CN219145628U

CN219145628U - Defrosting and frost preventing circuit for temperature control glass

Info

Publication number: CN219145628U
Application number: CN202320033250.XU
Authority: CN
Inventors: 马宏斌; 马思明; 许红; 刘浪; 李兴邦; 朱惠; 安长亮; 覃家川; 张昌; 陈洪明
Original assignee: Yunnan North Optical & Electron Instrument Co ltd
Current assignee: Yunnan North Optical & Electron Instrument Co ltd
Priority date: 2023-01-06
Filing date: 2023-01-06
Publication date: 2023-06-06
Anticipated expiration: 2033-01-06

Abstract

The utility model discloses a temperature-control glass defrosting and frostproofing circuit, which comprises a heating temperature setting circuit, a thermistor RT, a voltage comparator U2, an NMOS tube Q3 and an electrothermal film, wherein the heating temperature setting circuit is connected with the thermistor RT; the thermistor RT is positioned on the surface of the glass and is used for converting the temperature of the glass into a corresponding voltage signal and sending the voltage signal to the input end of the voltage comparator U2; the heating temperature setting circuit is used for setting heating temperature voltage and is connected to the other input end of the voltage comparator; the voltage comparator U2 is used for comparing the voltage of the set heating temperature with a voltage signal corresponding to the glass temperature, and is connected with and controls the on-off of the NMOS tube Q3 through a level signal output after the judgment; the NMOS tube Q3 is used for switching on or switching off the voltage of the heating electrothermal film covered on the surface of the glass. The utility model realizes the temperature control defrosting function, adopts the on-off of the NMOS transistor of the insulated gate field effect transistor to control the voltage of the electrothermal film on the glass to be switched on or off, reduces the volume of the circuit board, and improves the reliability and the service life of the circuit.

Description

Defrosting and frost preventing circuit for temperature control glass

Technical Field

The utility model relates to a temperature-control glass defrosting and frosting prevention circuit, and belongs to the field of temperature control of glass defrosting and frosting prevention electric heating.

Background

When the glass temperature is lower than a certain temperature, frosting on the glass affects the optical light transmission performance of the glass, so a heating film needs to be coated on the glass, the heating film is electrified and heated to defrost and prevent frosting, and in order to realize that the electrified heating is powered off after reaching the frosting prevention temperature or the defrosting temperature, the glass is not always electrified and heated to cause overheat and burst of the glass, and a temperature control heating mode is generally adopted. The device for switching on or switching off the electrothermal film on the glass in the traditional temperature control circuit is generally a relay, the volume of the relay is larger, the switching on and off is realized by means of contact and separation of internal contacts, and the reliability and the service life of the relay are lower than those of an NMOS (N-channel metal oxide semiconductor) tube of a semiconductor device.

Disclosure of Invention

The utility model aims to overcome the defects and provide a temperature control glass defrosting and frosting prevention circuit which uses a thermistor as a temperature sensor to convert the temperature of glass to be defrosted into a corresponding voltage signal to be sent to a voltage comparator. The voltage comparator is used as a temperature control judging device, compares the set heating temperature voltage with a voltage signal corresponding to the temperature of the glass to be defrosted and frosted, and controls the on-off of an NMOS (N-channel metal oxide semiconductor) transistor of the insulated gate field effect transistor by a level signal output after the judgment of the comparator, so that the voltage of a heating electric heating film on the glass is switched on or off, and the defrosting and frosting prevention purposes of the temperature control glass are realized.

The technical scheme of the utility model is as follows:

the utility model provides a control by temperature change glass defrosting frost prevention circuit, includes thermistor RT, voltage comparator U2, NMOS pipe Q3 and covers in the electric heat membrane on glass surface, thermistor RT is with glass temperature conversion corresponding voltage signal to send voltage comparator U2, voltage comparator U2 is as temperature control judgement device, compares the voltage signal that corresponds with the glass temperature with setting for heating temperature voltage, and the level signal control NMOS pipe Q3 of output after judging through comparator U2 makes and break-make to switch on or break off the voltage of heating the electric heat membrane on the glass, realize control by temperature change glass defrosting frost prevention purpose.

When the glass temperature is lower than the set heating temperature, the NMOS tube Q3 is conducted by a control signal sent by the voltage comparator U2, and the electric heating film coated glass is electrified and heated; when the glass temperature is higher than the set heating temperature, the NMOS tube Q3 is turned off by a control signal sent by the temperature control circuit, and the electric heating film coated glass is automatically powered off, so that the temperature control defrosting function is realized in a circulating and reciprocating mode.

The utility model has the beneficial effects that:

(1) The temperature control defrosting function is realized by automatically powering on and powering off the glass coated with the electrothermal film;

(2) The voltage of the electrothermal film on the glass is controlled to be switched on or off by switching on and off an NMOS tube of the insulated gate field effect transistor, so that the size of the circuit board is reduced, and the reliability and the service life of the circuit are improved.

