electroscope

Abstract

To provide an electroscope that can be miniaturized and can easily detect voltage.SOLUTION: An electroscope includes a connection circuit for electrically connecting a first conductor and a second conductor, and a display section for displaying a difference in temperature while abutting on the connection circuit. The connection circuit includes a first wiring member having a first end and a second end, a second wiring member connected to the first end and the second end of the first wiring member, a first PTC thermistor disposed near the first end, and a second PTC thermistor disposed near the second end. The first wiring member, the second wiring member, the first PTC thermistor, and the second PTC thermistor form one portion of a current route when voltage is generated between the first conductor and the second conductor each, the first end is an end in the first conductor side of the first wiring member in the current route, the second end is an end in the second conductor side of the first wiring member in the current route, and the Peltier coefficient of the first wiring member differs from that of the second wiring member.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a voltage detector device.

Background Art

[0002] Patent Document 1 discloses a DC voltage detector including: a charge detection unit that detects a charging voltage of a voltage detection object through a voltage detection fitting by hooking and locking the voltage detection fitting attached to the tip side of a cylindrical operation rod to the voltage detection object; a disconnection detection unit that detects a disconnection of a ground wire that earth-connects the voltage detection fitting through the charge detection unit; an operation inspection unit that checks whether the charge detection unit operates normally; and a display lamp or buzzer. Inside the operation rod of the DC voltage detector, a charge detection line that electrically connects the voltage detection fitting and the charge detection unit and an operation inspection line that electrically connects the voltage detection fitting and the operation inspection unit are accommodated.

[0003] When performing voltage detection using the above DC voltage detector, an operator fixes the ground wire to a rail with the operation rod extended and earth-connects the charge detection unit. Then, the voltage detection fitting is hooked and locked to the voltage detection object (specifically, an overhead wire). If the voltage detection object is in a charged state, a voltage is applied to the charge detection unit through the voltage detection fitting and the charge detection line locked to the voltage detection object, and the operator is notified that the voltage detection object is in a charged state by a display lamp or buzzer provided on the voltage detector main body.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the DC voltage detector described in Patent Document 1, since there are many components, the size of the detector itself tends to increase. Furthermore, the work procedure for performing voltage detection also tends to become complicated. Although Patent Document 1 discloses a device for detecting a DC voltage, the above points are the same in the case of a device for detecting an AC voltage.

[0006] Therefore, an object of the present invention is to provide a voltage detection device that can be miniaturized and enables easy voltage detection.

Means for Solving the Problems

[0007] [1] The voltage detection device according to one aspect of the present disclosure is a voltage detection device that detects whether a voltage is generated between a first conductor and a second conductor, and includes a connection circuit that electrically connects the first conductor and the second conductor, and a display unit that is in contact with the connection circuit and displays a temperature difference. The connection circuit includes a first wiring member having a first end and a second end, second wiring members connected to the first end and the second end of the first wiring member, respectively, a first PTC thermistor disposed near the first end, and a second PTC thermistor disposed near the second end. Each of the first wiring member, the second wiring member, the first PTC thermistor, and the second PTC thermistor constitutes a part of a current path when a voltage is generated between the first conductor and the second conductor. The first end is the end of the first wiring member on the first conductor side in the current path, and the second end is the end of the first wiring member on the second conductor side in the current path. The Peltier coefficients of the first wiring member and the second wiring member are different.

[0008] To each of the first end and the second end of the first wiring member included in the voltage detector described in [1] above, a second wiring member having a Seebeck coefficient different from that of the first wiring member is connected. Therefore, the Seebeck effect occurs at each of the first end and the second end of the first wiring member. When a voltage is generated between the first conductor and the second conductor, one of the first end and the second end functions as a heat generating portion and the other functions as a heat absorbing portion, so the temperatures at the first end and the second end are different from each other. The connection circuit is in contact with a display portion that displays the temperature difference. Therefore, when a voltage is generated between the first conductor and the second conductor, the regions of the display portion corresponding to the first end and the second end indicate different temperatures. Therefore, it is possible to easily determine whether or not a voltage is generated between the first conductor and the second conductor based on the temperature difference displayed on the display portion. The voltage detector includes a first PTC thermistor disposed near the first end and a second PTC thermistor disposed near the second end. Therefore, the first PTC thermistor is affected by the temperature at the first end, and the second PTC thermistor is affected by the temperature at the second end. When a voltage is generated between the first conductor and the second conductor, one of the first end and the second end functions as a heat generating portion and the other functions as a heat absorbing portion, so the temperature of the PTC thermistor disposed near the heat generating portion among the first PTC thermistor and the second PTC thermistor increases. As the temperature of the PTC thermistor reaches near the Curie temperature along with this temperature increase, the resistance value of the PTC thermistor rapidly increases. As a result, no current flows through the connection circuit, or a minute current flows. Therefore, by including the first PTC thermistor and the second PTC thermistor, the voltage detector can define the upper limit of the temperature at the heat generating portion and the lower limit of the temperature at the heat absorbing portion, and can further prevent overcurrent. As described above, since it is possible to easily determine whether or not a voltage is generated between the first conductor and the second conductor based on the temperature difference displayed on the display portion, the test result can be confirmed even from a location away from the object to be tested. Therefore, for voltage detection with a voltage detection device, work procedures for ensuring safety can be omitted, and the voltage detection device can easily inspect whether a voltage is generated between the first conductor and the second conductor by simply connecting the connection circuit to the first conductor and the second conductor. Furthermore, since the voltage detection device has a simple configuration with only a display unit attached to the connection circuit, it can also be miniaturized.

