Electric / electronic circuit and planar warmer

Abstract

To provide an electric / electronic circuit capable of reducing wear of a drive relay of a planar warmer operating by AC power supply.SOLUTION: An electric electronic circuit 11 controls a drive relay 12. The drive relay 12 cuts off or conducts an electric path 5 between an AC power supply 4 and a heater 22 of a planer warmer. The electric / electronic circuit 11 sends a first control signal S11 which commands changeover between a conduction state and a cut-off state to the drive relay 12 in a first period which is one period of an AC voltage supplied by the AC power supply 4. The electric / electronic circuit 11 controls a time to send a second control signal S12 in a second period which is one period of an AC voltage after the first period, based on a relay monitoring signal. The relay monitoring signal indicates whether the drive relay 12 in the first period is in the conduction state or the cut-off state. The second control signal S12 commands state change same as the first control signal S11 to the drive relay 12.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to an electric and electronic circuit and a planar heater, and particularly to an electric and electronic circuit for controlling a drive relay of a planar heater and a planar heater.

Background Art

[0002] Patent Document 1 discloses an electric carpet (planar heater) and a microcomputer (electric and electronic circuit). In the electric carpet described in Patent Document 1, the microcomputer switches the energized state (conductive state) and the de-energized state (cut-off state) of a relay (drive relay) that controls each of a plurality of heating regions of the electric carpet.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the contacts of the drive relay wear due to operation. In particular, when power is supplied to the heater of the planar heater from an AC power source, it is preferable that the absolute value of the AC voltage is small during the operation of the drive relay.

[0005] An object of the present disclosure is to provide an electric and electronic circuit capable of reducing wear of a drive relay of a planar heater operating with an AC power source, and a planar heater.

Means for Solving the Problems

[0006] An electric and electronic circuit according to an aspect of the present disclosure controls a drive relay that interrupts or conducts an electric circuit between an AC power source and a heater of a planar heater. In a first cycle, the electric and electronic circuit sends a first control signal. The first cycle is one cycle of the AC voltage supplied by the AC power source. The first control signal instructs the drive relay to switch between a conductive state and a cutoff state. The electric and electronic circuit controls the time to send a second control signal in a second cycle based on a relay monitoring signal. The relay monitoring signal indicates whether the drive relay is in the conductive state or the cutoff state in the first cycle. The second cycle is one cycle of the AC voltage after the first cycle. The second control signal instructs the drive relay to change to the same state as the first control signal.

[0007] A planar heater according to an aspect of the present disclosure includes the electric and electronic circuit, the drive relay, and a heater. The drive relay is controlled by the electric and electronic circuit. The heater is powered through the drive relay.

Advantages of the Invention

[0008] According to the electric and electronic circuit and the planar heater according to an aspect of the present disclosure, it is possible to reduce wear of the drive relay of the planar heater operating with an AC power source.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, the electrical and electronic circuit and the planar heater according to the embodiment will be described in detail with reference to the drawings.

[0011] (Embodiment) 1. Planar Heater As shown in FIG. 1, the planar heater 100 includes a controller 1, a main body 2, and a power supply unit 3. The planar heater 100 is a so-called electric carpet.

[0012] The controller 1 controls the temperature of the main body 2. More specifically, the controller 1 controls the temperature of the main body 2 in units of the heating area 21.

[0013] The main body 2 has, for example, one or more (one in FIG. 1) heating regions 21. The heating region 21 corresponds to the heating surface. The main body 2 includes a heater 22 and a temperature sensor 23 corresponding to the heating region 21. The heater 22 is a so-called heating wire. The temperature sensor 23 is a temperature measuring resistor such as a thermistor, for example. The heater 22 generates heat using the power supplied from an AC power supply 4 (see FIG. 2) via the controller 1 and heats the corresponding heating region 21. The temperature sensor 23 is provided, for example, for each heating region 21, and the controller 1 detects the temperature of the heating region 21 using the temperature sensor 23.

[0014] The power supply unit 3 supplies the power received from the AC power supply 4 to the main body 2 via the controller 1. The power supply unit 3 includes, for example, a plug and a wiring unit that connects the plug to the main body 2.

[0015] The AC power supply 4 is, for example, a commercial AC power supply, but is not limited to this as long as it is an AC power supply, and may be, for example, an AC generator, an inverter, or the like.

[0016] 2. Controller The details of the controller 1 will be described below.

[0017] FIG. 2 is a circuit diagram of the planar heater 100. The planar heater 100 includes an electric and electronic circuit 11 and a power supply circuit 13. Further, the planar heater 100 includes a drive relay 12, a heater 22, and a temperature sensor 23 for each heating region 21. The drive relay 12 and the heater 22 corresponding to the same heating region 21 are connected in series. That is, the drive relay 12 and the heater 22 corresponding to the same heating region 21 are provided in series in the circuit 5 corresponding to the heating region 21.

[0018] The controller 1 includes the electric and electronic circuit 11, the drive relay 12, and the power supply circuit 13 among the components of the planar heater 100.

