JP2004006463A - Temperature controlling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for controlling temperatures by detecting the characteristics of an electronic (electric) element whose characteristics change due to the temperatures by measuring a change in the electric characteristics of the element without separately using a sensor and by controlling the element. <P>SOLUTION: The temperature controlling method for the element is provided, where characteristics are changed by the temperatures, the temperature-electric characteristics of the electronic element that functions due to energization is captured as a temperature detection signal, and the amount of current and voltage to be energized to the elements is controlled. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a temperature control method for realizing an energy-saving circuit-type temperature / brightness adjustment method with high energy efficiency.
[0002]
[Prior art]
Conventionally, for example, in a temperature control device driven by a battery (for example, a deodorizer or a collector using a soldering iron or an adsorption / desorption reaction), there is no device capable of setting a high temperature rising temperature of 200 ° C. or more. In addition, there has been no other method of adjusting the temperature of the light emitting element except to provide a temperature sensor near the element to control the temperature or to maintain the balance by performing pulse driving.
[0003]
[Problems to be solved by the invention]
In the method of detecting and controlling a change in the electric characteristics of an electronic (electric) element whose characteristics change with temperature, a separate sensor is used, and the element is controlled by a resistance change and a luminance change of the sensor signal. A time delay, a displacement, or the like occurs between the element and the separate sensor, which limits the accuracy of control and causes an energy loss. In addition, since it is necessary to thermally couple or optically couple the element and the sensor separately by some method, the structure of the device to be used has to be complicated.
[0004]
SUMMARY OF THE INVENTION An object of the present invention is to provide a temperature control method that realizes temperature control with energy saving and low cost, and stabilizes luminance and illuminance of light emission. In the present invention, stabilizing the luminance and illuminance of light emission means that when the temperature of the light-emitting element fluctuates therein, the luminance and illuminance change, so by stabilizing the temperature inside the element, This means that luminance and illuminance are stabilized, and also stabilized against changes in environmental temperature.
[0005]
[Means for Solving the Problems]
According to the present invention, there is provided an element whose characteristics change according to temperature, the temperature-electric characteristic of an electronic element which functions by energization is taken as a temperature detection signal, and the amount of current and voltage applied to these elements is controlled. Is provided.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
In the method of the present invention, the characteristic change of an electronic (electric) element whose characteristic changes with temperature is controlled by detecting a resistance change or a forward voltage change of the element. Temperature and the like can be controlled without occurrence of a time delay or deviation, and thus control accuracy is improved. Also, unlike the conventional method, since no separate sensor is required, the structure of the device is simplified, and therefore, the reliability is improved, and an additional sensor is not required, which is economically advantageous. is there.
[0007]
According to the method of the present invention, the electric characteristics of the light emitting element, the heating element, the cooling element, and the like are taken out, and the signals are directly monitored and returned to the control system. That is, the temperature-electrical characteristics of an LED (light emitting diode), a halogen lamp, a heater, a Peltier element, and the like are taken as a temperature detection signal, and by controlling the amount of current and voltage applied to these elements, the precision of the luminance is improved. Control and energy-saving temperature control become possible.
[0008]
Specifically, in the case of an LED, a current amount or a forward voltage change due to a PN junction temperature change of a diode is directly taken out, and, for example, after amplifying the forward voltage change, the amplified voltage and a reference voltage are compared with a comparator. The result is compared by a circuit, and the result is output as an ON / OFF control signal, which is used as an LED applied voltage. Also, in the case of a heater, by monitoring the resistance value of the heater and outputting on / off of a current flowing therethrough by a comparison circuit, it is possible to control the temperature of the heater without newly providing a temperature sensor. Become.
[0009]
Referring to the drawings, as shown in FIG. 1, since there is a proportional relationship between the relative luminance of the light emitting element of the LED and the forward voltage, if the temperature rises, the luminance decreases. By setting a high voltage to be applied to the pixel, the luminance increases. As shown in FIG. 2, when the internal resistance of the heater changes as shown in FIG. 2 depending on the temperature, it can be kept constant by changing the voltage applied to the heater.