[0009] [2] In the voltage detection device according to [1] above, the display unit may be a heat-sensitive liquid crystal sheet. The heat-sensitive liquid crystal sheet changes the color that develops according to the temperature. Therefore, the temperatures of the heat generating part and the heat absorbing part can be displayed. Furthermore, since a voltage detection device can be obtained by forming a connection circuit on the heat-sensitive liquid crystal sheet, the voltage detection device can also be miniaturized.

[0010] [3] The voltage detection device according to [1] or [2] above may include a plurality of the first wiring members, and the second wiring member may be connected to the first end and the second end of each of the plurality of the first wiring members.

[0011] Since the voltage detection device according to [3] above includes a plurality of first wiring members, there are also a plurality of heat generating parts and heat absorbing parts. In this case, for example, according to the arrangement of the plurality of first wiring members, a pattern corresponding to the heat generating part and the heat absorbing part appears on the display unit. Therefore, it is easy to recognize the voltage detection result even from a location away from the voltage detection device.

[0012] [4] In the voltage detection device according to [3] above, two of the plurality of first wiring members are arranged opposite to each other, the first ends of the two first wiring members arranged opposite to each other face each other, and the second ends of the two first wiring members arranged opposite to each other face each other. The first PTC thermistor may be arranged opposite to the first end between the two first wiring members arranged opposite to each other, and the second PTC thermistor may be arranged opposite to the second end between the two first wiring members arranged opposite to each other.

[0013] In the voltage detector described in [4] above, the first PCT thermistor is disposed between a pair of first ends, and the second PCT thermistor is disposed between a pair of second ends. One of the first end and the second end functions as a heat generating portion. Therefore, in the voltage detector described in [4] above, since one of the first PCT thermistor and the second PCT thermistor is disposed between a pair of heat generating portions, the temperature of the PCT thermistor is likely to rise. As a result, the power consumption of the voltage detector during voltage detection can be reduced.

Effect of the Invention

[0014] According to the present invention, it is possible to provide a voltage detector that can be miniaturized and enables voltage detection easily.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same elements are denoted by the same reference numerals, and overlapping descriptions will be omitted. The dimensional ratios in the drawings do not necessarily match those for the description.

[0017] (First Embodiment) FIG. 1 is a schematic diagram of a state in which an electrification detection device 1 according to an embodiment is attached to an object to be electrified. FIG. 2 is a drawing for explaining the configuration of the electrification detection device according to an embodiment. Hereinafter, unless otherwise specified, a mode in which the electrification detection device 1 detects a DC voltage will be described.

[0018] The objects to be electrified shown in FIG. 1 are a first conductor 101A connected to a first electric wire 102A and a second conductor 101B connected to a second electric wire 102B. The first electric wire 102A and the second electric wire 102B are, for example, electric wires incorporated in a wiring system for transmitting high voltage. For example, as shown in FIG. 1, the first conductor 101A and the second conductor 101B are connection terminals electrically connected to the device 100, and the first electric wire 102A and the second electric wire 102B may be electric wires for charging the device 100 or taking out electricity from the device 100. Examples of the device 100 include a DC circuit breaker, a power converter such as a DC-DC converter, and a distribution board in a DC system.

[0019] The electrification detection device 1 is a device that detects whether a DC voltage (DC potential difference) is generated between the first conductor 101A and the second conductor 101B. When the first conductor 101A and the second conductor 101B are electrically connected to the device 100, detecting whether a DC voltage is generated between the first conductor 101A and the second conductor 101B corresponds to, for example, detecting the charging state in the device 100.

[0020] The electrification detection device 1 includes a connection circuit 10 that electrically connects the first conductor 101A and the second conductor 101B, and a thermosensitive liquid crystal sheet (display unit) 20 that is in contact with the connection circuit 10 and displays the detection result of the DC voltage.

[0021] The connection circuit 10 has a first end 10a connected to the first conductor 101A and a second end 10b connected to the second conductor 101B. The connection circuit 10 is configured by connecting four metal wires 11, metal wire 12, a first PTC thermistor 13A, and a second PTC thermistor 13B. The connection circuit 10 functions as a wiring part that electrically connects the first conductor 101A and the second conductor 101B.

[0022] The metal wire 11 has a first Peltier coefficient. Examples of the material of the metal wire 11 are alumel, tellurium, etc. The metal wire 12 has a second Peltier coefficient. The second Peltier coefficient is different from the first Peltier coefficient. Examples of the material of the metal wire 12 are chromel, bismuth, etc. As the material of the metal wire 12, for example, among the exemplified materials, it is a material having a Peltier coefficient different from that of the metal wire 11A.

