JPH06273233A - Radiant heat sensor - Google Patents

Abstract

PURPOSE:To protect a thermosensitive film, to perform precise detection according to existence/absence of food, and to carry out temperature compensation precisely without, depending on a temperature change in the inside of a freezer. CONSTITUTION:A sensor main body 18 is constructed by providing a sensor case 19, in the inside of which the first thermistor 21, a thermosensitive film 22, and the second thermistor 23 are arranged, on the upper wall face of a freezer chamber 12. An adospheric temperature of the inside 14 of the freezer is detected by the thermistor 21, while a temperature of the thermosensitive film 22 absorbing a radiant heat of the inside 14 of the freezer is detected by the thermistor 23. A cover 24, through which the radiant heat permeates, is arranged on the lower face part of the sensor main body 18. The themosensitive film 22 is protected from damage due to contact from the inside 14 of the freezer by the cover 24. The temperature difference between detected temperatures by the thermistors 21, 23 is detected in a timer time after a door 15 is closed, so that a temperature change depending on existence/absence of food A is precisely determined.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiant heat sensor for detecting the temperature of an object such as food contained in a storage chamber in a non-contact manner.

[0002]

2. Description of the Related Art As a radiant heat sensor for detecting the radiant heat emitted from an object such as food and detecting the temperature of the object in a non-contact state, there is, for example, one shown in FIG. That is, the radiant heat sensor 1 includes a sensor case 2 having an opening 2a and made of a heat insulating member, a first thermistor 3 for detecting an ambient temperature in the sensor case 2, and a heat sensitive film provided in the opening 2a. 4, this thermal film 4
It is composed of a second thermistor 5 for detecting the temperature of and a detection circuit 6.

The heat-sensitive film 4 has a property of being heated by radiant heat such as infrared rays received from the outside, and the radiant heat is detected by the second thermistor 5. The detection circuit 6 is a circuit for detecting the temperature of radiant heat based on the value of the difference between the detection signals of the first and second thermistors 3 and 5, and specifically, the first and second thermistors 3 and 5 The value of the difference between the detection signals is detected and amplified by the differential amplifier 7 and output as a temperature detection signal.

With such a structure, for example, when an object such as food is placed in the storage room, the radiant heat generated corresponding to the temperature of the object is absorbed by the heat sensitive film 4. In the radiant heat sensor 1, the temperature inside the sensor case 2 is detected by the first thermistor 3, and the temperature detection signal is input to the differential amplifier 7 of the detection circuit 6, while the second thermistor 5 causes the thermosensitive film 4 to be detected. Is detected, and the temperature detection signal is input to the differential amplifier 7 of the detection circuit 6. As a result, the differential amplifier 7 outputs a signal obtained by subtracting the first temperature detection signal from the temperature detection signal of the second thermistor 5 as a signal corresponding to the temperature of the object placed in the storage chamber.

This is because the ambient temperature in the sensor case 2 is actually added to the temperature detection signal of the heat sensitive film 4 by the second thermistor 5, and thus the differential amplifier 7 is used to The temperature compensation is performed by subtracting the component of the temperature detection signal with respect to the ambient temperature in the sensor case 2 detected by the thermistor No. 1 to accurately detect the temperature of the object placed in the storage chamber. .

[0006]

However, the conventional structure as described above has the following problems when it is applied to a refrigerator for refrigerating or freezing food, for example. That is, first, the heat-sensitive film 4 for absorbing radiant heat needs to be thin in order to reduce its heat capacity and improve detection accuracy, but this has low strength against external force, for example, There is a risk that the food may come into contact with and be damaged when the food is taken in and out, or when the inside of the refrigerator is cleaned.

Secondly, in the refrigerator, since the temperature difference between the inside of the refrigerator and the outside is large, when the outside air enters the inside of the refrigerator when the door is opened, the temperature of the wall surface inside the refrigerator is increased by the outside air temperature. Although it comes to rise, at this time, whether the radiant heat to the heat-sensitive film 4 was emitted from the food immediately after the door was closed in the case of containing the food and the case of only the opening / closing operation of the door, the temperature increased. It may not be possible to determine whether the light is being emitted from the wall surface inside the refrigerator, resulting in erroneous detection.

Thirdly, since the temperature inside the refrigerator fluctuates due to, for example, the operation and stop of the compressor for cooling the inside of the refrigerator, the temperature compensation by the first thermistor for detecting the ambient temperature cannot be sufficiently performed. False detection may occur depending on whether the door is opened and food is accommodated or when the door is simply opened and closed.

