JPH0540063A - Temperature-sensitive sensor - Google Patents

Abstract

PURPOSE:To enable sensitivity to be improved by connecting a plurality of semiconductor photovoltaic elements which constitute a temperature-sensitive portion in series and adding each electromotive force of these semiconductor photovoltaic elements. CONSTITUTION:A temperature-sensitive portion consists of an photo coupler where a semiconductor light-emitting device 1 and a semiconductor photovoltaic element 2 are built into a same package 1, thus enabling an electromotive force of the element 2 per one semiconductor photovoltaic element 2, namely approximately -2.5mV change to be generated at a temperature-detection signal for example when temperature is increased by 1 deg.C at the temperature- sensitive portion. When it is compared with 2 mV/ deg.C of a silicon transistor, the sensitivity is increased by 25%. In this case, if five elements 2 are connected in series, a change of an approximately -12.5mV occurs for a temperature increment of 1 deg.C at the temperature-sensitive portion. In this manner, when an addition electromotive force of a plurality of elements 2 is a temperature- detection signal, an extremely high sensitivity can be achieved and both the semiconductor light emitting device 1 and the semiconductor photovoltage element 2 to be miniaturized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor temperature sensor.

[0002]

2. Description of the Related Art Currently, various temperature sensitive sensors (temperature detecting devices) are put into practical use. Among them, the temperature sensor in which the temperature detection signal is provided in the form of voltage has characteristics such as small size and little change over time, and development of transistor type and integrated high-performance type has been promoted. ing.

However, in the case of the silicon transistor, the temperature coefficient is 2 mV / ° C., and the sensitivity is slightly insufficient for the purpose of highly accurate temperature measurement. There is also an excessive temperature rise prevention device that combines a temperature sensor and a control circuit. This excessive temperature rise prevention device is a device that issues an alarm or cuts off the load when the temperature exceeds a certain dangerous temperature. However, in the conventional overheat prevention device, the control unit is composed of many parts, and the device is inevitably large. There is a demand for a temperature sensor that enables downsizing of the excessive temperature rise prevention device.

[0004]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention has an object to provide a semiconductor type temperature sensitive sensor which has sufficient sensitivity and opens the way for downsizing of an excessive temperature rise prevention device. And

[0005]

In order to solve the above-mentioned problems, in the temperature-sensitive sensor of the present invention, the temperature-sensitive portion is composed of a semiconductor light-emitting element and a semiconductor photovoltaic element which receives the light and generates an electromotive force. In addition, the output of the photovoltaic element is used as a temperature detection signal. Normally, in the temperature sensor of the present invention, as shown in FIG. 1, the semiconductor light emitting element 1 and the semiconductor photovoltaic element 2 which generates electromotive force by receiving light from the light emitting element 1 are provided in the same package 3. Takes the built-in form. And, MOS transistor (power type is especially useful) is also built in the same package,
If the temperature detection signal is applied between the gate and the source, the function of preventing excessive temperature rise is provided as it is, and the device becomes a microminiature excessive temperature rise prevention device.

In the case of the temperature-sensitive sensor of the present invention, from the standpoint of further increasing the sensitivity, a plurality of semiconductor photovoltaic elements forming the temperature-sensing portion are provided as in claim 2, and these semiconductor photovoltaic elements are provided. The power elements are connected in series so that the respective electromotive forces are added, and the added electromotive force of all the semiconductor photovoltaic elements is used as a temperature detection signal, or as in claim 3,
A form in which a resistance element made of amorphous silicon (this resistance element also constitutes a part of the temperature sensing portion) is connected in parallel to the semiconductor photovoltaic element is very useful.
When there are a plurality of semiconductor photovoltaic elements (Claim 2), the resistance element made of amorphous silicon is usually connected in parallel to the series connection body of the semiconductor photovoltaic elements.

Semiconductor photovoltaic devices using single crystal silicon and amorphous silicon (hereinafter referred to as "a-S").
i)), but the latter a-Si
Is preferable because the manufacturing cost is low and the serial connection structure can be easily obtained. A tandem structure is also effective for the series connection configuration of semiconductor photovoltaic elements. The a-Si photovoltaic element includes a lower electrode and a B-doped p-type a-S.
An example is a pin-type solar cell obtained by sequentially forming an i layer, a non-doped a-Si layer, a P-doped n-type a-Si layer, and an upper electrode. In this case, a
A resistance element made of -Si can be simultaneously formed by utilizing the p-type a-Si layer and the n-type a-Si layer.

