JPH02234033A - Temperature detector - Google Patents

Abstract

PURPOSE:To improve reliability by utilizing the change in an output signal which is outputted from a temperature detecting terminal on the basis of the difference of temperature characteristics between a 1st and a 2nd detecting elements and obtaining a detected temperature as the boundary temperature of the 2nd detecting element. CONSTITUTION:An NTC thermistor 4 has the negative temperature characteristic in a fixed temperature range. And a V type thermistor 6, where a specified temperature To in the fixed temperature range is regarded as the boundary, has the negative temperature characteristic of a low temperature side area corresponding to the thermistor 4, and has the positive temperature characteristic on the side where the temperature is higher than the temperature To. Such a temperature detector 1 is arranged, for example, near the heat generating part of an air conditioning equipment and a prescribed voltage Vcc is supplied between lead wires 7a and 7b. In the temperature range where the temperature of the thermistor 4 or 6 is lower than the temperature To, the ratio between the impedance of the thermistor 6 and the whole impedance of the thermistor 4 or 6 is always fixed. Contrarily, in the temperature range where the temperature of the thermistor 4 or 6 is higher than the temperature To, the ratio is rapidly increased on the basis of the temperature characteristic of the thermistor 6. Thus, the temperature control for the air conditioning equipment can be performed by detecting the output signal V01.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a temperature detector, and more specifically, to a temperature detector used for temperature control or temperature abnormality detection for a heat generating object such as an air conditioner or an internal combustion engine. The present invention relates to a temperature sensor useful in the field of technology.

(Prior Art) Conventionally, as this type of temperature detection device, one shown in FIG. 6 is known.

The temperature detection device 30 shown in the figure consists of an NTC thermistor T as a detection element whose resistance-temperature characteristic (hereinafter referred to as "temperature characteristic") exhibits a negative characteristic in a constant temperature range, and a resistor R.
1 are connected in series, and their connection point is connected to one terminal of the comparator 31.

Further, the other terminal of the comparator 31 is connected to the connection point of the resistors R 2 and R 3 connected in series.

When a predetermined voltage Vcc is supplied from the power supply to the temperature detection device 30, the comparator 31 is supplied with a voltage corresponding to the change in the ambient temperature of the NTC thermistor Tk and a reference voltage from the resistors R2 and R3. An output signal (voltage) v0 corresponding to the change in the ambient temperature is obtained from the output terminal of the sensor, and desired temperature detection can be performed.

However, what about the temperature detection circuit 30 described above? Well,
In addition to the NTC thermistor Tk, circuit elements such as the comparator 31 and resistors R to R3 are essential, and the number of components increases.
In addition to raising the price and lowering the reliability of the device itself, this also increases the size of the entire device, which poses problems in terms of mountability in the target device.

(Problems to be Solved by the Invention) The present invention has been made in view of the above circumstances, and its purpose is to provide a temperature detector that can be lowered in price, improved in reliability, and also has excellent mounting performance. It is something to do.

[Structure of the Invention] (Means for Solving the Problems) The temperature detector of the present invention has the following characteristics over a certain temperature range:
a first detection element having a negative temperature characteristic; and a second detection element having a negative temperature characteristic corresponding to the first detection element in a low temperature side region of the temperature range and a positive temperature characteristic in a high temperature side region. are connected in series, and the connection point of the first and second detection elements is used as a temperature detection terminal, and an output is output from the temperature detection terminal based on the difference in temperature characteristics of both the detection elements. The detected temperature as the boundary temperature of the second detecting element is determined using the change in the signal.

(for production) The operation of the temperature detector described above will be explained below.

1st. When the temperature characteristics of the second sensing element change due to changes in the ambient temperature, the temperature sensing terminal detects the temperature at a certain temperature based on the difference in the temperature characteristics of the two sensing elements. An output signal is output that suddenly changes at a boundary temperature at which the characteristic of the detection element changes from negative to positive. Therefore, the temperature at which the output signal suddenly changes can be specified as the detected temperature.

(Example) Examples of the present invention will be described below with reference to FIGS. 1 to 4.

The temperature sensor 1 shown in FIG. 1 includes a disk-shaped insulating substrate 2, and chip-type electrode portions 3a disposed on the upper surface 2a of the substrate 2. 3b as a first detection element, and chip-type electrode portions 5a. 5b as a second detection element (details will be described later) 6;
Lead wires 7a, 7b, 7c attached to the substrate 2 and a lid 8 attached to cover the upper surface 2a of the substrate 2.
It is equipped with.

The upper end portion of the lead wire 7a passes through the substrate 2 to the upper surface portion 2.
a, and one electrode portion 3a of the NTC thermistor 4 is connected to this upper end.

Further, the upper end portion of the lead wire 7b passes through the substrate 2 and is exposed to the upper surface portion 2a, and the V-type thermistor 6 is connected to the upper end portion of the lead wire 7b.
One electrode portion 5a of the two electrodes is connected to each other.

Further, the upper end portion of the lead wire 7C penetrates the substrate 2 and is exposed on the upper surface portion 2a, and the both thermistors 4 are connected to the upper end portion of the lead wire 7C.
, 6 are commonly connected.

An equivalent circuit of the temperature detector 1 is shown in FIG.

