SU859837A1 - Temperature detector - Google Patents

Description

one

The invention relates to the field of temperature measurements and can be used in systems for the automatic control of technological process parameters.

A device for measuring temperature is known, in which pyroelectric l is used as a thermal element of the cell.

The closest in technical essence to the present invention is a device for measuring temperature, containing a MIS transistor with a pyroelectric layer under the gate,

The charge that occurs on the surface of the pyroelectric due to temperature variation controls the drain current of the transistor. An ammeter connected to the drain circuit of an NC transistor can be used to determine temperature changes.

The disadvantage of such a device operating in the temperature variation indication indication mode is that

it does not respond to slow temperature changes and thus has a high sensitivity threshold for the rate of temperature change.

The circuit of the invention is the reduction of the sensitivity threshold for the rate of temperature change.

The goal is achieved by introducing a source of stabilized voltage into the device.

10 and a thermistor applied to the gate of the MIS transistor, electrically isolated from it and connected to a source of stabilized voltage.

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The drawing shows a diagram of the device.

The temperature detector includes a MOSFET comprising a substrate 1 of lightly doped

Claims (2)

20 semiconductors, for example, and a highly doped source 2 and drain-3 regions of the opposite conductivity type 3 1 formed in the substrate I, electrodes 4 and 5, an insulating dielectric 6, a gate 7, the year of which is a pyroelectric layer 8, for example barium titanate or lithium niobate, the axis of polarization of which is perpendicular to the plane of the substrate 1, the electrode 9, designed to short the pyroelectric face when heating or cooling the device before the measurement starts, the thermistor 10 with a negative temperature coefficient An electrical resistor, electrically isolated from the gate 7 by a layer of dielectric P, but having good thermal contact with the pyroelectric 8 and the electrodes 7 and 9, and the source of stabilized voltage 12. The temperature indicator works as follows. The voltage across the gate of the MIS transistor relative to the substrate 1 is opposed not only by the bias voltage (the bias voltage source is not shown), but also by the pyroelectric voltage generated by the pyroelectric 8 as the temperature changes. When the temperature deviates from the set at a sufficiently high speed, electric charges arise on the pyroelectric 8 faces, caused by the development of the pyroelectric effect, which leads to a change in the conductivity of the channel of the MIS transistor, and therefore the drain current flowing through it. at low speeds, when the pyroelectric 8 does not work, the resistance of the thermistor 10 changes, and hence the current flowed through it from the source 12 of a stabilized voltage. Excess temperature causes an increase in current through the thermistor 10 and the power dissipated on it, resulting in. An additional heating of the resistor 10 occurs, a drop in its resistance and a further increase in the current through it. Thus, the resulting intensive self-heating of the thermistor 10 results in the presence of good thermal contact with the pyroelectric 8 to a rapid change in the temperature of the pyroelectric 8 and the drain current 3 of the MIS transistor, which indicates a deviation of the temperature from the specified value. Thus, in the proposed signaling device, the threshold of sensitivity on the rate of temperature change is significantly reduced. The detector with high reliability generates a signal about the temperature deviation from the setpoint, which allows its use in process control systems, where it is required to maintain the setpoint temperature with high accuracy. Claims of the temperature detector containing a MOSFET with a pyroelectric layer under the gate, characterized in that, to reduce the sensitivity threshold of the detector for the rate of temperature change, a stabilized voltage source and a thermistor applied to the MDP transistor, electrically isolated from it, are introduced into it. and connected to a stabilized voltage source. Sources of information taken into consideration in the examination of G. US Patent 3877308, CL. G 01 K 7/34, 1975. 2. US patent No. 3453887, G 01 K 5/18, published. 07.07.69 (prototype).