FIG. 2 shows an equivalent circuit in the case where a power MOS transistor is incorporated together with the temperature-sensitive sensor to form an excessive temperature rise prevention device. In FIG. 2, a plurality of semiconductor photovoltaic elements 2, ...
Are connected in series in the same direction, and a is
The -Si resistance elements R are connected in parallel, and the elements are connected so that the output voltage of the series connection body is applied between the gate and source of the MOS transistor TR. The load is connected between the source and drain of the MOS transistor TR.

For example, if a voltage equal to or higher than the threshold voltage is applied between the gate and source of the MOS transistor TR at room temperature, the MOS transistor TR is conductive in a normal state and the load is turned on. is there.
When the temperature rises, the output voltage gradually decreases, and when the temperature reaches a certain temperature, the output voltage drops below the threshold voltage and the MOS transistor TR is cut off, so that the load is turned off.
Since the output voltage of the photovoltaic element 2 can be adjusted by the number of elements connected in series, the resistance value of the resistance element R, etc., the overheating operation temperature can be freely selected and set from a wide range of temperatures.

When the temperature sensor of the present invention is used, packaging is performed and the relationship between the temperature and the output voltage is checked in advance. When a MOS is incorporated, the output voltage is further adjusted to a threshold voltage at a predetermined temperature.
Then, the light emitting element is placed in a place where temperature detection is to be performed while the light emitting element is emitting light.

[0011]

In the temperature-sensitive sensor of the present invention, the temperature-sensitive portion is composed of the optical coupler consisting of the semiconductor light-emitting element and the semiconductor photovoltaic element, and when the temperature-sensing portion has a temperature rise of 1 ° C. A change of about -2.5 mV occurs in the electromotive force of the photovoltaic element, that is, the temperature detection signal, per power element. The sensitivity is increased by 25% as compared with 2 mV / ° C of the above-mentioned silicon transistor. If 5 photovoltaic elements are connected in series, the temperature rise of 1 ° C in the temperature sensing part will be about-
A change of 12.5 mV occurs. Thus, when the added electromotive force of the plurality of semiconductor photovoltaic elements is the temperature detection signal, the sensitivity becomes extremely high.

In the temperature sensor of the present invention, both the semiconductor light emitting element and the semiconductor photovoltaic element can be extremely miniaturized, and since the semiconductor photovoltaic elements are easily integrated, a large number of them are connected in series. The size of the element is almost the same even if it takes such a form, and it is not necessary to increase the number of light emitting elements, and the suitability for miniaturization is not lost at all. Further, since the function of preventing excessive temperature rise can be provided without adding a particularly complicated control circuit to the extent of incorporating a MOS transistor, it is possible to realize a very small and inexpensive excessive temperature rise prevention device.

In addition, if there is a resistance element made of a-Si connected in parallel to the semiconductor photovoltaic element side,
Since this resistance element functions to increase the amount of change in the output voltage of the semiconductor photovoltaic element with respect to temperature, the sensitivity becomes higher. When the resistance element made of a-Si is connected in parallel with the photovoltaic element, as shown in FIG. 3, the generated voltage of the photovoltaic element becomes the voltage at the operating point determined by the resistance value of the resistance element. .. On the other hand, since a-Si has many defect levels, its resistance value has a large negative temperature coefficient as shown in FIG. 4 (FIG. 4 shows the case of the n-type a-Si layer). Therefore, when the temperature rises, the resistance value decreases, the current of the semiconductor photovoltaic element increases, and the operating point increases the current and moves to the low voltage side. As a result, the amount of change in the output voltage due to the temperature change of 1 ° C. is larger than that in the case where no resistance element is provided, and the sensitivity is further improved. FIG. 5 shows a case with a resistance element made of a-Si (solid line) and a case without resistance element made of a-Si (broken line).
The respective output voltage vs. temperature characteristics of are shown. It can be clearly seen that the former has a stronger inclination and better sensitivity.

