JP2000040630A - Signal transmitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To exactly detect the impedance fluctuation of a transformer generated due to resonance frequencies at the secondary side of a rotary transformer at the primary side. SOLUTION: The inductance of coils L1-L5 of resonance circuits 11-15 is set larger than the inductance of a secondary side coil L12 of a rotary transformer 10, the fluctuation of resonance frequencies due to gap fluctuation between cores is reduced, and a signal is transmitted to the primary side of the rotary transformer. At the primary side, only a frequency signal corresponding to the resonance frequencies is selected and generated from a sine wave signal oscillating circuit 16, and the impedance fluctuation of the transformer corresponding to the resonance frequencies of the secondary side resonance circuits 11-15 is detected at the primary side, and response to the operation of each switch S11-S15 is operated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal transmission device for transmitting a signal without contact using a separation type transformer, for example, used for a moving body such as a vehicle.

[0002]

2. Related Background Art Conventionally, as this type of apparatus, there is one as disclosed in, for example, JP-A-63-38055. The above device has a configuration in which a plurality of resonance circuits and a switch corresponding to the resonance circuit are connected to the coil on the rotating part side of the transformer, and the resonance circuit itself does not generate a resonance signal, but the impedance of the entire transformer is reduced. The frequency response greatly varies depending on the resonance frequency of each resonance circuit.

[0003] In the above device, the state of which switch has changed is detected by monitoring the impedance viewed from the fixed portion side at each resonance frequency of the resonance circuit on the rotating portion side of the transformer.

[0004]

However, in practice, the gap between the primary and secondary cores of the separation type transformer is
In the above device, the resonance frequency fluctuates greatly in the relationship between the inductance of each resonance circuit and the inductance of the rotating part side coil composed of the secondary side coil, and the resonance frequency fluctuates. There is a problem that it is difficult to detect the correct resonance frequency on the part side. That is, FIG. 5 shows a general signal transmission device including the above-mentioned conventional device. The signal transmission device has five capacitors C1 to C5 connected in parallel to the secondary side of the separation type transformer 10, and five capacitors C1 to C5. While configuring a resonance circuit, switches S11 to S15 corresponding to the resonance circuit are connected in series, and while the sine wave signal of a constant voltage is swept from the sine wave signal oscillation circuit 16 within a certain frequency range, the Apply to primary side. Then, the switches S11 to S15 on the secondary side are turned on / off.
By turning off, the frequency response of the impedance of the primary coil changes to a frequency region corresponding to each resonance frequency.

[0005] The discrimination circuit requires two criteria. That is, one is a reference for checking the amount of change in impedance, and the other is a reference for checking the oscillation frequency when the amount of change in impedance exceeds the reference. That is, it is determined whether or not the oscillation frequency matches the frequency set for each resonance circuit on the secondary side. Here, if the oscillation frequency matches a certain resonance frequency of the resonance circuit, it is determined that the switch connected in series to the resonance circuit is turned on.

As can be seen from the above-described determination method, if the preset resonance frequency greatly fluctuates for some reason, the frequency at which the impedance determined by the determination circuit fluctuates does not match the set frequency. as a result,
On / off of the specific switch cannot be determined on the secondary side, or erroneous determination may occur. That is, in the determination of the switch, the stability of the secondary resonance circuit is very important. In order to investigate the stability, a sine wave signal oscillation circuit 16 is connected to the primary side as shown in FIG. 5, a precision resistor 1 of 0.01Ω is connected in series, and a voltage difference between both ends of the resistor 1 is connected. Is largest, the oscillation frequency of the oscillation circuit 16 becomes the resonance frequency of the corresponding secondary-side resonance circuit.

In this device, the resonance frequency (KHz) of a specific resonance circuit was measured by changing the gap distance G between the cores of the transformer 10 to 0 to 2 mm and turning on / off the switches S11 to S15. Table 1 shows the measurement results.

