JP2000241256A - Element and device for detecting temperature - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely detect the temperature of objects to be detected by using a small number of temperature detection bodies. SOLUTION: A temperature sensor 103 composed of a sheet type polymer element is arranged in partially contact with respective coils. The temperature sensor 103 is connected to a detecting circuit 110, which detects the resistance value of the temperature sensor 103. The polymer element is a sheet type and brought into contact with the coils at more than one point, so this temperature sensor is considered to be constituted by connecting (n) polymer elements 103'-1 to 103'-n in series. When one polymer element 103' reaches limit temperature, the total resistance value of the temperature sensor 103 exceeds a limit resistance value, so an overheating state of one of the (n) coils 101-1 to 101-n in contact with the temperature sensor 103 can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature state detecting element and a temperature state detecting device for detecting a temperature state of a plurality of objects to be detected.

[0002]

2. Description of the Related Art Conventionally, in an apparatus having a plurality of heating elements, various techniques for detecting that each heating element is overheated have been proposed in order to protect the apparatus from overheating of the heating elements. An example of a device having a plurality of heating elements is a key drive unit of an automatic performance piano. The key drive unit of an automatic performance piano supplies a drive current based on performance data to a coil (heating element) vertically opposed to the rotating end of each key, so that the plunger rotates the key. The moving end is pushed up.
As a technique for detecting an overheated state of a heating element that generates heat by supplying an electric current, a technique in which a fuse is disposed on a substrate as a detection element is known. This utilizes the characteristic that an abnormality occurs in the current supplied to the coil in the overheated state.However, since the current abnormality does not always occur in the overheated state, it is necessary to accurately detect the overheated state. Could not.

[0003] Such a problem can be solved by installing a thermal fuse as a temperature detecting element in the vicinity of the heat generating element. There is a disadvantage that a thermal fuse must be installed near the heating element. Therefore, in the case of an apparatus having a plurality of heating elements, it is necessary to install thermal fuses corresponding to the number of heating elements, which is very expensive. For example, in the case of a key drive unit of an automatic performance piano, a temperature fuse must be installed near each coil for driving a plunger corresponding to each of the 88 keys, and the circuit configuration becomes complicated.
Further, such a large number of coils are installed in a wide range, and in order to install a large number of thermal fuses, a large installation space is required. Such a problem can be solved by installing a small number of thermistors at predetermined positions as temperature detectors.

[0004]

However, when a small number of thermistors are installed at predetermined positions, one thermistor must detect the overheating state of a plurality of heating elements, and a plurality of heating elements must be detected. Since the distances to the thermistors are different from each other, there is a problem that uniform detection cannot be performed. That is, since the temperature difference of the heating element detected by the thermistor increases as the distance increases, the overheating state of the heating element installed near can be detected with a high threshold value, but the heating temperature of the heating element installed far away can be detected. Overheating of the body cannot be detected without lowering the threshold.
Therefore, when the threshold value is set high with reference to the heating element installed near, the overheating state of the heating element installed far away cannot be accurately detected, and the heating element is installed far away. If the threshold value is set low on the basis of the heating element, there is a problem that the heating element installed nearby is overly sensitive to the overheating state. As described above, according to the technology for detecting the overheating state of the heating element, conventionally, when overheating is detected for a plurality of heating elements, the circuit configuration can be configured by arranging the temperature sensing elements corresponding to the number of heating elements. However, there is a problem that if the number of the detection objects is reduced, the detection cannot be performed with high accuracy.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has a temperature state detecting element and a temperature state detecting element capable of accurately detecting the temperature states of a plurality of objects to be detected using a small number of temperature detecting bodies. It is intended to provide a device.

