Air pressure detection system

Abstract

The invention provides an air pressure detection system comprising an air pressure sensor configured to detect external air pressure and generate a pulse signal; the pulse counter is configured to count the number of pulses of the pulse signal in a preset time interval and generate a pulse count value; the first comparator is configured to compare the pulse count value with a first preset reference value, further compare the pulse count value with a second preset reference value under the condition that the pulse count value is greater than the first preset reference value, and generate a first comparison result signal as an air pressure detection signal, the second preset reference value is larger than the first preset reference value, when the pulse count value is not larger than the first preset reference value, the air pressure detection signal indicates that the external air pressure changes, and when the pulse count value is larger than the second preset reference value, the air pressure detection signal indicates that the external air pressure does not change.

Description

Technical Field

[0001] The present invention relates to the field of circuits, and more particularly to an air pressure detection system. Background Art

[0002] Air pressure sensor is a kind of sensor widely used in industry, medical treatment, environmental protection and other fields. It can detect the change of air pressure and convert it into electrical signal output, so as to achieve accurate detection and / or control of air pressure. Summary of the invention

[0003] According to an embodiment of the present invention, the air pressure detection system includes: an air pressure sensor, configured to detect external air pressure and generate a pulse signal; a pulse counter, configured to count the number of pulses of the pulse signal within a preset time interval and generate a pulse count value; and a first comparator, configured to compare the pulse count value with a first preset reference value, and further compare the pulse count value with a second preset reference value when the pulse count value is greater than the first preset reference value, and generate a first comparison result signal as an air pressure detection signal, wherein the second preset reference value is greater than the first preset reference value, when the pulse count value is not greater than the first preset reference value, the air pressure detection signal indicates that the external air pressure has changed, and when the pulse count value is greater than the second preset reference value, the air pressure detection signal indicates that the external air pressure has not changed. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] The present invention can be better understood from the following description of specific embodiments of the present invention in conjunction with the accompanying drawings, in which:

[0005] Figure 1 A schematic diagram of the structure of a traditional air pressure detection system is shown.

[0006] Figure 2 Shown in Figure 1 Schematic diagram of the structure of the oscillator in the air pressure detection system shown.

[0007] Figure 3 A schematic structural diagram of an air pressure detection system according to an embodiment of the present invention is shown.

[0008] Figure 4 Shows Figure 3 The shown diagram is a flow chart of the air pressure detection system performing air pressure detection.

[0009] Figure 5 Shows the use of Figure 3 The schematic diagram of the state transition of the electronic cigarette in the air pressure detection system is shown. DETAILED DESCRIPTION

[0010] The features and exemplary embodiments of various aspects of the present invention will be described in detail below. In the detailed description below, many specific details are proposed to provide a comprehensive understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is only to provide a better understanding of the present invention by illustrating examples of the present invention. The present invention is by no means limited to any specific configuration and algorithm proposed below, but covers any modification, replacement and improvement of elements, parts and algorithms without departing from the spirit of the present invention. In the accompanying drawings and the following description, known structures and technologies are not shown to avoid unnecessary ambiguity in the present invention. In addition, it should be noted that the term "A is connected to B" used here can mean "A is directly connected to B" and can also mean "A is indirectly connected to B via one or more other elements".

[0011] Figure 1 FIG. 2 shows a schematic diagram of the structure of a conventional air pressure detection system. Figure 1 As shown, the air pressure detection system 100 includes an air pressure sensor 102, an oscillator 104, and a counter 106, wherein: in the air pressure sensor 102, the capacitance value of the capacitor C1 changes with the change of the external air pressure, the reset switch SW1 is in a closed state or an open state under the control of the pulse signal Vpulse1, and the current Ic generates a periodic ramp signal Vramp1 on the capacitor C1 as the reset switch SW1 switches between the closed state and the open state, and the comparator 1 compares the ramp signal Vramp1 with the reference voltage Vref1 and generates a pulse signal Vpulse1, wherein the time interval T0 between two adjacent pulses of the pulse signal Vpulse1 is C1 (Vref1 / Ic); the oscillator 104 generates a clock signal Clk1; the counter 106 counts the number of pulses of the pulse signal Vpulse1 within a preset time interval based on the clock signal Clk1. In this way, the capacitance value of the capacitor C1 can be converted into the number of pulses of the pulse signal Vpulse1, so that it can be judged whether the external air pressure changes according to the number of pulses of the pulse signal Vpulse1.

[0012] Currently, used in Figure 1 The oscillator 104 in the air pressure detection system 100 shown can be implemented in a variety of ways, but they all cannot deviate from the resistance (R) capacitance (C) mode or the current (I) capacitance (C) mode. Figure 2 Shown in Figure 1 The structure diagram of the oscillator 104 in the air pressure detection system 100 is shown in FIG. Figure 2As shown, in the oscillator 104, the bias current generator generates a bias current Ibias; when the reset switch SW2 is in the off state, the mirror current of the bias current Ibias generates a periodic ramp signal Vramp2 on the capacitor C2, and the comparator 2 compares the ramp signal Vramp2 with the reference voltage Vref2 generated by the reference voltage generator; when the ramp signal Vramp2 is greater than the reference voltage Vref2, the output of the comparator 2 changes from a low level to a high level, the reset switch SW2 changes from an off state to a closed state, and the voltage on the capacitor C2 is reset to 0V, so that the output of the comparator 2 is reversed from a high level to a low level, the reset switch SW2 changes from a closed state to an off state, and the mirror current of the bias current Ibias generates the ramp signal Vramp2 on the capacitor C2 again; the D flip-flop shapes the output of the comparator 2 into a clock signal Clk1 with a duty cycle of 50%.

