JPH065632Y2 - Rotation speed monitoring device - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a rotation speed monitoring device for monitoring whether or not the rotation speed of a rotator is within a normal range.

[Conventional technology]

A conventional rotation speed monitoring device for monitoring the rotation speed of a rotator obtains a pulse having a cycle corresponding to the rotation speed of the rotator from the rotary encoder 11 as shown in FIG. The counter 12 which is reset to 1 counts the count value P of the counter 12 and the digital comparator 1
3 and 14 compare with the upper limit set value A and the lower limit set value B, respectively.

The upper limit set value A corresponds to the upper limit of the normal range of rotation speed,
The lower limit setting value B corresponds to the lower limit value of the normal range of the rotation speed.

The digital comparator 13 has a count value P and an upper limit set value A.
When P> A, the output becomes high level, the digital comparator 14 compares the count value P with the lower limit setting value B, and when P <B, the output becomes high level, The outputs of the comparators 13 and 14 are transmitted through the OR circuit 15 to the display circuit 1
Added to 6. The display circuit 16, when the output of the OR circuit 15 is low level immediately before the reset of the counter 12,
That is, when the count value P is A ≧ P ≧ B, the fact that the rotation speed is within the normal range is held and displayed, and when the count value P P> A or P <B, the rotation speed is outside the normal range. Display and hold that there is.

The display is updated every fixed time (for example, 1 second).

[Problems to be solved by the invention]

The conventional rotation speed monitoring device as described above counts the pulses generated in a cycle corresponding to the rotation speed of the rotator and counts them as 2 pulses.
The digital comparators 13 and 14 compare and add the comparison result to the OR circuit 15 to determine whether the rotation speed is within the normal range.

However, among the integrated circuit components used in this rotation speed monitoring device, the digital comparators 13 and 14 are large, expensive, and have a large number of wirings. Two such digital comparators 13 and 14 are required. Therefore, there is a problem that the size becomes large as a whole, the cost becomes high, and the wiring becomes complicated.

It is an object of the present invention to provide a rotation speed monitoring device which can be downsized, inexpensive, and whose wiring can be simplified.

[Means for solving problems]

The rotation speed monitoring device of the present invention includes a rotary encoder that generates a pulse at a cycle corresponding to the rotation speed of a rotator, a signal that generates a latch signal at regular time intervals, and a signal that generates a reset signal immediately after this latch signal. A circuit, a counter for counting the pulse output from the rotary encoder, the maximum countable value being set to a value corresponding to the upper limit of the normal range of the rotation speed of the rotator, reset by the reset signal, and a comparison value. A digital comparator that compares the output value of the counter with the comparison value by setting the value corresponding to the lower limit of the normal range of the rotation speed of the rotator,
A latch circuit for detecting and holding the output of the digital comparator with the latch signal and a display for displaying "normal" or "abnormal" in response to the output of the latch circuit are provided.

[Action]

According to the configuration of this invention, the maximum countable value of the counter is set to a value corresponding to the upper limit of the normal range of the rotation speed of the rotator, and the comparison value given to the digital comparator is the lower limit of the normal range of the rotation speed of the rotator. Since the counter output value is compared with the comparison value by the digital comparator, when the rotation speed of the rotator is within the normal range, the counter output value is greater than the comparison value at the latch signal timing. Less than the maximum countable value,
When the rotation speed is lower than the normal range, the output value of the counter is smaller than the comparison value.

In addition, if the counter continues counting after the output value reaches the maximum countable value, the output value returns to zero and increases again from zero.Therefore, when the rotation speed is higher than the normal range, the counter reaches the maximum value. The count value exceeds the countable value, and the output value becomes smaller than the comparison value.

Therefore, by using only one digital comparator, it is possible to detect and display whether or not the rotation speed of the rotator is within the normal range. Therefore, the size can be reduced, the cost can be reduced, and the wiring can be simplified.

