JPH02259422A - Sensor circuit - Google Patents

Abstract

PURPOSE:To enable conversion of an output signal into the one of higher frequency without increasing the consumption of current, by providing a means of converting the output signal into that of a higher frequency than the one of a clock signal in accordance with the pulse width of the clock signal. CONSTITUTION:A signal detected by a flow sensor 10 is amplified by an amplifier 21. Next, voltage-time conversion is conducted by an inverting integration circuit 22 and a comparator 23. In other words, the voltage ViNT of an analog signal inputted to the circuit 22 is integrated as signals S1 to S3. Then, conversion is made into times t1 to t3 corresponding to these integrated values. In the case of signal S1, accordingly, it is outputted from the comparator 23 as a signal which is at an H level till the time t1 and then turns to be at an L level, and the other signals are also outputted in the same way. Thereafter, the signal outputted from the comparator 23 is shaped to be a rectangular wave in a wave-shaping circuit 25 and inputted to an AND gate 26, wherein a clock signal from an input terminal 28 and said inputted signal are subjected a logical processing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sensor circuit that converts a detected signal of a flow sensor or the like into an output signal.

[Conventional technology]

FIG. 6 is a block diagram showing a detection circuit of a conventional flow rate sensor.

In the figure, 60 is a flow sensor that detects the flow rate; 70
8 is a sensor circuit connected to the flow sensor 60 and driven by a battery, and 80 is a computer (microcomputer) connected to the sensor circuit 7o. The sensor circuit 70 also includes an amplifier 7.
1 and an A/D converter 72. In addition, 7
3 indicates an output signal from the A/D converter 72 to the computer 8o, and 81 indicates a clock signal from the computer 80 to the A/D converter 72.

Now, in the conventional detection circuit, the signal (analog signal) detected by the flow sensor 6o is sent to the amplifier 71 in the sensor circuit 7°.
Amplify with. Next, this signal is converted into a digital signal by an A/D converter 72. That is, the computer 80
The analog signal (
A pulse signal is generated according to the flow rate). This digital signal is then sent as an output signal 73 to the computer 8o. Thereafter, the computer 8o counts the number of pulses of the input signal and determines the flow rate.

In this way, the conventional detection circuit determines the flow rate detected by the flow sensor 60 by counting the number of pulses of the output signal 73, so the circuit can be saved compared to the case where the output signal 73 is used as a code signal. It has excellent features such as being able to connect to the computer 80 through a single line.

[Problem to be solved by the invention]

However, since the conventional detection circuit is configured as described above, it has the following drawbacks.

That is, when operating the sensor circuit 70 that is powered by a battery, intermittent drive is performed to minimize battery consumption. In this case, the clock signal 81 of the computer 80 is also limited to a low frequency (eg, 32.753 kHz). For this reason, when trying to improve the detection accuracy of the output signal, the number of pulses is increased, resulting in an increase in current consumption in the A/D converter 72, which has the disadvantage of shortening the life of the battery.

[Means to solve the problem]

The present invention has been made to solve this problem, and includes means for converting an output signal to a frequency higher than that of the clock signal according to the pulse width of the clock signal.

[For production]

The output signal is converted to a higher frequency than the clock signal according to the pulse width of the clock signal.

〔Example〕

Next, the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram of a sensor circuit showing one embodiment of the present invention.

In the figure, 10 is a flow sensor, 20 is a sensor circuit connected to the flow sensor 10 and driven by a battery, 28 is an input terminal for inputting a clock signal from a computer (not shown), and 29 is an output for outputting an output signal to the computer. It is a terminal. Also, 21 is an amplifier, 22 is an amplifier 22a
and a capacitor 22b.
3 is a comparator, 25 is a waveform shaping circuit that shapes the pulse waveform, 26 is an AND gate, and 27 is a conversion circuit (hereinafter referred to as 2f circuit) that converts the pulse signal into twice the frequency, which is the main part of the present invention. .

Although not shown in this embodiment, an output signal is sent to an external computer from the output terminal 29, and the flow rate is determined based on the number of pulses.

Further, FIG. 2 is a circuit diagram showing a detailed circuit of the 2f circuit 27 in FIG. 1.

In the figure, 31 is an input terminal, 32 is a resistor, 33 is a capacitor, 34 is a not gate, and 35 is an EX (Excl
usive) or gate.

Next, the operation of this embodiment will be explained. First, as shown in FIG. 1, a signal (analog signal) detected by the flow sensor 10 is amplified by an amplifier 21.

