CN213180370U

CN213180370U - Infrared sensor

Info

Publication number: CN213180370U
Application number: CN202022379940.XU
Authority: CN
Inventors: 李吉光; 李小荣; 郭红艳
Original assignee: Hangzhou Fuzhou Photoelectric Co ltd
Current assignee: Hangzhou Fuzhou Photoelectric Co ltd
Priority date: 2020-10-23
Filing date: 2020-10-23
Publication date: 2021-05-11
Anticipated expiration: 2030-10-23

Abstract

The utility model provides an infrared sensor, including infrared lens, the encapsulation shell, a substrate, sensing chip, memory chip and pin etc, sensing chip includes the response array, signal amplifier, the analog-to-digital voltage converter, the register etc, including sensing part and control part in the sensing array, sensing part turns into the signal of telecommunication relevant with the temperature with light signal, can detect ambient temperature simultaneously in order being used for signal comparison processing, sensing part adopts the MEMS chip that uses nano-material as the absorbed layer, control part and memory chip are used for the storage according to the rule calculation ambient temperature coefficient of prestore, and with behind the signal processing behind the digital voltage signal of analog-to-digital voltage conversion output with the calibration and the conversion between the output standard digital voltage signal of settlement. The pins, the lens, the thermopile sensing chip, the memory chip and the like are integrally packaged on the substrate.

Description

Infrared sensor

Technical Field

The utility model relates to a photoelectric signal conversion field especially relates to an integrated high sensitivity low-power consumption infrared sensor.

Background

It is known that in nature, all objects above absolute zero continuously radiate energy, the magnitude and wavelength distribution of the energy radiated outward by the object are closely related to the surface temperature of the object, and the higher the temperature of the object is, the stronger the infrared radiation capability is, so that the infrared temperature measurement has a wide application range. The infrared temperature measurement technology plays an important role in the aspects of production process monitoring, product quality control and monitoring, online fault diagnosis and safety protection of equipment, energy conservation and the like. The thermopile infrared sensor is a commonly used sensor in the fields of infrared gas measurement, smart home, security and the like, and has wide application space along with the development of the fields of the Internet of things and the like.

An existing thermopile infrared sensor is generally manufactured by a Micro-electro Mechanical Systems (MEMS) manufacturing process, and an output signal of the existing thermopile infrared sensor is an analog voltage signal generated by a thermopile through a seebeck effect and is communicated with a signal processing system through a reading circuit. A complete infrared thermopile application system usually includes corresponding optical system, for example adopt external fresnel lens etc. gather infrared signal, perhaps adopt complicated optical system, is adopting infrared filter at the chip package, but these systems are bulky, and the visual angle is narrower, and is not easy to control, and the focusing effect is relatively poor, is unfavorable for infrared system's application, to above-mentioned prior art shortcoming or not enough, the to-be-solved technical problem of the utility model is how to simplify its structure under the condition of enlarging infrared sensor's application restriction, improve sensitivity, improve the integration level, reduce the consumption, reduce cost simultaneously.

Disclosure of Invention

In order to solve the technical problem, the utility model provides an infrared sensor, including infrared lens, the encapsulation shell, a substrate, the sensor chip, memory chip and pin etc, the sensor chip includes the response array, signal amplifier, analog-to-digital voltage converter, the register etc, include sensing part and control part in the sensor array, the sensing part turns into the signal of telecommunication relevant with the temperature with light signal, can detect ambient temperature simultaneously and be used for signal comparison processing, the MEMS chip that uses nano-material as the absorbed layer is adopted to the sensing part, control part and memory core are used for the storage according to the calibration and the conversion between the rule calculation ambient temperature coefficient of prestore, the digital voltage signal of analog-to-digital voltage conversion chip output and the output standard digital voltage signal of settlement.