[0019] The electrical and electronic circuit 11 controls the temperature of the heating area 21 of the main body 2 based on an instruction received from the user via an input / output unit (not shown). The electrical and electronic circuit 11 is a so-called microcontroller and includes, for example, a plurality of semiconductor elements. More specifically, the electrical and electronic circuit 11 detects the temperature of the heating area 21 using a temperature sensor 23 corresponding to the heating area 21. Based on the temperature of the heating area 21 detected by the temperature sensor 23, the electrical and electronic circuit 11 controls the drive relay 12. When the temperature of the heating area 21 is lower than the set temperature based on the instruction received from the user, the electrical and electronic circuit 11 sends a conduction instruction signal for turning on the drive relay 12 and supplies power from the AC power supply 4 to the heater 22. On the other hand, when the temperature of the heating area 21 is equal to or higher than the set temperature based on the instruction received from the user, the electrical and electronic circuit 11 sends a cutoff instruction signal for turning off the drive relay 12 and stops the heat generation of the heater 22. Hereinafter, the conduction instruction signal and the cutoff instruction signal are collectively referred to as a control signal S1 (see FIG. 2). The electrical and electronic circuit 11 sends an operation signal based on the control signal to the drive relay 12.

[0020] Further, the electrical and electronic circuit 11 detects a zero-crossing point at which the absolute value of the voltage value becomes 0 based on the AC voltage Vac (see FIG. 3) of the AC power supplied from the AC power supply 4. Also, the electrical and electronic circuit 11 controls the transmission timing of the control signal based on the relationship between the zero-crossing point and a relay monitoring signal indicating whether the drive relay 12 is in a conduction state or a cutoff state. Details will be described later.

[0021] The drive relay 12 controls the conduction or cutoff of the circuit 5 between the power supply unit 3 and the heater 22 based on the control signal S1 from the electrical and electronic circuit 11. That is, the drive relay 12 controls the conduction or cutoff of the circuit 5 between the AC power supply 4 and the heater 22. The heater 22 is powered via the drive relay 12. The drive relay 12 is, for example, an a-contact type mechanical relay that conducts the circuit 5 only for the time when it receives an operation signal from the electrical and electronic circuit 11. Note that the drive relay 12 may be, for example, a latching type mechanical relay that switches between a conduction state and a cutoff state each time it receives a control signal.

[0022] The power supply circuit 13 is a power conversion circuit that converts the power from the AC power supply 4 into the power for driving the electric and electronic circuit 11. For example, the power supply circuit 13 converts the AC power with an effective voltage of 100V and a frequency of 60Hz supplied from the AC power supply 4, which is a lighting wire, into DC power of 5V and 12V. Note that the voltage and frequency of the power from the AC power supply 4, and the voltage value of the power for driving the electric and electronic circuit 11 are examples, and may be appropriately set based on the specifications of the AC power supply 4 and the electric and electronic circuit 11.

[0023] 3. Control of the driving relay Hereinafter, the timing at which the electric and electronic circuit 11 operates the driving relay 12 will be described in more detail.

[0024] (1) Operating timing The electric and electronic circuit 11 detects the zero-crossing point at which the absolute value of the voltage value of the AC power supplied from the AC power supply 4 becomes 0. More specifically, as shown in FIG. 3, the time t1 when the sign of the voltage Vac changes from negative to positive is detected. Note that the sign of the voltage Vac here indicates the direction in which the voltage is applied. For example, one of the voltage applied in the clockwise direction in FIG. 2 and the voltage applied in the counterclockwise direction in FIG. 2 is defined as positive and the other as negative. The time between one time t1 and the next time t1 corresponds to one cycle T1. FIG. 3 shows a plurality (two in FIG. 3) of one cycles T1. The period from the time t11, which is one time t1, to the time t12, which is the next time t1, is one cycle T11, which is one cycle T1. Also, the period from the time t12, which is the time t1, to the time t13, which is the next time t1, is one cycle T12, which is one cycle T1. The time width of one cycle T1 is 20 ms if the frequency of the voltage Vac is 50 Hz, and 16.6 ms if it is 60 Hz. The period between the time t1 and the time t2 when the sign of the immediately following voltage Vac changes from positive to negative is a half cycle T2.

[0025] As shown in FIG. 3, the electric and electronic circuit 11 provides a plurality of operation timings in each period T1 and operates at each of the plurality of operation timings. The plurality of operation timings are provided such that the time between two consecutive operation timings is equal. Note that the time between the start time t11 of one period T11 and the time of the first operation timing does not have to be 0 seconds or the time between two consecutive operation timings as long as it is constant. Similarly, the time between the time of the last operation timing and the start time t12 of the next period T12 does not have to be 0 seconds or the time between two consecutive operation timings as long as it is constant.

[0026] For example, the electric and electronic circuit 11 provides 16 operation timings during one period T1. For example, when the frequency of the voltage Vac is 50 Hz, it may be assumed that the first operation timing is simultaneous with the time t1 and the time between two consecutive operation timings is 1.25 ms. Alternatively, for example, the time between two consecutive operation timings may be 1.2 ms, which is shorter than 1.25 ms. Also, for example, when the frequency of the voltage Vac is 60 Hz, it may be assumed that the first operation timing is simultaneous with the time t1 and the time between two consecutive operation timings is 1.04 ms. Alternatively, for example, the time between two consecutive operation timings may be 1.00 ms, which is shorter than 1.04 ms.

