JPH0246875B2 - TEIONSHOOKEESUTONOONDOHYOJISOCHI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to displaying the temperature inside a refrigerator such as a low-temperature show case, and an object of the present invention is to accurately display the temperature inside the refrigerator and to effectively utilize a light emitting diode element.

Conventionally, there are digital displays and analog displays as temperature display means, but most of them are digital displays that display the temperature inside the refrigerator using numbers or the like. On the other hand, there is a storage temperature range for foods stored in a storage case, and if the internal temperature is within that storage temperature range, there is no need to display the internal temperature numerically; the internal temperature is simply within the storage temperature range. It is only necessary to judge whether the temperature inside the refrigerator is appropriate or abnormal, but displaying numbers is rather cumbersome, and it is not possible to instantly determine whether the temperature inside the refrigerator is appropriate or abnormal. In addition, when displaying the temperature inside the refrigerator using multiple light emitting diodes (hereinafter referred to as LEDs), it is necessary to check the number of LEDs that are lit, and the installation work of the LEDs to the show case becomes complicated and the installation location is also limited. be done. Furthermore, there is a difference in lifespan between LEDs that emit light all the time and LEDs that hardly emit light, and the lifespan of LEDs that emit light all the time is short.

The present invention has been made in view of the above-mentioned drawbacks, and one embodiment thereof will be described below with reference to the drawings. 1st
The figure is an electrical circuit diagram. 1 is a DC power supply with bus A,
Power is supplied via B. 2 is a temperature detection circuit, which is connected between bus bar A and bus bar B, and includes a series circuit of a first resistor R ₁ and a temperature sensor S such as a thermistor, and a series circuit of a second resistor R 2 and a first resistor R ₂ . It is composed of a bridge circuit including a series circuit of a variable resistor R ₁ ' and a second variable resistor R ₂ '. Note that the temperature sensor S is installed in the store case, for example, near a cold air outlet, and its impedance decreases as the temperature increases. Reference numeral 3 denotes an amplifier circuit composed of a first operational amplifier (hereinafter referred to as a first amplifier) 4 and a second operational amplifier (hereinafter referred to as a second amplifier) 5. The (-) input side of the first amplifier 4 and the (+) input side of the second amplifier 5 are connected to the midpoint between the first resistor R ₁ and the temperature sensor S. The (+) input side of the amplifier is connected to the midpoint between the second resistor 5 and the first variable resistor R ₁ ', and the (-) input side of the second amplifier 5 is connected to the first variable resistor R ₁ '. It is connected to the midpoint with the second variable resistor R ₂ '. Note that the (+) side input voltage of the first amplifier 4 and the second amplifier 5
The (-) side input voltage of the first and second variable resistors R ₁ ′,
Set by R ₂ ′. In addition, the (+) side input voltage of the first amplifier 4 and the (-) side input voltage of the second amplifier 5 are controlled by the temperature inside the refrigerator by the first and second variable resistors R ₁ ′ and R ₂ ′. When the temperature is higher, for example, 3°C to 10°C, the (+) side input voltage of the first amplifier 4 is higher than the (-) side input voltage of this amplifier, and the second amplifier 5
When the (+) side input voltage of the amplifier is lower than the (-) side input voltage of this amplifier and the internal temperature is within the appropriate temperature range, the (+) side input voltage of the first and second amplifiers 4 and 5 respectively When the (-) side input voltage of the first amplifier 4 is higher than the (-) side input voltage of the first amplifier 4 and the (-) side input voltage of the second amplifier 5 is lower than the (-) side input voltage when the temperature inside the refrigerator is lower than the appropriate temperature. The +) side input voltage is set in advance to be higher than the (-) side input voltage.

6 is a light emitting diode lighting circuit. _D1 is the first light emitting diode (hereinafter referred to as the first LED)
It is connected from the bus line A with the midpoint between the third resistor R ₃ and the fourth resistor R ₄ as the forward direction, and emits green light when energized. D ₂ is the second light emitting diode (hereinafter referred to as second LED) and is connected from the bus bar to the fifth resistor R ₅
and the sixth resistor R ₆ are connected with the midpoint direction as the forward direction, and when energized, they emit red light. In addition, first,
The second LEDs D ₁ and D ₂ are one LED as shown in Figure 2.
Built into LED element D and emitting light,
The emitted light color of the LED element D changes. Q is an NPN type transistor (hereinafter referred to as Tr), and its base is connected to the first amplifier 4 via the first diode _D1 '.
A second diode D ₂ ' is connected to the output side of the second
are connected to the output sides of the amplifiers 5, respectively, with the output side direction being the forward direction, and are also connected to the bus line A via the seventh resistor _R7 . Also, the collector is the third one,
It is connected to the output side of the first amplifier 4 via the fourth resistor R ₃ , R ₄ and the third diode D ₃ ′, and is connected to the output side of the first amplifier 4 via the fourth resistor R ₃ , R ₄ and the third diode D 3 ′. It is connected to the output side of the second amplifier 5 via a diode D ₄ '. Note that the third and fourth diodes D ₃ ' and D ₄ ' are connected with the output side directions of the first and second amplifiers 4 and 5 as forward directions, respectively. Also, the emitter of Tr Q has the bus line direction as the forward direction toward the bus bar 8, and the emitter of Tr Q
It is connected to bus B via a fifth diode D ₅ ' to satisfy the OFF condition.