Compared with the prior art, because the infrared sensor in this application is by lens, thermopile sensing chip and memory chip etc. integrative encapsulation on the base plate, thereby do not need external optical system or light filter etc. can adjust the angle of vision through the optical lens of different parameters, thereby make the system can be as required, survey key region, memory chip stores simultaneously and calculates the calibration parameter that obtains according to the proportion between the real-time digital voltage signal of predetermineeing rule calculation environment temperature coefficient, analog-to-digital voltage conversion chip output and the output standard voltage signal of settlement according to preset, then directly obtain standard digital voltage signal write in signal register after the calculation. Therefore, when the infrared sensor is connected with the corresponding interface system, the standard digital voltage signal is directly output, so that the calibration calculation is not needed to be carried out by adopting a separate chip or equipment, and the butt joint of the interface system and the infrared sensor is facilitated under the condition of simplifying the structure of the infrared sensor. The invention improves the reliability of the device and has the advantages of easy use and high cost performance.

Other features, objects and advantages of the present application will become more apparent upon reading of the following detailed description of non-limiting embodiments thereof, made with reference to the accompanying drawings.

Drawings

Fig. 1 is a diagram of an infrared sensor structure, wherein fig. 1 includes: the infrared sensor comprises an infrared lens 1, an infrared sensing array 2, an infrared signal processing circuit 3, a packaging tube cap 4, a bonding wire 5, a memory chip 6 and a base 7. The thermopile infrared sensor further comprises a base 7, wherein the thermopile infrared sensing array device 2, the signal processing circuit chip 3 and the storage chip 6 are both positioned on the upper surface of the base 7, and the thermopile infrared sensing array device 2, the signal processing circuit chip 3 and the storage chip 6 are separated by a distance, the storage chip 6 is connected with the signal processing circuit 3 through a bonding wire 5, and the pipe cap 4 covers the top of the base 7 and is positioned on the periphery of the infrared sensor chip 3 and the periphery of the storage chip 6; the infrared lens 1 is fixed on the pipe cap 4, and completely covers the through hole.

Fig. 2 is a schematic diagram of an infrared sensor system, in which 9 is an infrared sensor, 10 is a memory chip, 11 is an infrared sensor array, 12 is a signal processing circuit, and 13 is a logic control circuit.

Fig. 3 is a diagram of an infrared sensor signal processing and control circuit architecture, in which 14 is a data input/output (data IO), 15 is a clock signal CLK, 16 is a reference voltage, 17 is a circuit source voltage, 18 is a logic control module, 19-bit register storage module RAM, 20 is an analog-to-digital conversion module, 21 is a low-pass filter module, 22 is a preamplifier module, 23 is a signal multiplexer module, 24 is a sensor array, and includes mxn pixels, 25 is a reference temperature analog-to-digital conversion module, and 26 is a reference temperature circuit.

Detailed Description

The following detailed description of the embodiments of the present invention will be made with reference to the accompanying drawings. Aside from the specific details, this invention is capable of other embodiments and its several details are capable of modifications in various obvious respects, all without departing from the scope of the invention. In the description of the specification, numerous specific details are set forth in order to provide a thorough understanding of the present invention; however, the present invention may be practiced without some or all of these specific details. In other instances, well-known steps or elements have not been described in detail so as not to unnecessarily obscure the present invention. The same or similar components in the drawings will be denoted by the same or similar symbols. It is noted that the drawings are for illustrative purposes only and do not represent actual sizes or quantities of elements, and some details may not be drawn completely to simplify the drawings.

The conception, the specific structure and the technical effects of the present invention will be further described with reference to the accompanying drawings, so as to fully understand the objects, the features and the effects of the present invention.

The first embodiment of the utility model provides an infrared sensor, including lens, base plate, thermopile sensing chip, memory chip, encapsulation shell and pin etc.. The lens, the sensing chip and the storage chip are integrally packaged and formed on the substrate. According to the above, since the infrared sensor is integrally packaged and molded on the substrate by the lens, the sensing chip and the memory chip, no other external optical system is needed, and the memory chip stores the calibration coefficient obtained by calculating the proportion between the real-time digital voltage signal output by the analog-to-digital voltage conversion chip and the set output standard voltage signal according to the preset rule before being packaged, so that the infrared sensor directly outputs the digital voltage signal when being connected with the corresponding interface system.

To achieve the above and other related objects, the present invention provides an integrated infrared sensor, which is shown in fig. 1 and comprises:

an infrared sensor chip;

a memory chip;

an infrared lens.