The present invention has been made in view of the above circumstances, and firstly, an object thereof is to protect a heat-sensitive film,
Second, reliable detection according to the presence of food, third
Another object of the present invention is to provide a radiant heat sensor capable of accurately performing temperature compensation regardless of temperature fluctuations in the refrigerator.

[0010]

In order to achieve the first object, the radiant heat sensor of the present invention is provided with a sensor chamber having an opening facing the storage chamber and a temperature detecting chamber. The first temperature detecting means, the heat sensitive film absorbing the radiant heat in the storage chamber, the second temperature detecting means provided so as to detect the temperature of the heat sensitive film, and the first and second temperature detecting means. Control means for detecting the temperature of an object placed in the storage chamber by performing a detection operation based on the difference in temperature detected by the temperature detection means, and from the room provided between the thermal film and the storage room It is characterized in that it is composed of a cover that can transmit radiant heat.

In order to achieve the second object, the radiant heat sensor of the present invention, in addition to the above configuration, measures a door switch which is turned on / off according to opening / closing of the door of the storage chamber and a predetermined delay time. A timer means is provided, and the control means operates the timer means based on a detection signal output from the door switch, which indicates a closed state of the door of the storage chamber, and detects when the delay time elapses. It is characterized in that the temperature of an object placed in the storage chamber is detected by performing an operation.

In order to achieve the third object, the radiant heat sensor of the present invention has first and second sensor chambers having openings facing the storage chamber, and the first and second sensor chambers. First and second heat sensitive films respectively provided to absorb radiant heat in the storage chamber, and provided in the first and second sensor chambers to detect the temperatures of the first and second heat sensitive films. First and second temperature detecting means, a first cover provided between the first heat-sensitive film and the storage chamber to block radiant heat from the storage chamber, and the second heat-sensitive film. A second cover, which is provided between the storage compartment and the radiant heat from the storage compartment, and a detection operation is performed on the basis of a difference in temperature detected by the first and second temperature detection means, and the storage is performed. Objects placed indoors It provided with control means for detecting the temperature and has a characteristic where configured.

[0013]

According to the radiant heat sensor of claim 1, the ambient temperature in the storage chamber is detected by the first temperature detecting means,
The radiant heat in the storage chamber passes through the cover and is absorbed by the heat sensitive film, and the temperature of the heat sensitive film is detected by the second temperature detecting means. The control means can detect the temperature of the object placed in the storage chamber by performing a detection operation based on the difference between the temperatures detected by the first and second temperature detection means. Since the film is protected by the cover, it does not come into direct contact with the inside of the storage chamber, and problems such as damage to the heat-sensitive film are eliminated.

According to the radiant heat sensor of the second aspect, when the door of the storage chamber is opened and closed, the door switch can be turned on and off to detect the state, and the control means is such that the door switch is the storage chamber. The timer means is operated based on the output of the detection signal indicating the closed state of the door, and when the delay time elapses, the detection operation is performed to detect the temperature of the object placed in the storage chamber. If the object is not stored in the storage room only when the door is opened / closed, the presence of the object is erroneously detected because the temperature of the wall changes due to the outside air entering the storage room due to the opening / closing operation of the door. The problem is resolved.

According to the radiant heat sensor of the third aspect, since the first heat-sensitive film provided in the first sensor chamber is shielded from the heat radiation from the storage chamber by the first cover, The temperature detecting means detects the temperature according to the ambient temperature in the storage chamber, and the second heat-sensitive film provided in the second sensor chamber transmits the heat radiation from the storage chamber by the second cover. The second temperature detecting means detects the temperature due to heat radiation in the storage chamber. The control means is
The temperature of the object placed in the storage chamber can be detected by performing a detection operation based on the difference between the temperatures detected by the first and second temperature detecting means. At this time, the first temperature detecting means Since the arrangement state is the same as that of the second temperature detecting means, it is possible to accurately detect the detection component of the ambient temperature in the storage chamber, which the second temperature detecting means detects at the same time as the temperature of the radiant heat. Therefore, the temperature of the object in the storage chamber can be detected more accurately.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment in which the present invention is applied to a refrigerator freezer will be described below with reference to FIGS. First, in FIG. 1 showing the overall configuration, a freezer compartment 12 provided as a storage compartment in a refrigerator 11 is surrounded by a heat insulating member 13 and is insulated from the outside. The stored food A is cooled by the circulation of the cool air sent to the inside 14 of the refrigerator. A door 15 is provided in the front opening 12a of the freezer compartment 12 so as to be openable and closable by rotation, and a door switch 16 is turned on / off according to the opening / closing of the door 15.
(See FIG. 3) are provided.