[0023] The four metal wires 11 are referred to as metal wire 11A, metal wire 11B, metal wire 11C, and metal wire 11D, and a configuration example of the connection circuit 10 will be described in detail.

[0024] The connection circuit 10 has, in order from the first end 10a to the second end 10b, the metal wire 11A, the metal wire 12, the metal wire 11B, the second PTC thermistor 13B, the metal wire 11C, the first PTC thermistor 13A, and the metal wire 11D.

[0025] The metal wire 11A, the metal wire 12, the metal wire 11B, the second PTC thermistor 13B, the metal wire 11C, the first PTC thermistor 13A, and the metal wire 11D constitute a current path when a DC voltage is generated between the first conductor 101A and the second conductor 101B. In the form shown in FIG. 1, since the first conductor 101A and the second conductor 101B are arranged in parallel, the current path constituted by connecting the four metal wires 11, the metal wire 12, the first PTC thermistor 13A, and the second PTC thermistor 13B is folded back at the portion of the metal wire 11B.

[0026] Among the metal wire 11A, the end opposite to the metal wire 12 is the first end 10a. The metal wire 12 connects the metal wire 11A and the metal wire 11B. The metal wire 12 has a first end 12a joined to the metal wire 11A and a second end 12b joined to the metal wire 11B. In the above current path when current flows through the connection circuit 10, the first end 12a is the end of the metal wire 12 closer to the first conductor 101A, and the second end 12b is the end of the metal wire 12 closer to the second conductor 101B. The metal wire 11B connects the metal wire 12 and the second PTC thermistor 13B. The metal wire 11C connects the second PTC thermistor 13B and the first PTC thermistor 13A. The metal wire 11D is connected to the first PTC thermistor 13A, and the end of the metal wire 11D opposite to the first PTC thermistor 13A is the second end 10b.

[0027] The first PTC (Positive Temperature Coefficient) thermistor 13A is arranged near the first end 12a. The second PTC thermistor 13B is arranged near the second end 12b. In the forms shown in FIGS. 1 and 2, the first PTC thermistor 13A is arranged opposite to the first end 12a, and the second PTC thermistor 13B is arranged opposite to the second end 12b. The first PTC thermistor 13A and the second PTC thermistor 13B are temperature-dependent resistance elements having a high positive temperature coefficient (PTC). The resistance values of the first PTC thermistor 13A and the second PTC thermistor 13B are substantially constant below the Curie temperature and increase rapidly near the Curie temperature.

[0028] The connection circuit 10 is provided in contact with the temperature-sensitive liquid crystal sheet 20 on the first surface 21 of the temperature-sensitive liquid crystal sheet 20. For example, the four metal wires 11 (metal wires 11A to 11D), the metal wire 12, the first PTC thermistor 13A, and the second PTC thermistor 13B are bonded on the first surface 21. In the connection circuit 10, the first end 10a and the second end 10b may be located outside the temperature-sensitive liquid crystal sheet 20 when the temperature-sensitive liquid crystal sheet 20 is viewed in plan (when viewed from the thickness direction). That is, the portion of the metal wire 11A near the first end 10a and the portion of the metal wire 11D near the second end 10b may be located outside the temperature-sensitive liquid crystal sheet 20.

[0029] The temperature-sensitive liquid crystal sheet 20 is composed of a liquid crystal (for example, cholesteric liquid crystal) designed to change its color state according to temperature being printed on a resin sheet. The first surface 21 of the temperature-sensitive liquid crystal sheet 20 is the surface of the resin sheet. The second surface 22 of the temperature-sensitive liquid crystal sheet 20 is the liquid crystal surface. The second surface 22 is the surface opposite to the first surface 21 and is the color-developing surface.

[0030] The electrification detection device 1 is attached to the first conductor 101A and the second conductor 101B so that the second surface 22 is positioned on the side of the operator who confirms the electrification state, so that the color-developing state of the liquid crystal possessed by the temperature-sensitive liquid crystal sheet 20 can be visually recognized. Specifically, the temperature-sensitive liquid crystal sheet 20 is attached to the first electric wire 102A and the second electric wire 102B such that the first surface 21 is positioned on the sides of the first electric wire 102A and the second electric wire 102B in a state where the first end 10a and the second end 10b are connected to the first conductor 101A and the second conductor 101B.

[0031] In the connection circuit 10 of the electrification detection device 1, the first end 12a of the metal wire 12 is the first joint 2 between the metal wire 11 (specifically, the metal wire 11A) and the metal wire 12. The second end 12b of the metal wire 12 is the second joint 3 between the metal wire 11 (specifically, the metal wire 11B) and the metal wire 12. Since the first Peltier coefficient of the metal wire 11 and the second Peltier coefficient of the metal wire 12 are different, the Peltier effect occurs at each of the first joint 2 and the second joint 3.

[0032] When a DC voltage V exists between the first conductor 101A and the second conductor 101B, a current I represented by the formula (1) flows through the connection circuit 10. In the formula (1), it is assumed that the resistance components of the four metal wires 11 and the metal wire 12 are zero. I = V / (R1 + R2) ··· (1) In the formula (1), R1 [Ω] is the resistance value of the first PTC thermistor 13A, and R2 [Ω] is the resistance value of the second PTC thermistor 13B.

