulse signals are converted into multiple types of pulse signals having predetermined pulse widths different from each other, and each of the pulse signals is applied to a frequency-voltage converter to convert it into a DC voltage, and the pulse signals from the predetermined plurality of frequency-voltage converters are converted into a DC voltage. The output switching circuit is controlled by a switching signal obtained based on the magnitude of the DC output voltage, and the DC output voltage from one of the plurality of frequency-voltage converters is selectively outputted according to the rotational speed of the rotating body. Therefore, it is possible to obtain a DC output voltage with less pulsating voltage and short transient response time from low rotational speed to high rotational speed. Therefore, if the rotation speed detector of the present invention is applied to a motor speed control system, smooth low speed control can be performed.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an example of the rotational speed detector according to the present invention, FIG. 2 is a circuit diagram showing an example of the configuration of a pulse signal conversion circuit used in the present invention, and FIG. 3 is the circuit diagram shown in FIG. 4 is a circuit diagram showing a configuration example of a switching signal generation circuit used in the present invention, and FIG. 5 is a voltage waveform diagram of each part of the pulse signal conversion circuit.
A) and FIG. 5(B) are signal waveform diagrams of the main parts for explaining the operation of the switching signal generation circuit shown in FIG. 4, and FIG. A characteristic curve diagram showing the relationship with the DC output voltage, Figure 7 is a circuit configuration diagram showing an example of a conventional rotational speed detector, Figure 8 is a signal waveform diagram of each part of the circuit in Figure 7, and Figure 9 is a 8 is a signal waveform diagram showing the relationship between the input signal and the DC output voltage of the F/V converter in FIG. 7. FIG. DESCRIPTION OF SYMBOLS 1... Rotation detector, lla-11d... Frequency-voltage converter (F/V-1 inverter), 12... Pulse signal conversion circuit, 14... Switching signal generation circuit, 15...
Dehachi Hachi Nishiki Saki

Claims (1)

[Claims] Rotation in which a rotation detector that outputs a two-phase pulse signal with a frequency proportional to the rotational speed of the rotating body is used, and a DC voltage proportional to the rotational speed of the rotating body is output based on the two-phase pulse signal from the rotation detector. In the speed detector, a pulse signal conversion circuit that converts the two-phase pulse signal from the rotation detector into a plurality of types of pulse signals having different predetermined multiplication frequencies and each having the same or different predetermined pulse widths; , a plurality of frequency-voltage converters that respectively convert and output each pulse signal from the pulse signal conversion circuit into a DC voltage, and a plurality of frequency-voltage converters that receive DC output voltages from a predetermined plurality of frequency-voltage converters and output the DC voltages. a switching signal generation circuit that outputs a predetermined switching signal according to the magnitude of the voltage; and a DC output voltage from one of the plurality of frequency-voltage converters according to the rotational speed of the rotating body based on the switching signal. A rotation speed detector comprising an output switching circuit for selectively outputting.