The sensor body 18 is constructed as follows. That is, the sensor case 19 made of a heat insulating member having the opening 19a on the lower surface side and forming the sensor chamber 19b.
Is an opening 17 formed in the upper wall surface 17 of the freezer compartment 12.
It is fixed by a screw 20 so as to close a.
A first thermistor 21 is provided above the inside of the sensor case 19 as a first temperature detecting means provided so as to detect the ambient temperature inside the sensor case 19.

Further, in the opening 19a of the sensor case 19, the heat sensitive film 2 is formed so as to cover the opening 19a entirely.
2 are provided. The heat-sensitive film 22 has a property of absorbing radiant heat of infrared rays, and is adapted to receive radiant heat from the freezer compartment 12. The second thermistor 23 as the second temperature detecting means is arranged in the sensor case 19 in the vicinity of the heat sensitive film 22 and mainly detects the temperature of the heat sensitive film 22. Below the sensor case 19, a cover 24 is attached to the upper wall surface 17 of the freezer compartment 12 so as to cover the surface of the heat sensitive film 22. This cover 24, as shown in FIG.
It is in the form of a flat plate, and is made of, for example, a polycarbonate resin having a property of transmitting radiant heat due to infrared rays.

Next, referring to FIG. 3 showing the electrical structure, the above-mentioned first thermistor 21 and second thermistor 23 are provided.
Are connected between the DC power supply terminal VD and the ground with the resistors 25 and 26 connected in series.
The inverting input terminal of the differential amplifier 27 is the first thermistor 21.
Is connected to a common connection point of the resistor 25 and the non-inverting input terminal is connected to a common connection point of the second thermistor 23 and the resistor 26. The non-inverting input terminal of the comparator 28 is connected to the output terminal of the differential amplifier 27, and the inverting input terminal is connected to the output terminal of the voltage setting circuit 29. Voltage setting circuit 2
Reference numeral 9 is for outputting the divided voltage of the series circuit of the resistors 30 and 31 connected between the DC power supply terminal VD and the ground as the comparison reference voltage Vs. The output terminal of the comparator 28 is A
AND connected to one input terminal of the ND circuit 32
The output terminal of the circuit 32 is connected to the control signal output terminal P.

The timer circuit 33 as a timer means waits for the timer time to elapse in response to the signal from the door switch 16 and validates the output signal of the comparator 28. Is the inverter circuit 3
Input terminal A of the monostable multivibrator 35 via
And one of the input terminals of the AND circuit 36. A clock pulse signal having a predetermined cycle is applied to the other input terminal of the AND circuit 36. The door switch 16 outputs a signal of "H" level when the door 15 of the freezer compartment 12 is in an open state and an "L" level when the door 15 of the freezer compartment 12 is in a closed state.

Further, the clear terminals CLR of the plurality of D type flip-flops 37a to 37n for generating the timer time are commonly connected to the signal output terminal of the door switch 16, and the respective clock input terminals CP are AND.
Commonly connected to the output terminals of the circuit 36. The data input terminal Da of the flip-flop 37a is connected to the output terminal Q of the monostable multivibrator 35, and the output terminal Qa is connected to the data input terminal Db of the next-stage flip-flop 37b. Hereinafter, the data input terminals D and the output terminals Q of the subsequent flip-flops 37b to 37n are connected to each other, and the output terminal Qn of the last flip-flop 37n is connected to the other input terminal of the AND circuit 32.

Next, the operation of this embodiment will be described with reference to FIGS. 4 and 5. First, in the sensor main body 18, the first thermistor 21 outputs a detection voltage according to the ambient temperature of the inside 14 of the refrigerator, and the second thermistor 2
By 3, the detection voltage according to the temperature of the heat sensitive film 22 is output. In this case, the radiant heat such as infrared rays emitted according to the temperature of each part of the inside of the refrigerator 14 is absorbed by the radiant heat such as infrared rays transmitted through the cover 24 and reaching the heat-sensitive film 21. The temperature of the heat sensitive film 22 is detected by the second thermistor 23.

The first and second thermistors 21 and 23 have a general negative temperature characteristic and are shown in FIG.
As also shown, the resistance value thereof has the property of decreasing as the temperature rises. Therefore, when the temperature to be detected is low, the resistance value is large, the divided voltage of the resistor 25 or the resistor 26, that is, the output voltage to the differential amplifier 27 is low, and conversely, when the temperature to be detected is high, the thermistor 21 is detected. , 23 becomes smaller and the output voltage to the differential amplifier 27 becomes higher.