[0010]
For example, when the internal resistance increases in proportion to the temperature rise, the current applied to the heating element can be reduced by lowering the voltage applied to the heating element, thereby keeping the temperature of the heating element constant. It is. Depending on the type of the heater, there is a type in which the internal resistance is reduced by a rise in temperature. In this case, however, the relationship between the voltage applied to the heating element and the internal resistance does not change, and each characteristic is only reversed.
[0011]
Hereinafter, embodiments of the present invention will be described more specifically by taking a carbon heater as an example. As the modes, (1) description of a temperature control circuit using an AC power supply (FIG. 3), (2) an example of a practical circuit using a DC battery for portable purposes (FIG. 5), and (3) LED temperature An embodiment (FIG. 7) of a circuit for suppressing a change in relative luminance due to the following will be described.
[0012]
FIG. 3 shows a temperature control circuit when an AC 100 V power supply (frequency is, for example, 60 Hz) is used. A portion corresponding to R2 corresponds to a heater / temperature sensor. At the point A, the AC voltage is full-wave rectified, and the temperature is adjusted at a cycle of 120 Hz as shown in FIG. The carbon heater is a material having particularly good temperature rising characteristics, and is a material exhibiting NTC characteristics (characteristics having a negative temperature coefficient, that is, characteristics in which the resistance decreases as the temperature increases). If a heating element such as a carbon heater is also used as a sensor having NTC characteristics, energy can be saved. An example of a circuit using the same will be described.
[0013]
In order to accurately measure the temperature-electrical characteristics (resistance generated at a certain heating temperature, that is, potential) of the heating material at regular intervals of 1/120 seconds, this circuit employs a mechanism for detecting the potential of the heating element at zero crossing. It is provided to realize on / off control in which a load current is repeatedly supplied or not supplied to the heating element during one cycle after the measurement (approximately 1/120 seconds) according to the potential at that time. is there. As described above, it is a feature of the present invention to measure the temperature-electrical characteristics of the heating material itself at the zero cross point on the trace of the load current fluctuation.
[0014]
More specifically, as shown in FIG. 4A, when the voltage at the point A in FIG. 3A is a 0 V potential crossing the zero level, the temperature-electrical characteristics of the heat generating material can be measured. The SCR (thyristor) 2 is used only when the point A is at the zero level, depending on the potential at the point D (that is, from H level to L level, FIG. 4D). , Or not to flow (referred to as turn-on and turn-off).
[0015]
Therefore, when the point A is at a level other than the zero level, the SCR does not operate, and the ON / OFF continues for one cycle until the next zero crossing, regardless of the applied potential from the point D. That is, it controls whether or not current flows through the thyristor SCR to the heating element R2 for one cycle. The determination of the D potential (H or L level) related to the ON / OFF operation at the time of the zero crossing is performed by generating a potential corresponding to the temperature-electrical characteristic of the heating element which is also a temperature sensor in another system, and using the generated potential in the amplifier 3. , And after the comparison with the reference voltage by the comparator 4.
[0016]
In order to measure the potential of the heating element at the zero crossing point, a potential corresponding to the resistance of the heating element must be measured at point C and compared by the comparator 4. Therefore, at the time of the zero cross at the point B, the potential is reflected, that is, 0.7 V as shown in FIG. 4B, so that the transistor is not operated only at the time of the zero cross. Otherwise, when the potential of the heating element is not measured, the potential at the point B exceeds 0.7 V as shown in FIG. 4B, so that the transistor operates, the point C is grounded, and Become. A mechanism in which the potential at the point D becomes H / L by the potential at the point C at the time of zero crossing and the on / off switch of the load current operates will be described below.
[0017]
A mechanism is provided such that the potential of the point E (FIG. 4E) changes according to the point C, and the potential D becomes H level or L level according to the potential at the point E. The level of E is adjusted to the amplifier 3, and the comparator 4 is operated so as to output an H / L level potential according to the heat generation temperature. The carbon heater material has NTC characteristics. (As described above, the NTC characteristic means a negative temperature coefficient. The NTC thermistor has a characteristic that the resistance value decreases as the temperature increases.) The relationship between the resistance of the heating element used and the measurement temperature is as follows. For example, the resistance was 2.0Ω at 100 ° C. and 1.77Ω at 300 ° C.