Next, the inverting and integrating circuit 22 and the comparator 23 perform voltage-time conversion (VT conversion). That is,
Voltage Vl of the analog signal input to the inverting and integrating circuit 22
ll'r is integrated like the signals S and S3 shown in FIG. 3, respectively. Then, time t corresponds to this integral value.
,xt,. Therefore, in the case of the signal S1, it is output from the comparator 23 as a signal that is at the "H" level until time t1 and then becomes the rLJ level, and the other signals are output in the same way. Thereafter, the signal output from the comparator 23 is shaped into a rectangular wave by the waveform shaping circuit 25 and input to the AND gate 26.

The AND gate 26 performs logical processing on the slope signal from the input terminal 28 and the input signal.

FIGS. 4(a) to 4(g) are time charts showing signals input to and output from the AND gate 26. Here, (a) in the same figure is a clock signal, (b) to (d) in the same figure are VT conversion signals of signals S1 to S3, and (e) to (g) in the same figure are VT conversion signals of signals S1 to S3.
is the output signal for signals S, ~S3.

As is clear from this figure, the AND gate 26 is connected to the signal S
, ~S3, the clock signal is cut off for a time corresponding to the analog quantity. Therefore, a pulse signal (number of pulses) corresponding to the amount detected by the flow sensor 10 is output.

Next, the pulse signal output from the AND gate 26 is
The signal is input to the 2f circuit 27. The 2f circuit 27 receives a pulse signal from the input terminal 31 shown in FIG. and,
Input one directly to EX OR gate 35, and input the other to resistor 3.
2 and a capacitor 33, and a NOT gate 34, the signal is inputted to the EXOR gate.

FIG. 5 is a time chart showing signals input to and output from the 2f circuit 27 in FIG. Here, FIG. 3(a) shows a pulse signal input to the input terminal 31,
The figure (b) shows the waveform of the signal S4 shown in Fig. 2, and the figure (c) shows the waveform of the signal S4 shown in Fig. 2.
indicates the output signal of the output terminal 36.

Now, as shown in FIG. 2, the pulse signal input to the input terminal 31 (FIG. 5(a)) is directly transmitted to the EXOR gate 35.
Enter. On the other hand, the pulse signal input to the integrating circuit consisting of the resistor 32 and the capacitor 33 is
The waveform becomes dull due to the accumulation of charges. Since the signal is inverted by the NOT gate 34, a waveform as shown in FIG. Here, if the threshold values of rHJ and rLJ of the waveforms input via the not gate 34 are Vth (broken line), the frequency is twice as high as the frequency of the pulse signal shown in FIG. 5(a) by the EX-OR gate 35. The output terminal 29 outputs a waveform as shown in FIG.
can be obtained from.

In this way, the sensor circuit 20 in this embodiment can obtain an output signal having twice the frequency of the computer clock signal, so that the sensor circuit 20 can output the signal detected by the sensor without increasing current consumption as in the conventional case. can be converted with more precision.

Further, the delay in data reading time of the output signal on the computer side can be reduced.

In this embodiment, the circuit shown in FIG. 2 is used as the 2f circuit 27, but any other circuit may be used as long as it converts the input pulse signal to a high frequency.

〔Effect of the invention〕

As explained above, the present invention includes means for converting the output signal to a higher frequency than the clock signal according to the pulse width of the clock signal. It can be converted to frequency.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a sensor circuit showing an embodiment of the present invention, FIG. 2 is a circuit diagram showing a detailed circuit of the 2r circuit 27 in FIG. 1, and FIG.
Characteristic diagrams showing time conversion, Figures 4(a) to (g) are time charts showing signals input to and output from the AND gate 26, and Figure 5 is a signal input to the 2f circuit in Figure 2. FIG. 6 is a block diagram showing a detection circuit of a conventional flow rate sensor. 10... Flow sensor, 20... Sensor circuit, 21
... Amplifier, 22... Inverting and integrating circuit, 23... Comparator, 25... Waveform shaping circuit, 26... AND gate, 27... 2f circuit, 28... Input terminal,
29...Output terminal. Figure 1 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] In a battery-powered sensor circuit that converts a signal detected by a sensor into an output signal according to an input clock signal and sends out the output signal, the pulse width of the clock signal is higher than the clock signal according to the pulse width of the clock signal. A sensor circuit comprising means for converting an output signal into a frequency.