Drawings

Fig. 1: the utility model relates to a schematic diagram of a defrosting and frost preventing circuit of temperature control glass.

Detailed Description

Examples

As shown in FIG. 1, the temperature control glass defrosting and anti-frost circuit comprises a heating temperature setting circuit, a thermistor, a voltage comparator, an insulated gate field effect transistor NMOS tube and an electric heating film, wherein the thermistor converts the glass temperature into a corresponding voltage signal and sends the corresponding voltage signal to the input end of the voltage comparator, the heating temperature setting circuit is used for setting the heating temperature voltage and accessing the other input end of the voltage comparator, the voltage comparator is used as a temperature control judging device for comparing the set heating temperature voltage with the corresponding voltage signal of the glass temperature, the level signal output after judgment by the comparator is connected with and controls the on-off of the insulated gate field effect transistor NMOS tube, and the insulated gate field effect transistor NMOS tube is used for switching on or off the voltage of the heating electric heating film on glass, so that the temperature control glass defrosting and anti-frost purpose is realized.

When the glass temperature is lower than the set heating temperature, the control signal sent by the voltage comparator enables the NMOS tube of the insulated gate field effect transistor to be conducted, and the electric heating film plating glass is electrified and heated; when the glass temperature is higher than the set heating temperature, the control signal sent by the temperature control circuit turns off the NMOS transistor of the insulated gate field effect transistor, and the electric heating film coated glass is automatically powered off, so that the temperature control defrosting function is realized in a circulating and reciprocating mode.

In this embodiment, the main electronic components and functions in fig. 1 are:

RT is a thermistor, and the function is to convert the temperature of glass to be defrosted into a corresponding voltage signal and send the voltage signal to a voltage comparator;

u1 is a three-terminal voltage-stabilizing chip, and has the function of converting the vehicle-mounted power supply voltage 26V into voltage-stabilizing 12V as a working power supply of the circuit;

u2 is a voltage comparator integrated circuit chip, and is used as a temperature control judging device for comparing a set heating temperature voltage with a voltage signal corresponding to the temperature of glass to be defrosted and frosted;

q1 is a semiconductor diode, and is used for preventing reverse connection of a power supply, and the circuit cannot be damaged due to wrong connection of positive and negative polarities of the power supply;

q2 is a semiconductor triode, and is used for converting the output level signal of the voltage comparator integrated circuit chip into a driving signal of the grid electrode of the NMOS tube;

q3 is a semiconductor NMOS tube, and is used for switching on or switching off the voltage of the heating electrothermal film on the glass to realize the electrifying heating or non-electrifying of the electrothermal film;

the resistors R2, R3 and the potentiometer RP1 function to generate a set heating temperature voltage.

Claims

1. A defrosting and frost preventing circuit for temperature control glass is characterized in that:

the device comprises a heating temperature setting circuit, a thermistor RT, a voltage comparator U2, an NMOS tube Q3 and an electrothermal film;

the thermistor RT is positioned on the surface of the glass, and is used for converting the temperature of the glass into a corresponding voltage signal and sending the voltage signal to the input end of the voltage comparator U2;

the heating temperature setting circuit is used for setting heating temperature voltage and accessing the other input end of the voltage comparator;

the voltage comparator U2 is used for comparing the voltage of the set heating temperature with a voltage signal corresponding to the glass temperature, and the level signal output after judgment is connected with and controls the on-off of the NMOS tube Q3;

the NMOS tube Q3 is used for switching on or switching off the voltage of the heating electrothermal film covered on the surface of the glass.

2. The temperature-controlled glass defrost and anti-frost circuit of claim 1, wherein:

the three-terminal voltage stabilizer U1 is used for converting the vehicle-mounted power supply voltage 26V into a voltage stabilizing 12V and is used as a working power supply of the circuit.

3. The temperature-controlled glass defrost and anti-frost circuit according to claim 1 or 2, characterized in that:

the temperature control glass defrosting and frostproofing device is characterized by further comprising a triode Q2, wherein a collector electrode of the triode Q2 is connected to the output end of the voltage comparator U2, an emitter electrode of the triode Q2 is connected with a grid electrode of the NMOS tube Q3, and the NMOS tube Q3 is used for switching on or switching off a power supply for heating the electrothermal film, so that the temperature control glass defrosting and frostproofing purposes are realized.

4. The temperature-controlled glass defrost and anti-frost circuit according to claim 2, wherein:

the device also comprises a diode Q1 connected in series between the vehicle-mounted power supply voltage 26V and the three-terminal voltage stabilizer U1 and the electrothermal film.