CN216899260U

CN216899260U - Pyroelectric infrared sensor

Info

Publication number: CN216899260U
Application number: CN202220227818.7U
Authority: CN
Inventors: 张洁伟; 于磊; 周云
Original assignee: SHANGHAI NICERA SENSOR CO Ltd
Current assignee: SHANGHAI NICERA SENSOR CO Ltd
Priority date: 2022-01-27
Filing date: 2022-01-27
Publication date: 2022-07-05
Anticipated expiration: 2032-01-27

Abstract

A pyroelectric infrared sensor comprises a power supply input end Vdd, a signal output end Vout, a ground end GND, a sensing element chip, an N-channel junction field effect transistor Q1, a resistor R1, a resistor R2, a capacitor C1 and a capacitor C2. The grid electrode of the N-channel junction field effect transistor Q1 is connected with the first end of the sensitive element chip, the drain electrode is respectively connected with one end of a capacitor C2, one end of a resistor R2 and the signal output end Vout, and the source electrode is respectively connected with one end of a capacitor C1 and one end of a resistor R1. The common junction of the other end of the capacitor C2 and the other end of the resistor R2 is connected to the power input terminal Vdd. The second end of the sensing element chip, the other end of the capacitor C1 and the other end of the resistor R1 are all connected with the ground GND. The utility model has higher magnification, low cost and easy assembly.

Description

Pyroelectric infrared sensor

Technical Field

The utility model relates to a pyroelectric infrared sensor technology.

Background

A pyroelectric infrared sensor is a detector that converts an infrared radiation signal into an electrical signal. The existing pyroelectric infrared sensor mainly adopts a junction field effect transistor source electrode follower to amplify current, signal voltage is basically output in a 1:1 mode, an external amplifier is subsequently adopted to carry out filtering amplification treatment, and a pyroelectric sensor with a built-in voltage amplifier generally adopts an operational amplifier to amplify signals, the price of an operational amplifier chip is high, and related elements such as resistors, capacitors and the like are required to be configured to form an amplifying circuit, so that the manufacturing cost is high, and the complexity of product assembly is increased.

Disclosure of Invention

The utility model aims to provide a pyroelectric infrared sensor which has higher amplification factor, low cost and easy assembly.

The pyroelectric infrared sensor comprises a power supply input end Vdd, a signal output end Vout, a ground end GND, a sensitive element chip, an N-channel junction field effect transistor Q1, a resistor R1, a resistor R2, a capacitor C1 and a capacitor C2; the grid electrode of the N-channel junction field effect transistor Q1 is connected with the first end of the sensitive element chip, the drain electrode of the N-channel junction field effect transistor Q1 is respectively connected with one end of a capacitor C2, one end of a resistor R2 and a signal output end Vout, and the source electrode of the N-channel junction field effect transistor Q1 is respectively connected with one end of a capacitor C1 and one end of a resistor R1; the common joint of the other end of the capacitor C2 and the other end of the resistor R2 is connected with a power supply input end Vdd; the second end of the sensing element chip, the other end of the capacitor C1 and the other end of the resistor R1 are all connected with the ground GND.

In the pyroelectric infrared sensor, the capacitance of the capacitor C1 is in the microfarad level, and the capacitance of the capacitor C1 is more than 10 times the capacitance of the capacitor C2. Optionally, the capacitance of the capacitor C1 is 100 times the capacitance of the capacitor C2.

In the pyroelectric infrared sensor, a ratio of the resistance value of the resistor R2 to the resistance value of the resistor R1 is greater than or equal to 1 and less than 5. Optionally, the resistance R2 is equal to the resistance of the resistor R1.