[0033] As described above, since the Peltier effect occurs at the first joint 2 and the second joint 3, heat absorption or heat generation occurs at the first joint 2 and the second joint 3. The amount of heat Q absorbed or generated is represented by Equation (2). Q = (ΠB - ΠA) × I = (ΠB - ΠA) × {V / (R1 + R2)} ··· (2) In Equation (2), ΠA [J / A] is the first Peltier coefficient of the metal wire 11, and ΠB [J / A] is the second Peltier coefficient of the metal wire 12.

[0034] Since ΠA and ΠB are different, when there is a DC voltage V between the first conductor 101A and the second conductor 101B, one of the first joint 2 and the second joint 3 is a heat generating part, and the other is a heat absorbing part. Specifically, it is as follows.

[0035] When ΠA, ΠB, and V are such that ΠA < ΠB and V > 0 or ΠA > ΠB and V < 0, the first joint 2 is a heat absorbing part, and the second joint 3 is a heat generating part. On the other hand, when ΠA, ΠB, and V are such that ΠA < ΠB and V < 0 or ΠA > ΠB and V > 0, the first joint 2 is a heat generating part, and the second joint 3 is a heat absorbing part.

[0036] The first PTC thermistor 13A is arranged near the first joint 2 (the first end 12a). Therefore, the temperature of the first PTC thermistor 13A is affected by the temperature of the first joint 2. The second PTC thermistor 13B is arranged near the second joint 3 (the second end 12b). Therefore, the temperature of the second PTC thermistor 13B is affected by the temperature of the second joint 3. In other words, the fact that the first PTC thermistor 13A is arranged near the first joint 2 (the first end 12a) means that the first PTC thermistor 13A is arranged within the range affected by the temperature of the first joint 2 (the first end 12a). The fact that the second PTC thermistor 13B is arranged near the second joint 3 (the second end 12b) means that the second PTC thermistor 13B is arranged within the range affected by the temperature of the second joint 3 (the second end 12b).

[0037] The first PTC thermistor 13A only needs to be arranged in a range where the distance from the first end 12a is shorter than the distance from the second end 12b, and the second PTC thermistor 13B only needs to be arranged in a range where the distance from the second end 12b is shorter than the distance from the first end 12a. Thereby, the first PTC thermistor 13A can be more greatly affected by the temperature of the first end 12a (the first joint 2) than by the temperature of the second end 12b (the second joint 3), and the second PTC thermistor 13B can be more greatly affected by the temperature of the second end 12b (the second joint 3) than by the temperature of the first end 12a (the first joint 2). The shorter the distances from the first PTC thermistor 13A to the first end 12a and from the second PTC thermistor 13B to the second end 12b, the better.

[0038] The resistance value of the PTC thermistor is substantially constant below the Curie temperature and increases rapidly near the Curie temperature. The temperatures of the first joint 2 (the first end 12a) and the second joint 3 (the second end 12b) both rise or fall with the increase in the DC voltage V when both the first PTC thermistor 13A and the second PTC thermistor 13B are below the Curie temperature. Therefore, when one of the first joint 2 and the second joint 3 is a heat generating part, when the PTC thermistor near the heat generating part among the first PTC thermistor 13A and the second PTC thermistor 13B reaches near the Curie temperature, the resistance value of the PTC thermistor near the heat generating part increases rapidly. As a result, the amount of heat Q decreases. Therefore, when the PTC thermistor near the heat generating part reaches near the Curie temperature, the temperature of the joint functioning as the heat generating part among the first joint 2 and the second joint 3 is the upper limit, and the temperature of the joint functioning as the heat absorbing part among the first joint 2 and the second joint 3 is the lower limit.

[0039] The temperature-sensitive liquid crystal sheet 20 is in contact with the connection circuit 10. In the temperature-sensitive liquid crystal sheet 20, the coloring state of the liquid crystal contained in the temperature-sensitive liquid crystal sheet 20 changes according to the temperature. When a DC voltage V is generated between the first conductor 101A and the second conductor 101B, as described above, the temperatures of the first joint 2 and the second joint 3 change. Specifically, the temperature of the heat generating part among the first joint 2 and the second joint 3 rises, and the temperature of the heat absorbing part decreases.

[0040] Therefore, as shown in FIG. 3, in the temperature-sensitive liquid crystal sheet 20, a region affected by the temperature of the first joint 2 (hereinafter referred to as "region 201") and a region affected by the temperature of the second joint 3 (hereinafter referred to as "region 202") exhibit colors corresponding to the temperatures of the first joint 2 and the second joint 3, respectively. In the temperature-sensitive liquid crystal sheet 20, regions other than region 201 and region 202 (hereinafter referred to as "region 203") are not affected by the temperatures of the first joint 2 and the second joint 3 and exhibit colors corresponding to the temperature of the surrounding environment of the temperature-sensitive liquid crystal sheet 20. FIG. 3 is a drawing for explaining the state of the voltage detection device when a DC voltage is generated between the first conductor and the second conductor. In FIG. 3, the differences in color in regions 201 and 202 are represented by the shades of the color.