In order to meet the packaging and connection requirements in practical application, the thermopile infrared sensor further comprises:

the tube cap covers the top of the base and is positioned at the periphery of the infrared sensor chip and the storage chip;

the infrared sensor chip and the thermistor are both positioned on the upper surface of the base, and the infrared sensor chip and the storage chip are separated by a gap;

wherein the infrared lens is fixed on the pipe cap and completely covers the through hole.

The chips are connected through bonding wires.

The connection between the various parts is achieved in a manner common in the art.

The utility model discloses a theory of operation is as shown in figure 2, infrared sensor in this application before the encapsulation, the staff calculates the digital voltage signal of the sensor chip output that the test obtained and the output standard voltage signal of settlement according to predetermined rule to obtain corresponding ratio and regard as the calibration coefficient, and the storage is in memory chip, then with the memory chip and lens, the integrated package shaping of sensor chip on the circuit board that the storage has this calibration coefficient. The lens collects external infrared signals, focuses the external infrared signals to the sensing array, converts the external infrared signals into voltage signals after photoelectric conversion and amplification, and the sensing chip processing module can directly call the correction coefficient in the storage chip and calibrate the digital voltage signals output by the analog-to-digital voltage conversion chip according to the correction coefficient, so that the infrared sensor can output the calibrated digital voltage signals to corresponding equipment after being connected with a corresponding interface system, and calculation of different scenes is met. The system architecture is shown in fig. 2.

The array of infrared sensing portions is m rows X n columns, m and n are integers, for m arrays, where each row has n pixels. The pixel output is a voltage signal on the order of microvolts (μ V), and in a preferred embodiment, m =16, n =16, a = 4.

The sensing pixel adopts a thermopile MEMS structure, wherein a nanometer material layer with strong infrared absorption is added on the light absorption layer besides silicon or silicon compound commonly used in the field. In a preferred application example, the nano material adopts a lead selenide material. In a preferred application example, the nano material is a metal oxide material. In a preferred application example, the nano material is a metal nano material. In a preferred application example, the nano material adopts nano gold or nano silver material. In a preferred application example, the nano material adopts nano iron, nickel, aluminum, magnesium, zirconium, rare earth elements or oxides thereof and the like. In a preferred embodiment, the thermopile material employs polycrystalline N-type silicon and polycrystalline P-type silicon as thermocouple materials.

The signal processing and control circuit architecture of the infrared sensor is shown in fig. 3, signals in the sensing array are selected to the signal processing channels through the signal multiplexer, wherein the signal multiplexer is used for selecting different pixels, and the selected pixels transmit signals, namely, for each signal processing channel, the signal multiplexer is provided and is used for selecting the pixels of the sensor array distributed to the signal processing channel, wherein a pixels share 1 signal channel.

Each signal processing channel includes a preamplifier, an analog-to-digital converter.

The preamplifier is connected before the analog-to-digital converter (ADC) in each signal processing channel and, in a preferred embodiment, has a gain factor between less than 500 and greater than 100.

In a preferred embodiment, the preamplifier reference scheme employs an auto-zero (switched chopper) amplifier, which may be designed as a single stage.

In a preferred embodiment, the analog-to-digital conversion employs a slow analog-to-digital converter ADC with high resolution, such as the incremental Sigma-Delta ADC analog-to-digital conversion reference scheme.

This is achieved by integrating a low pass filter TPF (which may for example be part of the preamplifier or as an additional low pass filter TPF) before the analog-to-digital converter ADC, the low pass filter (TPF) being arranged in the analog-to-digital converter (ADC).

A low pass filter (TPF) having a cutoff frequency at least equal to the frame rate of the thermopile infrared sensor array multiplied by the number of pixels per signal processing channel.

The circuit can achieve the effects of high sensitivity and low power consumption.

The output of the analog-to-digital converter ADC is connected to a memory RAM area that is readable by the control circuit CRTL so that the digital output signal at the digital input-output port DIO is available for further processing.

The reference voltage VREF or REF/PTAT is a reference voltage for generating a temperature-independent voltage reference for the analog-to-digital converter, and a voltage reference with zero temperature coefficient can be realized by using bipolar transistors which can provide characteristics of positive temperature coefficient and negative temperature coefficient.