[0013] In order for the counter 106 to accurately count the number of pulses of the pulse signal Vpulse1 within a preset time interval, the preset time interval must be determined and not change with environmental parameters (e.g., temperature, etc.). However, there are differences between devices, differences in temperature response, and voltage fluctuations and differences in conventional semiconductor process manufacturing, which makes the air pressure detection system 100 work normally at room temperature, but may fail at high or low temperatures. For example, when the air pressure detection system 100 is used in an electronic cigarette, when the electronic cigarette is in a smoking state and the internal temperature is very high or when the electronic cigarette is in the cold outdoors, the frequency of the clock signal Clk1 output by the oscillator 104 will change slowly with the environmental parameters, and the capacitance value of the capacitor C1 will also change slowly with the environmental parameters. When the capacitance value change of the capacitor C1 does not match the frequency change of the clock signal Clk1, the counter 106 counts the number of pulses of the pulse signal Vpulse1 within the preset time interval incorrectly, resulting in an abnormal detection result of the air pressure by the air pressure detection system 100.

[0014] In view of the above situation, an air pressure detection system according to an embodiment of the present invention is proposed, which can solve the problem of the frequency change of the clock signal generated by the oscillator and the frequency change of the pulse signal generated by the airflow pressure sensor not matching as the environmental parameters change slowly (for example, the temperature changes), thereby ensuring that the air pressure detection system can work correctly in any environment.

[0015] Figure 3 FIG. 2 shows a schematic diagram of the structure of an air pressure detection system according to an embodiment of the present invention. Figure 3As shown, the air pressure detection system 300 includes an air pressure sensor 302, an oscillator 304, a counter 306, and a comparator 308, wherein: the air pressure sensor 302 is configured to detect the external air pressure and generate a pulse signal Vpulse; the oscillator 304 is configured to generate a clock signal Clk; the counter 306 is configured to count the number of pulses of the pulse signal Vpulse within a preset time interval T1 based on the clock signal Clk to obtain a pulse count value N; the comparator 308 is configured to compare the pulse count value N with a first preset reference value, and further compare the pulse count value N with a second preset reference value when the pulse count value N is greater than the first preset reference value, and generate a comparison result signal Vcomp1 as an air pressure detection signal, wherein the second preset reference value is greater than the first preset reference value, when the pulse count value N is not greater than the first preset reference value, the air pressure detection signal indicates that the external air pressure has changed, and when the pulse count value N is greater than the second preset reference value, the air pressure detection signal indicates that the external air pressure has not changed.

[0016] like Figure 3 As shown, in some embodiments, the first preset reference value is the difference (MQ) between the preset pulse count threshold M and the preset detection deviation threshold Q, and the second preset reference value is the sum (M-Q+H) of the first preset reference value (MQ) and the preset detection deviation hysteresis value H.

[0017] like Figure 3 As shown, in some embodiments, the air pressure detection system 300 further includes a comparator 310 and a reference value updating module 312, wherein: the comparator 310 is configured to compare the absolute difference between the pulse count value N and the preset pulse count threshold value M and the preset temperature tracking threshold value H and generate a comparison result signal Vcomp2 when the comparison result signal Vcomp1 indicates that the external air pressure has not changed; the reference value updating module 312 is configured to update the preset pulse count threshold value M by a predetermined updating method when the comparison result signal Vcomp2 indicates that the absolute difference between the pulse count value N and the preset pulse count threshold value M is not less than the preset temperature tracking threshold value T, thereby updating the first preset reference value and the second preset reference value. For example, the updating method here may include any one or more of the following updating algorithms:

[0018] 1) M = N,

[0019] 2) M = (M + N) / 2,

[0020] 3) or Wherein, K represents the number of preset time intervals for obtaining the preset pulse count threshold M, and Ni represents the pulse count value of the pulse signal Vpulse in the i-th preset time interval among the K preset time intervals T.

[0021] like Figure 3 As shown, in some embodiments, the reference value update module 312 is also configured to keep the preset pulse count threshold M unchanged so as to keep the first preset reference value and the second preset reference value unchanged when the comparison result signal Vcomp2 indicates that the absolute difference between the pulse count value N and the preset pulse count threshold M is less than the preset temperature tracking threshold T.