[0041] FIG. 4 is a drawing for explaining the state of the voltage detection device when no DC voltage is generated between the first conductor and the second conductor. As shown in FIG. 4, when no DC voltage V is generated between the first conductor 101A and the second conductor 101B, the temperatures of the first joint 2 and the second joint 3 do not increase or decrease. Therefore, regions 201 and 202 have the same color as region 203 (i.e., the color corresponding to the temperature of the surrounding environment).

[0042] Therefore, in the voltage detection device 1, it is possible to determine whether or not a DC voltage V is generated between the first conductor 101A and the second conductor 101B by observing the color development state of the temperature-sensitive liquid crystal sheet 20.

[0043] The connection circuit 10 is a wiring portion configured by connecting metal wires 11 and 12, a first PTC thermistor 13A, and a second PTC thermistor 13B. The voltage detection device 1 is configured by providing the connection circuit 10 on the temperature-sensitive liquid crystal sheet 20. Therefore, miniaturization of the voltage detection device 1 can be achieved. With the configuration of the voltage detection device 1, a thin voltage detection device 1 can also be realized.

[0044] As described in this embodiment, by using the temperature-sensitive liquid crystal sheet 20 for the display unit that displays colors corresponding to temperatures, it is easier to further achieve the above-mentioned miniaturization and thinning.

[0045] Regions 201 and 202 exhibit colors corresponding to the temperatures of the first joint 2 and the second joint 3. Therefore, based on the colors of regions 201 and 202, it is also possible to determine which of the first joint 2 and the second joint 3 is the heat generating part or the heat absorbing part. Furthermore, the first Peltier coefficient ΠA of the metal wire 11 and the second Peltier coefficient ΠB of the metal wire 12 are also known. That is, the magnitude relationship between ΠA and ΠB is also known. Therefore, the magnitude relationship between the potentials of the first conductor 101A and the second conductor 101B can also be grasped.

[0046] As described above, in the voltage detector 1, if the first end 10a and the second end 10b are attached to the object to be voltage-detected, it is possible to determine whether a DC voltage V is generated between the first conductor 101A and the second conductor 101B based on the color development state of the thermosensitive liquid crystal sheet 20. Therefore, complicated preparation work for voltage detection is unnecessary. That is, with the voltage detector 1, it is possible to easily voltage-detect the object to be voltage-detected.

[0047] When using the voltage detector 1, it is easy to pre-attach the voltage detector 1 to an arbitrary location of the object to be voltage-detected. Furthermore, since it is only necessary to check the color of the thermosensitive liquid crystal sheet 20, even if the operator is away from the voltage detector 1, it is possible to determine whether a DC voltage V is charged or applied to the object to be voltage-detected. Therefore, the voltage detector 1 has improved safety for voltage detection.

[0048] The voltage detector 1 includes a first PTC thermistor 13A and a second PTC thermistor 13B. Therefore, PTC thermistors can be arranged near the first joint 2 and the second joint 3.

[0049] For example, if a PTC thermistor is arranged only at one of the first joint 2 and the second joint 3, depending on the sign of the DC voltage V (that is, which of the first conductor 101A and the second conductor 101B is the high potential side), the joint near the PTC thermistor functions as a heat absorbing part, so the resistance value of the PTC thermistor does not increase, and there is a risk of overcurrent.

[0050] On the other hand, the voltage detector 1 includes two PTC thermistors (a first PTC thermistor 13A and a second PTC thermistor 13B), the first PTC thermistor 13A is disposed near the first junction 2, and the second PTC thermistor 13B is disposed near the second junction 3. Therefore, since one of the first PTC thermistor 13A and the second PTC thermistor 13B is disposed near the heat generating portion, the overcurrent can be prevented. Further, as described above, the upper limit temperature of the heat generating portion and the lower limit temperature of the heat absorbing portion are also defined by the actions of the first PTC thermistor 13A and the second PTC thermistor 13B. Therefore, the temperature of the voltage detector 1 can be maintained within a certain safe range.

[0051] If there is one junction exhibiting the Peltier effect in the connection circuit of the voltage detector, depending on the sign of the DC voltage V (i.e., which of the first conductor 101A and the second conductor 101B is the high potential side), the junction functions as a heat absorbing portion. In this case, for example, if the temperature in the region 203 shown in FIG. 3 (i.e., the ambient temperature of the voltage detector) is below the color developing range of the temperature-sensitive liquid crystal sheet 20, the temperature of the heat absorbing portion is also below the color developing range. Therefore, even though a DC voltage V is generated between the first conductor 101A and the second conductor 101B, it is determined that the DC voltage V is not detected.

[0052] On the other hand, the voltage detector 1 has a first junction 2 and a second junction 3 that exhibit the Peltier effect, and one of the first junction 2 and the second junction 3 functions as a heat generating portion. Therefore, with the voltage detector 1, the DC voltage V between the first conductor 101A and the second conductor 101B can be reliably detected. Therefore, electric shock due to non-detection of the voltage can be prevented. Since one of the first junction 2 and the second junction 3 functions as a heat generating portion, it is also possible to prevent overcurrent as described above by the action of the PTC thermistor disposed near the heat generating portion among the first PTC thermistor 13A and the second PTC thermistor 13B.