[0027] Thereby, when the first operation timing is simultaneous with the time t1, the time from the last operation timing to the start time t12 of the next period T1 becomes longer than the time between two consecutive operation timings. Therefore, it is possible to absorb the detection error of the start time t1 of one period T1, the error of the time between two consecutive operation timings, and the influence of the operation time lag of the electric and electronic circuit 11. In this case, from the first operation timing to the eighth operation timing are included in the half period T2.

[0028] As shown in FIG. 3, in each period T1 of the electric and electronic circuit 11, the period from time t1 to time t3 is defined as the control period T3, and the relationship between the transmission timing of the control signal S1 and the period of the alternating voltage is controlled during the control period T3. The control period T3 includes the period T2 from time t1 to the time t2 immediately after time t1 when the sign of the voltage Vac changes from positive to negative. For example, the control period T31 in one period T11 is the period from time t11 to time t31. Also, the control period T32 in one period T12 is the period from time t12 to time t32. Here, the period length of the control period T31 is equal to the period length of the control period T32. The time t3 is, for example, the ninth operation timing.

[0029] (2) Monitoring of the drive relay The electric and electronic circuit 11 detects whether the drive relay 12 is in the conducting state or the cutoff state based on the relay monitoring signal at each operation timing. Here, the relay monitoring signal indicates whether the drive relay 12 is in the conducting state or the cutoff state at least during the period T2. Note that during the period from time t2 to the next time t1, the relay monitoring signal may or may not indicate whether the drive relay 12 is in the conducting state or the cutoff state.

[0030] Note that the electric and electronic circuit 11 may monitor whether the drive relay 12 is in the conducting state or the cutoff state a plurality of times at each operation timing, and detect whether the drive relay 12 is in the conducting state or the cutoff state based on the plurality of monitoring results. Thereby, false detection of the relay monitoring signal due to the signal strength or noise of the relay monitoring signal, the operation time lag of the drive relay 12, etc. can be reduced.

[0031] (3) Control of the transmission timing of the control signal The electrical and electronic circuit 11 controls the relationship between the transmission timing of the control signal S12 and one cycle T12 of the AC voltage based on the relay monitoring signal in one cycle T11 in which the control signal S11 is transmitted among a plurality of cycles T1 of the AC voltage when the same type of control signal S12 is transmitted next. The same type of control signal S12 refers to a control signal that instructs the drive relay 12 to change to the same state as the control signal S11. That is, the control signal S12 of the same type as the conduction instruction signal S11 is a conduction instruction signal. Also, the control signal S12 of the same type as the cutoff instruction signal S11 is a cutoff instruction signal.

[0032] Hereinafter, for each case where the control signal S1 (both the control signal S11 and the control signal S12) is a conduction instruction signal and where the control signal S1 is a cutoff instruction signal, a method by which the electrical and electronic circuit 11 controls the transmission timing of the control signal will be described in detail.

[0033] (3.1) Control of the transmission timing of the conduction instruction signal When the electrical and electronic circuit 11 transmits the conduction instruction signal S11 during the control period T31 within one cycle T11 of the AC voltage, based on the relay monitoring signal, it determines whether the drive relay 12 is in the conduction state or the cutoff state at a plurality of timings within the control period T31. And when the control period T31 includes a period in which the drive relay 12 is in the conduction state, the electrical and electronic circuit 11 controls such that the time from the start time t12 of one cycle T12 of the AC voltage to the transmission time t6 of the conduction instruction signal S12 is greater than the time from the start time t1 of the previous one cycle T11 of the AC voltage to the transmission time t5 of the conduction instruction signal S11 when the conduction instruction signal S12 is transmitted next.

[0034] Hereinafter, a specific example will be given for a detailed explanation.

[0035] FIG. 4 is a graph showing a relay monitoring signal in one cycle T11 of an AC voltage. In FIG. 4, ON indicates a conducting state and OFF indicates a cutoff state. The transmission time t4 of the conduction instruction signal S11 is time t41. Also, time t21 is the zero-crossing point immediately after time t11 in one cycle T11. That is, the period from time t11 which is time t1 to time t21 which is time t2 corresponds to a half cycle T2. Note that the control period T31 starts at time t11 and ends at time t3. Time t3 is later than time t2 and earlier than the end time of one cycle T11. That is, the control period T3 includes the half cycle T2 (see FIG. 3) from the zero-crossing point t11 to the zero-crossing point t21 in one cycle T11. Note that since the relay monitoring signal does not indicate the state of the drive relay 12 between time t2 and time t3, it is not shown in FIG. 4.

[0036] The drive relay 12 changes from the cutoff state to the conducting state at time t41 in one cycle T11. Therefore, the relay monitoring signal indicates that the drive relay 12 is in the cutoff state during the period from the start time t11 of one cycle T11 to time t41. On the other hand, the relay monitoring signal indicates that the drive relay 12 is in the conducting state during the period from time t41 to time t2. Therefore, the period T4 during which the relay monitoring signal indicates that the drive relay 12 is in the conducting state is included in the control period T31. More specifically, when the electric and electronic circuit 11 detects from the relay monitoring signal that the drive relay 12 is in the conducting state at a plurality of operation timings included in the control period T31, it determines that the period T4 exists.