The differential amplifier 27 includes the first and second amplifiers.
The difference between the detected voltages of the thermistors 21 and 23 is calculated and output as the detected temperature output VT. That is,
Since the second thermistor 23 actually contains a temperature component due to the ambient temperature, it is intended to obtain a signal output from which the temperature component due to the ambient temperature detected by the first thermistor 21 is subtracted. As a result, the temperature of the radiant heat component absorbed by the heat sensitive film 22 can be detected from the output terminal of the differential amplifier 27. In the comparator 28, when the detected temperature output VT given from the differential amplifier 27 is larger than the comparison reference voltage Vs given from the voltage setting circuit 29, the detection signal S is AN.
It is output to the D circuit 32.

At this time, if the "H" level signal is applied to the other input terminal of the AND circuit 32, the "H" level signal is output to the control signal output terminal P. The signal applied to the other input terminal of the AND circuit 32 is output from the timer circuit 33 as follows.

Now, when the door 15 of the freezer compartment 12 is opened by the user, the door switch 16 is turned on.
The "H" level signal is input to the timer circuit 33. At this time, each of the flip-flops 37a to 37n of the timer circuit 33 is in a reset state by being simultaneously given a signal of "H" level to the clear terminal CLR.

On the other hand, the "H" level signal from the door switch 16 is inverted by the inverter circuit 34 to the "L" level.
It is given to the monostable multivibrator 35 and the AND circuit 36 as a level signal. At this time, the output terminal Q of the monostable multivibrator 35 is in the "L" level state, and the output of the clock signal is blocked in the AND circuit 36.

Next, when the door 15 is closed, the output signal of the door switch 16 is inverted to the "L" level. Then, each of the flip-flops 37a to 37n of the timer circuit 33 is
The input signal to the clear terminal CLR becomes "L" level and the reset state is released. Further, the monostable multivibrator 35 is supplied with an "H" level signal via the inverter circuit 34, and outputs an "H" level signal from the output terminal Q for a predetermined time.
Then, in the AND circuit 36, when the "H" level signal is applied to one terminal, the clock pulse signal applied to the other input terminal is output, and the flip-flops 37a to 37n.
To each clock pulse input terminal CP.

As a result, in the flip-flop 37a, the "H" level signal is applied to the data input terminal Da when the first clock pulse signal is applied, so that the flip-flop is applied from the output terminal Qa. A signal of "H" level is applied to the data input terminal Db of 37b. At this time, another flip-flop 37
In b to 37n, when the first clock pulse signal is applied, since the "L" level signal is applied to the input terminals Db to Dn, the output terminals Qb to Qn are applied to the "L" level signal. Is being output.

After that, when the next clock pulse signal is applied, the flip-flop 37b causes the data input terminal Db.
The "H" level signal applied to the output terminal Qb
Outputs an "H" level signal from the flip-flop 3
7c to the data input terminal Dc. Less than,
Similarly, when n clock pulse signals are output, “H” is output from the output terminal Qn of the flip-flop 37n.
A level signal is output and applied to the other input terminal of the AND circuit 32.

As a result, the AND circuit 32 is input from the comparator 28 after the timer time from the time when the door 15 is closed to the time when n clock pulse signals are output has elapsed as the delay time. The detection signal S is output to the control output terminal P, and the detection signal S when compared by the comparator 28 according to the detection temperature signal VT at this time is obtained as the state of the inside of the refrigerator 14. In this case, when the detection signal S is output, it is determined that the food A is stored in the refrigerator 14 and the cooling operation of the refrigerator 14 is performed.

Since the presence or absence of the detection signal S is determined after the timer time has elapsed as described above, it is accurately determined whether or not food has been stored in the refrigerator 14 as described below. It is possible.

That is, first, the door 1 for the freezer compartment 12
Since various modes according to opening and closing of 5 are possible, this will be described with reference to FIG. Regarding the opening / closing operation of the door 15 of the freezer compartment 12 by the user, there are cases where (1) only the opening / closing operation is performed and no food is stored, and (2) food is stored. In each of them, the method of changing the temperature of the inside 14, that is, the temperature detected by the sensor main body 18 differs depending on the length of the opening time of the door 15, the presence or absence of food in the inside, the temperature of the stored food, and the like. come.