[0053] When using PTC thermistors with low Curie temperatures as the first PTC thermistor 13A and the second PTC thermistor 13B, and a thermosensitive liquid crystal sheet that develops color at a slight temperature, the power consumption of the voltage detection device 1 can be reduced. The power consumption of the voltage detection device 1 can also be reduced when using metal wires for the metal wire 11 and the metal wire 12 that have a large difference in their Peltier coefficients, low thermal conductivity, and small specific heat.

[0054] (Second Embodiment) The number of the metal wire 11 and the metal wire 12 with different Peltier coefficients is not limited to the number exemplified in the first embodiment. The second embodiment is an example of a form in which the number of the metal wire 11 and the metal wire 12 with different Peltier coefficients is different from that in the first embodiment.

[0055] FIG. 5 is a schematic diagram of a voltage detection device according to the second embodiment. The voltage detection device 1A includes a connection circuit 10A and a thermosensitive liquid crystal sheet 20. FIG. 5 is a drawing when the voltage detection device 1A is viewed from the second surface 22 side of the thermosensitive liquid crystal sheet 20. In FIG. 5, for the purpose of explaining the configuration of the connection circuit 10A, it is shown as a drawing in a state where the thermosensitive liquid crystal sheet 20 is seen through, and the thermosensitive liquid crystal sheet 20 is indicated by a dashed line. In FIG. 5, for convenience of explanation, the first conductor 101A and the second conductor 101B are also illustrated by dashed lines.

[0056] The connection circuit 10A has a first end 10a connected to the first conductor 101A and a second end 10b connected to the second conductor 101B. The connection circuit 10A is configured by connecting seven metal wires 11, four metal wires 12, a first PTC thermistor 13A, and a second PTC thermistor 13B. The connection circuit 10A is a wiring part that electrically connects the first conductor 101A and the second conductor 101B.

[0057] The fact that the Peltier coefficients of the metal wire 11 and the metal wire 12 are different is the same as that of the voltage detection device 1. That is, the metal wire 11 has a first Peltier coefficient, and the metal wire 12 has a second Peltier coefficient. The first Peltier coefficient and the second Peltier coefficient are different.

[0058] Seven metal wires 11 are referred to as metal wire 11A, metal wire 11B, metal wire 11C, metal wire 11D, metal wire 11E, metal wire 11F, and metal wire 11G, and four metal wires 12 are referred to as metal wire 12A, metal wire 12B, metal wire 12C, and metal wire 12D. The connection relationship among the seven metal wires 11, the four metal wires 12, the first PTC thermistor 13A, and the second PTC thermistor 13B will be described.

[0059] The connection circuit 10A has, in the direction from the first end 10a to the second end 10b, the metal wire 11A, the metal wire 12A, the metal wire 11B, the second PTC thermistor 13B, the metal wire 11C, the first PTC thermistor 13A, the metal wire 11D, the metal wire 12B, the metal wire 11E, the metal wire 12C, the metal wire 11F, the metal wire 12D, and the metal wire 11G in this order.

[0060] Among the metal wires 11A, the end opposite to the metal wire 12A is the first end 10a. The metal wire 12A connects the metal wire 11A and the metal wire 11B. The metal wire 12A has a first end 12a connected to the metal wire 11A and a second end 12b connected to the metal wire 11B. The metal wire 11B connects the metal wire 12A and the second PTC thermistor 13B. The metal wire 11C connects the second PTC thermistor 13B and the first PTC thermistor 13A. In the second embodiment, the metal wire 11D connects the first PTC thermistor 13A and the metal wire 12B. The metal wire 12B connects the metal wire 11D and the metal wire 11E. The metal wire 12B has a first end 12a connected to the metal wire 11D and a second end 12b connected to the metal wire 11E. The metal wire 11E connects the metal wire 12B and the metal wire 12C. The metal wire 12C connects the metal wire 11E and the metal wire 11F. The metal wire 12C has a first end 12a connected to the metal wire 11E and a second end 12b connected to the metal wire 11F. The metal wire 11F connects the metal wire 12C and the metal wire 12D. The metal wire 12D connects the metal wire 11F and the metal wire 11G. The metal wire 12D has a first end 12a connected to the metal wire 11F and a second end 12b connected to the metal wire 11G. The end of the metal wire 11G opposite to the connection end with the metal wire 12D is the second end 10b connected to the second conductor 101B.

[0061] In the above connection relationship, in the current path when current flows through the connection circuit 10A, the first end 12a of each of the metal wires 12A to 12D is the end on the side of the first conductor 101A of each of the metal wires 12A to 12D, and the second end 12b of each of the metal wires 12A to 12D is the end on the side of the second conductor 101B of each of the metal wires 12A to 12D.

[0062] The first PTC thermistor 13A is disposed near the first end 12a of the metal wire 12A, and the second PTC thermistor 13B is disposed near the second end 12b of the metal wire 12A.

