CN212254372U - Voltage acquisition circuit for infrared thermometer - Google Patents

Abstract

The utility model discloses a voltage acquisition circuit for infrared thermometer, including infrared probe and rather than the signal conditioning circuit that cooperatees, signal conditioning circuit is configured into: the infrared sensor and the NTC are respectively connected with TPS + and TR + pins of the infrared probe to collect the temperature of a human body and the ambient temperature; the MCU is used for providing a reference bias voltage AIP of 2.7-3V for the infrared sensor and the NTC; a capacitor C5 connected in parallel with the NTC for filtering low frequency noise in the AIP signal; a standard resistor R4 arranged at one end of the NTC and used for removing signal noise at two ends of R4 through a capacitor C6 connected in parallel; and the capacitor C3 is connected with the C6 in series to filter the TR + signal output by the infrared probe to the ground. The utility model provides a voltage acquisition circuit for infrared thermometer, it is through design signal conditioning circuit for the output signal of sensor is reliable and more stable, and the interference killing feature is effectively strengthened.

Description

Voltage acquisition circuit for infrared thermometer

Technical Field

The utility model relates to a voltage acquisition circuit for infrared thermometer.

Background

A non-invasive infrared thermometer, whose thermometer end is designed to transmit infrared radiation to a sensing element, is provided to be kept at a distance (5 to 15 cm) from the surface of an object, and usually includes an MCU, an infrared temperature sensor, a display module, an a/D converter, an alarm circuit, etc., and the red sensor generally includes a thermopile for detecting the temperature of a human body and a thermistor for detecting the ambient temperature, and in this case, in order to convert the infrared radiation from the object to heat energy, a heat absorber is usually attached to the hot end of the thermopile of the infrared sensor, and the method is used to convert the infrared radiation from the object to an electric signal, which can be realized by using the TPS infrared sensor generally 334 according to needs, but the analog signal cannot directly reflect the actual temperature of the object due to the temperature difference between the two thermopiles, therefore, the heat per resistor with negative temperature coefficient is usually needed to perform ambient temperature compensation, in the prior art, the single chip microcomputer directly reads a digitized temperature measurement value, the temperature measurement value is further compensated through a program built in the single chip microcomputer, no conditioning is performed on sampling data, the test temperature is unstable, the data jitter is large, and the temperature deviation tested by the sensor when the sensor is interfered is large.

SUMMERY OF THE UTILITY MODEL

An object of the present invention is to solve at least the above problems and/or disadvantages and to provide at least the advantages which will be described later.

To achieve these objects and other advantages in accordance with the purpose of the invention, there is provided a voltage acquisition circuit for an infrared thermometer, comprising an infrared probe and a signal conditioning circuit cooperating therewith, the signal conditioning circuit being configured to:

the infrared sensor and the NTC are respectively connected with TPS + and TR + pins of the infrared probe to collect the temperature of a human body and the ambient temperature;

the MCU is used for providing a reference bias voltage AIP of 2.7-3V for the infrared sensor and the NTC;

a capacitor C5 connected in parallel with the NTC for filtering low frequency noise in the AIP signal;

a standard resistor R4 arranged at one end of the NTC and used for removing signal noise at two ends of R4 through a capacitor C6 connected in parallel;

and the capacitor C3 is connected with the C6 in series to filter the TR + signal output by the infrared probe to the ground.

Preferably, the infrared sensor further comprises a capacitor C7 connected in parallel with the infrared sensor for filtering high-frequency noise in an output signal of the infrared sensor.

The utility model discloses at least, include following beneficial effect: the utility model discloses a design and infrared sensor, heat sensitive sensor matched with signal conditioning circuit, sampling data to heat sensitive sensor carries out the signal conditioning, effectively solved among the prior art because of the test temperature unstability that the signal collection is not handled and is leaded to, the big problem of data beat, make the output signal of sensor more reliable and more stable, take care of to infrared sensor's sampling data simultaneously, effectively solved among the prior art the great problem of the temperature deviation that tests out when infrared sensor receives external factor interference, make its interference killing feature obtain effective the reinforcing.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

Drawings

Fig. 1 is a schematic structural diagram of a signal conditioning circuit according to an embodiment of the present invention.

Detailed Description

The present invention is further described in detail below with reference to the drawings so that those skilled in the art can implement the invention with reference to the description.

