JP2002236954A - On-vehicle unit for etc - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an on-vehicle unit for ETC having improved communication performance by preventing the fluctuation of circuit characteristics resulting from dew condensation and a change in a temperature without cost increase. SOLUTION: The on-vehicle unit for ETC mounted on a vehicle using a toll road includes a communication circuit 11 for transmitting and receiving information with an on-road unit, a CPU 10 for reading and writing at least security information with a detachably attached IC card 2, and a power supply part 15 for feeding the communication circuit 11 and the CPU 10, and an upper surface of the communication circuit 11 is coated with a shield cover. A heating means 15 is arranged adjacent to a circuit part including at least the communication circuit 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-board terminal for automatic toll collection (hereinafter referred to as "ETC on-board unit") for communicating with on-road units on a toll road, and more particularly to a method for detecting fluctuations in antenna characteristics. E that improved communication performance by preventing
It relates to a vehicle-mounted device for TC.

[0002]

2. Description of the Related Art In recent years, an ETC system for avoiding vehicle congestion by a toll collection procedure at a toll road has been well known. In this case, a vehicle using a toll road is provided with an on-board ETC device. Is installed.

That is, in this type of ETC system, radio communication is performed between an ETC road machine on the tollgate side and an on-board ETC device on the vehicle side to automatically receive a toll road usage fee. Is configured.

FIGS. 10 and 11 are a block diagram and a perspective view, respectively, showing a conventional vehicle-mounted device for ETC (hereinafter, also simply referred to as a vehicle-mounted device).
Reference numeral 2 denotes an IC card mounted on the vehicle-mounted device 1.

The vehicle-mounted device 1 has a CPU 10 composed of a microcomputer. The CPU 10 includes a communication circuit 11 for transmitting and receiving information to and from a road device (not shown), an antenna 12, and a detachable IC. An IC card I / F 13 to which the card 2 is attached, and a SAM (Secure A
Application Module) 13 is connected.

The CPU 10 reads and writes at least security information and the like from the IC card 2 via the IC card I / F 13 and the SAM 14. The upper surface of the communication circuit 11 is covered with a shield cover (not shown) in order to block electromagnetic noise.

The vehicle-mounted device 1 is provided with a power supply unit 15 for supplying power to the CPU 10 and each circuit. The power supply unit 15 is supplied with power from the vehicle-side power supply 3 (vehicle-mounted battery, accessory power supply, etc.). The battery voltage is
The power is converted to the operating voltage of each circuit.

Next, the operation of the conventional ETC on-board unit shown in FIGS. 10 and 11 will be described. First, the driver mounts the IC card 2 in which self-information is stored in the vehicle-mounted device 1 and drives the vehicle.

When the vehicle arrives at the tollgate, the data signal received from the on-road unit at the tollgate is input to the communication circuit 11 via the antenna 12, converted into a digital signal, and processed by the CPU 10 and the SAM 14. You.

At this time, the data to be stored in the received data is transmitted via the IC card I / F 13 to the IC card 2.
Is stored in

On the other hand, the IC card 2 stores data to be transmitted to a roadside device. The transmission data to the roadside device is read from the IC card 2 via the IC card I / F 13 and the SAM 14 under the control of the CPU 10,
It is transmitted from U10 to the on-road unit via the communication circuit 11 and the antenna 12.

By the way, as is well known, when the vehicle-mounted device 1 is used in a cold region, the temperature of the vehicle-mounted device 1 may be extremely reduced, and it may be impossible to compensate for the characteristics of the communication circuit 11.

Normally, the communication circuit 11 in the vehicle-mounted device 1 is equipped with a high-frequency analog signal processing circuit for processing a communication signal, and has a configuration in which electric characteristics are easily changed by temperature.

Therefore, in order to avoid the above-mentioned problems, an operating temperature range of the communication circuit 11 is limited, or an expensive temperature characteristic compensating circuit is used to correct a change in electrical characteristics due to temperature. Need to be added to increase the circuit scale.