[0063] In one embodiment, as shown in FIG. 5, the metal wire 12A and the metal wire 12B may be disposed opposite to each other in a direction orthogonal to the extending direction of the metal wire 12A (or the metal wire 12B), and the metal wire 12C and the metal wire 12D may be disposed opposite to each other in a direction orthogonal to the extending direction of the metal wire 12C (or the metal wire 12D). Specifically, the metal wire 12A and the metal wire 12B may be disposed such that the first end 12a of the metal wire 12A and the first end 12a of the metal wire 12B face each other, and the second end 12b of the metal wire 12A and the second end 12b of the metal wire 12B face each other. The metal wire 12C and the metal wire 12D may be disposed such that the first end 12a of the metal wire 12C and the first end 12a of the metal wire 12D face each other, and the second end 12b of the metal wire 12C and the second end 12b of the metal wire 12D face each other.

[0064] In one embodiment, as shown in FIG. 5, the first PTC thermistor 13A and the second PTC thermistor 13B may be disposed between two oppositely arranged metal wires 12A and 12B. Specifically, the second PTC thermistor 13B is disposed between the second ends 12b of the metal wire 12A and the second ends 12b of the metal wire 12B, and the first PTC thermistor 13A may be disposed between the first ends 12a of the metal wire 12A and the first ends 12a of the metal wire 12B.

[0065] Since the temperature-sensitive liquid crystal sheet 20 is the same as that of the voltage detector 1 shown in FIGS. 1 and 2, the description thereof is omitted. The installation form of the connection circuit 10A with respect to the temperature-sensitive liquid crystal sheet 20 is the same as the installation form of the connection circuit 10 with respect to the temperature-sensitive liquid crystal sheet 20.

[0066] Also in the connection circuit 10A, metal wires 11 having a different Peltier coefficient from the metal wires 12 are joined to both ends of each of the four metal wires 12 (metal wires 12A to 12D). Similar to the case of the first embodiment, the portion of the first end 12a of the metal wire 12 joined to the metal wire 11 is referred to as the first joint portion 2, and the portion of the second end 12b of the metal wire 12 joined to the metal wire 11 is referred to as the second joint portion 3.

[0067] One of the first joint portion 2 (first end 12a) and the second joint portion 3 (second end 12b) of each of the metal wires 12A to 12D with the metal wire 11 functions as a heat generating portion, and the other functions as a heat absorbing portion. Since the temperature-sensitive liquid crystal sheet 20 is in contact with the connection circuit 10A, when a DC voltage V is generated between the first conductor 101A and the second conductor 101B, among the temperature-sensitive liquid crystal sheet 20, the regions corresponding to the respective heat generating portions (and the vicinity thereof), the regions corresponding to the respective heat absorbing portions (and the vicinity thereof), and the regions away from the plurality of heat generating portions and heat absorbing portions exhibit different colors. Therefore, similar to the case of the first embodiment, the voltage detector 1A can also perform voltage detection on the object to be detected.

[0068] In each of the metal wires 12A to 12D, one of the first joint 2 (first end 12a) and the second joint 3 (second end 12b) with the metal wire 11 functions as a heat generating part, and the other functions as a heat absorbing part. The operational effects are the same as those in the first embodiment. The voltage detecting device 1A has a first PTC thermistor 13A and a second PTC thermistor 13B. The first PTC thermistor 13A is disposed near the first end 12a of the metal wire 12A, and the second PTC thermistor 13B is disposed near the second end 12b of the metal wire 12A. The operational effects are also the same as those in the first embodiment. Therefore, the voltage detecting device 1A has at least the same operational effects as the voltage detecting device 1.

[0069] The voltage detecting device 1A has seven metal wires 11 (metal wires 11A to 11G) and four metal wires 12 (metal wires 12A to 12D), and the metal wires 11 are disposed at both ends of each of the four metal wires 12 (metal wires 12A to 12D). Therefore, as described above, one of the first joint 2 and the second joint 3 of each of the metal wires 12A to 12D with the metal wire 11 functions as a heat generating part, and the other functions as a heat absorbing part. Accordingly, when a DC voltage V is generated between the first conductor 101A and the second conductor 101B, in the thermosensitive liquid crystal sheet 20, in the regions corresponding to the plurality of heat generating parts, colors corresponding to the temperatures of the heat generating parts are developed, and in the regions corresponding to the plurality of heat absorbing parts, colors corresponding to the temperatures of the heat absorbing parts are developed. When a DC voltage V is generated between the first conductor 101A and the second conductor 101B, a pattern (color developing pattern) corresponding to the arrangement pattern of the four metal wires 12 is displayed on the thermosensitive liquid crystal sheet 20.

[0070] For example, in the arrangement of the seven metal wires 11 and the four metal wires 12 shown in FIG. 5, the first end 12a of the metal wire 12A and the first end 12a of the metal wire 12B face each other, the second end 12b of the second end of the second end 12b of the metal wire 12A and the metal wire 12B face each other, the first end 12a of the metal wire 12C and the first end 12a of the metal wire 12D face each other, and the second end 12b of the metal wire 12C and the second end 12b of the metal wire 12D face each other. In such an arrangement form, colors corresponding to the heat generating part and the heat absorbing part appear alternately along the longitudinal direction of the thermosensitive liquid crystal sheet 20.

