JPS5839317B2 - comparison detection device - Google Patents

Description

[Detailed Description of the Invention] The present invention compares a set amount such as a set time with a change amount such as an elapsed time, displays a remaining amount such as a remaining time, and when the change amount reaches a set amount, a certain amount of change is displayed. The present invention relates to a comparison detection device that obtains a detection signal, and is particularly designed to perform a reliable and stable comparison operation between a set amount and a change amount using a simple configuration.

Hereinafter, an example of the present invention will be explained with reference to the drawings, taking as an example the case where the present invention is applied to a timer, thus displaying the remaining time of the difference between the set time and the elapsed time, and detecting this when the elapsed time reaches the set time. let's.

In FIG. 1, reference numeral 1 denotes a clock pulse generator that generates clock pulses of a constant frequency, and includes a series circuit of a resistor 2 and a capacitor 3 that constitute a charging circuit, a discharging transistor 4, and a comparison amplifier. transistors 5 and 6
and voltage dividing resistors 7 and 8 that provide a reference voltage to the comparison amplifier.
and a switching transistor 9.

When the power is turned on, a charging current flows to the capacitor 3 through the resistor 2, and the voltage across the capacitor 3, that is, the base voltage 8 of the transistor 5, is applied to the resistor 2 as shown in FIG.
and rises with a time constant determined by capacitor 3, and this rises with a time constant determined by capacitor 3.
and the voltage at the connection point of 8, that is, the reference voltage given to the base of the transistor 6.

When the voltage is exceeded, the transistor 5 is turned on, which turns on the transistor 9, which turns on the transistor 4, the charge in the capacitor 3 is discharged through the transistor 4, and the voltage 8 instantly falls to the ground potential.

Therefore, transistor 5 is turned off, transistors 9 and 4 are also turned off, and the same process as described above is repeated until capacitor 3 is no longer charged.

Therefore, a clock pulse S of a constant period is obtained at the collector of the transistor 5, as shown in FIG.

In this case, as shown by the broken line in FIG. 2, when the power supply voltage +■oo fluctuates and the way the voltage VB rises changes, the reference voltage (■) also changes.

The frequency of the clock pulse S is held constant regardless of fluctuations in the power supply voltage +OO.

A counter 10 counts the above-mentioned clock pulses S from the clock pulse generator 1.

This counter 10 has m flip-flop circuits 11m.
. . . 111 are connected in cascade so that the current value can be taken out as an m-bit code.

12 is a digital-to-analog converter which converts the output of the counter 10 into an analog signal and generates a comparison signal whose value changes according to elapsed time.

This digital-to-analog converter 12 includes transistors 13 to 15 and a switching transistor 16n corresponding to the upper n (H≦m) bits of the counter 10.
・16, and transistor 16n...16, each with a resistance value of 2 n I R1
. . . consists of a resistor R and a transistor 17, the series circuits of the switching transistor and the resistor are connected in parallel, and the flip-flop circuit 11n of the upper n bits of the counter 10... - The output of 111 is supplied to the bases of switching transistors 16n...16.

The base voltage of the transistor 13 is held constant, and the collector of the transistor 14 is connected to the transistor 1.
If only transistor 16n of transistor 161 is turned on, a current of 2n-21 flows, and only transistor 163 and 161 are turned on, a current of 2n-21 flows. When it turns on, (2n-3+2°-1) ■.

A current proportional to the output code of the upper n bits of the counter 10 converted into an analog value flows.

A current proportional to the collector current of the transistor 14 flows through the transistor 15, and a current proportional to the current flowing through the transistor 15 flows through the transistor 17.

Therefore, as shown in FIG.
Each time the counter 10 counts 2m-0 clock pulses S, the comparison current (2) increases stepwise by a constant value, for example, every minute.

flows. , 20 is a time setting circuit which generates a reference signal having a value corresponding to a set time.

It consists of transistors 21 to 25 and a setting variable resistor 26, and the variable resistor 26 has so-called B-type resistance.

Since the base voltage of the transistor 21 is held constant, as the position of the movable element moves away from the ground end, the potential of the movable element and hence the base voltage of the transistor 24 rises, and the current flowing through the transistor 24 increases.

Since a current proportional to the current flowing through the transistor 24 flows through the transistor 25, the current flowing through the transistor 25 is determined by the position of the mover of the variable resistor 26.

Therefore, if a certain period of time is set according to the time scale provided in connection with the variable resistor 26, as shown in FIG. flows.

30 is a level comparator, and the above-mentioned comparison current ■.

is compared with a reference current, and when the former reaches the latter, that is, when the elapsed time becomes equal to the set time, an output in a constant state is generated.