Further, the power supply unit 15 being driven becomes higher than the ambient temperature by 30 ° C. to 40 ° C. or more. Therefore, when the vehicle-mounted device 1 is used in a high temperature environment, the amount of heat generated in the power supply unit 15 is large. The element (such as a power transistor) is heated to a very high temperature, which may cause burning or breakage of the element in the power supply unit 15.

Therefore, in order to prevent such an abnormal rise in temperature, it is necessary to take measures to prevent the temperature from rising, such as mounting a heat sink for heat radiation on the power supply unit 15.

Further, when the engine is started in an environment where the vehicle interior is in a high humidity or low temperature environment and the vehicle interior temperature rises rapidly due to heating at the time of starting, the interior of the vehicle-mounted device 1 (for example, a communication circuit) 11 may be formed on the upper surface.

If the power of the vehicle-mounted device 1 is turned on in such a state of dew condensation, there is a possibility that the vehicle-mounted device 1 may be damaged or malfunction due to electric leakage. In order to prevent such problems due to dew condensation, it is necessary to take measures to prevent dew condensation, such as applying a waterproof coating on a substrate on which the circuit unit is mounted.

However, it is difficult to apply the waterproof coating to the communication circuit 11 on which the high-frequency analog signal processing circuit is mounted, since the electrical characteristics change when the waterproof coating is applied.

[0020]

As described above, the conventional on-vehicle device for ETC includes an expensive temperature characteristic compensating circuit in order to perform characteristic compensation for a temperature change in at least the circuit section including the communication circuit 11. Therefore, there is a problem that the cost is increased and the circuit scale is increased.

Further, it is necessary to mount a heat sink for heat radiation on the power supply unit 15 in order to prevent an abnormal rise in temperature, and similarly, there is a problem that the circuit scale is increased.

Furthermore, since a waterproof coating cannot be applied to the circuit section including the communication circuit 11,
There has been a problem that dew condensation prevention measures cannot be realized.

The present invention has been made in order to solve the above-mentioned problems, and without increasing the cost.
It is an object of the present invention to provide a vehicle-mounted device for ETC in which a change in circuit characteristics due to dew condensation or temperature change is prevented and communication performance is improved.

[0024]

An ETC on-vehicle device according to a first aspect of the present invention is an ETC on-vehicle device mounted on a vehicle using a toll road, and transmits and receives information to and from a road device. Communication circuit and IC that can be detachably mounted
A CPU for reading and writing at least security information from / to a card, and a communication circuit and a power supply unit for supplying power to the CPU, wherein the upper surface of the communication circuit is covered by a shield cover, and those placed close to heat generating means in the circuit portion including at least the communication circuit.

According to a second aspect of the present invention, in the vehicle-mounted ETC device according to the first aspect, the heat generating means is configured to be shared by a power supply.

According to a third aspect of the present invention, in the vehicle-mounted device for ETC according to the first aspect, the heat generating means is constituted by a power transistor in the power supply unit, and the power transistor is closely attached to a shield cover of the communication circuit. It was done.

According to a fourth aspect of the present invention, the vehicle-mounted ETC device according to any one of the first to third aspects further includes a temperature detecting means for detecting a temperature of the circuit portion,
U drives the heating means to raise the temperature when the detected temperature of the circuit section satisfies a predetermined low-temperature condition.

According to a fifth aspect of the present invention, in the vehicle-mounted ETC device according to the fourth aspect, the temperature detecting means is constituted by a thermistor arranged close to the circuit section.

The vehicle-mounted device for ETC according to claim 6 of the present invention is the vehicle-mounted device for ETC according to claim 4 or 5, wherein
Has a sleep function and releases the sleep function when a low-temperature condition is satisfied.

According to a seventh aspect of the present invention, in the vehicle-mounted device for ETC according to any one of the fourth to sixth aspects, the heating means includes a heating element driven and controlled by the CPU. When the low temperature condition is satisfied, the heating element is driven.