For example, in FIGS. 4 (a) and 4 (b),
Changes in the temperature VT detected by the sensor body 18 when the food is not stored in the refrigerator 14 only by opening and closing the door 15 and the door opening time is short (a) and long (b) (thick) (Indicated by a solid line). From now on, when the door 15 is opened only for a short time (time t2), the detected temperature VT at the time of closing the door 15 (time t3) does not rise so much, but when the door 15 is opened for a long time. At (time t1 to t3), the temperature of members such as the wall surface of the interior 14 rises due to the outside air, so the detected temperature VT becomes considerably high when the door 15 is closed. On the other hand, the same figure (c), (d)
As shown in FIG. 5, when the cooled food is stored in the refrigerator 14, since the food has a large heat capacity, the door 15
Even if the opening time is long, the temperature of the inside 14 does not rise sharply.

Further, in the figures (e), (f), (g),
As shown in (h), when the door 15 is opened and then the food is stored in the refrigerator 14, the detected temperature VT at the time when the door 15 is closed (time t3) is stored. It depends on whether the temperature of the food is low-temperature food or normal-temperature food, and the opening time of the door 15 is not much affected.

That is, when the temperature is detected at the time when the door 15 is closed (time t3), it becomes indistinguishable between the case where food is stored in the refrigerator 14 and the case where the door 15 is only opened and closed for a long time. There is a problem that causes false detection,
In this way, since the detection operation is performed by the timer circuit 33 after the elapse of a certain timer time (time t4 in the figure), it is possible to reliably determine whether or not the food is contained.

According to this embodiment, since the cover 24 capable of transmitting radiant heat such as infrared rays is provided on the front surface of the heat-sensitive film 22, food is stored in the freezer compartment 12 or cleaned. In doing so, the heat-sensitive film 22 will not be accidentally contacted and damaged, and the heat-sensitive film 22 can be thinned to increase the sensitivity. Further, since the outside air does not directly flow into the heat sensitive film 22 from the freezer compartment 12 side by using the flat cover 24, dew condensation or frost formation of the heat sensitive film 22 is eliminated, and responsiveness at the time of temperature detection and The decrease in sensitivity can be prevented.

According to this embodiment, the timer circuit 3
3 and the door switch 16 are provided, and the temperature detection signal V after a predetermined delay time elapses from the time when the door 15 is closed
Since the detection operation is performed based on T, whether the temperature in the refrigerator is increased only by the opening / closing operation of the door 15 when the door 15 is closed, or the temperature in the refrigerator is increased because food is stored. It becomes possible to perform an accurate detection operation by avoiding the detection operation in a state where it is not possible to distinguish whether or not it is present.

FIG. 6 shows a second embodiment of the present invention. Hereinafter, parts different from the first embodiment will be described with reference to FIG. That is, in the present embodiment, a timer circuit 38 is provided instead of the timer circuit 33. Further, in this embodiment, the fan switch 39 for detecting the operating state of the fan of the evaporator for performing the cooling operation of the refrigerator is used. The operation of the evaporator fan is normally performed intermittently according to the temperature state of the inside of the refrigerator 14, and when the door 15 is opened during operation, it is closed based on a signal from the door switch 16. The operation is stopped during that period.

In FIG. 6, the signal output terminal of the fan switch 39 is connected to one input terminal of the AND circuit 36 and also to the set terminal S of the RS flip-flop 40. The signal output terminal of the door switch 16 is connected to the reset terminal R of the RS flip-flop 40 and also to the clear terminals CLR of the flip-flops 37a to 37n. The output terminal Q of the RS flip-flop 40 is connected to the input terminal A of the monostable multivibrator 35.

According to the above structure, after the door 15 is opened,
When the door switch 16 is closed and the signal from the door switch 16 is switched from the "H" level to the "L" level, the flip-flops 37a to 37n of the timer circuit 38 are cleared by the clear terminal CLR.
Is reset to release the reset state, and the reset terminal R of the RS flip-flop 40 is supplied with the "L" level signal.

During the opening / closing operation of the door 15, when the evaporator fan is operating, when the door switch 16 is turned off, and when the evaporator fan is stopped, the next time the evaporator fan is operated, The fan switch 39 turns on. According to this AN
The "H" level signal is supplied to one input terminal of the D circuit 36, and the clock pulse signal is supplied to the flip-flops 37a to 37n.
The “H” level signal is applied to the set terminal S of the RS flip-flop 40, and the “H” level signal is applied to the input terminal A of the monostable multivibrator 35.