[0006]

According to a first aspect of the present invention, there is provided a temperature detecting element having a resistance value that changes in accordance with a temperature change, wherein a plurality of temperature detecting objects are provided. A temperature state detecting element for detecting a state, wherein the plurality of detection objects are respectively arranged in proximity to a partial detection body which is a part of the temperature detection body, and based on a temperature change of any of the plurality of detection objects. The resistance value of the temperature detector changes with the change of the resistance value of the partial detector close to the detection target. According to a second aspect of the present invention, in the temperature state detecting element according to the first aspect, when at least one of the partial sensing elements reaches a limit temperature, the resistance value significantly changes. . According to a third aspect of the present invention, in the temperature detecting element according to the first aspect, the partial sensing element is an element whose resistance value changes remarkably when the temperature reaches a limit temperature. The body is formed by connecting a plurality of the elements. Further, according to a fourth aspect of the present invention, in the temperature state detecting element according to the second or third aspect, the partial detection body has a resistance value at a critical temperature at which the detection target body normally operates. The multiplied number may be smaller than the resistance value of the partial detector at the limit temperature. Further, according to a fifth aspect of the present invention, in the temperature state detecting element according to the second or third aspect, the partial sensing element has a resistance value at a critical temperature at which the detection target normally operates. The value divided by the number may be larger than the resistance value of the partial detector at the limit temperature. According to a sixth aspect of the present invention, there is provided a temperature state detecting device for detecting a temperature state of a plurality of objects to be detected, wherein the temperature state detecting element according to any one of the first to fifth aspects and the temperature detecting body are provided. Detecting means for detecting the temperature state of the plurality of detection target objects based on the change in the resistance value. According to a seventh aspect of the present invention, power supply to the plurality of detection targets is controlled according to a detection result of the temperature state detecting element according to any one of the first to fifth aspects.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

[0008] 1. Configuration of Embodiment The embodiment is configured to detect overheating of a plurality of heating elements (coils) installed in a key drive unit of an automatic performance piano with a single temperature detector (temperature sensor).
Here, FIG. 1 is a diagram showing a configuration of the embodiment,
(A) And (b) is sectional drawing of the key drive part of an automatic performance piano. As shown in FIG. 1, a key drive unit 100 of an electronic piano includes a plurality of coils 101-1 to 101-n for driving a plunger corresponding to each key (key).
Are installed in the yoke 102. Temperature sensor 10
Reference numeral 3 denotes a temperature detector for detecting an overheated state of the coils 101-1 to 101-n. In the present embodiment, as the temperature sensor 103, a polymer element having a PTC (Positeve Temperature Coefficient) characteristic in which the resistance value increases as the temperature rises is used. Since the polymer element is in a sheet shape and can be arranged so that a part of the sheet is in contact with each of the coils 101-1 to 101-n,
A plurality of coils 101-1 to 101-1 are formed by one polymer element.
01-n can be detected. As shown in FIG. 1, the coils 101-1 to 101-1 arranged in two rows
The temperature sensor 103 is installed at the center of 101-n, and the heat conductors 104-1 to 104-n are inserted between the coils 101-1 to 101-n and the temperature sensor 102, and the coil 101-1 is inserted. The temperature difference between the temperature sensor 103 and the temperature sensor 103 is reduced.

FIG. 2 is a diagram showing an electrical configuration for detecting an overheating state by the temperature sensor 103. As shown in FIG.
As shown in FIG. 2, the temperature sensor 103 includes a detection circuit 110
The detection circuit 110 is connected to the temperature sensor 10.
3 is configured to be detected. In Figure 2 "
Rp ″ is the resistance value of the entire sheet-like polymer element used for the temperature sensor 103. The polymer element is in the form of a sheet and is in contact with the coils 101-1 to 101-n at a plurality of contact points. The temperature sensor 103 is shown in FIG.
As shown in the figure, n polymer elements 103'-1 to 103 '
3′-n can be regarded as being connected in series.
When the resistance value of each of the polymer elements 103 ′-1 to 103 ′ -n is R, the resistance value Rp of the entire temperature sensor 103 is
Is N times the resistance value R of each of the temperature sensors 103′-1 to 103′-n, that is, Rp = N × R.