[0037] The period T4 indicates the time difference between the time t4 when the drive relay 12 changes from the cutoff state to the conducting state and the immediately subsequent zero-crossing point t2. That is, the longer the period length of the period T4, the greater the time difference between the time t4 when the drive relay 12 changes from the cutoff state to the conducting state and the immediately subsequent zero-crossing point t2. Therefore, when the electric and electronic circuit 11 next transmits the conduction instruction signal S12, it performs control so that the period T4 becomes shorter.

[0038] FIG. 5 is a graph showing a relay monitoring signal in one cycle T12 of an AC voltage. One cycle T12 is a period after one cycle T11 and includes the time t5 when the conduction instruction signal S12 is sent. The electric and electronic circuit 11 controls the sending time t51 of the conduction instruction signal S12 so that the time difference between the time t12 which is the start time t1 of one cycle T12 and the sending time t5 of the conduction instruction signal S12 is longer than the time difference between the time t11 which is the start time t1 of one cycle T11 and the sending time t4 of the conduction instruction signal S11. Here, one cycle T11 corresponds to the first cycle, and one cycle T12 corresponds to the second cycle. Also, the conduction instruction signal S11 sent in one cycle T11 corresponds to the first control signal, and the conduction instruction signal S12 sent in one cycle T12 corresponds to the second control signal. Specifically, the sending time t51 of the conduction instruction signal S12 is such that the time difference from the start time t1 of the immediately preceding one cycle T1 is larger by a time difference dt1 than the sending time t41 of the conduction instruction signal S11. The time difference dt1 is, for example, the time between two consecutive operation timings. For example, if the electric and electronic circuit 11 sends the conduction instruction signal S11 at the third operation timing in one cycle T11, it sends the conduction instruction signal S12 at the fourth operation timing in one cycle T12. As a result, the period T4 from the time t51 to the time t22 is shorter by the time length of the time difference dt1 than the period T4 (see FIG. 4) from the time t41 to the time t21.

[0039] The electric and electronic circuit 11 determines whether there is a period T4 in one cycle T12 in the same manner as in one cycle T11. And if the length of the period T4 is not zero, then when sending the conduction instruction signal S12 next time, the electric and electronic circuit 11 controls the sending time t5 of the conduction instruction signal S12 so that the time difference between the start time t1 of one cycle T1 and the sending time t5 of the conduction instruction signal S12 is longer than the time difference between the start time t1 of one cycle T1 and the sending time t5 of the conduction instruction signal S12 in one cycle T12. That is, when the electric and electronic circuit 11 sends the conduction instruction signal S12 next after the conduction instruction signal S11, it further increases the time difference between the start time t1 of the immediately preceding one cycle T1 and the sending time t5 of the conduction instruction signal S12 by the time difference dt1. As a result, each time the electric and electronic circuit 11 sends the conduction instruction signal S11, the period T4 becomes shorter.

[0040] FIG. 6 is a graph showing a relay monitoring signal in another one cycle T11 of the AC voltage. One cycle T11 shown in FIG. 6 is a cycle after one cycle T12 shown in FIG. 5. In one cycle T11 shown in FIG. 6, the transmission time t4 of the conduction instruction signal S11 is time t42. Also in one cycle T11 shown in FIG. 6, period T4 exists.

[0041] FIG. 7 is a graph showing a relay monitoring signal in one cycle T12 of the AC voltage for transmitting a conduction instruction signal S12 next to one cycle T11 shown in FIG. 6. The electric and electronic circuit 11 controls the transmission time t5 of the conduction instruction signal S12 so that the time difference between the start time t12 of one cycle T12 and the transmission time t5 of the conduction instruction signal S12 is longer than the time difference between the start time t11 of one cycle T11 and the transmission time t42 of the conduction instruction signal S11. When the transmission time t5 of the conduction instruction signal S12 is the same as or later than the zero crossing point t2, the drive relay 12 is in an off state during the period from time t1 to time t2. That is, in the control period T3, there is no period T4 in which the relay monitoring signal indicates that the drive relay 12 is in a conductive state. More specifically, the electric and electronic circuit 11 determines that there is no period T4 when it does not detect from the relay monitoring signal even once that the drive relay 12 is in a conductive state at a plurality of operation timings included in the control period T3.

[0042] By the above operation, the period T4 in which the relay monitoring signal indicates that the drive relay 12 is in a conductive state becomes sufficiently short. When the electric and electronic circuit 11 no longer detects the period T4, it controls to keep the difference between the start time t1 of each cycle T1 of the AC voltage and the transmission time t5 of the conduction instruction signal S1 constant. For example, when the period T4 exists when the conduction instruction signal S1 is transmitted at the eighth operation timing and the period T4 does not exist when the conduction instruction signal S1 is transmitted at the ninth operation timing, the electric and electronic circuit 11 sets to transmit the conduction instruction signal S1 at the ninth operation timing. Thereby, the electric and electronic circuit 11 can perform control to reduce the time difference between the transmission time of the conduction instruction signal S1 and the zero crossing point t2 and reduce the wear of the contacts of the drive relay 12.