[0008]

[Table 1]

From the above measurement results, it has been found that the resonance frequency of each resonance circuit greatly varies depending on the gap distance between the cores. In Table 1, Cn is the capacitance (capacity) of each of the capacitors C1 to C5. Also, for example, in signal transmission in a vehicle, the importance of the response to the ON / OFF state of the switch is often different.
For example, the response to the on / off state of the horn of the automobile needs to be as quick as possible, but the response to switches such as air conditioners and stereos is not a big problem if it is slightly slower. However, in the above-described device, the scan of the output frequency of the sweep oscillation circuit is always constant with respect to each resonance frequency. Therefore, when the number of switches is increased, the response operation to the on / off of the switch that requires a quick response is delayed. There was a problem.

The present invention has been made in view of the above-mentioned problems, and the influence of the fluctuation of the gap between the cores of the separation type transformer on the resonance frequency of each resonance circuit is very small.
It is an object to provide a signal transmission device that can be stabilized. Another object of the present invention is to provide a signal transmission device capable of accurately detecting a primary-side impedance fluctuation generated by a secondary-side resonance frequency of a separation-type transformer.

Another object of the present invention is to quickly detect a change in impedance on the primary side with respect to a switch operation in accordance with the importance of a response.

[0012]

In order to achieve the above object, according to the present invention, a plurality of resonance circuits connected in parallel to a secondary coil of a separation type transformer and having different resonance frequencies include a coil and a capacitor connected in series. And the inductance of the coil of the resonance circuit is reduced by 2
Make it larger than the inductance of the secondary coil,
Connected to the primary side coil of the separation type transformer,
Control means including an oscillation circuit including a resistance-tuned oscillation circuit that selects and generates a frequency signal corresponding to the resonance frequency of each of the resonance circuits on the next side, and a check timing signal generation circuit that controls selection of the frequency signal by the oscillation circuit And a signal transmission device for transmitting an operation state of a switch connected to each of the resonance circuits to the primary side coil of the separation type transformer as an impedance variation.

That is, the inductance of the coil of the resonance circuit is set to be larger than the inductance of the secondary coil of the separation type transformer, so that the fluctuation of the resonance frequency caused by the fluctuation of the gap between the cores is reduced. Only the frequency signal corresponding to the resonance frequency is selected and generated, and the change in the impedance of the transformer at that time is detected on the primary side.

The signal transmission device is connected to a primary side coil of the separation type transformer, and detects a change in the primary side impedance caused by a resonance frequency of each of the secondary side resonance circuits. Detecting means comprising a coil; and output means comprising a latch circuit for outputting the detection result to an operating means (relay circuit) corresponding to each of the switches, wherein the control means includes a detection level of the detecting means and the output. The selection of the output path of the means may be controlled, and the selection may be performed in synchronization with the selection of the frequency signal. This eliminates the need for conventional frequency discrimination means.

Further, it is preferable that the control means separately sets the frequency signal selection cycle according to, for example, the importance of the response to each of the switches.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A signal transmission apparatus according to the present invention is shown in FIG.
4 through FIG. FIG. 1 is a configuration diagram illustrating an example of a schematic configuration of a signal transmission device according to the present invention. 1, the same components as those in FIG. 5 are denoted by the same reference numerals for convenience of explanation.

In the figure, a signal transmission device constitutes a separation type transformer according to the present invention, and uses a rotary transformer 10 having a fixed portion having a fixed primary side and a rotatable rotating portion having a secondary side. It was what was. The secondary coil L12 has one coil L1 for each of the capacitors C1 to C5.
To L5 are connected in series, and a plurality of resonance circuits 11 to 15 having resonance frequencies f1 to f5, respectively, and switches S11 to S15 connected to the respective resonance circuits 11 to 15 are connected in parallel. I have.

