JP2000206155A - Heat couple type digital input apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make convertible the presence/absence of voltage impression into a digital value with a simple circuit constitution by detecting the presence/absence of an impressed voltage from a resistance value of a secondary resistor body thermally coupled to a primary resistor body which impresses a voltage to be detected. SOLUTION: When power is supplied to an electromagnetic switch 2, a voltage is impressed to both ends of a primary resistor body 9, whereby the resistor body generates by itself and at the same time operates as a constant temperature heating element to be a high resistance value. The heat is transmitted to a secondary resistor body 10 through heat coupling. A temperature of the secondary resistor body 10 is consequently raised and the secondary resistor body has a low resistance value. As a result, an input voltage V1 of a digital input part 8 becomes a low level, whereby it is detected that the power is supplied to the electromagnetic switch 2. On the other hand, when the power supply to the electromagnetic switch 2 is shut, no voltage is impressed to both ends of the primary resistor body 9, and the primary resistor body does not heat by itself and radiates heat, thereby decreasing a temperature to be a low resistance vale. The temperature of the secondary resistor body 10 is lowered and the secondary resistor body shows a high resistance value. The input voltage V1 of the digital input part 8 becomes a high level, thereby, it is detected that the power supply to the electromagnetic switch 2 is shut.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital input device which converts the presence or absence of application of a voltage (or current) to a circuit to be controlled into a digital value and takes it into a control device. For example, when performing control to monitor the stoppage of power supply to the motor and to issue an alarm, it is necessary to take into the control device whether or not voltage (or current) is applied to the motor as a digital value. The present invention relates to a digital input device used in such a case.

[0002]

2. Description of the Related Art FIG. 1 shows an example of the prior art. Figure 1 shows 2
This is a circuit for driving five three-phase induction motors by using the electromagnetic switch of (2), and is an example of monitoring the power supply state to the electromagnetic switch of (2). When the switch 1 is turned on, the power supply 3 is turned on to the electromagnetic switch 2, the main contact 4 is turned on, and the three-phase induction motor 5 is started. On the other hand, the auxiliary contact 6 is also turned on, and the on state of the auxiliary contact 6 is detected by the digital input unit 8 via the voltage level converter 7. 3 for 2 electromagnetic switches
When the power supply is cut off, the main contact 4 is turned off and the three-phase induction motor 5 is stopped. On the other hand, the auxiliary contact 6 is also turned off and the off state of the auxiliary contact 6 is detected at the digital input unit 8 via the voltage level converter 7. Further, as another conventional technique, as described in JP-A-5-5758, heat generated from a resistor connected in series to a circuit is transmitted to a thermistor, and a current flowing through the resistor is determined based on a change in the resistance value of the thermistor. Current detection device for determining the effective value of

[0003]

The prior art shown in FIG. 1 is a contact type in which an auxiliary contact of the electromagnetic switch is used to monitor the power supply state of the electromagnetic switch. Therefore, for contact stability, a voltage above a certain value (for example, 24V or 48V)
Had to be applied to the contacts.

However, since the digital input section is generally 5 V or less, a power supply for contact application and a voltage level conversion section are indispensable, and there has been a problem that the circuit configuration becomes complicated and the cost increases. In addition, there were problems of poor contact and welding of the contacts.

Further, in the above prior art of the current detecting device, an effective current value detecting circuit comprising an ambient temperature detecting means, a temperature detecting circuit, a subtraction circuit and a square root circuit is indispensable in order to obtain the effective value of the current. However, there has been a problem that the method is complicated and the cost is high. Also, in order to take the presence or absence of a current as a digital value into the control device, it is necessary to convert an analog value that is an effective current value into a digital value that indicates the presence or absence of a current.

An object of the present invention is to digitize the presence or absence of application of a voltage (or current) to the above-mentioned controlled circuit by a contactless method.

It is another object of the present invention to eliminate the need for a power supply for contact application, a voltage level converter, and the above-described effective current value detection circuit.

[0008]

In order to achieve the above object, a digital input device for applying a voltage to be detected is provided.
A secondary-side resistor and a secondary-side resistor that is thermally coupled to the primary-side resistor and whose resistance value changes with temperature are provided, and the presence or absence of an applied voltage is digitized by the resistance value of the secondary-side resistor. is there.