According to another embodiment of the utility model, the pyroelectric infrared sensor comprises a power supply input end Vdd, a signal output end Vout, a ground end GND, a sensing element chip, a P-channel junction field effect transistor Q2, a resistor R1, a resistor R2, a capacitor C1 and a capacitor C2; the grid electrode of the P-channel junction field effect transistor Q2 is connected with the first end of the sensitive element chip, the drain electrode of the P-channel junction field effect transistor Q2 is respectively connected with one end of a capacitor C2, one end of a resistor R2 and a signal output end Vout, and the source electrode of the P-channel junction field effect transistor Q2 is respectively connected with one end of a capacitor C1 and one end of a resistor R1; the common joint of the other end of the capacitor C2 and the other end of the resistor R2 is connected with a ground terminal GND; the second end of the sensing element chip, the other end of the capacitor C1 and the other end of the resistor R1 are all connected with a power supply input end Vdd.

The utility model has at least the following advantages:

1. the pyroelectric infrared sensor realizes the amplification of the output signal of the sensitive element chip by only adopting a few discrete components, has a simple circuit structure, and greatly reduces the manufacturing cost compared with the scheme of adopting an operational amplifier for amplification;

2. the pyroelectric infrared sensor amplifies weak output signals, greatly reduces the requirement on a subsequent processing circuit, is easy to be matched with a cheap singlechip with an AD conversion function for use, can flexibly realize various functions by utilizing the singlechip to directly process the signals, and has wider application range.

Drawings

Fig. 1 shows a schematic circuit diagram of a first embodiment of the pyroelectric infrared sensor of the present invention.

Fig. 2 shows a schematic circuit diagram of a second embodiment of the pyroelectric infrared sensor of the present invention.

Detailed Description

The utility model is further described below with reference to the accompanying drawings.

Fig. 1 shows a schematic circuit diagram of a pyroelectric infrared sensor according to a first embodiment of the present invention. Please refer to fig. 1. The pyroelectric infrared sensor according to the first embodiment of the utility model comprises a power supply input end Vdd, a signal output end Vout, a ground end GND, a sensing element chip 1, an N-channel junction field effect transistor Q1, a resistor R1, a resistor R2, a capacitor C1 and a capacitor C2.

The power input terminal Vdd is used for connecting an external power supply, the signal output terminal Vout is used for outputting a signal to the outside, and the ground terminal GND is used for grounding.

The grid of the N-channel junction field effect transistor Q1 is connected with the first end of the sensitive element chip 1, the drain of the N-channel junction field effect transistor Q1 is respectively connected with one end of a capacitor C2, one end of a resistor R2 and the signal output end Vout, and the source of the N-channel junction field effect transistor Q1 is respectively connected with one end of a capacitor C1 and one end of a resistor R1. The common junction of the other end of the capacitor C2 and the other end of the resistor R2 is connected to the power input terminal Vdd.

The second end of the sensor chip 1, the other end of the capacitor C1 and the other end of the resistor R1 are all connected to the ground GND.

The sensitive element chip 1 has extremely high bulk resistance, so a low-noise junction field effect transistor with extremely high input impedance is adopted for signal amplification. The resistor R1 helps the N-channel junction field effect transistor Q1 establish a direct current static operating point Vs, and the capacitor C1 bypasses an alternating current part at the static operating point Vs, so that an alternating current signal at a critical frequency to be processed is short-circuited to the ground. The capacitor C2 functions as a high frequency filter to control high frequency noise. The voltage signal generated by the sensing element chip 1 is converted into a current signal through an N-channel junction field effect transistor Q1.

In the present embodiment, the capacitance of the capacitor C1 is in the microfarad level, and the capacitance of the capacitor C1 is more than 10 times (including 10 times) the capacitance of the capacitor C2. Optionally, the capacitance of the capacitor C1 is 100 times the capacitance of the capacitor C2.

In the present embodiment, the ratio of the resistance values of the resistor R2 and the resistor R1 is greater than or equal to 1 and less than 5. Optionally, the resistor R2 has the same resistance value as the resistor R1, so as to facilitate the N-channel jfet Q1 to operate at a proper static operating point. Increasing the ratio of R2/R1 can increase the amplification, but is not conducive to establishing a proper operating point for the jfet.