As is clear from this equivalent circuit, the NTC thermistor 4 and the V-type thermistor 6 are connected in series through the electrode portions 3b and 5b. The lead wire 7a is used as a power terminal for providing a predetermined voltage Vcc, the lead wire 7b is used as a ground terminal, and the electrode portions 3b and 5b are
The lead wires 7C, which are commonly connected to each other, are made to function as temperature detection terminals.

Here, the NTC thermistor 4 and the V-type thermistor 6
Figure 3(a) shows the temperature characteristics of . This will be explained with reference to (b) as well.

The NTC thermistor 4, as shown in FIG. 3(a),
It has a negative temperature characteristic in which the value of impedance zl decreases as the temperature rises within a certain temperature range.

On the other hand, as shown in FIG. 3(b), the V-type thermistor 6 operates at a specific temperature (boundary temperature) within a certain temperature range.
It has negative temperature characteristics that are the same or have the same ratio as the NTC thermistor 4 in which the value of the impedance Z2 decreases on the low temperature side with To as the boundary, and also at a specific temperature T. It has a positive temperature characteristic in which the value of impedance Z2 increases on the higher temperature side.

A specific example of such a V-type thermistor 6 is BaT.
iO. One example is a system in which barium Ba in PTC is replaced with strontium S and lead P, which have the same valence and approximate ionic radius (SrPb) and TiOi system (Electro Ceramics: May 1988 issue). :"
(See “V-type characteristic PTC material”).

Next, the operation of the temperature detector 1 having the above structure will be explained with reference to FIG. 4 as well.

This temperature detector 1 is placed, for example, near a heat generating part of an air conditioner, and the lead wire 7a. A predetermined voltage V e C is supplied between 7b and 7b.

The temperatures of the NTC thermistor 4 and the V-type thermistor 6 are at the specific temperature T. In a temperature range lower than , the ratio of the impedance z2 of the V-type thermistor 6 to the overall impedance (21 + 22) of both thermistors 4 and 6 is Z2 /
(Zl +22) C is always constant, and conversely, the temperature of both thermistors 4 and 6 is the specified temperature T. In a higher temperature range, the ratio Z2/(Zl+22) increases rapidly due to the positive temperature characteristic of the V-type thermistor 6.

Therefore, at this time, the following relationship (1) holds true.

...(1) From the relationship of this equation (1), the temperature detection terminal 7
The output signal (voltage) Ver from c is at a specific temperature T as shown in FIG. It increases rapidly after .

Therefore, this output signal V. By detecting , the temperature of the heat generating part of the air conditioner to be detected by the temperature detector 1 can be specified, and the temperature of the air conditioner can be controlled.

According to the temperature detector 1 described in detail above, the first temperature detector 1 having the above-mentioned temperature characteristics. Temperature detection is possible just by using the second detection element, which reduces the number of parts and reduces costs, improves reliability, and also allows for miniaturization, allowing high-density mounting in air conditioning equipment, etc. becomes.

Next, another example of the embodiment of the present invention will be described with reference to FIG.

The temperature detector IA shown in the figure is different from the one shown in FIG. 2 in that the lead wire 7b is used as a power supply terminal and the lead wire 7a is used as a ground terminal.

In the case of this temperature detector IA, both thermistors 4, 6,
is the specific temperature T. In the temperature range lower than
The ratio Z1/ (Z1+22) of the impedance z1 of the TC thermistor 4 and the overall impedance (Z+22)
) becomes constant, and conversely, for a certain temperature T. In a temperature range higher than that, the ratio z1/(zt +Z2) will drop sharply. Therefore, in this case, the following (
2) The formula holds true.

...(2) From the relationship of this equation (2), the temperature detection terminal 7
The output signal V from C. 2 becomes as shown in Figure 4,
As in the case described above, the temperature of a heat generating part of an air conditioner or the like can be specified.

The present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the invention.

[Effects of the Invention] According to the present invention described in detail above, with the above configuration, the number of parts can be significantly reduced compared to the conventional device, and the cost can be lowered and reliability improved. It is possible to provide a temperature sensor that can also be improved.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway perspective view of an embodiment of the present invention, Fig. 2 is a circuit diagram of the embodiment, and Fig. 3(a) is an NTC in the same device.
Figure 3 (b) is a temperature characteristic diagram of the V-type thermistor in the same embodiment, Figure 4 is a temperature characteristic diagram of the output signal of the device shown in the same embodiment and Figure 5, and Figure 5 is a temperature characteristic diagram of the thermistor. 6 is a circuit diagram showing another example of the embodiment of the present invention, and FIG. 6 is a circuit diagram of a conventional device. 1, IA...Temperature detector, Fig. 1 Fig. 2 (a) (b) Fig. 3 Fig. 4

Claims (1)

[Claims] A first detection element having negative temperature characteristics over a certain temperature range, a negative temperature characteristic corresponding to the first detection element in the low temperature region of the temperature range, and a positive temperature characteristic in the high temperature region. A second detecting element having a characteristic is connected in series, and a connection point between the first and second detecting elements is a temperature detecting terminal. A temperature detector characterized in that a detected temperature as a boundary temperature of the second detection element is determined by utilizing a change in an output signal output from a temperature detection terminal.