Also, as a part for a digital input device, 1
A secondary-side resistor and a secondary-side resistor which is thermally coupled to the primary-side resistor and whose resistance value changes with temperature are provided. In addition, a positive temperature coefficient thermistor or a negative temperature coefficient thermistor whose resistance value changes rapidly by applying a voltage to the primary resistor and self-heats to provide a sudden change in the resistance value is provided in the secondary resistor. A characteristic thermistor is provided.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a digital input device according to the present invention will be described below with reference to FIG. FIG. 2 is a circuit for driving five three-phase induction motors using two electromagnetic switches, and is an example of monitoring the power supply state to the two electromagnetic switches by voltage. The three-phase induction motor 5 is connected to a three-phase AC power source via four main contacts of two electromagnetic switches. Two electromagnetic switches are connected to three power supplies and one switch. 1 of 9
The secondary-side resistor (positive-characteristic thermistor in this embodiment) is connected in parallel to the two electromagnetic switches.

The secondary resistor (negative thermistor in this embodiment) is thermally coupled to the primary resistor and electrically insulated from the primary resistor. The 10 secondary resistors are fed by 11 resistors and connected to 8 digital inputs.
The primary-side resistor 9 has a low resistance value when power is not supplied, has a high resistance value when power is supplied, and is selected as a constant-temperature heating element that maintains a predetermined temperature. The ten secondary-side resistors are selected to have a high resistance value in a predetermined low temperature state and have a low resistance value in a predetermined high temperature state. 11
Are selected so that the digital input unit of 8 can recognize the high level and the low level of the voltage V1 divided by the high resistance value and the low resistance value of the 10 secondary resistors.

FIG. 3 shows the relationship between the primary resistor 9 and the secondary resistor 10 and V1. When power is supplied to the electromagnetic switch 2, a voltage is applied to both ends of the primary resistor 9. 1 of 9
The secondary-side resistor operates as a constant-temperature heater having a high resistance value simultaneously with self-heating. The heat of the primary-side resistor 9 is conducted to the secondary-side resistor 10 by thermal coupling, and the temperature of the secondary-side resistor 10 rises to a low resistance value.

As a result, the input voltage V1 of the digital input unit 8 becomes low level, so that the digital input unit 8 detects that power is supplied to the electromagnetic switches 2. When the power supply to the electromagnetic switch 2 is cut off, no voltage is applied to both ends of the primary-side resistor 9. The primary-side resistor No. 9 does not generate heat by itself, and its temperature is lowered by heat radiation to have a low resistance value. As a result, the temperature of the ten secondary-side resistors thermally coupled decreases, and the ten secondary-side resistors have a high resistance value. Since the input voltage V1 of the digital input unit 8 becomes high level, the digital input unit 8 detects that the power supply of the electromagnetic switch 2 is cut off.

FIG. 4 shows another embodiment. Figure 4 shows the 9-1
A secondary resistor is connected in series with the two electromagnetic switches,
This is an example in which the state of power supply to the electromagnetic switch 2 is monitored by current.

FIG. 5 shows the relationship between the primary resistor 9 (negative characteristic thermistor in this embodiment) of FIG. 4, the secondary resistor 10 (negative thermistor in this embodiment) and V2 in FIG. And 9 primary-side resistors, 10 secondary-side resistors, and 11
By selecting the resistors as shown in FIG. 5, the same effect as in the embodiment of FIG. 2 can be obtained.

FIG. 6 shows another embodiment. FIG. 6 shows an example of monitoring overcurrent to twelve loads. The load of 12 is 1 of 9
It is connected to a secondary-side resistor (positive-characteristic thermistor in this embodiment), one switch, and three power sources. The primary-side resistor 9 has a low resistance value at a predetermined current or less, has a high resistance value in an overcurrent state, and is selected as a constant temperature heating element that maintains a predetermined temperature. FIG. 7 shows a relationship between the primary resistor 9 and the secondary resistor 10 (negative thermistor in this embodiment) and V3.