〔Example〕

An embodiment of this invention will be described with reference to FIG. As shown in FIG. 1, this rotation speed monitoring device generates a rotation encoder 1 that generates a pulse at a cycle corresponding to the rotation speed of a rotator, and a latch signal LT at regular time intervals (for example, 1 second). The signal generation circuit 2 that generates the reset signal RS immediately after the latch signal LT, and the maximum countable value is set to a value corresponding to the upper limit of the normal range of the rotation speed of the rotator and is reset by the reset signal RS. A counter 3 that counts pulses output from the rotary encoder 1, and a comparison value is set to a value corresponding to a lower limit of a normal range of the rotation speed of the rotator, and an output value of the counter 3 is compared with the comparison value. Digital comparator 4
A latch circuit 5 for detecting and holding the output of the digital comparator 4 with the latch signal LT, and a display 6 for displaying "normal" or "abnormal" in response to the output of the latch circuit 5. .

The details will be described below.

In this rotation speed monitoring device, a pulse output from the rotary encoder 1 is divided by 16 by a 4-bit decrementing counter 7 at a cycle corresponding to the rotation speed of the rotator and added to the counter 3.

The signal generation circuit 2 includes a crystal oscillator 2A, a reduction counter 2B that reduces the frequency of a crystal oscillation pulse output from the crystal oscillator 2A, and generates a latch signal LT having a narrow pulse width of 1 Hz, and the reduction counter 2B. And a delay circuit 2c that generates a reset signal RS that is a little delayed from the latch signal LT output from the latch signal LT. The latch signal LT is generated every one second, and the reset signal RS is generated a little later than the latch signal LT. Occur.

The counter 3 is two 4-bit preset counters 3.
It is composed of A and 3B, and the maximum countable value is decimal 2
55, the preset value is the decimal number 125, and counts the output pulse of the decrementing counter 7. At this time, the reset signal RS output from the signal generation circuit 2
Resets every 1 second. Therefore, the output value of the counter 3 becomes a preset value at the time of reset, and then increases every time the output pulse of the declining counter 7 is input. When the counter 3 continues counting without being reset after the output value reaches the maximum countable value, the output value returns to zero and increases from zero again.

The digital comparator 4 uses, for example, “11” as the comparison value.
110100 ", that is, a decimal number 244 is set, the output value of the counter 3 is compared with the comparison value, and when the output value of the counter 3 is smaller than the comparison value, the output becomes" 1 ", and when the output value of the counter 3 is opposite, the output is output. Becomes "0".

The latch circuit 5 is composed of a D flip-flop, and detects and holds the output of the digital comparator 4 in response to the latch signal LT output from the signal generation circuit 2. At the timing of this detection and holding, since one second has elapsed after the counter 3 was reset, the output value of the counter is obtained by adding the preset value to the number of pulses input to the counter 3 in one second. The result of comparison between the value and the comparison value is held in the latch circuit 5.

The display 6 displays "normal" when the output of the latch circuit 5 is at a low level, and displays "abnormal" when it is at a high level.

Hereinafter, the operation of this rotation speed monitoring device will be described using specific numerical examples.

For example, the rotation speed of the stirring motor of the immune reaction tank is usually 10
It is 00r.pm, and the rotary encoder 1 is 120 per rotation.
The rotary encoder 1, which generates a pulse of 1000 pulses and is connected to the stirring motor of 1000 rpm, generates a pulse of 2000 Hz, that is, 2000 pulses per second. The output pulse of the rotary encoder 1 is frequency-divided by the decreasing counter 7 and added to the counter 3. The counter 3 counts the pulses input to the counter 3 in 1 second by the reset signal RS and the latch signal LT. The counter 3 has 8 bits, the maximum countable value is 255, and when the output value is 255 and further pulses are input, the output value becomes 0, and then 1, 2,
The output value will change as 3 ...

Now, assuming that the preset value of the counter 3 is 125 and the comparison value of the digital comparator 4 is 244, when the output value of the counter is between 245 and 255 when the latch signal LT is generated, the output of the digital comparator 4 becomes low level. Is displayed and "normal" is displayed.