[0014]

Embodiments of the temperature-sensitive sensor of the present invention will be described below. Needless to say, the present invention is not limited to the following embodiments. -Example 1-High-luminance red L as a semiconductor light-emitting element that constitutes the temperature sensing portion
An ED (light emitting diode) was prepared.

A combination of a semiconductor photovoltaic element and a resistance element made of a-Si, which also constitutes the temperature sensing portion, was prepared as follows. First, a Cr layer of 2000 liters was formed on an insulating substrate by electron beam (EB) vapor deposition, and patterned by photolithography to provide a lower electrode having a predetermined shape. Next, a p-type a-Si layer with a thickness of 100Å,
An i-type a-Si layer having a thickness of 5000Å and an n-type a-Si layer having a thickness of 100Å are sequentially laminated and patterned by a photolithography technique to provide a photoelectric conversion layer, and then an ITO layer is formed by electron beam (EB) vapor deposition. Was formed to a thickness of 1000Å and patterned to provide an upper electrode having a predetermined shape. The pattern configuration is such that nine 0.2 mm × 0.4 mm size cells are connected in series, and an n-type a-Si layer and ITO are used.
Resistor element (5
MΩ) is simultaneously formed on the insulating substrate.

High-brightness red LED prepared as described above
(Light emitting diode), semiconductor photovoltaic element, and aS
The resistance element made of i was made to face each other with a gap of 0.5 mm, and as shown in FIG. 1, it was packaged with resin to obtain a temperature sensitive sensor. When the high-brightness red LED was driven at 5 mA, the output voltage vs. temperature characteristic of the semiconductor photovoltaic element was measured, and the result showed the same tendency as the characteristic shown by the solid line in FIG.

Example 2 In Example 1, power MOS transistors having a threshold voltage of 3 V were packaged at the same time so as to have the electrical connection shown in FIG. In this case, the power MOS transistor was conductive at room temperature, but the temperature was about 60 ° C.
Then, the power MOS transistor was cut off.

[0018]

As described above, in the temperature-sensitive sensor of the present invention, the temperature-sensitive portion is composed of the optical coupler consisting of the semiconductor light-emitting element and the semiconductor photovoltaic element, so that the sensitivity is very high and the size is small. The device for preventing excessive temperature rise can be easily realized by using a MOS transistor together, and is therefore extremely useful.

In addition to the temperature sensor of the second aspect of the present invention,
Since the added electromotive force of the plurality of semiconductor photovoltaic elements is the temperature detection signal, there is an advantage that the sensitivity is higher. In addition, the temperature sensor of the invention of claim 3 is connected in parallel a
Since the resistance element made of -Si functions to increase the amount of change in the output voltage of the semiconductor photovoltaic element with respect to temperature, there is an advantage that the sensitivity is higher.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration example of a temperature sensor of the present invention.

FIG. 2 is an equivalent circuit diagram of a configuration example of an excessive temperature rise prevention device using the temperature sensor of the present invention.

FIG. 3 is a graph showing voltage-current characteristics of a semiconductor photovoltaic element and a resistance element made of a-Si.

FIG. 4 is a graph showing the resistance vs. temperature characteristic of the resistance element made of n-type a-Si.

FIG. 5 is a graph showing a temperature characteristic of an output voltage of a semiconductor photovoltaic element with and without a resistance element made of a-Si connected in parallel.

[Explanation of sign]

 1 Semiconductor Light Emitting Element 2 Semiconductor Photovoltaic Element 3 Package Ra-Si Made Resistor Element TR MOS Transistor

[Procedure amendment]

[Submission date] November 9, 1991

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 4

[Correction method] Change

[Correction content]

[Figure 4]

Claims (3)

[Claims] 1. A temperature-sensing section is composed of a semiconductor light-emitting element and a semiconductor photovoltaic element that receives the light to generate an electromotive force.
A temperature sensor in which the output of the photovoltaic element is a temperature detection signal. 2. A plurality of semiconductor photovoltaic elements forming a temperature sensing portion are provided, and these semiconductor photovoltaic elements are connected in series so that the respective electromotive forces are added to each other. The added electromotive force of the element serves as a temperature detection signal.
The temperature sensor described. 3. The temperature sensor according to claim 1, wherein a resistance element made of amorphous silicon is connected in parallel to the semiconductor photovoltaic element.