When an overcurrent flows to the load due to a short circuit in the load or the like, the primary-side resistor 9 has a high resistance value at the same time as self-heating and operates as a constant-temperature heating element. The heat of the primary-side resistor 9 is conducted to the secondary-side resistor 10 by thermal coupling, and
The temperature of the secondary resistor rises to a low resistance value.

Thus, when the input voltage V3 of the digital input unit 8 becomes low level, the digital input unit 8 detects that an overcurrent has flowed to the load. According to this embodiment, since the primary-side resistor 9 has a high resistance value due to the overcurrent, the overcurrent to the load is suppressed, and there is an effect of preventing the load from burning.

FIG. 8 shows an embodiment in which a transformer is used as the load in FIG. 6, and the same effects as in FIG. 6 can be obtained.

FIG. 9 shows another embodiment. FIG. 9 is an example of monitoring the power use state of the office, and turns on or off the lamp of the power use indicator to confirm that all the power of the office equipment such as a personal computer and the lighting in the office is shut off. Here is an example. Fifteen office machines in the group of 14 office machines are connected to three power supplies via one switch in the eighteen office equipment distribution boards. 17 lights in the 16 lighting groups are connected to 3 power supplies via 1 switch in the 19 lighting distribution board. Between the 1 switch and the 14 office groups in the 18 office equipment distribution board, and between the 1 switch and the 16 lighting group in the 19 lighting distribution board, 9 primary-side resistors (In this embodiment, a positive temperature coefficient thermistor) is connected in parallel.

Each of the ten secondary resistors (the positive characteristic thermistor in this embodiment) is connected in series to twenty power indicators. When any one switch is turned on, a voltage is applied to both ends of the nine primary resistors connected to that switch. The primary-side resistor 9 operates as a constant-temperature heater having a high resistance value simultaneously with self-heating. The heat of the primary-side resistor 9 is conducted to the secondary-side resistor 10 by thermal coupling, and the temperature of the secondary-side resistor 10 increases to a high resistance value. Twenty power indicator units are connected in series.
Detects that the circuit of the secondary resistor has a high resistance value,
Turn on the power usage lamp.

On the other hand, when all the one switches are turned off, no voltage is applied to both ends of the nine primary resistors connected to all the one switches. The primary-side resistor No. 9 does not generate heat by itself, and its temperature is lowered by heat radiation to have a low resistance value. Thereby, the temperature of the ten secondary-side resistors thermally coupled decreases, and the ten secondary-side resistors have a low resistance value. The power use indicator detects that the circuit of ten secondary resistors connected in series has a low resistance value, and turns off the power use lamp. Thus, it is only necessary to confirm that all the switches have been shut off at a single power supply indicator, and there is an energy saving effect of preventing waste of power due to forgetting to switch off.

FIGS. 10, 11, 12, and 13 show another embodiment, in which a plurality of secondary resistors are connected to form a logic circuit. FIG. 10 shows an example in which ten secondary-side resistors are connected in series. FIG. 11 shows the truth table of FIG. The input voltage V4 of the digital input unit changes to the state shown in FIG. 11 according to the state of one switch of the circuit A 21 and the one switch of the circuit B 22 in FIG. FIG.
Is an example in which ten secondary resistors are connected in parallel. FIG. 13 shows the truth table of FIG.
The input voltage V of the digital input unit depends on the state of one switch of the circuit C in FIG. 12 and one switch of the circuit D in 24.
5 is in the state of FIG.

Thus, a logic circuit can be formed by connecting ten secondary-side resistors in series or in parallel, and an effect of simplifying the logic operation on the control device side can be obtained. Also,
The wiring from the digital input section to the secondary-side resistor can be minimized, and the wiring cost can be reduced.

FIG. 14 shows another embodiment. FIG.
This is an example of monitoring a sensor that converts a physical quantity such as a pressure sensor into an electrical quantity or a physical quantity output from a sensor controller that exceeds an upper / lower limit or a sensor abnormality alarm. Twenty-seven alarm output circuits in the twenty-five sensor controllers are connected to nine primary-side resistors (positive-characteristic thermistors in this embodiment). Both ends of the ten secondary-side resistors (negative-characteristic thermistors in this embodiment) are connected to the eight digital inputs via the twenty-six output terminals of twenty-five sensor controllers.
When the 25 sensor controllers detect that the physical quantity exceeds the upper and lower limits or the sensor is abnormal, the 27 alarm output circuit sets 9-1
A voltage is applied to the secondary resistor.