It will be understood that terms such as "having," "including," and "comprising," as used herein, do not preclude the presence or addition of one or more other elements or groups thereof.

It should be noted that in the description of the present invention, the terms indicating the orientation or the positional relationship are based on the orientation or the positional relationship shown in the drawings, and are only for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the indicated device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus should not be construed as limiting the present invention.

In the description of the present invention, it should be noted that, unless explicitly stated or limited otherwise, the terms "mounted," "disposed," "sleeved/connected," "connected," and the like are used in a broad sense, and for example, "connected," may be fixedly connected, detachably connected, or integrally connected, mechanically connected, electrically connected, directly connected, indirectly connected through an intermediate medium, or connected between two elements.

Fig. 1 shows a voltage acquisition circuit implementation form for an infrared thermometer according to the present invention, which includes an infrared probe 1 and a signal conditioning circuit matched therewith, wherein the signal conditioning circuit is configured to:

the infrared sensor 2 and the thermal sensor NTC 3 are respectively connected with TPS + and TR + pins of the infrared probe to collect the temperature of a human body and the ambient temperature;

the MCU (not shown) provides a reference bias voltage AIP of 2.7-3V for the infrared sensor and the NTC, and is configured to adopt the MCU integrated with the operational amplifier to amplify the sampling signal so as to meet the requirements of later data analysis and processing;

a capacitor C54 connected in parallel with the NTC for filtering low frequency noise in the AIP signal;

a standard resistor R45 arranged at one end of the NTC and used for removing signal noise at two ends of R4 through a capacitor C66 connected in parallel;

and the capacitor C37 is connected with the C6 in series to filter the TR + signal output by the infrared probe to the ground, in the structure, the capacitor C5 forms a low-frequency noise filtering circuit of the AIP reference signal, the capacitor C6 removes the noise of the signal at two ends of a standard reference resistor tap, and the capacitor C3 filters the TR + signal to the ground to ensure the reliability of the signal. During operation, after the infrared temperature sensor detects infrared rays emitted by a measured object, the infrared signals are converted into temperature signals, the temperature signals are converted into weak electric signals, the temperature signals are converted into digital signals which can be read by the MCU through the A/D analog-to-digital converter matched with the MCU to obtain voltage original data of the thermopile (measured human body), and original data of digital signal environment temperature output by the thermal sensor in the same way are obtained.

As shown in fig. 1, in another example, the infrared sensor further includes a capacitor C78 connected in parallel to filter high-frequency noise in an output signal thereof, the capacitor C7 is used for filtering out the high-frequency noise of the AIN output signal, and abnormal fluctuation of a signal sent to the MCU is avoided.

The above embodiments are merely illustrative of a preferred embodiment, but not limiting. When the utility model is implemented, the proper replacement and/or modification can be carried out according to the requirements of users.

The number of apparatuses and the scale of the process described here are intended to simplify the description of the present invention. Applications, modifications and variations of the present invention will be apparent to those skilled in the art.

While embodiments of the invention have been disclosed above, it is not intended to be limited to the applications listed in the specification and the examples. It can be applicable to various and be fit for the utility model discloses a field completely. Additional modifications will readily occur to those skilled in the art. The invention is therefore not to be limited to the specific details and illustrations shown and described herein, without departing from the general concept defined by the claims and their equivalents.

Claims (2)

1. A voltage acquisition circuit for an infrared thermometer comprising an infrared probe and a signal conditioning circuit cooperating therewith, the signal conditioning circuit configured to:

the infrared sensor and the NTC are respectively connected with TPS + and TR + pins of the infrared probe to collect the temperature of a human body and the ambient temperature;

the MCU is used for providing a reference bias voltage AIP of 2.7-3V for the infrared sensor and the NTC;

a capacitor C5 connected in parallel with the NTC for filtering low frequency noise in the AIP signal;

a standard resistor R4 arranged at one end of the NTC and used for removing signal noise at two ends of R4 through a capacitor C6 connected in parallel;

and the capacitor C3 is connected with the C6 in series to filter the TR + signal output by the infrared probe to the ground.

2. The voltage acquisition circuit for an infrared thermometer of claim 1 further comprising a capacitor C7 connected in parallel with the infrared sensor for filtering high frequency noise in its output signal.

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