[0018]
Specifically resistor for realizing constant R1 = 100Ω, R2 = 2.0Ω, R3 = 1kΩ, and R4 = 10 k.OMEGA, the power supply voltage _{V 0} to be used to 5V. The potential at the point C is R2 / (R2 + R1) × V ₀ = 0.098 V, and the voltage at the point E is 0.098 V × (R4 / R3 + 1) = 1.08 V at the point C. Similarly, a value obtained by substituting 1.77Ω for R2 is 0.87V. That is, at the time of zero crossing at 100 ° C., a potential of 1.08 V is generated at the point E, and at 300 ° C., a potential of 0.87 V is generated.
[0019]
From this, a potential difference of 1.08-0.87 = 0.21 V is generated at a change of 200 ° C., so that a potential difference of 1 mV / ° C. is generated. For example, when a carbon heater is used for the soldering iron, if the optimum temperature of the soldering iron is 380 ° C., the potential G of the comparator 4 may be set to 0.87V−0.08V = 0.79V. Become.
[0020]
In the above embodiment, for example, when the G potential is set to 0.87 V, an H level signal is output at 0.7 V of 0.87 V or less, and an L level signal is output at 0.9 V. The operation is performed as output. That is, the trace at the point D shown in FIG. This output causes the on / off operation of the SCR. In addition, since the carbon heater is porous in performing gas adsorption and desorption reactions, the heater itself is an inexpensive and useful material as an adsorption and desorption material, but it is used in such a way as to maintain the desorption temperature. Is also possible. FIG. 4F shows the potential change at the point F in FIG.
[0021]
Conventionally, even if a temperature sensor is placed near a heating element, a delay in response, that is, hysteresis always occurs due to thermal contact resistance and heat capacity at the interface, and hunting causes a heat loss, resulting in a conversion efficiency of electric energy. However, the greatest effect of the method of the present invention is that the temperature sensor is completely integrated with the heating element, so that the thermal loss can be minimized as much as possible. It is in. Therefore, by saving energy, it becomes possible to drive a soldering iron or an adsorption / desorption module with a battery, which was impossible in the past, and to make the module portable.
[0022]
FIG. 5 shows an example of a temperature control circuit when the battery is actually driven, that is, when the heating element is energized by the DC power supply 7 (for example, 12 to 16 V). The difference from FIG. 3 is that a clock pulse having a portion corresponding to a zero cross is generated, and a zero potential for monitoring the temperature-electrical characteristics of the heating element R2 is periodically generated by the clock pulse as in FIG. Is a point. Specifically, FIG. 6A shows the clock waveform at point A in FIG. The clock is generated by the clock circuit 8.
[0023]
Further, a point corresponding to the thyristor SCR2 in FIG. 3 is constituted by a V-MOS (FET). The gate potential of the FET is turned on / off by the output potential of the logic element 9 in the preceding stage. Further, the output potential of the logic element 9 is configured such that the gate of the logic element 9 is opened and output only when the pulse A generated from the clock circuit 8 is at the zero level. Therefore, the voltage at the point C (FIG. 6C) corresponding to the potential for temperature adjustment changes only when the potential at the point A is zero, as in FIG.
[0024]
Similarly to FIG. 3, the potential measured at the point C is amplified by the amplifier 3 and is compared with the set voltage G by the comparator 4. When the potential is low, the potential is output from the comparator 4 as an H level and higher than G. In the case of voltage, it is output as L level. The output waveform at point D in FIG. 6D indicates this. Reflecting the output, the V-MOS is kept on or off for one cycle, and the potential at the point F (FIG. 6 (f)) becomes the potential at the point C (FIG. 6 (f)). According to FIG. 6 (c), on / off of the current is controlled and the temperature is adjusted. FIG. 6E shows the potential at point E in FIG.
[0025]
Instead of the comparator 4 used in FIGS. 3 and 5, a window comparator may be used. In addition, such a heating element is used in a PTC characteristic (a characteristic having a positive temperature coefficient. In a thermistor having a positive temperature coefficient, when the element temperature exceeds a set temperature, the electric resistance rapidly increases. It can be used in the same way even if the temperature decreases and the electric resistance decreases.