The operation will be explained below based on the electric circuit diagram shown in FIG. For example, if the compressor of the cooling system breaks down and the temperature inside the refrigerator gradually rises and exceeds the upper limit temperature of 10°C, the impedance of the temperature sensor S decreases and the (+) side input voltage of the first amplifier 4 decreases. (-)
The (+) side input voltage of the second amplifier 5 is higher than the (-) side input voltage. Therefore, the output voltage of the first amplifier 4 becomes a high potential (hereinafter referred to as "H"), and the output voltage of the second amplifier 5 becomes a low potential (hereinafter referred to as "L"),
The base of Tr Q is drawn to the "L" output of the second amplifier 5 and has a low voltage, and Tr Q is turned off.
Therefore, since the output of the first amplifier 4 is "H" and the Tr Q is OFF, no current flows through the first LED D ₁ and no green light is emitted. On the other hand, from the bus A the second LED D ₂ , the fifth resistor R ₅ and the fourth diode
Since current flows to the second amplifier 5 via D ₄ ', the second LED D ₂ emits red light. Therefore,
LED element D indicates high temperature in red.

As the cooling operation resumes, the temperature inside the refrigerator gradually decreases, the temperature of the temperature sensor S decreases, and its impedance gradually increases. When the temperature inside the refrigerator falls below the upper limit temperature of 10°C and falls within the appropriate temperature range, the impedance of the temperature sensor S increases, so the first amplifier 4 remains unchanged and its (+) side input voltage changes to the (-) side. higher than the input voltage, and the (+) side input voltage of the second amplifier 5 is higher than its (-) side input voltage. Therefore, the first amplifier 4 maintains the output "H", and the second amplifier 5 maintains the output "H".
Therefore, the first and second diodes D ₁ ′ and D ₂ ′ are reverse biased, and the base current flows through Tr Q via the seventh resistor R ₇ to turn it on, and the collector voltage decreases. In addition, the outputs of the first and second amplifiers 4 and 5 are "H".
reverse biases the third and fourth diodes D ₃ ′ and D ₄ ′. Therefore, the current flows from bus A to first LED D ₁
and the fourth resistor R ₄ to the collector of the Tr Q, and from the bus A through the second LED D ₂ and the sixth resistor R ₆ to the collector of the Tr Q, the emitter, and the fifth diode D. ₅ ' and flows to bus B through the first,
The second LEDs D ₁ and D ₂ emit green and red light, respectively, and the LED element D displays the appropriate temperature in orange, which is a mixture of green and red.