In this embodiment, the resonance frequencies f1 to f5 of the respective resonance circuits are set to fn + 1 = 1.2 × fn so as to be separated by about 1.2 times so as not to interfere with each other.
The value shall be designed to be about 20. In addition, n shows the integer of 1-5. The resonance frequency f of each of the resonance circuits 11 to 15
n is represented by the following formula: fn = 1 / 2π · √ [(L12 + Ln) Cn]. Here, L12 and Ln are the inductances of the secondary coil and each of the coils L1 to L5, and Cn is each of the capacitors C1 to
The capacitance of C5 is shown. Further, as described above, in practical use, the gap between the primary side and the secondary side core of the separation type transformer fluctuates for various reasons.
The inductance L12 of the secondary coil on the secondary side fluctuates greatly.

Therefore, according to the present invention, the coils L1 to L5 having an inductance Ln larger than the inductance L12 of the secondary coil are provided in each of the resonance circuits 11 to 15, so that the fluctuation of the resonance frequency fn is suppressed to a large extent. . In addition, the fluctuation amount when the resonance frequency fluctuated due to the fluctuation of the inter-core gap was measured by the same method as described in the above-mentioned prior art. In the experiment, the inductance L12 of the secondary coil was 30 to 1 due to the change of the gap of 0 to 2 mm.
It fluctuates by 0 μH. Therefore, in this experiment, the resonance frequency was measured in the same manner as in the conventional example using the coils L1 to L5 having an inductance Ln of 470 μH. However, the capacitance of the capacitor was changed accordingly. Table 2
It is the measurement result.

[0020]

[Table 2]

As can be seen from the experimental results in Table 2, the inductance Ln of the coil of each of the resonance circuits 11 to 15 is:
It is desirable that the inductance is at least 10 times larger than the inductance L12 of the secondary coil. From this result, in this embodiment,
Inductance Ln is about 12 to 5 of inductance L12.
It shall be set to 0 times.

As described above, when the inductance Ln is set to be at least ten times larger than the inductance L12, the resonance frequency varies even if the inductance L12 varies due to the variation in the gap between the primary and secondary cores of the transformer. The rate was kept to a very small value of about one-tenth or less. The conditions under which the impedance of each resonance circuit is minimized are: 1. The oscillation frequency of the oscillation circuit is substantially equal to the resonance frequency of the resonance circuit. This is a case where two conditions are met when the corresponding switches S11 to S15 are on.

Therefore, in the present embodiment, the inductance of the coil of the resonance circuit is set to be larger than the inductance of the secondary coil.
Even if the inductance of the secondary coil fluctuates, the fluctuation of each resonance frequency can be suppressed to a very small value, and as a result, 1 is generated by turning on / off a switch in a resonance circuit connected to the secondary side of the rotary transformer. The change in impedance on the secondary side can be accurately detected.

FIG. 2 is a configuration diagram showing an example of a specific configuration of the signal transmission device according to the present invention. In FIG. 2, the same components as those in FIG.
The same reference numerals are added. In the figure, the secondary side of the rotary transformer 10 has the same configuration as in FIG. Rotary transformer 10
The primary-side coil L11 is connected to a resistance-tuned oscillation circuit 16 constituting an oscillation circuit according to the present invention and a detection coil Ls constituting detection means according to the present invention.

The resistance tuning oscillation circuit 16 is connected to each of the resistors R1 to R5 and the switches S21 to S25 in parallel with each other. The resistance tuning oscillation circuit 16 has a constant voltage and a resistance of the resistors R1 to R5. Generates a sine wave with a frequency proportional to the resistance value. In other words, the resistance values of the resistors R1 to R5 are determined by adjusting the oscillation frequency from the resistance tuning oscillation circuit 16 to the resonance circuits 11 to 12 on the secondary side.
It is set so as to coincide with the 15 resonance frequencies f1 to f5. The sine wave signal from the resistance tuning oscillation circuit 16 is divided by the detection coil Ls and the primary side coil L11.

An AC-DC conversion circuit 17 is connected to both ends of the detection coil Ls, and converts the voltage difference between both ends into a DC signal. The converted DC signal is compared with a reference signal from a reference signal generation circuit 19 by a comparator circuit 18 and its signal level (voltage) is checked. That is, the AC-DC conversion circuit 17
Outputs a DC signal corresponding to the impedance variation generated by the resonance frequency of the resonance circuits 11 to 15, and the reference signal generation circuit 19 outputs the reference signal of the five signal levels Vref1 to Vref5 via the switches S31 to S35. A signal is output, and the comparator circuit 18 makes it possible to compare and determine which resonance frequency the DC signal has responded to. The comparison result of the comparator circuit 18 is output to the latch circuits 21 to 25.