According to an eighth aspect of the present invention, in the on-vehicle ETC device according to the seventh aspect, the temperature detecting means and the heating element are disposed in close contact with a shield cover of a communication circuit.

According to a ninth aspect of the present invention, in the vehicle-mounted device for ETC according to the seventh or eighth aspect, the heating element is constituted by a resistance element having an on / off switch circuit.

The ETC according to claim 10 of the present invention.
In the vehicle-mounted device, the CPU according to any one of claims 4 to 9, wherein the CPU detects that the detected temperature immediately after power-on of the circuit unit is equal to or lower than a predetermined temperature, or increases the detected temperature immediately after power-on of the circuit unit. When the rate of change indicates a predetermined value or more, it is determined that the low temperature condition has been satisfied.

The ETC according to claim 11 of the present invention.
In the vehicle-mounted device, the criterion of the low-temperature condition according to claim 10 corresponds to the dew temperature of the circuit unit.

The ETC according to claim 12 of the present invention.
In the vehicle-mounted device according to any one of claims 4 to 9, the criterion for the low-temperature condition corresponds to the lower limit temperature of the characteristic compensation range of the circuit section.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, Embodiment 1 of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing a first embodiment of the present invention, and the same components as those described above (see FIGS. 10 and 11) are denoted by the same reference numerals or are denoted by “A” after the reference numerals. The details are omitted.

In this case, the block configuration of the vehicle-mounted device 1A is the same as that described above (see FIG. 10). In FIG. 1, a power supply unit 15 in the on-vehicle device 1A is arranged close to the CPU 10, the communication circuit 11, the antenna 12, the IC card I / F 13, and the SAM 14.

That is, the CPU 10 and the SAM 14
Are arranged on the same printed circuit board together with the power supply unit 15, the IC card I / F 13 is arranged on the back surface of the printed circuit board on which the power supply unit 15 is mounted, and the communication circuit 11 and the antenna 12 are mounted on the power supply unit 15. It is arranged on a printed circuit board which is arranged so as to overlap the placed printed circuit board.

In the vehicle-mounted device 1A configured as shown in FIG. 1, when the power supply unit 15 is turned on by turning on an ignition switch (not shown), the operation voltage of each circuit unit is generated from the power supply unit 15 and the power supply unit 15 is discarded. Heat is generated.

The waste heat from the power supply unit 15 is transferred to the circuit unit (CPU 10, communication circuit 11, IC card I / F)
13, the SAM 14, etc.) and raises the temperature of at least the circuit section including the communication circuit 11.

As a result, it is possible to prevent dew condensation in the circuit section in the vehicle-mounted device 1A. Further, even if dew has already occurred in the circuit portion, the dew can be dried, and malfunction or destruction of the circuit portion due to the dew can be prevented.

In particular, by radiating radiant heat (see a two-dot chain line) from the power supply unit 15 to the communication circuit 11 to which the waterproof coating cannot be applied,
Can be reliably prevented, the resistance of the circuit section to dew condensation can be improved, and the communication function can be effectively improved.

Further, since the power supply unit 15 is also used as a heat generating means for preventing dew condensation, the circuit scale does not increase.
There is no cost increase.

Further, by heating with the power supply unit 15,
Since the temperature of the communication circuit 11 rises by a certain amount, the communication circuit 1
Therefore, it is possible to simplify the low-temperature electrical characteristic compensating circuit with respect to No. 1 and to realize a reduction in size and cost of the entire circuit.

Further, since the circuit section including the communication circuit 11 absorbs the heat generated by the power supply section 15, the heat resistance of the power supply section 15 is improved, and operation in a high temperature environment is possible without mounting a heat sink. Become.

Embodiment 2 Although in the above-mentioned first embodiment, to the communication circuit 11, the power supply unit as a heat generating means 15
Are simply arranged close to each other, but the power transistor in the power supply unit 15 may be closely arranged on the shield cover of the communication circuit 11.

