JP2000196427A - Timer circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive and accurate circuit in small scale by connecting a pulse generating circuit to an input terminal, connecting an integration circuit to the output of a pulse signal, connecting the output of the integration circuit to one input of a comparator circuit, connecting the output of a reference voltage generating circuit to the other input, connecting the output of the comparator circuit to an output terminal and forwardly connecting a diode to the input of the integration circuit. SOLUTION: When an input signal is inputted from an input terminal 11 to a pulse generating circuit 12, the pulse generating circuit 12 outputs a pulse signal. By changing the duty of the pulse signal, timer time is set. When the pulse signal is inputted to an integration circuit 13, the integration circuit 13 outputs an integration circuit output signal. The integration circuit output signal provided by successively inputting the pulse signal to the integration circuit 13 is inputted to a comparator circuit input terminal 14a of a comparator circuit 14 and compared with the output signal of a reference voltage generating circuit 15 inputted to a comparator circuit input terminal 14b of the comparator circuit 14, and timer time is obtained from an output signal outputted to an output terminal 16 by the comparator circuit 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a timer circuit.

[0002]

2. Description of the Related Art A conventional timer circuit will be described below.

As shown in FIG. 3, a conventional timer circuit has an input terminal 1 and an integration circuit 2 connected to the input terminal 1.
And The output of the integration circuit 2 is connected to one comparison circuit input terminal 4a of the comparison circuit 4, and the output of the reference voltage generation circuit 3 is connected to the other comparison circuit input terminal 4b. Was connected to the output terminal 5. Further, as shown in FIG. 4, the integrating circuit 2 was constituted by a resistor 6 connected to the input terminal 1 and a capacitor 7 connected between the signal path and the ground.
The timer time is determined by the charging time of the capacitor 7. FIG. 5 shows the state of the timer time. That is, 8 is an input signal input to the input terminal 1, 9 is an integration circuit output signal output from the integration circuit 2, and 10 is an output signal of the comparison circuit 4. The integration circuit output signal 9 is input to the comparison circuit input terminal 4a of the comparison circuit 4, and the integration circuit output signal 9 is compared with the output of the reference voltage generation circuit 3 input to the comparison circuit input terminal 4b of the comparison circuit 4. The output of the circuit 4 becomes the output signal shown by 10, and 1
The timer time indicated by 0a was obtained. In order to extend the timer time 10a, a large-capacity electrolytic capacitor is used for the capacitor 7.

A conventional timer circuit, which is another system different from the above, will be described with reference to FIGS. 6 and 7. FIG.

The timer circuit shown in FIG. 6 has an input terminal 26 and an oscillation circuit 27 connected to the input terminal 26. A resistor 29 and a capacitor 30 are connected to an oscillation terminal 28a of the oscillation circuit 27. One of the resistors 29 is connected to a reference voltage terminal 28b of the oscillation circuit 27,
Was connected to ground. Further, the output of the oscillating circuit 27 is provided by a counter circuit 31,
The output terminals 32 were connected to the outputs of the first and second outputs, respectively.
The timer time is determined by the frequency of the oscillation signal from the resistor 29 and the capacitor 30 connected to the oscillation circuit 27. FIG. 7 shows the state of the timer time. That is, 33 is an input signal input to the input terminal 26, and 34 is an oscillation signal output from the oscillation circuit 27. The number of pulses of the oscillation signal 34 is counted by the counter circuit 31. When the number of pulses reaches the predetermined count, the output of the counter circuit 31 becomes the output signal 35
The timer time shown in FIG. 6 was obtained. By using a small-capacity ceramic capacitor as the capacitor 30 for determining the timer time of the timer circuit and increasing the count-up number of the counter circuit 31 even if the frequency of the oscillation signal 34 is increased, a long timer time can be obtained. Was obtained.

[0006]

In the conventional configuration shown in FIG. 3, an electrolytic capacitor is used for the capacitor 7 in order to obtain a long timer time. There is a problem that it is difficult to obtain a large and accurate long timer time.

In a timer circuit composed of an oscillation circuit 27 and a counter circuit 31 shown in FIG.
Even if a ceramic capacitor having a small capacitance is used, a long timer time can be obtained. However, since the oscillation circuit 27 and the counter circuit 31 are composed of many active elements, the area occupied by these two circuits is large. However, there was a problem that the cost was high.

The present invention has been made to solve such a problem, and has as its object to obtain a long-time timer with high accuracy at low cost.