The primary-side resistor 9 operates as a constant-temperature heater having a high resistance value simultaneously with self-heating. The heat of the primary-side resistor 9 is conducted to the secondary-side resistor 10 by thermal coupling,
The temperature of the secondary-side resistor of No. 10 rises to a low resistance value. 8
When the input voltage V6 of the digital input section becomes low level, the digital input section 8 detects the alarm output from the 25 sensor controllers. According to this embodiment, the power supply for contact application and the voltage level converter required when the alarm output by the relay contact is taken into the control device are not required, and the effects of low cost, space saving, and energy saving can be obtained.

FIG. 15, FIG. 16, FIG. 17, FIG. 18, FIG.
9, FIG. 20, FIG. 21, and FIG. 22 show embodiments of the digital input device component of the present invention. 9 primary side resistor and 10 2
The secondary resistor contacts 28 thermal conductors for thermal coupling. The same effect can be obtained by contacting the primary resistor 9 and the secondary resistor 10 with the thermal conductor 28 by sintering or bonding to the thermal conductor 28 or fixing with a screw. 1 of 9
29 connection terminals for applying a detected voltage are connected to the secondary resistor. Ten connection terminals for connecting a digital input unit are connected to ten secondary-side resistors. 29,30
The same effect can be obtained even if the connection terminal is a lead wire, a plate-like electrode, or an electrode for a chip component.

FIG. 15 shows a 9-1 on one side of the 28 heat conductor.
This is an example in which the secondary resistor and the ten secondary resistors are in contact with each other,
The effect of miniaturization is obtained. FIG. 16 shows an example in which the connection terminals 29 and 30 are arranged opposite to each other, and an effect of improving the electrical withstand voltage between the connection terminals 29 and 30 is obtained as compared with FIG. 17 and 19 show an example in which 9 primary-side resistors and 10 secondary-side resistors are embedded in 28 heat conductors, wherein 9 primary-side resistors and 10 secondary-side resistors are embedded. The effect of improving the thermal conductivity between them is obtained.

FIGS. 18 and 20 show examples in which the connection terminals 29 and 30 are arranged opposite to each other. The improvement of the electrical withstand voltage between the connection terminals 29 and 30 is shown in FIGS. 17 and 19, respectively. The effect is obtained. FIG. 21 shows an example in which 9 primary-side resistors are in contact with one surface of the 28 heat conductors and 10 secondary-side resistors are in contact with the other surface. Is obtained. FIG. 22 shows an example in which the connection terminals 29 and 30 are arranged opposite to each other. The effect of improving the electrical withstand voltage between the connection terminals 29 and 30 is obtained as compared with FIG.

[0030]

According to the present invention, since the non-contact type is used, there is an effect that there is no malfunction due to contact failure and welding which is peculiar to the contact type, and high reliability is secured. In addition, there is no noise and there is an effect of a long life. Since the digital value can be captured by the power supply of the digital input unit, the need for a contact application power supply and a voltage level conversion unit is eliminated, and there is an effect of reducing cost, space, and energy.

Further, since it is not necessary to obtain the effective current value, there is no need for a current effective value detection circuit, which has the effect of reducing cost and space. Because of heat conduction, it is suitable for low-speed response applications, and has a filter effect and a hysteresis effect on electric noise of a circuit to be controlled. Since the resistor and the heat conductor are solid elements, they have a simple structure, and have mechanical vibration and shock resistance effects.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a conventional driving circuit for a three-phase induction motor using an electromagnetic switch.

FIG. 2 is a drive circuit of a three-phase induction motor using an electromagnetic switch according to one embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between a primary-side resistor, a secondary-side resistor, and V1 in FIG. 2;

FIG. 4 is a drive circuit of a three-phase induction motor using the electromagnetic switch according to one embodiment of the present invention.

FIG. 5 is a diagram showing a relationship between a primary-side resistor, a secondary-side resistor, and V2 in FIG. 4;

FIG. 6 is a diagram showing a circuit for monitoring an overcurrent according to one embodiment of the present invention.