As a result, similarly to the first embodiment, when the predetermined timer time has elapsed, the "H" level signal is applied to the other input terminal of the AND circuit 32,
At that time, the detection signal S output from the comparator 28 is output to the control signal output terminal P.

By operating the timer circuit 38 in accordance with the operating state of the evaporator fan in this way, the following effects can be obtained. That is,
For example, when the evaporator fan is operating when the door 15 of the freezer compartment 12 is opened / closed, the evaporator fan is operated again from the time when the door 15 is closed, so that cold air circulates in the interior 14 to cool. Is done,
A variation curve of the detected temperature VT as shown by the solid line in FIG. 4 is obtained, but when the evaporator fan is stopped,
Since the cold air is not circulated in the interior 14, the interior 14 that has risen due to the inflow of outside air is indicated by the chain double-dashed line in the figure.
It takes time for the temperature to drop.

Then, the door 15 is closed and the door switch 1
After 6 is turned on, the timer circuit 38 performs the timer operation on condition that the evaporator fan is operated, so that the detection operation is always performed in the same manner as in the operation of the evaporator fan shown by the solid line in FIG. Therefore, it is possible to reliably determine whether the door 15 is opened or closed and the food A is stored.

FIG. 7 shows a third embodiment of the present invention. Hereinafter, parts different from the first embodiment will be described with reference to FIG. That is, in this embodiment, the timer circuit 41 is provided instead of the timer circuit 33. Then, in the present embodiment, the detection signal of the defrosting detection unit 42 that detects whether or not the evaporator for performing the cooling operation of the refrigerator is performing the defrosting operation is used.

In FIG. 7, the output terminal of the defrost detecting section 42 is connected to one input terminal of the AND circuit 43 and also connected to one input terminal of the AND circuit 45 via the inverter circuit 44. . The other input terminal of the AND circuit 43 is connected to the output terminal Qn of the flip-flop 37n, and the other input terminal of the AND 45 is connected to the output terminal Qk of the kth flip-flop 37k, for example. The output terminals of the AND circuits 43 and 45 are connected to the input terminals of the OR circuit 46, and the output terminal of the OR circuit 46 is connected to the other input terminal of the AND circuit 32.

According to the above structure, after the door 15 is opened,
When the signal from the door switch 16 is closed and switched from the "H" level to the "L" level, the flip-flops 37a to 37n of the timer circuit 41 respond to the input of the clock pulse signal in the same manner as described above. The signal output of the level sequentially moves to the subsequent flip-flop. At this time, when the evaporator defrosting operation is not performed, the AND circuit 45 outputs the “L” level signal from the output terminal of the defrost detection unit 42, and the inverter circuit 44 outputs the signal. The "H" level signal is supplied, and the AND circuit 43 is supplied with the "L" level signal.

As a result, when the flip-flop 37k of the timer circuit 41 outputs the "H" level signal, AND
Since the "H" level signal is given to the AND circuit 32 via the circuit 45 and the OR circuit 46, the delay time between the flip-flops 37a to 37k, that is, k clock pulse signals are input in the detection operation. It will be done at the point of time.

On the other hand, when the defrosting operation of the evaporator is carried out and the defrosting detecting section 42 outputs the "H" level signal, the AND circuit 45 causes the inverter circuit 44 to operate.
An “L” level signal is given via the AND circuit 4 and
3 is supplied with an "H" level signal.

As a result, when the flip-flop 37n of the timer circuit 41 outputs the "H" level signal, AND
Since the AND circuit 32 is supplied with the "H" level signal via the circuit 43 and the OR circuit 46, the detection operation is performed with a delay time between the flip-flops 37a to 37n, that is, n (n) clock pulse signals. > K) It will be performed when it is input.

That is, when the opening / closing operation of the door 15 is performed, the defrosting operation of the evaporator is being performed, which means that the evaporator fan is also stopped at the same time, and the cooling operation of the inside 14 is stopped and cooling is performed. It is in a state of reduced ability. In such a state, as shown in FIG. 4 described above, since it corresponds to the change curve of the detected temperature when the evaporator fan is stopped (shown by the chain double-dashed line in the figure), the defrosting operation is performed. By delaying the detection operation start time (time t4 in the drawing) when not being performed until the detection operation start time shown in the time t5 in the drawing, the case of only the opening / closing operation of the door 15 and the food A are stored. It is possible to reliably determine the case.