[0043] (3.2) Control of Transmission Timing of Interruption Instruction Signal When the electric and electronic circuit 11 sends out the interruption instruction signal S11 during the control period T3 within one cycle T11 of the AC voltage, based on the relay monitoring signal, it determines whether the drive relay 12 is in the conducting state or the interrupted state at any one of a plurality of operation timings within the control period T3. And when the drive relay 12 is in the conducting state during the control period T3, when the electric and electronic circuit 11 next sends out the interruption instruction signal S12, it controls so that the time from the start time t1 of one cycle T1 of the AC voltage to the transmission time of the interruption instruction signal S12 is smaller than the time from the start time t1 of the previous one cycle T1 of the AC voltage to the transmission time of the interruption instruction signal S11.

[0044] Hereinafter, a specific example will be given for detailed explanation.

[0045] FIG. 8 is a graph showing the relay monitoring signal in a certain one cycle T11 of the AC voltage. The transmission time t6 of the interruption instruction signal S12 is the time t61.

[0046] The drive relay 12 changes from the conducting state to the cut-off state at time t61. Therefore, the relay monitoring signal indicates that the drive relay 12 is in the operating state during the period from the start time t11 of one cycle T11 to time t61. On the other hand, when the drive relay 12 changes from the conducting state to the cut-off state, even if a plurality of contacts inside the drive relay 12 are separated from each other, as long as a voltage is applied to the drive relay 12, the conducting state may be maintained by arc discharge. Therefore, the relay monitoring signal also indicates that the drive relay 12 is in the conducting state during the period T6 from time t61 to the zero-crossing point t21. Therefore, during the control period T3, the relay monitoring signal indicates that the drive relay 12 is in the conducting state. More specifically, the electric and electronic circuit 11 detects whether the drive relay 12 is in the conducting state or the cut-off state based on the relay monitoring signal at any one of a plurality of operation timings included in the control period T3. If the drive relay 12 is in the conducting state, it is determined that the period T6 exists. One of the plurality of operation timings included in the control period T3 is, for example, the third operation timing in one cycle T11.

[0047] As will be described later, when there is no period T6 in the control period T3 at all, at one of the plurality of operation timings included in the control period T3, the relay monitoring signal indicates that the drive relay 12 is in the cut-off state. Therefore, when the electric and electronic circuit 11 next sends out the cut-off instruction signal S12, it performs control to separate the sending time t7 of the cut-off control signal S12 from the zero-crossing point t2 so that the period T6 is less likely to occur.

[0048] FIG. 9 is a graph showing a relay monitoring signal in another one cycle T12 of an AC voltage. One cycle T12 is after one cycle T11 and is a cycle in which a cutoff instruction signal S12 is sent. The electrical and electronic circuit 11 controls the sending time t71 of the cutoff instruction signal S12 such that the time difference between the time t12 which is the start time t1 of one cycle T12 and the sending time t71 of the cutoff instruction signal S12 is shorter than the time difference between the start time t11 of one cycle T11 and the sending time t61 of the cutoff instruction signal S11. Here, one cycle T11 corresponds to the first cycle, and one cycle T12 corresponds to the second cycle. Also, the cutoff instruction signal S11 sent in one cycle T11 corresponds to the first control signal, and the cutoff instruction signal S12 sent in one cycle T12 corresponds to the second control signal. Specifically, the sending time t71 of the cutoff instruction signal S12 is such that the time difference from the start time t1 of the immediately preceding one cycle T1 is shorter by a time difference dt2 than the time difference between the sending time t61 of the cutoff instruction signal S11 and the start time t1 of the immediately preceding one cycle T1. The time difference dt2 is, for example, the time between two consecutive operation timings. For example, if the electrical and electronic circuit 11 sends the cutoff instruction signal S12 at the sixth operation timing in one cycle T11, it sends the cutoff instruction signal S12 at the fifth operation timing in one cycle T12. In one cycle T12, in the period T6 from the time t51 to the zero-crossing point t21, the relay monitoring signal may indicate that the drive relay 12 is in the conducting state.

[0049] In one period T12, similar to one period T11, the electric and electronic circuit 11 determines whether the relay monitoring signal indicates that the drive relay 12 is in the conducting state. When the relay monitoring signal indicates that the drive relay 12 is in the conducting state, when further sending the cutoff instruction signal S12 next time, the time difference between the start time t1 of one period T1 and the sending time t7 of the cutoff instruction signal S12 is made shorter than the time difference between the start time t1 of one period T1 and the sending time t5 of the cutoff instruction signal S12 in one period T12 of one period T1. That is, when the electric and electronic circuit 11 sends the cutoff instruction signal S12 next after the cutoff instruction signal S11, it further reduces the time difference between the start time t1 of the immediately preceding one period T1 and the sending time t7 of the cutoff instruction signal S12 by a time difference dt2. Thereby, each time the electric and electronic circuit 11 sends the conduction instruction signal S11, the period T6 becomes longer.