The latch circuits 21 to 25 constitute output means according to the present invention, and latch the comparison result of the comparator circuit 18, for example, a comparison result having a signal level of "0" or "1". The check timing signal generation circuit 26 constitutes a control means according to the present invention, sequentially outputs timing signals T1 to T5 at a predetermined cycle, and controls on / off of switches S21 to S25 and S31 to S35,
The selection control of the frequency signal and the reference signal is performed, and the output control of the latch circuits 21 to 25 is performed. According to this control, in the present embodiment, the switches S11 to S11 are output from the comparator circuit 18 via the latch circuits 21 to 25 through the latch circuits 21 to 25.
Each relay circuit 3 which is a means for operating a load or the like corresponding to S15
1 to 35 can be controlled.

Next, the operation of the signal transmission device shown in FIG. 2 will be described with reference to the timing chart of FIG. The check timing signal generating circuit 26 generates each of the timing signals T1 to T5 in order at a constant period shown in FIG. That is, in the present embodiment, the cycle of the timing check performed by the check timing signal generation circuit 26 is 10 m
In sec, the rise time of each timing signal, that is, the check timing of each switch is set to 2 msec.

In such a state, the check timing signal generation circuit 26 sequentially generates the timing signals T1 to T5 to control the on / off of the switches S21 to S25 and S31 to S35, and the latch circuits 21 to 25. Output control. By this control, the resistance tuning oscillation circuit 1
6 is an oscillation frequency f1 which is a constant voltage and is proportional to the resistance value of the resistors R1 to R5 connected by the switches S21 to S25.
Generate a sine wave frequency signal of f5.

That is, for example, at the timing when the timing signal T1 rises, the oscillation frequency becomes f1
Then, at that time, the resonance circuit 11 on the secondary side can be checked. Here, if the switch S11 is on, the largest resonance current flows on the secondary side of the rotary transformer 10, and this resonance state causes
The impedance with respect to the frequency f1 on the secondary side decreases, and the voltage difference between both ends of the detection coil Ls increases. As a result, the DC signal output from the AC-DC conversion circuit 17 increases, and the signal level of the DC signal is compared by the comparator circuit 18 with the signal level of the reference signal from the reference signal generation circuit 19.

In this embodiment, the signal level of the reference signal is also switched according to the selection timing of the timing signals T1 to T5. In the comparator circuit 18, when the signal level of the DC signal is higher than the signal level of the reference signal, the output as the comparison result becomes "1". At this timing, since the timing signal T1 rises, the latch circuit 21 becomes active, the output from the comparator circuit 18 becomes the output signal of the latch circuit 21 as it is, and the relay circuit 31 can operate. That is, when the switch S11 is turned on, the relay circuit 31 corresponding to the switch S11 is operated.

When the timing signal T1 rises, the switch S11 is turned off, and the switch S11
When the other switches are in the ON state, the resonance frequency on the secondary side and the oscillation frequency on the primary side are different and separated from each other. Therefore, the resonance current becomes very small, and the voltage difference of the detection coil Ls does not increase. Therefore, the relay circuit 31 does not operate.

Even if a plurality of switches among the switches S11 to S15 are switched to the ON state, in the present embodiment, the resonance frequencies are preset to frequencies that do not interfere with each other. The comparison result of the comparator circuit 18 checked at the timing can be held in each latch circuit for each cycle of the selection timing of the timing signals T1 to T5, and the output thereof can control the operation of the relay circuit.

Therefore, in the present embodiment, as in FIG. 1, the inductance of the coil of the resonance circuit is set to be larger than the inductance of the secondary coil, so that the inductance of the secondary coil varies due to the gap variation between the cores. However, the fluctuation of each resonance frequency can be suppressed to a very small value, whereby the impedance fluctuation caused by the resonance frequency on the secondary side of the rotary transformer can be accurately detected on the primary side.