FIG. 3 shows polymer elements (each of the polymer elements 103'-1 to 103'-) used for the temperature sensor 103.
n, the resistance-temperature characteristics of 103 ') unless otherwise specified. In the graph shown in FIG. 3, the horizontal axis indicates temperature, and the vertical axis indicates resistance. Referring to FIG. 3, the resistance value of the polymer element 103 ′ at room temperature A (° C.) is R
(Ω), and the polymer element 103 ′ has a critical temperature T (° C.)
It can be seen that the resistance value becomes Rt (Ω) when the resistance value rises to the maximum value. Then, the resistance value Rt at the limit temperature T (° C.)
(Ω) is a sufficiently large value, that is, Rt >> R, as compared with the resistance value R (Ω) of the polymer element 103 ′ at normal temperature A (° C.). Thus, the temperature sensor 103 is connected to all the coils 101-1 in the yoke 102.
Polymer element 103'-1-10 in contact with -101-n
3′-n can be regarded as being connected in series, so that one temperature sensor 103 can detect an overheated state of the heating element installed over a wide range.

2. Operation of Embodiment Next, the operation of the embodiment having the above configuration will be described. The detection circuit 110 shown in FIG.
Is detected at a predetermined time interval, and when the detected resistance value Rp exceeds a preset limit resistance value Rc, it is determined that any of the coils 101-1 to 101-n is in an overheated state. judge. The room temperature A
Total resistance value of the temperature sensor 103 at (° C.) N × R
(Ω) and a value smaller than the resistance value Rt (Ω) at the limit temperature T (° C.) of any of the polymer elements 103 ′-1 to 103 ′ -n constituting the temperature sensor 103, that is, A value in which Rc satisfies Rt>Rc> N × R is set in advance.

FIG. 4 is a graph showing changes in the temperature () and the resistance () of the polymer element 103'-1 over time. Here, for simplicity of description, an example in which the coil 101-1 generates heat among the coils 101-1 to 101-n illustrated in FIG. 1 will be described. In addition, the coil 101-other than the coil 101-1
The description will be made on the assumption that the temperatures of 2 to 101-n do not rise from the normal temperature, and that the resistance values remain unchanged at R (Ω).
Hereinafter, the resistance value detected by the detection circuit 110 at each of the detection times t0, t1, and t2 shown in FIG. 4 will be described.

First, at the detection time t0, the coil 1
01-1 does not generate heat, and the temperature of the polymer element 103'-1 is room temperature A (° C.). Therefore, the resistance value of the polymer element 103′-1 at the detection time t0 is R (Ω). As described above, the polymer elements 103'-1 to 103 '
−n are connected in series and the other polymer elements 10
The resistance values of 3′-2 to 103′-n are all R (Ω).
Therefore, the total resistance value Rp of the temperature sensor 103 at the detection time t0 is And it is determined that the key drive unit 100 is not in an overheated state.

Next, at the detection time t1, the coil 1
01-1 generates heat and the temperature of the polymer element 103'-1 becomes B
(° C.), and the resistance value at this time is Rb
(Ω). However, the temperature of the polymer element 103'-1 at the detection time t1 is lower than the limit temperature T.
(° C.), the polymer element 103′-1
Is substantially equal to the resistance value R (Ω) at normal temperature. The resistance value of the polymer element 103 ′ is
This is because, as shown in FIG. 3, it has a characteristic of dramatically increasing at a limit temperature T (° C.). Therefore, the detection time t1
The total resistance Rp of the degree sensor 103 at And it is determined that the key drive unit 100 is not in an overheated state.