[0050] FIG. 10 is a graph showing the relay monitoring signal in another one period T11 of the AC voltage. The one period T11 shown in FIG. 10 is after the one period T12 shown in FIG. 9. In the one period T11 shown in FIG. 10, the sending time t6 of the conduction instruction signal S11 is the time t62. Note that in the one period T11 shown in FIG. 10, the relay monitoring signal indicates that the drive relay 12 is in the conducting state during the control period T3.

[0051] FIG. 11 is a graph showing a relay monitoring signal in one cycle T12 of an AC voltage that sends a cutoff instruction signal S12 next to one cycle T11 shown in FIG. 10. The electrical and electronic circuit 11 controls the transmission time t72 of the cutoff instruction signal S12 such that the time difference between the start time t12 of one cycle T12 and the transmission time t72 of the cutoff instruction signal S12 is longer than the time difference between the start time t11 of one cycle T11 and the transmission time t62 of the cutoff instruction signal S11. When the transmission time t7 of the cutoff instruction signal S12 is the same as or before the zero-crossing point t1, the driving relay 12 is surely in the cutoff state at time t1, and arc discharge does not occur in the half cycle T2 from time t1 to time t2 thereafter. That is, when it is detected whether the driving relay 12 is in the conduction state or the cutoff state based on the relay monitoring signal at an arbitrary timing included in the control period T3, the state becomes such that the driving relay 12 can be determined to be in the cutoff state.

[0052] Thereby, the time difference between the transmission time of the cutoff instruction signal S1 and the zero-crossing point t1 becomes sufficiently close. When the electrical and electronic circuit 11 determines that the driving relay 12 is in the cutoff state throughout the control period T3, it controls to keep the difference between the start time t1 of each cycle T1 of the AC voltage and the transmission time t7 of the cutoff instruction signal S12 constant. For example, when the electrical and electronic circuit 11 determines that the driving relay 12 is in the conduction state during the control period T3 when sending the cutoff instruction signal S1 at the second operation timing, and determines that the driving relay 12 is in the cutoff state throughout the control period T3 when sending the cutoff instruction signal S1 at the first operation timing, it is set to send the cutoff instruction signal S1 at the first operation timing. Therefore, the electrical and electronic circuit 11 can perform control to reduce the time difference between the transmission time of the cutoff instruction signal S1 and the zero-crossing point t1 and reduce the wear of the contacts of the driving relay 12.

[0053] Note that in adjusting the transmission timing of the cutoff instruction signal S1, the transmission time t7 of the cutoff instruction signal S1 is controlled to be earlier based on the start time t1 of each cycle T1 of the AC voltage. The reason is that in order to reduce the possibility of arc discharge, it is preferable that the time when the driving relay 12 is switched from the conduction state to the cutoff state is earlier than the zero-crossing point t1.

[0054] 4. Effects The electrical and electronic circuit 11 according to the embodiment controls the drive relay 12. The drive relay 12 cuts off or conducts the electric circuit 5 between the AC power supply 4 and the heater 22 of the planar heater 100. The electrical and electronic circuit 11 sends out a control signal S11 in one cycle T11 which is one cycle of the AC voltage Vac supplied by the AC power supply 4. The control signal S11 instructs the drive relay 12 to switch between the conducting state and the cut-off state. The electrical and electronic circuit 11 controls the time when the control signal S12 is sent out in one cycle T12 based on the relay monitoring signal in one cycle T11. The relay monitoring signal indicates whether the drive relay 12 is in the conducting state or the cut-off state. One cycle T12 is one cycle of the AC voltage Vac after one cycle T11. The control signal S12 instructs the drive relay 12 to change to the same state as the control signal S11. Thereby, it becomes possible to control the time when the control signal S12 is sent out to a timing more suitable for the operation of the drive relay 12 than the time when the control signal S11 is sent out.

[0055] Also, in the electrical and electronic circuit 11 according to the embodiment, the control signal S11 and the second control signal S12 are conduction instruction signals for changing the drive relay 12 from the cut-off state to the conducting state. When the relay monitoring signal indicates that the drive relay 12 includes a period T4 in which it is in the conducting state in the control period T3 of one cycle T1, the electrical and electronic circuit 11 makes the difference between the start time t12 of one cycle T12 and the time t5 when the control signal S12 is sent out larger than the difference between the start time t11 of one cycle T1 and the time t4 when the control signal S11 is sent out, so as to control the time t5 when the control signal S12 is sent out. Thereby, it becomes possible to make the time t5 when the control signal S12 which is a conduction instruction signal is sent out approach the zero-crossing point t2. Therefore, the wear of the drive relay 12 can be reduced.

[0056] In the electrical and electronic circuit 11 according to the embodiment, the control signal S11 and the control signal S12 are cut-off instruction signals for changing the driving relay 12 from the conducting state to the cut-off state. When the relay monitoring signal indicates that the driving relay 12 is in the conducting state during the control period T3 of one cycle T1, the electrical and electronic circuit 11 controls the time t7 at which the control signal S12 is sent so that the difference between the start time t12 of one cycle T12 and the time t7 at which the control signal S12 is sent is smaller than the difference between the start time t11 of one cycle T11 and the time t6 at which the control signal S11 is sent. As a result, it becomes possible to bring the time t5 at which the control signal S12, which is a cut-off instruction signal, is sent closer to the zero-crossing point t1. Therefore, wear of the driving relay 12 can be reduced.

