JPH0731479B2 - Electrical detector display device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device of an electrical detection device, which is a temperature detection device used in a general household or a prediction of ovulation used in the field of agriculture and livestock. It can be applied to a detection device or the like.

Configuration of conventional example and its problems In recent years, electrical detection devices that perform electrical detection by level determination and display the output by a light emitting display means such as an LED for use have been applied in various aspects. It has become.

FIG. 1 shows a conventional example of an LED drive circuit when an LED is used as a display means of these electrical detection devices.

In FIG. 1, 1 to 5 are voltage comparators and their output terminals are open collectors. 6-10 LED, 11-15 L
It is a current limiter of ED, and LED lights up according to the output of voltage comparators 1-5.

Reference numerals 16 to 21 are reference voltage dividing resistors for supplying a reference voltage to each of the voltage comparators 1 to 5.

The operation of the LED drive circuit configured as above is as follows.

The detected voltage Vx is input to the input terminals of the voltage comparators 1 to 5, and the voltage Vx is lower than the reference voltage divided by the power source 21 and the series connection of 16 to 20, Considering the case of gradually rising, the outputs of the voltage comparators 1 to 5 are at a high level in the initial stage, and the LED does not light. The voltage Vx rises, the output of the voltage comparator 5 becomes a low level, and the current of the LED 10 is generated and turned on. Each time the voltage Vx rises and exceeds the reference voltage, the voltage comparator changes from 4 → 3 →
2 → 1 and each output becomes low level, and LED is 9 accordingly
→ 8 → 7 → 6 are lit up, and finally LEDs 6 to 10 are all lit up, so-called bar display is performed.

FIG. 2 is also a conventional example, similarly to the above, 31 to 35 are voltage comparators, 36 to 40 are LEDs, 41 to 45 are LED current limiters, and 46 to 51 are reference setting resistors for voltage comparators. Is.

In this example, when the output of the voltage comparator 35 becomes low level, the LED 40 first lights up.

Next, when the output of the voltage comparator 34 becomes low level, the LED 39 lights up, and at the same time, the anode side of the LED 40 of the resistor 45 also becomes low level, so the LED 40 is extinguished. Similarly, when the voltage comparator goes from 33 → 32 → 31 and the output becomes low level in sequence, the LED
Also, the so-called dot display is performed in which the LEDs are turned on sequentially in the order of 38 → 37 → 36.

However, the above-mentioned configuration has a drawback that a large amount of current is consumed when driving the LED. For example, in the circuit of Figure 1, all LEDs are lit to indicate the final level.

In the circuit of FIG. 2, despite the dot display,
Since the LEDs are turned off by bypassing the current, the same level of current that would turn on all the LEDs will be produced at the final level. Further, when changing the brightness of the LED, it is necessary to change all the resistors connected in series to the LED at the same time, which is difficult to change.

OBJECT OF THE INVENTION The present invention provides a display device that improves the above-mentioned drawbacks, consumes less current in an electrical detection device, and can easily change the brightness of an LED.

According to the present invention, an exclusive OR gate is connected for every two adjacent output terminals of a plurality of level judgment devices, and only one output terminal of the level judgment device at the upper or lower end is connected. High or low level is input to the other input terminal of the sum gate, each output terminal of the exclusive OR gate is connected to the LED drive circuit, and one terminal of the LED is connected to the output terminal of the LED drive circuit, The other terminals of the LED are collectively connected to a current limiter.

Further, the equivalent circuit of the exclusive OR gate is composed of transistors.

Description of Embodiments FIG. 3 shows an embodiment of a display device of an electrical detection device of the present invention.

Reference numerals 61 to 65 are voltage comparators whose output terminals are not open collectors, and 66 to 70 are exclusive OR gates, which connect two outputs that are in phase with each other to the input terminals. Also, the output of only the voltage comparator 61 is input to the exclusive OR gate 66 at the upper end, and the other input terminals are connected to the high level.

71 to 75 are inverters which invert the output of the exclusive OR gate. Reference numerals 76 to 80 are LEDs, which are used to perform lighting display. Reference numeral 81 is an LED current limiter, which connects the anodes of LEDs 76 to 80 between the point and the power supply. Reference numerals 82 to 87 are resistors for generating a reference voltage.

The operation of the display circuit configured as described above is as follows.

When the detected voltage Vx is lower than the reference voltage set by the resistor 87, the output of the voltage comparator 65 is at a high level. Similarly, the voltage comparators 61-64 are also at high level. Therefore, the LEDs 76-80 are extinguished because all inputs of the exclusive-OR gates 66-70 are at the same value and the output terminals are all at the low level, so that the outputs of the inverters 71-75 are at the high level.

When the reference voltage set by the Vx resistor 87 is exceeded, the output of the voltage comparator 65 becomes low level. On the other hand, since the output of the voltage comparator 64 is still high level, the input of the exclusive OR gate 70 becomes a different value and the output becomes high level, so that the output of the inverter 75 becomes low level and a current is generated in the LED 80. Light up.