[0009]

In order to achieve this object, a timer circuit according to the present invention has a pulse generating circuit inserted between an input terminal and an integrating circuit. A diode is inserted in the direction, and a small-capacity ceramic capacitor is used for the capacitor of the integration circuit. As a result, it is possible to obtain a long timer time with high accuracy.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention provides an input terminal, a pulse generation circuit connected to the input terminal, an integration circuit connected to the output of the pulse generation circuit, An output of the integration circuit is connected to one input, and the other input includes a comparison circuit connected to an output of the reference voltage generation circuit, and an output terminal connected to an output of the comparison circuit. The integrating circuit is a timer circuit in which a diode is connected to the input of the integrating circuit in the forward direction. Thus, by providing the pulse generation circuit and connecting the diode in the forward direction to the output of the pulse generation circuit and the input of the integration circuit, a long-time timer circuit can be obtained even if the capacitance of the capacitor of the integration circuit is small. be able to. Further, since the capacity of the capacitor of the integration circuit can be reduced, a high-precision long timer time can be obtained by using a high-precision ceramic capacitor as the capacitor of the integration circuit.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a timer circuit according to the present invention.

In FIG. 1, reference numeral 11 denotes an input terminal, which is connected to a pulse generating circuit 12. The output of the pulse generation circuit 12 is connected to an integration circuit 13
The output of the integration circuit 13 is connected to one comparison circuit input terminal 14a of the comparison circuit 14. The output of the reference voltage generation circuit 15 is connected to the other comparison circuit input terminal 14b of the comparison circuit 14. The output of the comparison circuit 14 is connected to an output terminal 16. In this timer circuit, the integration circuit 13
Is a diode 17 having an anode connected to the input side,
An integrator 18 is connected to the cathode side of the diode 17. The integrator 18 includes a resistor 19 connected in series, and a capacitor 20 connected between the output of the resistor 19 and the ground. The capacitor 20 uses a high-precision ceramic capacitor.

The operation of the timer circuit configured as described above will be described below with reference to FIG.

In FIG. 2, reference numeral 21 denotes an input signal input to the input terminal 11. When the input signal 21 is input to the pulse generation circuit 12, a pulse signal 22 is output from the output of the pulse generation circuit 12. In this embodiment, the duty of the pulse signal 22 is 1%.
About. By changing the duty of the pulse signal 22, the timer time 25 can be set. By inputting the pulse signal 22 to the integration circuit 13, the integration circuit 13 outputs an integration circuit output signal 23 shown in FIG. That is, by charging the capacitor 20 with the first pulse 22a through the resistor 19, a first output waveform 23a of the integration circuit output signal 23 is obtained, and the capacitor 20 is further charged with the second pulse 22b through the resistor 19. Thus, a second output waveform 23b is obtained from the integration circuit output signal 23. The integration circuit output signal 23 obtained by sequentially inputting the pulse signal 22 to the integration circuit 13 is input to the comparison circuit input terminal 14a of the comparison circuit 14, and the integration circuit output signal 23 is output to the comparison circuit of the comparison circuit 14. The output of the comparison circuit 14 is compared with the output of the reference voltage generation circuit 15 input to the input terminal 14b. The output of the comparison circuit 14 becomes an output signal indicated by 24, and a timer time indicated by 25 is obtained. That is, in the present invention, the integration circuit 1
By using a high-precision ceramic capacitor as the third capacitor 20, a high-precision timer time 25 can be obtained and a long timer time 25 can be obtained. For example, when the resistance 19 is 400 kΩ and the capacitor 20 is 0.3 μF, a long timer time of about 5 seconds can be obtained.

[0015]

As described above, according to the present invention, a pulse generating circuit is inserted between an input terminal and an integrating circuit.
In the integration circuit, a diode is inserted in a forward direction at the input of the integration circuit, and a small-capacity ceramic capacitor is used as a capacitor of the integration circuit, so that a long time with high accuracy can be obtained.

Further, the circuit configuration can be reduced in size, the area occupied by the timer circuit can be reduced, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of a timer circuit according to an embodiment of the present invention.

FIG. 2 is a time chart of the timer circuit.

FIG. 3 is a block diagram of a conventional timer circuit.

FIG. 4 is a circuit diagram of an integration circuit of the timer circuit.

FIG. 5 is a time chart of the timer circuit.

FIG. 6 is a block diagram of another conventional timer circuit.

FIG. 7 is a time chart of the timer circuit.

[Explanation of symbols]

 Reference Signs List 11 input terminal 12 pulse generation circuit 13 integration circuit 14 comparison circuit 15 reference voltage generation circuit 16 output terminal 17 diode

Claims (1)

[Claims] An input terminal, a pulse generation circuit connected to the input terminal, an integration circuit connected to an output of the pulse generation circuit, and an output of the integration circuit connected to one input. A comparison circuit connected to the output of the reference voltage generation circuit at the other input; and an output terminal connected to the output of the comparison circuit. The integration circuit connects a diode to the input of the integration circuit in the forward direction. Timer circuit.