Next, at the detection time t2, the coil 1
01-1 generates heat, and the temperature of the polymer element 103'-1 has risen to the limit temperature T (° C.), and the resistance value at this time is Rt (Ω). FIG. 5 shows the state of the temperature sensor 103 at the detection time t2. As shown in FIG.
In the temperature sensor 103 at the detection time t2, the resistance value of the polymer element 103′-1 is Rt (Ω), and the resistance values of the polymer elements 103′-2 to 103′-n are R (Ω). Therefore, the total resistance value Rp of the temperature sensor 103 is as follows: Rp = Rt + (R × (N−1)) Here, as described above, since Rt> Rc, the total resistance value Rp of the temperature sensor 103> the limit resistance value Rc
And it is determined that one of the coils of the key drive unit 100 is in an overheated state.

As described above, one of the polymer elements 10
Since the total resistance value Rp of the temperature sensor 103 exceeds the limit resistance value Rc when 3 ′ reaches the limit temperature T (° C.), a sheet-like polymer element (equivalent to a series connection of the polymer elements 103 ′) Temperature sensor 10 using
It can be detected that any one of the n coils 101-1 to 101-n in contact with 3 is in an overheated state. Therefore, the circuit configuration can be simplified since it is sufficient that the detection value of one temperature detector can be recognized. Also, even if any of the coils 101-1 to 101-n generates heat and the resistance value changes at any position, the overall change in the resistance value is the same, so that the overheating of the individual heating elements occurs. The states can be detected almost equally. Therefore, there is no need to set a threshold value according to the distance from the heating element, and the threshold value for detection can be set finely, so that the performance limit can be increased and the detection accuracy can be increased. become.
In addition, since overheating of a plurality of heating elements can be detected using a small number of temperature sensing elements, a space for installing a large number of temperature sensing elements is not required. In addition, in the event that the temperature sensor is to be replaced entirely, the temperature sensor is a single unit instead of being separated like a temperature fuse, so it can be replaced in a lump, making replacement easy. .

3. Modifications The present invention is not limited to the above-described embodiments, and various modifications as described below are possible.

In the above-described embodiment, the case where one of the plurality of heating elements generates heat is described as an example. However, even when the plurality of heating elements generate heat, it is possible to detect an overheated state similarly. Not even. In addition, not only the overheated state but also the fact that the temperature of the detection target body is lower than the normal temperature state may be detected as an abnormal temperature state. In addition, the setting of the threshold value serving as a predetermined reference for determining that the detected object has reached the critical temperature at which the detected object has reached a normal operation based on the resistance value detected by the temperature sensor 103 is not limited to the above embodiment. But, for example,
If all the polymer elements 103 'rise to R + α, Rc> (R + α) × N is set, and all the polymer elements 103 ′ are set.
Even when the resistance value of the temperature sensor 3 ′ rises to R + α due to the rise of the temperature of 3 ′, the temperature sensor 103 as a whole can be configured not to detect the overheating state. In this case, the resistance value is R
+ Α is a resistance value at a critical temperature at which the detection target (coil) normally operates.

In the above embodiment, the temperature sensor 10
In FIG. 3, a sheet-shaped polymer element is used, and a part close to each detection object is used as a partial detection object. As shown in FIG. 6, a plurality of polymer elements 203-1 to 203-n are thermally conductive. It may be configured to be sandwiched between the rubber 204 and the like.
In this case, each of the polymer elements 203-1 to 203-
If n is connected in series, the same effect as in the above embodiment can be obtained.

In the above embodiment, the temperature sensor 103 is
Although installed at the center of the coils 101-1 to 101-n arranged in a row, it is not limited to this, and can be installed at various positions as shown in FIG. For example, FIG.
As shown in FIG. 7A, the coil 101-1 may be installed below the yoke 102 so as to be located below the coils 101-1 to 101-n, or as shown in FIG. ~
It may be installed inside the yoke 102 so as to be located on the side surface of 101-n. Further, the above-described polymer element is formed in a tape shape, and for example, as shown in FIG. 8, a part of the temperature sensor 103 is brought into contact with the coils 101-1 to 101-n installed at remote positions. If the temperature sensor 103 is provided in the first place, there is no need to provide a heat conductor.

