JPS6310772B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for directly converting temperature into period (time).

The present invention utilizes a relaxation oscillator that uses an active element of a relaxation oscillator, which will be described later, to also function as a temperature-sensitive element, and is devised to generate electrical oscillations with a period having a linear relationship with the temperature of the element. - It concerns a periodic converter, ie a temperature-time converter.

Relaxation oscillators are already known.

In a normal relaxation oscillator, due to the temperature dependence of the electrical characteristics of the active element, which is one of its components,
Fluctuations in the ambient temperature of the active element lead to changes in the oscillation period, accompanied by environmental temperature errors in the oscillation period. Since this error is relatively large, a temperature compensation circuit for the oscillation period is usually added.

Therefore, by taking advantage of this, the active element has the function of a temperature sensing element in addition to its original function, that is, by actively utilizing the temperature dependence of the electrical characteristics of the active element, Temperature can be directly converted to period. The relationship between the ambient temperature of the active element and the oscillation cycle at this time is that as the ambient temperature of the active element rises (falls), the oscillation cycle becomes shorter (longer).
However, depending on the conditions of the oscillation circuit, it may show the opposite tendency or an intermediate tendency between the two. However, in any case, simply using a known relaxation oscillator circuit and using the active element of the circuit as a temperature sensing element is insufficient to directly convert temperature into a period, that is, over a wide temperature range. It is not possible to obtain a converter that has a temperature-period conversion characteristic curve that is linear over time and has excellent performance.

Therefore, the present invention not only makes active use of the temperature dependence of the electrical characteristics of active elements, but also skillfully makes the most of the temperature dependence by using an original configuration of the oscillation circuit to achieve a satisfactory temperature - A periodic conversion device was realized. That is, a group of passive elements based on a parallel circuit of a capacitor and a resistor is inserted into the accumulated electrical energy release circuit, that is, the discharge circuit, of a relaxation oscillator in which the active element also serves as a temperature sensing element, and the electrical characteristics of the active element are By making the most of the temperature dependence of , we have realized a temperature-period direct conversion device that has linear temperature-period conversion characteristics with a large degree of freedom and excellent performance over a wide temperature range.

Conventionally, in many devices that directly convert temperature into period, the conversion characteristic curve is nonlinear, and even when measures are taken to linearize it, the linearity is insufficient and the circuit is complicated. Some argued for its practicality, arguing that if the operating temperature was limited to a narrow range, the characteristic curve could be considered nearly linear. On the other hand, in a temperature-period conversion device using an oscillator using a dedicated temperature-sensitive element, there is an environmental temperature error in the oscillation cycle based on the temperature dependence of the electrical characteristics of the active element, and temperature compensation for the oscillation cycle is required separately. It was.

For example, in ``Japanese Patent Application Laid-Open No. 54-103088 "Temperature/Frequency Converter"'' which uses a relaxation oscillator with a heat-sensitive thyristor as an active element, a relaxation oscillation output with a period approximately proportional to the breakover voltage of the thyristor can be obtained. However, due to the nature of the temperature dependence of the bookover voltage, a satisfactory conversion characteristic curve cannot be obtained, so another example using a low current source instead of a constant voltage source is presented, and the linearity of this characteristic curve is improved. However, no specific figures are given.

Also, heat-sensitive resistance elements (such as thermistors)
In the ``Japanese Patent Application Laid-Open No. 51-381 "Temperature Detection and Display Device"'' using a voltage-controlled self-propelled multivibrator, the temperature-pulse interval (period) is It is stated that linear approximation of the conversion characteristic curve is possible.

The present invention has been made in view of the above points, and
It is an object of the present invention to provide a temperature-period direct conversion device having a simple circuit configuration and excellent characteristics and performance.

In the circuit shown below, a current-controlled negative resistance element is used as an active element (which also serves as a temperature-sensitive element), and among them, the base-to-base resistance and open standoff ratio are the parametric variables of the circuit, and the element's We made exclusive use of programmable union transistors (hereinafter abbreviated as ``PUT''), whose characteristics such as peak current, valley current, and offset voltage can be freely programmed.

All PUTs used were molded type _N13T1 (model number) _manufactured by NEC Corporation.

Figure 1 shows the basic circuit of a negative resistance relaxation oscillator using this PUT, which is well known.

DC constant voltage V ₁ from DC stabilized power supply or other sources
The positive side of the power supply [V] is connected to the terminal + _V1 in Figure 1, and the negative side of the terminal is connected to 0. _C1 is a capacitor,
R ₁ to R ₄ are resistances.