Because the forward voltage of the PN junction diode has a negative temperature coefficient, and the voltage difference between the base electrode and the emitter electrode of the bipolar transistor under two different current densities has a positive temperature coefficient, the voltage quantity with the two opposite characteristics can form a voltage reference with a zero temperature coefficient.

In a preferred embodiment, the reference voltage with zero temperature coefficient is 1.25V.

Meanwhile, for bipolar transistors with different current densities (assuming that the area of the transistor Q1 is 1/N of the transistor Q2 and the flowing current is M times of the transistor Q2), the temperature Δ Vbe of the voltage difference between the bipolar transistors can be expressed as Δ Vbe = kT/Q × ln (mn), where k is boltzmann's constant, T is absolute temperature, and Q is electronic charge, so that the voltage difference Δ Vbe is selected to represent the actual temperature.

The control module provides control signals, such as a clock CLK, and provides a desired source voltage of a voltage source VSS and one or more reference voltages VEF, among others, to which ESD circuit blocks may be attached.

In one example of application, the analog-to-digital voltage converter adopts a 16-bit analog-to-digital voltage conversion module.

In one example, the memory chip is an Electrically Erasable Programmable Read Only Memory (EEPROM). In one application example, the external interface adopts an I2C digital interface.

In one example of an application, the lens used is a silicon lens.

In one example of an application, the lens used is a germanium lens.

The structure and the field angle of the infrared lens can be adjusted as required, in an application example, the field angle of the infrared lens is 6 degrees x 6 degrees, in an application example, the field angle of the infrared lens is 110 degrees x 110 degrees, and in an application example, the field angle of the infrared lens is 270 degrees x 270 degrees.

The infrared sensing chip can adopt chips of different models as required, and in an application example, the chip in the application is a thermopile sensing chip. In one application example, the sensing chip in the present application is preferably a MEMS chip.

In summary, the present application provides an integrated infrared sensor, which includes an infrared lens, a package housing, a substrate, a sensing chip, a memory chip, and pins, wherein the sensing chip includes an sensing array, a signal amplifier, an analog-to-digital voltage converter, a signal comparison processor, a signal register, and the like, the sensing array includes a sensing portion and a reference control portion, the reference control portion can detect an ambient temperature for signal comparison processing, and the reference control portion and the memory chip are used for storing calibration and conversion between an ambient temperature coefficient, a digital voltage signal output by the analog-to-digital voltage conversion chip, and a set output standard digital voltage signal according to a pre-stored rule. In the using process, an external optical system is not needed, accurate measurement can be realized without calibration, the reliability of the device is improved, and the device has the advantages of easiness in use and high cost performance.

Claims

1. An infrared sensor is characterized in that the infrared sensor comprises an infrared lens, a packaging shell, a substrate, a sensing chip, a storage chip and pins, wherein the sensing chip comprises a sensing array, a signal amplifier, an analog-to-digital voltage converter and a register, the sensing array comprises a sensing part and a signal conversion and control part, the sensing part converts optical signals into electric signals related to temperature and can detect ambient temperature for signal comparison processing, the sensing part adopts an MEMS chip using nano materials as an absorption layer, the storage chip is used for storing ambient temperature coefficients calculated according to a pre-stored rule, after the signal conversion and control part processes the electric signals, digital voltage signals output by an analog-to-digital voltage conversion module and set output standard digital voltage signals are calibrated and converted, and the pins are output to the outside, the lens, the thermopile sensing chip, the memory chip and the like are integrally packaged on the substrate.

2. The infrared sensor as set forth in claim 1, wherein the sensing chip is a MEMS chip, and the infrared absorption layer is made of metal or metal compound nano material.

3. The infrared sensor of claim 1, characterized in that the signal processing in the sensing array is selected by a signal multiplexer to signal processing channels, each signal processing channel comprising a preamplifier, an analog-to-digital converter, wherein the analog-to-digital converter employs a slow analog-to-digital converter with high resolution, while a low pass filter is integrated before the analog-to-digital conversion, the output of the analog-to-digital converter being connected to a memory area.

4. The infrared sensor as set forth in claim 1, wherein the signal conversion and control section includes a temperature-independent voltage reference as a reference voltage for the analog-to-digital converter, the voltage being implemented by a bipolar transistor.