FIGS. 2 and 3 are a block diagram and a perspective view, respectively, showing Embodiment 2 of the present invention using a power transistor as a heating means.
1 (see FIG. 1), the same reference numerals are given, or "B" is added after the reference numerals, and the details are omitted.

In FIG. 2 and FIG.
The power transistor 5 is disposed in close contact with (close to) a shield cover (not shown) of the communication circuit 11. The power transistor TR is connected to
In particular, the circuit element generates a large amount of heat.

As is well known, the metal shield cover on the communication circuit 11 is used to protect the communication circuit 1 from external electromagnetic noise.
1 is protected and radiation noise radiated from the communication circuit 11 is suppressed.

In this case, when the power supply unit 15 is turned on,
Waste heat is generated from the power transistor TR, which is a main heat generation source, and the waste heat propagates from the power transistor TR to the shield cover (metal) of the communication circuit 11 with high efficiency.

As described above, by bringing the power transistor TR, which generates a large amount of heat, into contact with the shield cover of the communication circuit 11, waste heat generated by the power transistor TR is effectively transmitted to the shield cover of the communication circuit 11, and communication is performed. Since the temperature of the circuit 11 rises, dew condensation on the circuit portion can be reliably prevented.

Further, even when the power supply unit 15 is turned on in a low temperature environment, the waste heat generated from the power transistor TR heats the high-frequency analog circuit in the communication circuit 11 via the shield cover. Can normally operate the communication circuit 11 that cannot satisfy the temperature characteristics.

Further, even when the power supply section 15 is turned on in a high temperature environment, the power transistor TR is effectively cooled, so that the temperature rise of the power transistor TR can be suppressed.

Further, since the power transistor TR in the power supply section 15 is used as a heat generating means, the size and cost can be reduced, the resistance to dew condensation at low temperatures can be improved, and the electric characteristic compensation circuit can be simplified. By improving the heat resistance of the power supply unit 15 at a high temperature, the heat sink can be omitted.

Embodiment 3 In the first embodiment,
In 2, the power supply unit 15 or the power transistor TR is simply used as a heating unit, but the driving conditions of the power supply unit 15 may be changed according to the temperature (or temperature change) immediately after the power of the circuit unit is turned on.

FIGS. 4 and 5 are a block diagram and a perspective view, respectively, showing a third embodiment of the present invention in which the temperature immediately after the power is turned on is a driving condition of the power supply unit 15, and is described above (see FIGS. 1 to 3). The same symbols are assigned to the same
Alternatively, “C” is appended to the reference numeral, and the detailed description is omitted.

In FIGS. 4 and 5, the vehicle-mounted device 1C comprises:
In addition to the same configuration as described above (see FIGS. 2 and 3),
A temperature detecting means 20 (for example, a thermistor) connected to 10C is provided.

The temperature detecting means 20 is provided on a printed circuit board so as to be close to the circuit section of the vehicle-mounted device 1C, and inputs the detected temperature Tc to the CPU 10C. In addition, the power supply unit 15 is disposed near the center of the board of the vehicle-mounted device 1C as in FIG.

On the other hand, the CPU 10C in the vehicle-mounted device 1C has, in addition to the processing functions described above, a sleep function for shifting to the low power consumption mode, a function for determining the low temperature condition of the circuit section based on the detected temperature Tc, and A function of adjusting the heat generation temperature of the power supply unit 15 according to conditions.

That is, the CPU 10C monitors the temperature Tc of the circuit section of the vehicle-mounted device 1C via the temperature detecting means 20,
If the power-on temperature Tc of the circuit portion immediately determines the state easy to generate dew condensation (low temperature condition) releases the sleep function, maintain the state the power consumption is large in the power supply 15.

At this time, the low temperature condition may be the case where the detected temperature Tc immediately after the power supply of the circuit section is turned on is lower than a predetermined temperature, or the case where the rate of change of the detected temperature Tc is higher than a predetermined value. a predetermined temperature below the temperature T
When at least one of c and a temperature change rate equal to or more than a predetermined value is indicated, it is determined that the low temperature condition is satisfied.