In the conventional circuit shown in FIG. 1, electrical energy is supplied to the capacitor _C1 from the power supply and charges are accumulated. The charging voltage of capacitor C _{1 is}
and resistor R ₃ , and when the voltage exceeds the peak voltage of PUT, the capacitor
The charge on C ₁ is discharged through PUT, and the voltage on capacitor C ₁ at this time decreases with a time constant consisting of capacitor C ₁ and resistor R ₄ (ignoring the internal resistance of PUT). When that voltage drops to the valley voltage of PUT,
The discharge current is cut off and the process returns to the previously described charging process (starting from the valley voltage). In this way, charging and discharging are repeated alternately (periodically), causing so-called relaxation oscillation.

In the conventional circuit shown in Figure 1, if the ambient temperature of the PUT changes, the offset voltage, valley voltage, etc. of the PUT will change (due to the temperature dependence of the electrical characteristics of the PUT), and the oscillation period will change. This oscillation cycle can be output between terminals T or T' and 0 in FIG. 1, or from both ends of any element in the oscillation circuit (for example, capacitor C ₁ ). The waveform of this output voltage is a pulse wave or a sawtooth wave. By inputting this output voltage to a universal counter or the like, the oscillation period (time) can be output as a digital quantity.

The temperature-period conversion characteristic curve, which represents the relationship between the ambient temperature of PUT and the oscillation period when PUT, which is the active element of a relaxation oscillator, is also used as a heat-sensitive element, is determined by the configuration of the oscillation circuit, the type and characteristics of PUT, and the power supply voltage. , the base-to-base resistance, the open standoff ratio, and the constants of each element in the oscillation circuit. Among these, the discovery that the configuration of the discharge circuit plays a major role, greatly influencing the linearity of the conversion characteristic curve and the performance of the conversion characteristic, forms the basis of the present invention.

Therefore, embodiments of the present invention will be sequentially described below with reference to the drawings and according to the configuration of the discharge circuit. Note that making the PUT as an active element function as a temperature sensing element, connecting a DC power supply, detecting an output signal, etc. are all as explained in FIG. 1.

First, as a first embodiment, a case will be described in which a capacitance element and a resistance element connected in parallel and a resistance element connected in series are inserted into the discharge circuit.

A capacitor C ₂ and a resistor R ₆ are connected in parallel, and a resistor R ₅ is connected in series to the PUT of the discharge circuit.
FIG. 2 shows a circuit when the electrode is inserted into the cathode K side, and FIG. 3 shows two representative circuits when the electrode is inserted into the anode A side.

An example of the conversion characteristic curve using the circuit shown in Figure 2 is
FIG. 4 shows resistance R ₆ as a parameter. Similarly, a characteristic curve using the circuit shown in FIG. 3 is shown in FIG.

Although the capacitor C ₂ and the resistor R ₆ are connected in parallel in FIG. 4 and FIG. 5, the only difference is the insertion point (other conditions are the same), but the characteristics of the two are far from each other. However, characteristic curves with good linearity can be selected from FIGS. 4 and 5, respectively.

FIG. 6 shows a characteristic curve of another example using the circuit of FIG. 2, with the capacitor C ₂ and the resistor R ₆ as parameters. The straight line of this characteristic curve is not good.

Note that instead of the above embodiment, a capacitance element and a resistance element connected in parallel may be inserted into the discharge circuit.

Resistor inserted in common branch of charging circuit and discharging circuit
_R5 is commonly used to obtain the voltage drop due to charging and discharging current, which is necessary as the input voltage of the measuring instrument to analyze the oscillation state (transient phenomenon of charging and discharging), but in practical circuits, it is usually a branch dedicated to discharge. Insert into the tract. This also applies to the next embodiment.

Next, as a second embodiment, a case where a capacitance element and a resistance element are connected in parallel, and an inductance element and a resistance element are connected in series are inserted into a discharge circuit.

As mentioned above, there are various insertion points, but one example is shown in FIG. FIG. 8 shows an example of a characteristic curve using the circuit shown in _FIG . =
0.09 [Ω] at 20 [℃]) was added. It can be seen that the linearity is much better than that of the characteristic curve shown in FIG. In Figure 8, capacitor C ₂ = 1 [μF], resistor R ₆ = 10 [KΩ]
The characteristic curve has no hysteresis phenomenon over the temperature range of -60 to 110 [°C], extremely good reproducibility, temperature detection accuracy of ±0.2 [°C], and linearity of ±0.1 [%].
It can be seen that it has extremely excellent performance. The temperature coefficient of the oscillation period is -0.20 to -0.30 [%/
°C] (at -60 to 110 °C), and has good conversion efficiency. PUT ambient temperature t _a [℃] and oscillation period T [m
S] is as shown in the following (Equation 1).

t _a = 442.25−737.8T (1 set) In addition, the above discharge circuit is a combination of a capacitance element and a resistance element connected in parallel, an inductance element, or an inductance element and a resistance element connected in series or parallel. may be inserted.