On the other hand, for example, if the temperature sensor that controls the operation of the compressor fails and the compressor continues to operate, the temperature of the temperature sensor S decreases as the temperature inside the refrigerator decreases, and its impedance further increases. When the temperature inside the refrigerator falls below the lower limit temperature of 3°C in the appropriate temperature range, the voltage between both terminals of the temperature sensor S increases, and the (+) side input voltage of the first amplifier 4 becomes lower than the (-) side input voltage. , the second amplifier 5 remains its (+)
The side input voltage is higher than the (-) side input voltage. Therefore, the output of the first amplifier 4 becomes "L", and the Tr Q
The base of Tr is drawn to the output "L" of the first amplifier 4 through the first diode _D1 and becomes a low potential.
Q becomes OFF. Therefore, the first LED D ₁ and the third
through the resistor R ₃ and the third diode D ₃ ′.
A current flows to the amplifier 4, and the first LED D ₁ ' emits green light. On the other hand, the second amplifier 5 maintains the output "H", but since Tr Q is OFF, the second LED
No current flows through D ₂ and no red light is emitted. Therefore, the LED element D displays a low temperature in green. On the other hand, when the compressor stops operating and the temperature inside the refrigerator rises, the operation opposite to the above is performed, and as the temperature inside the refrigerator rises, the LED element D changes from the green low temperature indication to the orange appropriate temperature indication. Switch. Therefore, when the temperature inside the refrigerator is high, the LED element D emits red light, when the temperature is within the appropriate temperature range, it emits orange light, and when the temperature is low, it emits green light. Such display operation is as shown in FIG. Therefore, there is no need to approach the display each time to check the temperature inside the refrigerator and read the number when the temperature inside the refrigerator is displayed numerically.
Even if you are far from the LED element D, as long as you can judge its emitted light color, you can instantly determine whether the temperature inside the refrigerator is within the appropriate temperature range, high temperature, or low temperature.
Also, compared to using a plurality of LEDs and determining the temperature inside the refrigerator based on the number of LEDs lit, there is no need to check the number of LEDs lit, and the temperature inside the refrigerator can be determined instantly in the same way as above. On the other hand, LED element D1
Since the temperature is displayed individually, the installation work is simplified and there are no restrictions on the installation location. Furthermore, when the temperature inside the refrigerator is at an appropriate temperature for a longer period of time than when it is high or low, the first and second LEDs D ₁ and D ₂ are emitted simultaneously to emit orange, which is a mixed color of green and red. Therefore, there is almost no difference in the lifespan of the first and second LEDs D ₁ and D ₂ and the LED element D
In addition, when the LED is configured to emit green light to indicate low temperature, red light to indicate appropriate temperature, and mixed color orange to indicate high temperature, for example, an LED that emits green light will emit light. If a malfunction occurs, the appropriate temperature will be displayed in red even though the temperature inside the refrigerator is high, but in this example, the green light indicates the low temperature, the red light indicates the high temperature, and the orange light indicates the appropriate temperature. For example, if the first LED D ₁ that emits green light fails to emit light, the temperature display will stop or a red high temperature display will be displayed, and the appropriate temperature will not be displayed even though the temperature inside the refrigerator is high.

As described above, according to the present invention, in a temperature display device such as a low-temperature display case, the temperature inside the refrigerator can be displayed in three color-coded ranges by causing one or both of the two primary colors of the light emitting diode element to emit light. Therefore, the user can instantly and accurately judge the temperature inside the refrigerator from a remote location. In particular, the width of the temperature range displayed in both mixed colors can be changed and set very easily using a single variable resistor, making it highly versatile for the low-temperature case it is attached to and the types of food stored. Get rich.

In particular, high temperatures for one primary color and low temperatures for the other primary color.
Since the appropriate temperature is displayed using a mixture of both colors, both light emitting diode elements emit light during the optimum temperature display, which takes the longest display time, so the life spans of both light emitting diode elements are balanced and the light emitting diode elements can be used effectively. be.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram, FIG. 2 is a schematic diagram of a light emitting diode element, and FIG. 3 is an explanatory diagram of the display operation of the light emitting diode element with respect to the internal temperature. 1...DC power supply, 2...Temperature detection circuit, S...
Temperature sensor, R ₁ ′, R ₂ ′...first and second variable resistors, 3...amplification circuit, 4, 5...first and second operational amplifiers, 6...light-emitting diode lighting circuit, _D1 ,
_D2 ...First and second light emitting diodes, D...Light emitting diode element, Q...Transistor.

Claims (1)

[Claims] 1. A bridge circuit consisting of a series circuit of a resistor and a temperature sensor that detects the internal temperature, a resistor, a variable resistor, and a series circuit of the resistor, and a bridge circuit that connects the voltages across the variable resistors to input terminals of mutually different polarities. a first operational amplifier and a second operational amplifier each inputting a terminal voltage of the temperature sensor to another input terminal; and a first operational amplifier connected to an output side of the first operational amplifier; one light emitting diode that emits one primary color when the output thereof is at a high potential; and a parallel relationship with the one light emitting diode, and connected to the output side of the second operational amplifier, the output of the second operational amplifier. a light emitting diode element consisting of another light emitting diode that emits a primary color different from the one primary color when the voltage is high, and the output of either of the operational amplifiers is turned off when the voltage is low; It consists of a transistor that turns on when both outputs of both operational amplifiers are at a high potential, and the light emitting diode element emits and mixes the primary colors of both light emitting diodes simultaneously when the outputs of both operational amplifiers are at a high potential. If the outputs of the two operational amplifiers have different polarities, the outputs of the two operational amplifiers are combined to emit the primary color of one of the light emitting diodes to display a low temperature lower than the optimum temperature of the other light emitting diode. A temperature display device such as a low-temperature display case, characterized in that it emits primary colors to display a high temperature higher than the appropriate temperature.