[0026]
Examples of applications using this circuit include an energy-saving soldering iron circuit, a circuit for deodorizing, deodorizing, collecting, condensing, and dispersing chemical substances, and a lighting stabilizing circuit.
[0027]
FIG. 7 shows an example of the illumination stabilization circuit. Diodes are also considered temperature sensors. Light emitting diodes also have temperature characteristics. The brightness of the LED greatly changes depending on the temperature of the PN junction inside the light emitting diode. For example, if the temperature changes by about 20 ° C., the relative luminance changes by several tens of percent.
[0028]
In machine vision, pattern detection, and the like, when the illumination luminance changes, the image processing conditions fluctuate greatly, resulting in a decrease in recognition accuracy. Conventionally, when measuring or aligning a precise position, the installation conditions of the lighting are restricted, and in the morning and evening when the environmental temperature changes drastically, the inspection results and control results are greatly affected. It often results in degradation. Such a problem can be solved by directly detecting the temperature change of the light emitting element and changing the voltage applied to the light emitting element accordingly.
[0029]
That is, a circuit configuration that detects a current change or a change in a forward voltage in accordance with the junction temperature, converts the change amount into a voltage, and reflects the potential in the drive voltage of the LED that is a light emitting element. This solves the above problem.
[0030]
In some cases, the LED drive voltage is modulated to solve the luminance error caused by the temperature change. It is. The present invention is a light emission control method which adjusts the amplitude of the modulation voltage in accordance with the luminance change due to the ambient temperature of the LED in response to such a modulation voltage.
[0031]
As shown in FIG. 7, the forward current of the LED light emitting element 11 is output by the differential amplifier 12 as a drop potential difference. An appropriate potential 16 is added to the drop potential by the adder circuit amplifier 13, and the generated voltage is inverted by the inverting amplifier 14, and is applied to the LED again through the buffer circuit 15. The voltage applied to the LED is changed according to the current change, and thus the forward current can be kept constant. That is, by keeping the current constant, it is possible to keep the emission luminance constant.
[0032]
【The invention's effect】
According to the present invention, since it is not necessary to provide the load resistance and the current detection, it is possible to realize an energy saving in which the temperature rise time is short and the energy loss is small. In addition, the illumination accuracy applied to a work, which is a life in machine vision and the like, is stabilized without being affected by the environmental temperature. In particular, in LED lighting and the like, since the pull-up voltage can be adjusted by directly monitoring the PN junction temperature inside the light-emitting element, fine-grained temperature adjustment can be performed. In addition, since loss at the time of temperature adjustment is small, heater heating or the like can be performed by the battery.
[Brief description of the drawings]
FIG. 1 is a diagram showing a relationship between relative luminance of a light emitting element of an LED and forward voltage.
FIG. 2 is a relationship diagram between a relative temperature of a heating element and a forward voltage.
FIG. 3 shows an example of a temperature control circuit according to the present invention.
FIG. 4 is a diagram showing voltages at respective points in FIG. 3;
FIG. 5 shows another embodiment of the temperature control circuit.
FIG. 6 is a diagram illustrating voltages at respective points in FIG. 5;
FIG. 7 shows an example of a lighting stabilization circuit diagram.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Stabilized power supply 2 ... Thyristor 3 ... Amplifier 4 ... Comparator 5 ... Transistor R2 ... Heating element

Claims (4)

A method for controlling the temperature of an element, characterized in that the characteristic changes depending on the temperature, the temperature-electric characteristic of an electronic element that functions by energization is taken as a temperature detection signal, and the amount of current and voltage applied to these elements is controlled. 2. The temperature control method according to claim 1, wherein the element whose characteristics change with temperature is a light emitting element, a heating element, or a cooling element. The device according to claim 2, wherein the light emitting element is an LED, an element that emits fluorescence or phosphorescence by electronic excitation, light excitation or chemical excitation, an incandescent lamp, a halogen lamp, the heating element is a heater or a Peltier element, and the cooling element is a Peltier element. Temperature control method. The temperature control method according to claim 1, wherein the temperature-electric characteristic has a positive or negative temperature coefficient.

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