[0022] It should be noted that the preset pulse count threshold M, the preset detection deviation threshold Q, the preset detection deviation hysteresis value H, and the preset temperature tracking threshold T can be preset by the manufacturer or user of the air pressure sensor 302 according to the type of the air pressure sensor 302. The air pressure sensor 302 can be implemented as Figure 1 The structure of the air pressure sensor 102 is shown. The oscillator 304 can be implemented as Figure 2 The structure of the oscillator 104 is shown. After the air pressure detection system 300 is powered on, the reference value initially used by the comparator 308 is the first preset reference value (MQ), and the comparison result signal Vcomp1 initially output by the comparator 308 is a logic low level.

[0023] In the air pressure detection system 300 according to an embodiment of the present invention, since the reference value used by the comparator 308 is adjusted following the slow change of the environmental parameters, the comparison result signal output by the comparator 308 will not change due to the change of the pulse count value caused by the slow change of the environmental parameters, so adaptive hysteresis type air pressure detection that is insensitive to the slow change of the environmental parameters can be implemented.

[0024] Figure 4 Shows Figure 3 The schematic diagram of the process of performing air pressure detection by the air pressure detection system shown in FIG. Figure 4As shown, the process of the air pressure detection system 300 performing air pressure detection includes: S402, the counter 306 counts the number of pulses of the pulse signal Vpulse output by the air pressure sensor 302 within a preset time interval T1 to obtain a pulse count value N; S404, the comparator 308 compares the pulse count value M with a first preset reference value (M - Q), and further compares the pulse count value M with a second preset reference value (M - Q + H) when the pulse count value M is greater than the first preset reference value (M - Q); S406, when the pulse count value M is not greater than either the first preset reference value (M - Q) or the second preset reference value (M - Q + H), the comparator 308 generates a comparison result signal Vcomp1 to indicate that the external air pressure has changed; S408, when the pulse count value M is greater than the second preset reference value (M - Q + H), the comparator 308 generates a comparison result signal Vcomp1 to indicate that the external air pressure has not changed; S410, the comparator 310 compares the absolute difference between the pulse count value N and the preset pulse count threshold M with the preset temperature tracking threshold H; S412, when the comparison result signal Vcomp2 indicates that the absolute difference between the pulse count value N and the preset pulse count threshold M is not less than the preset temperature tracking threshold T, the reference value update module 312 updates the preset pulse count threshold M; and S414, when the comparison result signal Vcomp2 indicates that the absolute difference between the pulse count value N and the preset pulse count threshold M is less than the preset temperature tracking threshold T, the reference value update module 312 keeps the preset pulse count threshold M unchanged.

[0025] Figure 5 shows the use of Figure 3 The state transition diagram of an electronic cigarette with the air pressure detection system shown. As Figure 5 shown, when (M - N) < (Q - H), the electronic cigarette is in a non-discharging state; when (M - N) > Q, the electronic cigarette is in a discharging state; in the case where the electronic cigarette is in a non-discharging state, when (Q - H) < (M - N) < Q, the electronic cigarette remains in the non-discharging state; and in the case where the electronic cigarette is in a discharging state, when (Q - H) < (M - N) < Q, the electronic cigarette remains in the discharging state.

[0026] The present invention can be implemented in other specific forms without departing from its spirit and essential features. For example, the algorithms described in specific embodiments can be modified without the system architecture departing from the basic spirit of the present invention. Therefore, the current embodiments are to be considered in all respects as illustrative and not restrictive, and the scope of the present invention is defined by the appended claims rather than the above description, and all changes falling within the meaning and equivalents of the claims are thus included in the scope of the present invention.

Claims

1. An air pressure detection system, comprising: an air pressure sensor configured to detect external air pressure and generate a pulse signal; A pulse counter, configured to count the number of pulses of the pulse signal within a preset time interval and generate a pulse count value; as well as A first comparator is configured to compare the pulse count value with a first preset reference value, and further compare the pulse count value with the second preset reference value when the pulse count value is greater than the first preset reference value, and generate a first comparison result signal as an air pressure detection signal, the second preset reference value is greater than the first preset reference value, when the pulse count value is not greater than the first preset reference value, the air pressure detection signal indicates that the external air pressure has changed, and when the pulse count value is greater than the second preset reference value, the air pressure detection signal indicates that the external air pressure has not changed.

2. The air pressure detection system according to claim 1, wherein: The first preset reference value is a difference between a preset pulse count threshold and a preset detection deviation threshold, and the second preset reference value is a sum of the first preset reference value and a preset detection deviation hysteresis value.

3. The air pressure detection system according to claim 2, further comprising: a second comparator configured to compare the absolute difference between the pulse count value and the preset pulse count threshold and a preset temperature tracking threshold and generate a second comparison result signal when the air pressure detection signal indicates that the external air pressure has not changed; as well as The reference value updating module is configured to update the preset pulse count threshold by a predetermined updating method so as to update the first preset reference value and the second preset reference value when the second comparison result signal indicates that the absolute difference between the pulse count value and the preset pulse count threshold is not less than the preset temperature tracking threshold.

4. The air pressure detection system according to claim 3, wherein: The reference value updating module is also configured to keep the preset pulse count threshold unchanged so as to keep the first preset reference value and the second preset reference value unchanged when the second comparison result signal indicates that the absolute difference between the pulse count value and the preset pulse count threshold is less than the preset temperature tracking threshold.

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