[0057] In the electrical and electronic circuit 11 according to the embodiment, the control period T3 includes a half cycle T2 from the zero-crossing point t1 of the AC voltage Vac to the next zero-crossing point t2 in the first cycle T11. Thereby, in the electrical and electronic circuit 11, it becomes easy to bring the time at which the control signal S12 is sent closer to the zero-crossing point.

[0058] The planar heater 100 according to the embodiment includes an electrical and electronic circuit 11, a driving relay 12, and a heater 22. The driving relay 12 is controlled by the electrical and electronic circuit 11. The heater 22 is powered through the driving relay 12. As a result, wear of the driving relay 12 can be reduced, and the planar heater 100 can be made to have a longer life.

[0059] The planar heater 100 according to the embodiment further includes a temperature sensor 23. The temperature sensor 23 measures the temperature of the heating area 21 heated by the heater 22. The electrical and electronic circuit 11 determines the contents of the first control signal S11 and the second control signal S12 based on the temperature of the heating area 21 measured by the temperature sensor 23. As a result, wear of the driving relay 12 due to temperature control of the planar heater 100 can be reduced, and the planar heater 100 can be made to have a longer life.

[0060] (Other Modification Examples According to the Embodiment) (1) In the planar heater 100 according to the embodiment, it is assumed that there is one heating region 21, but the planar heater 100 may include a plurality of heating regions 21. In this case, the planar heater 100 includes a drive relay 12, a heater 22, and a temperature sensor 23 for each heating region 21. Further, the planar heater 100 has a circuit 5 including a series circuit of the drive relay 12 and the heater 22 for each heating region 21. In this case, the electric and electronic circuit 11 may control the transmission timing of the control signal as described above for one drive relay 12, or may control the transmission timing of the control signal as described above for all the drive relays 12.

[0061] (2) In the planar heater 100 according to the embodiment, the relay monitoring signal indicates the state of the drive relay 12 only during the half cycle T2. Here, the relay monitoring signal may be a signal (OFF) that always indicates an off state from the zero-crossing point t2 to the end time of one cycle T1. In this case, when controlling the transmission timing of the conduction instruction signal S1, the transmission timing of the conduction instruction signal S1 is delayed so that the state of the drive relay 12 indicated by the relay monitoring signal is in an off state throughout one cycle T1. Further, when controlling the transmission timing of the cutoff instruction signal S1, the transmission timing of the cutoff instruction signal S1 is advanced so that the state of the drive relay 12 indicated by the relay monitoring signal is in an off state throughout one cycle T1.

[0062] Also, the relay monitoring signal may always indicate whether the drive relay 12 is in a conductive state or an off state. In this case, when controlling the transmission timing of the conduction instruction signal S1, the transmission timing of the conduction instruction signal S1 is delayed so that the state of the drive relay 12 indicated by the relay monitoring signal is in an off state in the half cycle from the zero-crossing point to the next zero-crossing point. Further, when controlling the transmission timing of the cutoff instruction signal S1, the transmission timing of the cutoff instruction signal S1 is advanced so that the state of the drive relay 12 indicated by the relay monitoring signal is in an off state in the half cycle from the zero-crossing point to the next zero-crossing point.

[0063] (Aspect) The electric and electronic circuit (11) according to the first aspect controls a drive relay (12). The drive relay (12) interrupts or conducts an electric circuit (5) between an AC power supply (4) and a heater (22) of a planar heater (100). The electric and electronic circuit (11) sends out a first control signal (S11) in a first period (T1) which is one period of the AC voltage (Vac) supplied by the AC power supply (4). The first control signal (S11) instructs the drive relay (12) to switch between a conducting state and an interrupting state. The electric and electronic circuit (11) controls the time to send out a second control signal (S12) in a second period (T12) based on a relay monitoring signal. The relay monitoring signal indicates whether the drive relay (12) is in a conducting state or an interrupting state in the first period (T11). The second period (T12) is one period of the AC voltage after the first period (T11). The second control signal (S12) instructs the drive relay (12) to make the same state change as the first control signal (S11).

[0064] According to the electric and electronic circuit (11) according to the above aspect, it is possible to control the time to send out the second control signal (S12) to a timing more suitable for the operation of the drive relay (12) than the time to send out the first control signal (S11).

[0065] In the electric and electronic circuit (11) according to the second aspect, in the first aspect, the first control signal (S11) and the second control signal (S12) are conduction instruction signals for changing the drive relay (12) from an interrupting state to a conducting state. When the relay monitoring signal indicates that the period (T4) during which the drive relay (12) is in a conducting state is included in the control period (T3) of the first period (T11), the difference between the start time (t12) of the second period (T12) and the time (t5) to send out the second control signal (S12) is made larger than the difference between the start time (t11) of the first period (T11) and the time (t4) to send out the first control signal (S11), and the time (t5) to send out the second control signal (S12) is controlled.

[0066] According to the electrical and electronic circuit (11) according to the above aspect, it is possible to bring the time (t5) when the control signal (S12), which is a conduction instruction signal, is sent closer to the zero-crossing point. Therefore, wear of the drive relay (12) can be reduced.