Fig. 2 shows a schematic circuit diagram of a pyroelectric infrared sensor according to a second embodiment of the present invention. Please refer to fig. 2. The pyroelectric infrared sensor according to the second embodiment of the utility model comprises a power supply input end Vdd, a signal output end Vout, a ground end GND, a sensing element chip 1, a P-channel junction field effect transistor Q2, a resistor R1, a resistor R2, a capacitor C1 and a capacitor C2.

The grid electrode of the P-channel junction field effect transistor Q2 is connected with the first end of the sensitive element chip 1, the drain electrode of the P-channel junction field effect transistor Q2 is respectively connected with one end of a capacitor C2, one end of a resistor R2 and a signal output end Vout, and the source electrode of the P-channel junction field effect transistor Q2 is respectively connected with one end of a capacitor C1 and one end of a resistor R1; the common junction of the other end of the capacitor C2 and the other end of the resistor R2 is connected to the ground GND.

The second end of the sensing element chip 1, the other end of the capacitor C1 and the other end of the resistor R1 are all connected with a power supply input end Vdd.

The pyroelectric infrared sensor only adopts a single field effect tube to amplify (can amplify dozens of times) the output signal of the sensitive element chip, the circuit structure is simpler, and the manufacturing cost is greatly reduced compared with the scheme of amplifying by adopting an operational amplifier.

Claims

1. A pyroelectric infrared sensor is characterized by comprising a power supply input end Vdd, a signal output end Vout, a ground end GND, a sensitive element chip, an N-channel junction field effect transistor Q1, a resistor R1, a resistor R2, a capacitor C1 and a capacitor C2;

the grid electrode of the N-channel junction field effect transistor Q1 is connected with the first end of the sensitive element chip, the drain electrode of the N-channel junction field effect transistor Q1 is respectively connected with one end of a capacitor C2, one end of a resistor R2 and a signal output end Vout, and the source electrode of the N-channel junction field effect transistor Q1 is respectively connected with one end of a capacitor C1 and one end of a resistor R1; the common joint of the other end of the capacitor C2 and the other end of the resistor R2 is connected with a power supply input end Vdd;

the second end of the sensitive element chip, the other end of the capacitor C1 and the other end of the resistor R1 are all connected with a ground end GND.

2. The pyroelectric infrared sensor as claimed in claim 1, wherein the capacitance of the capacitor C1 is in microfarad level, and the capacitance of the capacitor C1 is more than 10 times the capacitance of the capacitor C2.

3. The pyroelectric infrared sensor as claimed in claim 2, wherein the capacitance of the capacitor C1 is 100 times the capacitance of the capacitor C2.

4. The pyroelectric infrared sensor as claimed in any one of claims 1 to 3, wherein the ratio of the resistance value of the resistor R2 to the resistance value of the resistor R1 is 1 or more and less than 5.

5. The pyroelectric infrared sensor as claimed in claim 4, wherein the resistance R2 is equal to the resistance R1.

6. A pyroelectric infrared sensor is characterized by comprising a power supply input end Vdd, a signal output end Vout, a grounding end GND, a sensitive element chip, a P-channel junction field effect transistor Q2, a resistor R1, a resistor R2, a capacitor C1 and a capacitor C2;

the grid electrode of the P-channel junction field effect transistor Q2 is connected with the first end of the sensitive element chip, the drain electrode of the P-channel junction field effect transistor Q2 is respectively connected with one end of a capacitor C2, one end of a resistor R2 and a signal output end Vout, and the source electrode of the P-channel junction field effect transistor Q2 is respectively connected with one end of a capacitor C1 and one end of a resistor R1; the common joint of the other end of the capacitor C2 and the other end of the resistor R2 is connected with a ground terminal GND;

and the second end of the sensitive element chip, the other end of the capacitor C1 and the other end of the resistor R1 are connected with a power supply input end Vdd.