Further, in the above embodiment, since the polymer element 103 'whose electric resistance increases in a predetermined temperature state is used as an element constituting the temperature detector,
Although the polymer elements 103 'are connected in series, if an element whose electric resistance decreases in a predetermined temperature state is used, a temperature sensor 103 in which the elements are connected in parallel may be used. In this case, the polymer element 1 at room temperature A (° C.)
03 ′ is R (Ω), and the polymer element 103 ′
Falls to the limit temperature T '(° C), the resistance value becomes Rt'
(Ω). The resistance value Rt ′ (Ω) at the limit temperature T ′ (° C.) is sufficiently smaller than the resistance value R (Ω) of the polymer element 103 ′ at normal temperature A (° C.), that is, Rt ′ <<. It is R. Therefore, the resistance value Rp of the temperature sensor 103 at the normal temperature A (° C.) is 1 / Rp = (1 / R) × N = N / R Rp = R / N, and the limit resistance value Rc is represented by Rt ′ <Rc < What is necessary is just to set so that it may become R / N. That is, the polymer element 1
Since the resistance value Rp of the temperature sensor 103 when 03′-1 reaches the limit temperature T ′ (° C.) is Rt << R, 1 / Rp = (1 / Rt ′) + ((N−1) ) / R) Rp = (Rt ′ × R) / (R + Rt ′ (N−1)) <Rt ′ <Rc Therefore, the resistance value Rp of the temperature sensor 103 detected by the detection circuit 110 is equal to the limit resistance value Rc. When the temperature falls below the critical temperature, it can be determined that the detection target has reached the critical temperature at which it operates normally.

The threshold value serving as a predetermined reference for judging that the detection target has reached a critical temperature at which the detection target body normally operates based on the resistance value detected by the temperature sensor 103 'is also set as follows.
If all polymer elements 103 'decrease to R-α, if Rc <(R-α) / N, then the resistance value becomes R-α depending on the temperature state of all polymer elements 103 ′. In this case, the temperature sensor 103 'may not be detected as reaching the critical temperature as a whole.

Also, the polymer elements 203-1 to 203-n
Not limited to this, a thermistor or a fuse may be used as long as it is a temperature detector whose resistance value changes abruptly at a predetermined temperature. In short, when a plurality of temperature detectors are used in a state of being connected in series, a value obtained by multiplying the resistance value (R + α) at the critical temperature at which the detection target (coil) normally operates by the number of elements (N) ( (R + α) × N) is smaller than the resistance value (Rt) at the limit temperature of the temperature detector (Rt> (R +
α) × N) Any type of temperature detector may be used. On the other hand, when a plurality of temperature detectors are used in a state of being connected in parallel, the resistance value (R-α) at the critical temperature at which the detection target (coil) normally operates is determined by the number of elements (N).
Any value can be used as long as the value ((R−α) / N) obtained by dividing the temperature detection element is larger than the resistance value (Rt ′) at the limit temperature of the temperature detection element. Note that the same applies to the case where one element is treated as a plurality of connected elements as in the above embodiment. In this case, a portion close to each detection target is regarded as each element, The number N corresponds to the number of detection targets. When one temperature detector is configured by connecting a plurality of elements in this manner, it is not always necessary to provide the same number of elements as the number of each detection target. Based on an attribute that partially changes in any place of the one temperature detecting object and a predetermined criterion, as a whole temperature detecting object, it is determined whether or not the detection target (coil) has reached a critical temperature at which the coil operates normally. The number of elements is not limited as long as it can be detected.

In the above-described embodiment, the heating element is described by taking the coil in the key drive unit of the automatic performance piano as an example. However, the present invention is not limited to this. Alternatively, a coil that drives a pedal drive unit of a piano may be used. In addition, pipe organ key drive, pedal drive, stop (sound plug) drive,
It may be a moving part such as a swell (sound insulation plate) drive.