In the present embodiment, the above configuration eliminates the need for a power source on the secondary side of the rotary transformer, and the most complicated oscillator circuit AC
Since the DC conversion circuit, the comparator circuit, and the like can be shared for each resonance circuit, the overall circuit configuration can be simplified, and the manufacturing cost can be reduced.
Further, in the present embodiment, instead of the continuous sweeping in the range of the oscillation frequency as in the related art, only the oscillation frequency corresponding to the resonance frequency is sequentially swept. Fast response.

In this embodiment, since the check timing signal generation circuit simultaneously controls the oscillation frequency and the latch circuit, there is an effect that the circuit configuration can be further simplified. In the present embodiment, the signal level of the reference signal is set to be switchable by the timing signal. However, the present invention is not limited to this, and the signal level of the reference signal can be set to be constant. In such a case, the circuit configuration can be further simplified.

In the case where the operation of the switch on the secondary side of the rotary transformer is performed artificially, the operation time is usually on the order of several tens of msec. It is desirable to set it short. Normally, the check timing required for resonance frequency detection is limited by the switching time of each analog switch and the time required until the operation of each circuit is stabilized. For example, the number of switches on the secondary side is several tens. Even
In consideration of the above restrictions, if the check cycle of each switch is set shorter than the set value of the present embodiment, it is possible to cope with this.

In the above embodiment, the check timing for each switch operation by the check timing signal generation circuit is set to the same cycle. For example, in signal transmission in a vehicle, the importance of the response to the on / off state of the switch is important. Are often different. For example, the response to the on / off state of the car horn is:
It is necessary to be as quick as possible in order to notify the pedestrian as soon as possible, but the response to a switch such as an air conditioner or stereo is not a big problem even if it is slightly slow.

Therefore, according to the present invention, it is possible to set different response times for each switch operation. That is, as shown in the timing signal chart of FIG. 4, the timing signal T1 corresponds to the operation of the switch S1, which requires the quickest response, for example, the operation of the horn of a car. In the present embodiment, the check timing of the switch S1 by the check timing signal generation circuit 26 has a cycle of 4 msec, so that the maximum delay time of the relay circuit operation with respect to the switch operation is 4 msec or less. Also, the check timing for the other switches S2 to S5 has a cycle of 16 msec,
The maximum delay time is 16 msec or less.

Therefore, in this embodiment, since the check cycle for checking each switch can be flexibly set according to the importance of the response to each switch, the primary-side impedance fluctuation with respect to the operation of the switch having a high response importance can be set. Can be detected quickly. In the embodiment,
Although the case of oscillating a sine wave has been described, the present invention is not limited to this. For example, an oscillation circuit that oscillates a rectangular wave, a triangular wave, or the like can be used.

The separation type transformer according to the present invention is not limited to a rotary transformer, but may be anything as long as the transformer cores are used with a gap between a primary coil and a secondary coil with a gap therebetween. Needless to say.
For example, the transformer cores may be arranged so as to be relatively movable so that the gap between them may change, or at least one of the transformer cores may be arranged so as to be rotatable around a certain axis, or both transformer cores may be arranged. May be applied to a separation type transformer which is fixedly arranged via a gap.

[0042]

As described above, according to the present invention, a plurality of resonance circuits each having a different resonance frequency are provided in parallel with the secondary coil of the separation type transformer. In a signal transmission device for transmitting an operation state of a connected switch to a primary coil of the separation type transformer, an inductance of a coil of each resonance circuit is made larger than an inductance of a secondary side coil of the separation type transformer. As a result, the influence on the resonance frequency of each resonance circuit due to the fluctuation of the gap between the cores of the separation type transformer is suppressed to a very small value, and the resonance becomes stable.

An oscillation circuit connected to the primary side coil of the separation type transformer for selecting and generating a frequency signal corresponding to a resonance frequency of each of the secondary side resonance circuits; And control means for controlling the selection of the transformer, it is possible to accurately detect the impedance change of the transformer caused by the resonance frequency of the secondary side of the separation type transformer on the primary side.