FIG. 7 is a diagram illustrating a relationship between a primary-side resistor, a secondary-side resistor, and V3 in FIG. 6;

FIG. 8 is a diagram illustrating an example in which a transformer is used as the load in FIG. 6;

FIG. 9 is a diagram of monitoring a power use state of an office in an embodiment of the present invention.

FIG. 10 is a circuit in which secondary-side resistors according to an embodiment of the present invention are connected in series.

FIG. 11 is a diagram showing a truth table of FIG. 10;

FIG. 12 is a circuit in which secondary-side resistors according to one embodiment of the present invention are connected in parallel.

FIG. 13 is a diagram showing a truth table of FIG. 12;

FIG. 14 is a diagram showing a circuit for monitoring an alarm output from a sensor controller according to one embodiment of the present invention.

FIG. 15 is a view showing a structure of a component for a digital input device according to an embodiment of the present invention.

FIG. 16 is a view showing the structure of a component for a digital input device according to another embodiment of the present invention.

FIG. 17 is a view showing the structure of a component for a digital input device according to another embodiment of the present invention.

FIG. 18 is a view showing the structure of a component for a digital input device according to another embodiment of the present invention.

FIG. 19 is a view showing the structure of a component for a digital input device according to another embodiment of the present invention.

FIG. 20 is a view showing a structure of a component for a digital input device according to another embodiment of the present invention.

FIG. 21 is a view showing the structure of a component for a digital input device according to another embodiment of the present invention.

FIG. 22 is a view showing the structure of a component for a digital input device according to another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Switch, 2 ... Electromagnetic switch, 3 ... Power supply, 4 ... Main contact, 5 ... Three-phase induction motor, 6 ... Auxiliary contact, 7 ... Voltage level conversion part, 8 ... Digital input part, 9 ... Primary resistance Body, 1
0: Secondary resistor, 11: Resistance, 12: Load, 13: Transformer, 14: Office equipment group, 15: Office equipment, 16: Lighting group, 17: Lighting, 18: Office equipment distribution board, 19 ... Lighting distribution board, 20: power indicator, 21: circuit A, 22:
Circuits B, 23: Circuit C, 24: Circuit D, 25: Sensor controller, 26: Output terminal, 27: Alarm output circuit, 2
8 ... thermal conductor, 29 ... connection terminal for applying a detected voltage, 3
0 ... Connection terminal for connecting digital input section.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Haruhisa Suzuki 5-2-1 Omikacho, Hitachi City, Ibaraki Prefecture Inside Hitachi Process Computer Engineering Co., Ltd. (72) Inventor Hideo Otani 5-chome Omikacho, Hitachi City, Ibaraki Prefecture No. 1 Hitachi Process Computer Engineering Co., Ltd. (72) Inventor Yasuharu Kamata 5-2-1 Omika-cho, Hitachi City, Ibaraki Prefecture Hitachi Process Computer Engineering Co., Ltd. (72) Inventor Tomonori Kaneko Omika, Hitachi City, Ibaraki Prefecture 2-2-1, Machi-cho, Hitachi, Ltd. Omika Plant, Hitachi, Ltd. (72) Inventor Yasunori Nomoto 5-2-1, Omika-cho, Hitachi, Ibaraki F-term, Omika Plant, Hitachi Ltd. F-term (reference) 2G035 AA10 AA12 AA22 AB04 AB08 AC01 AC03 AD06 AD45 AD64 5 J050 AA11 AA37 AA42 AA49 CC01 FF36

Claims (3)

[Claims] In a digital input device, a primary-side resistor for applying a voltage to be detected and a secondary-side resistor thermally coupled to the primary-side resistor and having a resistance value that changes with temperature are provided. Thermal-coupled digital input device. 2. A thermal input type digital input device according to claim 1, wherein a primary side resistor and a secondary side resistor are provided. 3. The heat-coupled type according to claim 1, wherein a positive-characteristic thermistor or a negative-characteristic thermistor is used for the primary-side resistor, and a positive-characteristic thermistor or a negative-characteristic thermistor is used for the secondary-side resistor. Digital input device.