For example, if the rotary encoder 1 generates a pulse of 1936 Hz, 1936 ÷ 16 = 121 [pieces] of pulses are input to the counter 3 per second, and the output value of the counter 3 when the latch signal LT is generated. Becomes 125 + 121 = 246. Since this output value 246 is between the comparison value 244 and the maximum countable value 255, the output of the digital comparator 4 becomes a low level and is displayed as "normal".

When the rotary encoder 1 is generating a pulse of 1912 Hz, the number of input pulses to the counter 3 per second is 119 and 120 alternately.

When the number of pulses is 119, the output value of the counter 3 is 2
44, "abnormal" is displayed and the number of pulses is 12
When the number is 0, it becomes 245 and is displayed as "normal".

In the case of this embodiment, the maximum countable value of the counter 3 is 25.
5, the preset value is 125, and the comparison value of the digital comparator 4 is 244. Therefore, the display 6 should display the frequency of the input pulse input from the rotary encoder 1 to the counter 3 as shown in the following table. , 1920 ~
It is normally displayed in the range of 2080 Hz, that is, in the range of 960 to 1040 rpm.

When the frequency of the input pulse exceeds 6000 Hz, "normal" is displayed again, but there is no problem because the number of revolutions cannot exceed twice the normal value. Also, fluctuations in the oscillation frequency of the crystal oscillator 2A do not pose a practical problem.

The rotation speed monitoring apparatus of this embodiment sets the maximum countable value of the counter 3 to a value corresponding to the upper limit of the normal range of the rotation speed of the rotator, and gives a comparison value to the digital comparator 4 to the rotation speed of the rotator. Since a value corresponding to the lower limit of the normal range is set and the output value of the counter 3 is compared with the comparison value by the digital comparator 4, when the rotation speed of the rotator is within the normal range, the counter 3 is set at the timing of the latch signal LT. Is larger than the comparison value and less than or equal to the maximum countable value, and the rotation speed is lower than the normal range, the output value of the counter 3 is smaller than the comparison value. When the counter 3 continues counting after the output value reaches the maximum countable value, the output value returns to zero and increases again from zero. Therefore, when the rotation speed is higher than the normal range, the counter 3 3 counts beyond the maximum countable value and its output value becomes smaller than the comparison value.

Therefore, it is possible to detect and display whether or not the rotation speed of the rotator is within the normal range by using only one digital comparator 4. Therefore, it can be downsized,
It is cheap and wiring can be simplified.

[Effect of device]

According to the rotation speed monitoring device of the present invention, the maximum countable value of the counter is set to a value corresponding to the upper limit of the normal range of the rotation speed of the rotator, and the comparison value given to the digital comparator is set to the normal value of the rotation speed of the rotator. Set the value equivalent to the lower limit of the range and compare the output value of the counter with the comparison value by the digital comparator, so it can detect whether the rotation speed of the rotator is within the normal range by using only one digital comparator. Can be displayed. Therefore, the size can be reduced, the cost can be reduced, and the wiring can be simplified.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional example. 1 ... Rotation encoder, 2 ... Signal generating circuit, 3 ... Counter, 4 ... Digital comparator, 5 ... Latch circuit, 6 ...
display

Claims (2)

[Scope of utility model registration request] 1. A rotary encoder that generates a pulse at a cycle corresponding to a rotation speed of a rotator, a signal generation circuit that generates a latch signal at regular time intervals and a reset signal immediately after the latch signal, and a maximum. A countable value is set to a value corresponding to the upper limit of the normal range of the rotation speed of the rotator, is reset by the reset signal, and counts the pulses output from the rotary encoder; and a comparison value of the rotator. A digital comparator that sets a value corresponding to the lower limit of the normal range of the rotation speed and compares the output value of the counter with the comparison value, a latch circuit that detects and holds the output of the digital comparator with the latch signal, and the latch circuit "Normal" in response to the output of
A rotation speed monitoring device having a display for displaying "abnormal". 2. The counter is a preset counter, the preset value is set so that the maximum countable value is a value corresponding to the upper limit of the rotation speed of the rotator, and the comparison is made according to the preset value. The rotation speed monitoring device according to claim (1), wherein the value is set to a value corresponding to the lower limit of the rotation speed of the rotator.