Next, when Vx exceeds the voltage set by the resistors 87 and 86, the outputs of the voltage comparators 64 and 65 both become low level, the inputs of the exclusive OR gate 70 become the same value, and the output low level. Then, the output of the inverter 75 becomes high level and LED8
Although 0 is turned off, the input of the exclusive OR gate 69 has a different value, so that the LED 79 is turned on.

As described above, so-called dot display is performed by sequentially turning on the LEDs. The LED current at this time is only the current of the lighting LED.

FIG. 4 shows an example of using the temperature detecting device according to the embodiment of the present invention.

In FIG. 4, 90 to 94 are voltage comparators whose output terminals are not open collectors, 95 to 104 are transistors, and the outputs of the voltage comparators 90 to 93 other than the voltage comparator 94 at the lower end are NP.
One N-transistor and one PNP transistor are connected. An NPN transistor is connected to the voltage comparator 94, and it is connected to a voltage comparator adjacent to the collector of the PNP transistor.
LEDs 106-109 are connected to the collector of the NPN transistor. 110 is an LED current limiter, which is a transistor 101-1
LE connected to the emitter of 04 and the collector of transistor 99
It is connected between the point where the anode of D105 and the power supply are connected together. Reference numeral 111 is an NTC thermistor whose resistance value changes with temperature, and 112 to 118 are resistors that form a bridge circuit.

The operation of the temperature detecting device configured as above will be described below.

Now, the voltage set by the thermistor 111 and the resistor 112 is
Since the temperature is low and therefore the resistance value of the thermistor 111 is large, when the voltage is lower than the reference voltage set by the resistor 118, all the outputs of the voltage comparators 90 to 94 are at the low level. Therefore,
All the PNP transistors 101 to 104 are on.
On the other hand, the NPN transistors 95 to 99 are all off. Therefore, the LEDs 105 to 109 do not light.

Next, when the temperature rises and the resistance value of the thermistor 111 decreases and exceeds the reference voltage set by the resistance value 118, the output of the voltage comparator 94 goes high and the transistor 95 turns on. A current is generated in the LED 109 through the transistor 101 that has been operated, and the LED 109 lights up.

Next, when the voltage comparator 94 goes high, the transistor
101 turns off, LED109 turns off, and transistor 96 turns on.
A current is generated in the LED 108, and the LED 108 lights up.

As described above, the LEDs sequentially perform dot display by an operation equivalent to that of the exclusive OR gate of the above-described embodiment.

FIG. 5 is an external view of the main body of the embodiment of FIG. 4, in which 120 is an LED display portion, 121 is a thermistor-sealed pipe, and 122 is a main body. The temperature is calibrated at an appropriate oil temperature of 160 ° C. to 200 ° C. for tempura cooking, and the tip of the pipe 121 can be put into oil to measure the oil temperature. The resolution in this case can be arbitrarily set depending on the number of level detection devices.

As described above, according to the present invention, the level can be displayed by the LED with a simple structure, the current consumption is small, and the battery can be driven. Also, because all LEDs can determine the current by one current limiter,
The brightness can be easily changed by changing the current of D.

EFFECTS OF THE INVENTION According to the present invention, by connecting an exclusive OR gate for every two adjacent outputs of a plurality of level determination devices, the LED corresponding to the level detected by the plurality of LEDs corresponding to the plurality of levels is set to 1. It is possible to provide a display circuit with a simple structure capable of lighting only one piece and consuming less current. Also, the LED current can be changed by changing the resistance value of one current limiter, and the brightness can be easily changed. In addition, the number of parts may be small, and the circuit configuration is simple.

[Brief description of drawings]

1 and 2 are electric circuit diagrams showing a conventional example of a display device using LEDs, FIG. 3 is an electric circuit diagram of an embodiment of the display device of the electrical detection device of the present invention, and FIG. FIG. 5 is an electric circuit diagram of another embodiment of the present invention, and FIG. 5 is a perspective view showing the appearance of an embodiment of an electrical detection device to which the present invention is applied. 61,62,63,64,65 …… Level judgment device, 66,67,68,69,70…
… Exclusive OR gate, 76,77,78,79,80 …… LED.

Claims (2)

[Claims] 1. A plurality of level judging devices, wherein an exclusive OR gate is connected to every two adjacent output terminals of adjacent level judging devices, and one of the upper or upper end level judging devices is connected. Input a high or low level to the other input terminal of the exclusive OR gate connected only to the output terminal, connect each output terminal of the exclusive OR gate to the LED drive circuit, and
Connect one LED terminal to the output terminal of the ED drive circuit
A display device for an electrical detection device configured by connecting all the other terminals to a current limiter collectively. 2. An exclusive OR gate is used as an NPN transistor and a PNP.
The collector of the PNP transistor and the collector of the NPN transistor, which are configured by combining with the transistor, are connected to the output terminals of the level judgment device and the bases of the NPN transistor and the PNP transistor are connected to the output terminals of the adjacent level judgment device. The display device of the electrical detection device according to claim 1, wherein the and PLEDs are connected to each other by an LED, and the emitters of the PNP transistors are collectively connected to the current limiter.