FIG. 8 and FIG. 9 show a fourth embodiment of the present invention, and the portions different from the first embodiment will be described below. That is, in FIG.
Is configured as follows. That is, the sensor case 48 is made of a heat insulating member that has two openings 48a and 48b on the lower surface side and forms the first and second sensor chambers 50 and 51.

The opening 48 is formed in the first sensor chamber 50.
A heat sensitive film 52 is provided so as to cover the entire surface a, and a first thermistor 5 as a first temperature detecting means is provided in the vicinity thereof.
3 are provided. In the second sensor chamber 51, a heat sensitive film 54 is provided so as to cover the entire opening 48b, and a second thermistor 55 as a second temperature detecting means is provided in the vicinity thereof.

Below the sensor case 48, the sensor chamber 5
A cover 56 is attached to the upper wall surface 17 of the freezer compartment 12 so as to cover the heat sensitive films 52 and 54 of 0 and 51 over the entire surface. The cover 56 covers the first sensor chamber 50.
The portion opposite to is the first cover 56a made of a material that blocks radiant heat due to infrared rays.
The second cover 56b is made of a material that transmits radiant heat due to infrared rays.

According to this structure, the heat sensitive film 52 provided in the first sensor chamber 50 is directly heated because the radiant heat such as infrared rays from the inside 14 is blocked by the first cover 56a. The first thermistor 53 detects the ambient temperature of the inside 14 by absorbing the radiant heat corresponding to the temperature of the member such as the wall surface of the inside 14 without being stored. On the other hand, since the radiant heat of the infrared rays from the inside 14 penetrates the second cover 56b and hits the heat sensitive film 54 provided in the second sensor chamber 51, the temperature of the food etc. stored in the inside 14 The heat corresponding to is absorbed and the temperature is detected.

In this case, the ambient temperature of the freezer compartment 12 largely fluctuates with the tendency shown by the broken line in FIG. 9 during the operation period and the stop period of the compressor for cooling the inside 14, but Since the infrared rays emitted from the inside of the refrigerator 14 are blocked by the first cover 56a, the heat-sensitive film 52 does not receive the radiant heat due to the temperature rise of the members inside the refrigerator 14, and only the ambient temperature of the inside 14 It is possible to obtain a detection voltage with little fluctuation according to the above, and therefore, as shown by the solid line in FIG. 9, it is possible to obtain a temperature detection signal VT with a gentle slope excluding the influence of radiant heat.

In other words, the temperature compensation of the detected temperature signal can be performed more accurately, and when the food A is stored in the compartment 14, its fluctuation can be detected to reliably detect the presence or absence of the food. It will be possible.

FIG. 10 shows a fifth embodiment of the present invention, and the cover 24 used in each of the first to third embodiments.
The outer shape of the cover 57 or 58 which replaces the above is shown. The cover 57 is formed with a large number of elongated transmission holes 57a, and the cover 58 is formed with a large number of rectangular transmission holes 58a in a lattice shape. In these covers 57 or 58, it is not necessary to use the polycarbonate resin or the like as described above, and
This is because the radiant heat of the infrared rays of No. 4 can be absorbed by the heat-sensitive film 22 through the transmission holes 57a or 58a. Therefore, also in this embodiment, the heat sensitive film 22 can be protected and prevented from being damaged.

In each of the above embodiments, the case where the sensor cases 19 and 48 are provided has been described, but the present invention is not limited to this, and for example, a space surrounded by the heat insulating material 13 can be used as a sensor chamber. .

[0061]

As described above, according to the radiant heat sensor of the present invention, the following effects can be obtained. That is, according to the radiant heat sensor of claim 1, since the cover capable of transmitting radiant heat is provided between the heat-sensitive film and the storage chamber, even when the heat-sensitive film is thinned to increase its sensitivity, the heat-sensitive film is stored in the storage chamber. This has an excellent effect of preventing a problem that the thermal film is contacted and damaged when the article is stored.

According to the radiant heat sensor of the second aspect, the timer means is provided, and when the door switch receives the signal indicating the closed state of the door of the storage chamber, the timer means causes the timer operation to be performed and the predetermined delay time elapses. When the door is opened / closed and the object is not stored in the storage room, the opening / closing operation of the door causes outside air to enter the storage room and the wall surface. There is an excellent effect that it is possible to perform a reliable detection operation by preventing a problem that the presence of an object is erroneously detected due to the change of the temperature of the.