Further, as shown in FIG.
When a coil 03 (temperature detector) is interposed in the power supply path of the coil 101 (detection target), if the coil 101 is overheated, the resistance value Rp of the polymer element 103 exceeds the limit resistance value Rc. The input current of the coil 101 becomes very small. As described above, the polymer element 103 includes the coil 101
Can also function as a fuse for limiting power supply in the event of overheating. Further, when it is determined that the temperature of the detection target has reached the critical temperature based on the resistance values of the temperature sensors detected by the detection circuits 110 and 210, power supply to the detection target may be stopped. .

[0026]

As described above, according to the present invention,
It is possible to accurately detect the temperature state of a plurality of detection targets using a small number of temperature detection targets.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of an embodiment.

FIG. 2 is a diagram illustrating an electrical configuration of the embodiment.

FIG. 3 is a graph showing a relationship between temperature and resistance of a polymer element.

FIG. 4 is a graph showing the relationship between temperature and resistance of a polymer element over time.

FIG. 5 is a diagram illustrating a state when the coil is overheated.

FIG. 6 is a diagram illustrating a configuration of a temperature sensor according to a modification.

FIG. 7 is a diagram illustrating an installation mode of a temperature sensor according to a modified example (part 1).

FIG. 8 is a diagram illustrating an installation mode of a temperature sensor according to a modified example (part 2).

FIG. 9 is a diagram when a temperature sensor functions as a fuse.

[Explanation of symbols]

100: key drive unit, 101: coil, 102
... Yoke, 103, 203 ... Temperature sensor, 104,
204: thermal conductor, 110, 210: detection circuit.

Continued on the front page (72) Inventor Motoomi Goto 10-1 Nakazawa-cho, Hamamatsu-shi, Shizuoka Prefecture Inside Yamaha Corporation (72) Inventor Shigeru Muramatsu 10-1 Nakazawa-cho, Hamamatsu-shi, Shizuoka Prefecture Yamaha Corporation F-term ( Reference) 2F056 MS06

Claims (7)

[Claims] 1. A temperature state detection element for detecting a temperature state of a plurality of detection target bodies, the temperature detection element including a temperature detection body whose resistance value changes based on a temperature change, wherein the plurality of detection target bodies are the temperature detection elements. The temperature detection is performed in accordance with a change in the resistance value of the partial detection body that is disposed close to the detection target based on a temperature change of any one of the plurality of detection targets, each being disposed close to the partial detection body that is a part of the body. A temperature state detecting element, wherein a resistance value of a body changes. 2. The temperature state detection element according to claim 1, wherein the resistance value changes significantly when at least one of the partial detection bodies reaches a limit temperature. 3. The temperature state detecting element according to claim 1, wherein the partial sensing element is an element whose resistance value significantly changes when a temperature reaches a limit temperature, and wherein the temperature sensing element includes a plurality of the temperature sensing elements. A temperature state detection element characterized by being configured by connecting elements. 4. The temperature state detecting element according to claim 2, wherein the partial detection body has a value obtained by multiplying a resistance value at a critical temperature at which the detection target body operates normally by the number of the partial detection bodies. A temperature detection element having a resistance value smaller than a resistance value of the partial detection body at a limit temperature. 5. The temperature state detecting element according to claim 2, wherein the partial detection body has a value obtained by dividing a resistance value at a critical temperature at which the detection target body normally operates by the number of the partial detection bodies. A temperature detecting element having a resistance value higher than a resistance value at a limit temperature of the partial detecting element. 6. A temperature state detection device for detecting a temperature state of a plurality of detection target bodies, wherein the temperature state detection element according to claim 1 and a change in the resistance value of the temperature detection body. Detecting means for detecting the temperature state of the plurality of detection target objects based on the temperature condition. 7. A temperature state detection device, wherein the power supply to the plurality of detection targets is controlled in accordance with the detection result of the temperature state detection element according to any one of claims 1 to 5.