The criterion of the low-temperature condition (the predetermined temperature or the predetermined value of the rate of change in temperature rise) corresponds to the dew condensation temperature here.

In other words, the condition for determining the condition in which dew condensation easily occurs on the circuit portion of the vehicle-mounted device 1C is that the temperature Tc at the time of power-on is lower than a predetermined temperature and that the temperature Tc per unit time increases by a certain threshold. The former condition corresponds to a case in which the vehicle-mounted device 1C can form dew with night dew on the morning of a cool season or the like.

The latter condition is a condition in which the temperature of the vehicle-mounted device 1C is rapidly rising due to a rapid rise in the outside temperature (such as when the engine is started at a low temperature and the interior of the vehicle is being heated by the heater).
The temperature of the vehicle-mounted device 1C is significantly lower than the outside air temperature,
This corresponds to the case where the outside air is cooled more than C and dew condensation easily occurs.

When the detected temperature Tc immediately after power-on of the circuit section satisfies the above-mentioned low-temperature condition (condensation on the substrate or a possibility of dew condensation in the future), the CPU 10C determines the current consumption of the vehicle-mounted device 1C. Is normally controlled so as not to decrease.

That is, the CPU 10C controls the SAM 14 and the power supply unit 15 (heat generating means) so as to maintain a state in which a large amount of heat is generated due to normal power consumption, and drives the temperature to increase, thereby forming dew condensation on the circuit unit of the vehicle-mounted device 1C. To prevent

Further, even if dew condensation has already occurred, the dew condensation can be dried, and malfunction or destruction due to the dew condensation can be prevented.

On the other hand, when the detected temperature Tc does not indicate the dew condensation state, it goes without saying that the sleep function is enabled to reduce unnecessary power consumption.

Therefore, it is possible to improve the resistance to dew condensation at low temperatures, simplify the low-temperature electrical characteristic compensating circuit, downsize the circuit, and reduce the cost while avoiding unnecessary power consumption.

Although the predetermined temperature serving as a criterion for canceling the sleep function is made to correspond to the dew condensation temperature here, it may be made to correspond to the lower limit temperature of the characteristic compensation range of the circuit section including the communication circuit 11. Good.

In this case, by maintaining the heat generation amount by releasing the sleep function, the circuit section can be maintained at a temperature equal to or higher than the lower limit temperature of the characteristic compensation range, and deterioration of the circuit characteristics can be prevented.

The CPU 10C having a sleep function
Releases the sleep function to maintain the heat value, but even if the CPU does not have the sleep function, the heat value is increased when the detected temperature Tc of the circuit section is equal to or lower than a predetermined temperature. For this purpose, the power supply unit 15 may be driven to raise the temperature more than usual.

Embodiment 4 It should be noted that the first to the first embodiments
In No. 3, the power supply unit 15 was also used as a heating means.
Another heating element driven under the control of U may be provided.

FIGS. 6 and 7 are a block diagram and a perspective view, respectively, showing a fourth embodiment of the present invention in which another heating element is provided. The same reference numeral is given, or “D” is appended after the reference numeral, and the detailed description is omitted.

In FIG. 6 and FIG. 7, the vehicle-mounted device 1D is
In addition to the same configuration as described above (see FIGS. 4 and 5),
A heating element 21 (for example, a resistance element having an on / off switch circuit) driven by 10D is provided.

The heating element 21 is arranged near the center of the printed circuit board of the vehicle-mounted device 1D. The CPU 10D monitors the detected temperature Tc, and drives the heating element 21 when it is determined that dew condensation is likely to occur in the on-vehicle device 1D and the circuit unit (low temperature condition is satisfied).

The heat of the heating element 21 raises the temperature of the CPU 10D, the communication circuit 11, the SAM 14, the IC card I / F 13 and the like to prevent the occurrence of dew condensation. As described above, the low-temperature condition may be the case where the detected temperature Tc at power-on is equal to or lower than a predetermined temperature, or the case where the rate of change of the detected temperature Tc is equal to or higher than a predetermined value.