[0071] Therefore, by arranging the four metal wires 12 so that a desired pattern that more clearly indicates the presence of the DC voltage V appears on the thermosensitive liquid crystal sheet 20, it is possible to more easily determine whether or not a DC voltage V is generated between the first conductor 101A and the second conductor 101B. In particular, it is easy to determine whether or not a DC voltage V is generated between the first conductor 101A and the second conductor 101B even from a location far from the power detector 1A.

[0072] One of the first joint 2 (first end 12a) and the second joint 3 (second end 12b) of each of the metal wires 12A to 12D with the metal wire 11 functions as a heat generating part, and the other functions as a heat absorbing part. In the power detector 1A, the presence or absence of the DC voltage V is determined by the difference in temperature between the heat generating part and the heat absorbing part being displayed as a difference in color on the thermosensitive liquid crystal sheet 20. Therefore, the metal wires 12A to 12D may be arranged so that the first joint 2 and the second joint 3 are separated from each other to such an extent that they are not affected by each other's temperature.

[0073] In the form illustrated in FIG. 5, the first PTC thermistor 13A is arranged between the two oppositely arranged first ends 12a, and the second PTC thermistor 13B is arranged between the two oppositely arranged second ends 12b. In such an arrangement, the temperature of the first PTC thermistor 13A is affected by the two first ends 12a (first joint 2), and the temperature of the second PTC thermistor 13B is affected by the two second ends 12b (second joint 3). Therefore, since the temperatures of the first PTC thermistor 13A and the second PTC thermistor 13B are more likely to change, the power consumption of the power detector 1A during power detection can be reduced.

[0074] As described above, the embodiments of the present invention have been described, but the present invention is not limited to the above embodiments. The present invention is defined by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

[0075] The first wiring member and the second wiring member are wiring members having different Peltier coefficients. Therefore, the examples of the first wiring member and the second wiring member are not limited to metal wires. For example, one of the first wiring member and the second wiring member may be a wiring member composed of a p-type semiconductor, and the other may be a wiring member composed of an n-type semiconductor.

[0076] The connection circuit may be wound around the temperature-sensitive liquid crystal sheet.

[0077] The temperature-sensitive display sheet described in the first embodiment and the second embodiment is an example of a display unit that displays a color corresponding to the temperature. The display unit is not limited as long as it can display the difference in temperature. The display unit may be, for example, a sheet (temperature-indicating sheet) coated with a temperature-indicating material whose color changes when a specific temperature is reached, a label (temperature-indicating label), or the like.

[0078] The number of the first wiring member and the second wiring member is not limited to the number exemplified in the first and second embodiments.

[0079] The voltage detector can also detect an alternating voltage by connecting a rectifier circuit using a diode or the like to the first end 10a and the second end 10b of the connection circuit 10. In this case, the voltage detector can inspect whether or not an alternating voltage is applied to the object to be detected.

[0080] The various embodiments and modifications described above may be combined without departing from the spirit of the present invention.

Description of Reference Numerals

[0081] 1, 1A... Voltage detector, 10, 10A... Connection circuit, 10a... First end, 10b... Second end, 12a... First end, 12b... Second end, 13A... First PTC thermistor, 13B... Second PTC thermistor, 20... Temperature-sensitive liquid crystal sheet (display unit), 101A... First conductor, 101B... Second conductor.

Claims

1. A voltage detecting device for detecting whether a voltage is generated between a first conductor and a second conductor, comprising: A connection circuit for electrically connecting the first conductor and the second conductor; A display unit in contact with the connection circuit and displaying a temperature difference; Comprising; The connection circuit includes: A first wiring member having a first end and a second end; Second wiring members respectively connected to the first end and the second end of the first wiring member; A first PTC thermistor disposed near the first end; A second PTC thermistor disposed near the second end; Having; Each of the first wiring member, the second wiring member, the first PTC thermistor, and the second PTC thermistor constitutes a part of a current path when a voltage is generated between the first conductor and the second conductor; The first end is the end of the first wiring member on the first conductor side in the current path; The second end is the end of the first wiring member on the second conductor side in the current path; The Peltier coefficients of the first wiring member and the second wiring member are different; Voltage detecting device.

2. The display unit is a thermosensitive liquid crystal sheet. The voltage detecting device according to claim 1.

3. Comprising a plurality of the first wiring members; The second wiring members are connected to the first ends and the second ends of the plurality of first wiring members respectively; The voltage detecting device according to claim 1 or 2.

4. Two of the plurality of first wiring members are disposed opposite to each other; The first ends of the two first wiring members disposed opposite to each other are opposite to each other, and the second ends of the two first wiring members disposed opposite to each other are opposite to each other; The first PTC thermistor is disposed opposite to the first end between the two first wiring members disposed opposite to each other; The second PTC thermistor is disposed opposite to the second end between the two first wiring members disposed opposite to each other; The voltage detecting device according to claim 3.

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