[0067] In the electrical and electronic circuit (11) according to the third aspect, in the first aspect, the first control signal (S11) and the second control signal (S12) are cut-off instruction signals for changing the drive relay (12) from the conduction state to the cut-off state. When the relay monitoring signal indicates that the drive relay (12) is in the conduction state during the control period (T3) of the first cycle (T11), the electrical and electronic circuit (11) makes the difference between the start time (t12) of the second cycle (T12) and the time (t7) when the second control signal (S12) is sent smaller than the difference between the start time (t11) of the first cycle (T11) and the time (t6) when the first control signal (S11) is sent, and controls the time (t7) when the second control signal (S12) is sent.

[0068] According to the electrical and electronic circuit (11) according to the above aspect, it is possible to bring the time (t5) when the control signal (S12), which is a cut-off instruction signal, is sent closer to the zero-crossing point. Therefore, wear of the drive relay (12) can be reduced.

[0069] In the electrical and electronic circuit (11) according to the fourth aspect, in the second or third aspect, the control period (T3) includes the period (T2) from the zero-crossing point of the alternating voltage (Vac) to the next zero-crossing point in the first cycle (T11).

[0070] According to the electrical and electronic circuit (11) according to the above aspect, it becomes easy to bring the time when the control signal (S12) is sent closer to the zero-crossing point.

[0071] The planar heater (100) according to the fifth aspect includes the electrical and electronic circuit (11) according to any one of the first to fourth aspects, a drive relay (12), and a heater (22). The drive relay (12) is controlled by the electrical and electronic circuit (11). The heater (22) is powered through the drive relay (12).

[0072] According to the planar heater (100) according to the above aspect, it is possible to reduce the wear of the drive relay (12) and achieve a longer life of the planar heater (100).

[0073] The planar heater (100) according to the sixth aspect further includes a temperature sensor (23) that measures the temperature of the heating surface (21) heated by the heater (22) in the fifth aspect. The electric and electronic circuit (11) determines the contents of the first control signal (S11) and the second control signal (S12) based on the temperature of the heating surface (21) measured by the temperature sensor (23).

[0074] According to the planar heater (100) according to the above aspect, it is possible to reduce the wear of the drive relay (12) by temperature control and achieve a longer life of the planar heater (100).

Description of Reference Numerals

[0075] 100 Planar heater 1 Controller 2 Main body part 3 Power supply part 4 AC power supply 5 Circuit 11 Electric and electronic circuit 12 Drive relay 13 Power supply circuit 21 Heating area (heating surface) 22 Heater 23 Temperature sensor Vac AC voltage S11 Control signal (first control signal) S12 Control signal (second control signal) T1 One cycle T11 One cycle (first cycle) T12 One cycle (second cycle) T2 Half cycle (period) T3 Control period T4 Period T6 Period t1, t11, t12 Start time (zero-crossing point) t2 Time (zero-crossing point) Transmission times of t4, t41, t42 (time) Transmission times of t5, t51 (time) Transmission times of t6, t61, t62 (time) Transmission times of t7, t71, t72 (time) Time differences of dt1, dt2

Claims

1. An electric and electronic circuit for controlling a drive relay that interrupts or conducts an electric circuit between an AC power supply and a heater of a planar heater, in a first period that is one period of the AC voltage supplied by the AC power supply, a first control signal for instructing the drive relay to switch between a conducting state and a cutoff state is sent out, based on a relay monitoring signal indicating whether the drive relay is in the conducting state or the cutoff state in the first period, in a second period that is one period of the AC voltage after the first period, the time for sending out a second control signal for instructing the drive relay to change to the same state as the first control signal is controlled, the electric and electronic circuit.

2. The first control signal and the second control signal are conduction instruction signals for changing the drive relay from the cutoff state to the conducting state, when the relay monitoring signal indicates that the drive relay is in the conducting state during the control period of the first period, the electric and electronic circuit controls the time for sending out the second control signal so that the difference between the start time of the second period and the time for sending out the second control signal is greater than the difference between the start time of the first period and the time for sending out the first control signal, The electric and electronic circuit according to Claim 1.

3. The first control signal and the second control signal are cutoff instruction signals for changing the drive relay from the conducting state to the cutoff state, when the relay monitoring signal indicates that the drive relay is in the conducting state during the control period of the first period, the electric and electronic circuit controls the time for sending out the second control signal so that the difference between the start time of the second period and the time for sending out the second control signal is smaller than the difference between the start time of the first period and the time for sending out the first control signal, The electric and electronic circuit according to Claim 1.

4. The control period includes the period from the zero-crossing point of the AC voltage to the next zero-crossing point in the first period, The electric and electronic circuit according to Claim 2 or 3.

5. The electric and electronic circuit according to any one of Claims 1 to 3, the drive relay controlled by the electric and electronic circuit, a heater powered through the drive relay, A planar heater comprising:

6. further comprising a temperature sensor for measuring the temperature of the heating surface heated by the heater, The electric and electronic circuit determines the content of the first control signal and the second control signal based on the temperature of the heating surface measured by the temperature sensor. The planar heating device according to claim 5.

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