Figure 9 shows one of the characteristic curves in Figure 8,
Furthermore, the characteristic curve is shown when resistance R ₃ is used as a parameter.

Each constant shown in the lower column of Figures 4 and 5 is
Similar to PUT, these values are close to those of a unijunction transistor (hereinafter abbreviated as "PJT"), which is a type of current-controlled negative resistance element. This means that using UJT as an active element instead of PUT,
Moreover, it is suggested that a temperature-period linear conversion device with excellent performance can be realized even by using a relaxation oscillator in which this UJT functions as a temperature sensing element.

Although the above-mentioned embodiments all use current-controlled negative resistance elements as active elements and temperature-sensitive elements, voltage-controlled negative resistance elements may also be used. Since the above two types of negative resistance elements have dual properties, in order to realize a temperature-period conversion device using a voltage-controlled negative resistance element, it is necessary to use a current-controlled negative resistance element. An oscillation circuit that is dual to the oscillation circuit used in the above embodiment may be used.

In addition to the embodiments described above, the present invention includes various other aspects within the scope of the claims, such as selection of active elements, modification of the oscillation circuit, and adoption of a two-power supply system.

Next, the effects of the present invention will be described.

A. Over a wide temperature range, the temperature-period conversion characteristic curve has no hysteresis, good reproducibility, and extremely excellent linearity can be easily obtained.

Good temperature detection sensitivity.

The temperature coefficient of the oscillation period is large, and the conversion efficiency is good.

E. Since the active element of the oscillation circuit is also used as a temperature sensing element, there is essentially no environmental temperature error in the oscillation cycle based on the temperature dependence of the electrical characteristics of the active element.

The active element that functions as a temperature sensing element is small, has a small heat capacity, and has good heat dissipation, so it responds quickly to rapid temperature changes and rarely disturbs the temperature and temperature distribution of the object to be measured. Further, it is easy to increase the density of temperature measurement points in temperature measurement and temperature distribution measurement in a narrow place.

The simplest relaxation oscillator is used as the oscillator, and the means for improving the conversion characteristics is also simple. Therefore, the circuit and configuration of the conversion device are extremely simple, and the circuit can be integrated.

As described above, a compact, lightweight, low-cost, and highly reliable conversion device can be obtained.

The oscillation period can be selected over a wide range from long periods to short periods.

Since electromagnetic coupling of the oscillating voltage (pulse waveform or sawtooth waveform) of the oscillation circuit is easy, it is convenient for wireless transmission of the oscillation periodic signal.

When the oscillator's period of electrical oscillation is transmitted remotely as an output signal, it is not affected by electrical noise mixed in the transmission circuit, resistance of the circuit, and leakage resistance, so it can be effectively used for remote measurement and control.

By connecting a digital counter (for example, a universal counter) to the output terminal of the conversion device, it is possible to output a digital value of time corresponding to temperature without using an AD (analog-digital) converter. This output can be easily output as a digital temperature value by a computing unit (for example, a microcomputer), and can be effectively used in detecting, transmitting, and controlling temperature information.

Since the present invention has the above-mentioned effects and features, it can be applied in a wide variety of fields. For example, it is expected to be used as a converter for detecting outside air temperature and cooling water temperature required for automobile engine control.

[Brief explanation of the drawing]

Figure 1 is a conventional relaxation oscillation circuit diagram, Figures 2 and 3 are circuit diagrams of the first embodiment of the present invention, and Figures 4 to 6.
FIG. 7 is a circuit diagram of the second embodiment of the present invention, and FIGS. 8 and 9 are conversion characteristic curve diagrams thereof. PUT...programmable union transistor, A is its anode, K is its cathode, G is its gate, _C1 , _C2 ...capacitor, _R1 to _R6 ...resistance, _L1 ...inductance,
T, T'...Output terminal, +V ₁ ...Positive terminal of DC constant voltage power supply.

Claims (1)

[Claims] 1. A charging circuit in which a first capacitor is connected between a positive electrode and a negative electrode of a DC power source via a first resistor;
A circuit that applies a voltage obtained by dividing a DC power supply voltage by a second resistor and a third resistor to a programmable union transistor as a gate bias voltage;・In a relaxation oscillator comprising a discharge circuit connected between the anode and cathode of a unidirectional transistor, in which the programmable unidirectional transistor also functions as a temperature sensing element, a fourth oscillator of the discharge circuit Instead of the resistor, a second capacitor and a fifth resistor are connected in parallel, and a sixth resistor is connected in series, or a second capacitor and a fifth resistor are connected in parallel, and a sixth resistor is connected in series. 1. A temperature-period conversion device characterized in that a temperature-period conversion characteristic is linearized by inserting into the discharge circuit a resistor connected thereto and an inductance element connected in series.