According to the radiant heat sensor of the third aspect, the first and second sensor chambers are provided, the heat sensitive film is provided in each of them, and the temperature detecting means is provided, and the first and second covers provide the first and second sensor chambers. Since the radiant heat to the first heat-sensitive film is blocked and the radiant heat to the second heat-sensitive film is transmitted, the first temperature detecting means detects the temperature according to the ambient temperature in the storage chamber, Since the temperature detecting means detects the temperature due to the heat radiation in the storage chamber, the first temperature detecting means has the same arrangement state as the second temperature detecting means, and the second temperature detecting means has the temperature of the radiant heat. At the same time, it is possible to accurately detect the detection component of the ambient temperature in the storage chamber that is being detected, and thus it is possible to detect the temperature of the object in the storage chamber more accurately. Achieve the results.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view of the entire configuration showing a first embodiment of the present invention in a state of being installed in a refrigerator.

FIG. 2 is an external perspective view of a cover.

FIG. 3 is an electrical configuration diagram of a detection circuit.

FIG. 4 is an operation explanatory view showing a time change of an output signal of the sensor in various situations.

FIG. 5 is a diagram showing electrical characteristics of the thermistor.

FIG. 6 is a diagram corresponding to FIG. 3 showing a second embodiment of the present invention.

FIG. 7 is a view corresponding to FIG. 3 showing a third embodiment of the present invention.

FIG. 8 is a view corresponding to FIG. 1 showing a fourth embodiment of the present invention.

FIG. 9 is an explanatory view of the action of temperature change of each part shown corresponding to the operating state of the compressor.

FIG. 10 is a view corresponding to FIG. 2 showing a fifth embodiment of the present invention.

FIG. 11 is a vertical sectional side view of a sensor showing a conventional example.

[Explanation of symbols]

12 is a freezing room (storage room), 13 is a heat insulating member, 14 is inside, 15 is a door, 16 is a door switch, 18 is a sensor body,
19 is a sensor case, 19b is a sensor chamber, 21 is a first thermistor (first temperature detecting means), 22 is a heat sensitive film, 23 is a second thermistor (second temperature detecting means),
24 is a cover, 27 is a differential amplifier (control means), 28 is a comparator, 29 is a voltage setting circuit, 33, 38 and 41 are timer circuits (timer means), 35 is a monostable multivibrator, and 37a to 37n are D. Type flip-flops,
39 is a fan switch, 40 is an SR flip-flop,
42 is a defrost detection unit, 47 is a sensor body, 48 is a sensor case, 50 and 51 are first and second sensor chambers, and 52 and 54.
Is the first and second heat sensitive films, and 53 and 55 are the first and second heat sensitive films.
Of the thermistors (first and second temperature detecting means), 56 is a cover, 56a is a first cover, and 56b is a second cover.

Front page continuation (72) Inventor Nobumitsu Sato 1-6 Ota Toshiba-cho, Ibaraki-shi, Osaka Toshiba Abu E-E Co., Ltd. Osaka office

Claims (3)

[Claims] 1. A sensor chamber having an opening facing the storage chamber, a first temperature detecting means provided to detect a temperature in the sensor chamber, and a heat sensitive film for absorbing radiant heat in the storage chamber. The second temperature detecting means is provided to detect the temperature of the heat sensitive film, and a detection operation is performed based on the difference between the temperatures detected by the first and second temperature detecting means, and the temperature sensitive film is placed in the storage chamber. A radiant heat sensor, comprising: a control means for detecting the temperature of the stored object; and a cover which is provided between the heat-sensitive film and the storage room and through which radiant heat from the room can be transmitted. 2. A door switch for turning on and off according to opening and closing of a door of the storage room, and timer means for measuring a predetermined delay time, wherein the control means controls the door of the storage room output by the door switch. The temperature of an object placed in the storage chamber is detected by operating the timer means based on a detection signal indicating a closed state and performing a detection operation when the delay time has elapsed. The radiant heat sensor according to 1. 3. First and second sensor chambers having openings facing the storage chamber, and first and second sensor chambers provided in each of the first and second sensor chambers for absorbing radiant heat in the storage chamber. Heat sensitive film, first and second temperature detecting means provided in the first and second sensor chambers to detect the temperatures of the first and second heat sensitive films, and the first heat sensitive film. A first cover provided between the film and the storage chamber to block radiant heat from the storage chamber, and a radiant heat transmitted from the storage chamber provided between the second heat-sensitive film and the storage chamber. Second
And a control means for performing a detection operation based on the difference between the temperatures detected by the first and second temperature detection means to detect the temperature of an object placed in the storage chamber. Radiant heat sensor.