Each resonance circuit connected to the secondary side coil includes a series connection of the coil and a capacitor, is connected to a primary side coil of the separation type transformer, and is connected to the secondary side resonance circuit. Depending on the oscillation frequency generated by the oscillation circuit that selects and generates the frequency signal corresponding to the resonance frequency,
The impedance of the series resonance circuit greatly changes to 1
It is possible to detect accurately on the secondary side.

The signal transmission device is connected to a primary side coil of the separation type transformer, and detects detection means for detecting the resonance state, and output means for outputting the detection result to operation means corresponding to each switch. The control unit controls the detection level of the detection unit and the selection of the output path of the output unit, and performs these selections in synchronization with the selection of the frequency signal. The change in impedance of the transformer caused by the resonance frequency on the secondary side can be accurately detected on the primary side.

Since the control means sets the selection cycle of the frequency signal separately for each switch, the primary side can quickly detect the impedance change of the transformer with respect to the switch operation according to the importance of the response. Can be done.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an example of a schematic configuration of a signal transmission device according to the present invention.

FIG. 2 is a configuration diagram illustrating an example of a specific configuration of a signal transmission device according to the present invention.

FIG. 3 is a timing chart showing an example of a chart of a timing signal generated by a check timing signal generation circuit shown in FIG. 2;

FIG. 4 is a timing chart showing another example of the timing signal chart.

FIG. 5 is a configuration diagram illustrating an example of a schematic configuration of a conventional signal transmission device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 precision resistor 10 rotary transformer (separable transformer) 11 to 15 resonance circuit 16 sine wave signal oscillation circuit (resistance tuning oscillation circuit) 17 AC-DC conversion circuit 18 comparator circuit 19 reference signal generation circuit 21 to 25 latch circuit 26 check Timing signal generation circuit 31 to 35 Relay circuit Ls detection coil L1 to L5 Resonant circuit coil L11 Primary coil L12 Secondary coil S11 to S15, S21 to S25, S31 to S35 Switch T1 to T5 Timing signal

Claims (6)

[Claims] A plurality of resonance circuits connected in parallel to a secondary coil of a separation-type transformer, each having a different resonance frequency, wherein an operation state of a switch connected to each of the resonance circuits is determined. A signal transmission device for transmitting to a primary coil of a separation type transformer, wherein a coil is provided in the resonance circuit, and an inductance of the coil is made larger than an inductance of a secondary side coil of the separation type transformer. . 2. An oscillation circuit connected to a primary side coil of the separation type transformer, the signal transmission apparatus selecting and generating a frequency signal corresponding to a resonance frequency of each of the secondary side resonance circuits, The signal transmission device according to claim 1, further comprising control means for controlling selection of a frequency signal by the oscillation circuit. 3. The signal transmission device according to claim 1, wherein the resonance circuit includes the coil and a capacitor connected in series. 4. A separation type transformer comprising a plurality of resonance circuits connected in parallel to a secondary coil of the separation type transformer, wherein an operation state of a switch connected to each of the resonance circuits is changed by the primary type of the separation type transformer. An oscillation circuit connected to a primary coil of a separation type transformer for selecting and generating a frequency signal corresponding to a resonance frequency of each of the secondary resonance circuits; Control means for controlling selection of a frequency signal by the control unit. 5. The detection device according to claim 1, wherein the signal transmission device is connected to a primary coil of the separation type transformer, and detects a change in the impedance of the primary side caused by a resonance frequency of each of the resonance circuits on the secondary side. Means, and output means for outputting the detection result to operation means corresponding to each of the switches, wherein the control means controls a detection level of the detection means and selection of an output path of the output means, and 5. The signal transmission device according to claim 2, wherein the selection is performed in synchronization with the selection of the frequency signal. 6. 6. The signal transmission device according to claim 2, wherein the control unit separately sets a cycle of selecting the frequency signal according to each of the switches.