This is constructed by connecting the emitter sides of transistors 31 and 32 in common, and connecting a constant current source 33 to the connection point, and the base of transistor 31 connects to the collector of transistor 17 of digital-to-analog converter 12 and the time setting circuit. A constant reference voltage (2) is connected to the collector of the transistor 25 of 20, and the base of the transistor 32 is supplied with a constant reference voltage from a reference voltage source 40.

is supplied by M. For example, the reference voltage source 40 has a power terminal grounded through a series circuit of a resistor 41 and diodes 42 and 43, and a series circuit of resistors 44 and 45 connected in parallel to the series circuit of diodes 42 and 43. ,! resistance 44
The configuration is such that, for example, the reference voltage VD of (2) 7 can always be obtained from the connection points 45 and 45 regardless of fluctuations in the power supply voltage +voo.

Furthermore, 50 is a meter circuit, transistors 17 and 25
The connection point between the collector of the transistor 31 and the base of the transistor 31 is grounded through diode-connected transistors 51 and 52, and a resistor 53 and a meter 54, and a resistor 55 is connected in parallel with the resistor 53 and the meter 54. .

As mentioned above, the comparison current (2) increases stepwise by a constant value at the collector-emitter of the transistor 17 of the digital-to-analog converter 12 every time a constant time elapses.

On the other hand, a reference current of a constant value, which is adjusted for a preset time, flows through the emitter collector of the transistor 25 of the time setting circuit 20.

Therefore, the elapsed time does not reach the set time and the comparison current ■.

While the reference current is smaller than the reference current, the difference between
-I.

As shown in Figure 3, a current that decreases stepwise by a constant value every time a certain period of time passes is applied to the meter circuit.
0, and a current proportional to this current flows into meter 5.
It flows to 4.

Since the current ■M (=1e■o) is compared to the difference between the set time and the elapsed time, that is, the remaining time, by attaching a time scale to the meter 54, this remaining time can be calculated. is displayed.

On the other hand, the base voltage of the transistor 31 of the level comparator 30 is the current I (=I, -
Io), the current decreases stepwise by a constant value every time a certain period of time elapses, but as long as the elapsed time does not reach the set value, the current By flowing, at least the reference voltage mentioned above■.

The voltage is higher, transistor 31 is on, and transistor 32 is off.

When the elapsed time reaches the set time, that is, the current ■.

When the current reaches the current ■, no current flows through the diode-connected transistors 51 and 52 of the meter circuit 50, and the base voltage vM drops sharply to the base voltage of the transistor 32 (■).

becomes lower, transistor 31 is off, transistor 3
2 is reversed to the on state.

When the transistor 32 is turned on, the transistor 61 is turned on, and as shown in FIG. 3, the potential ED at the connection point between the resistors 62 and 63 on its collector side rises from the ground potential to a positive potential, thereby generating a trigger pulse. Formation circuit 6
The trigger pulse PD is obtained from 4, and this is the OR circuit 6.
5 to a flip-flop circuit 66, which is inverted.

Therefore, for example, when the switch 67 is operated in advance, a trigger pulse is appropriately supplied from the trigger pulse forming circuit 68 to the flip-flop circuit 66 through the OR circuit 65, and the flip-flop circuit 66 is in a reset state. If the device 69 is turned off, when the set time is reached and the flip-flop circuit 66 is reversed by the trigger pulse PD, it becomes set and the device 69 is automatically turned on.

Conversely, if the flip-flop circuit 66 is in the set state in advance and the device 69 is turned on, when the set time is reached and the flip-flop circuit 66 is inverted by the trigger pulse PD, this becomes the reset state. and the device 69 is automatically turned off.

According to the above-mentioned comparison detection device according to the present invention, when a transistor through which a current according to a set amount flows and an output side of a transistor through which a current according to a change amount flows are connected, and a current exceeding a certain level flows through the connection point. Since it is connected to the display meter through an element that exhibits a nearly constant voltage, a current proportional to the residual amount of the difference between the set amount and the amount of change flows through the display meter.
The remaining amount can be displayed accurately.

Moreover, the voltage at this connection point is compared with a fixed reference voltage to detect whether the amount of change has reached the set value, and when the voltage at the connection point reaches the set value, the voltage at the connection point will drop sharply. , this can be detected reliably.

Note that diode-connected transistors 51 and 52
Instead, a diode itself or a suitable constant voltage element may be used.

[Brief explanation of the drawing]

FIG. 1 is a connection diagram of an example when the comparison detection device according to the present invention is used as a timer, and FIGS. 2 and 3 are waveform diagrams for explaining the same. 25 is a first transistor, 17 is a second transistor,
30 is a level comparator, 40 is a reference voltage source, and 54 is a display meter.

Claims (1)

[Claims] 1 A first transistor through which a current of a reference magnitude according to a set amount flows, and a second transistor through which a current whose magnitude changes according to the amount of change flows, and the output of the first and second transistors The two sides are connected in common, and the connection point is connected to one input end of the level comparator, and is also connected to the display through an element that exhibits a nearly constant voltage when a current of a constant flow flows, and the reference voltage A source is connected to the other input terminal of the level comparator, and a current corresponding to the difference between the current of the reference magnitude and the current whose magnitude changes flows through the display, and the magnitude of the magnitude changes from the level comparator. A comparison and detection device is constructed so that a constant detection signal is generated when a current whose value changes reaches a current of the above-mentioned reference magnitude.