As described above, by raising the temperature of the heating element 21 when the low-temperature condition is determined, the resistance to dew condensation can be improved, the electric characteristic compensation circuit for low temperature can be simplified, and the circuit can be miniaturized. And cost reduction,
The need for a heat sink can be eliminated.

Embodiment 5 FIG. It should be noted that the first to the first embodiments
In 4, the heating element 21 is arranged at the center of the printed circuit board so as to be close to the communication circuit 11. However, the heating element 21 may be arranged in close contact with the shield cover of the communication circuit 11.

FIGS. 8 and 9 are a block diagram and a perspective view, respectively, showing a fifth embodiment of the present invention in which the heat generating element 21 is disposed in close contact with the shield cover of the communication circuit 11 (see FIGS. 1 to 7). The same components as those described above are denoted by the same reference numerals or by adding an “E” after the reference numerals, and detailed descriptions thereof will be omitted.

In FIG. 8 and FIG.
0 and the heating element 21 are arranged in close contact with the shield cover of the communication circuit 11. The CPU in the vehicle-mounted device 1E
10E has a function of monitoring the temperature Tc of the communication circuit 11.

That is, the CPU 10E controls the communication circuit 11
When it is determined that the temperature falls below the temperature compensation range for satisfying the performance (low temperature condition in which the detected temperature Tc is equal to or lower than the lower limit temperature), the heating element 21 is driven to heat the communication circuit 11. .

At this time, the temperature of the communication circuit 11 is effectively increased by the heating element 21 which is in close contact with the shield cover.
Can be reliably operated normally.

As described above, the detected temperature Tc of the communication circuit 11
Is lower than a predetermined temperature corresponding to the lower limit temperature of the characteristic compensation range, by driving the heating element 21 to heat the communication circuit 11, the operation characteristics for wireless communication can be ensured even at a low temperature. .

In this case, the CPU 10E includes the communication circuit 11
Of the communication circuit 11 when the vehicle enters a low-temperature environment while the vehicle is traveling, and the characteristics of the communication circuit 11 at a low temperature can be reliably compensated.

Note that Embodiment 5 is replaced by Embodiments 1 to
As described above, in combination with the above-described embodiment, in addition to improving the resistance to dew condensation, simplifying the electrical characteristic compensation circuit for low temperature, reducing the size and cost of the circuit, and eliminating the need for a heat sink. .

[0087]

As described above, according to the first aspect of the present invention, there is provided an on-board ETC device mounted on a vehicle using a toll road, for transmitting and receiving information to and from a road device. C for reading and writing at least security information between a communication circuit and an IC card detachably mounted
In the vehicle-mounted ETC device provided with a PU and a power supply unit for supplying power to the communication circuit and the CPU, and the upper surface of the communication circuit is covered with a shield cover, since the heat-generating means is arranged close to at least the circuit unit including the communication circuit In addition, there is an effect that an in-vehicle device for ETC in which communication characteristics are improved by preventing a change in circuit characteristics due to dew condensation or a temperature change without increasing costs is obtained.

According to a second aspect of the present invention, in the first aspect, since the heat generating means is also configured by the power supply section, fluctuations in circuit characteristics due to dew condensation and temperature changes can be prevented without increasing costs. There is an effect that a vehicle-mounted device for ETC in which the communication performance is improved by preventing the vehicle-mounted device is obtained.

According to a third aspect of the present invention, in the first aspect, the heat generating means is also constituted by a power transistor in the power supply unit, and the power transistor is disposed in close contact with the shield cover of the communication circuit. There is an effect that an in-vehicle device for ETC in which communication characteristics are improved by effectively preventing a change in circuit characteristics due to dew condensation or a temperature change without causing an increase in cost is obtained.

According to a fourth aspect of the present invention, in any one of the first to third aspects, there is provided a temperature detecting means for detecting a temperature of the circuit section, and the CPU detects the temperature of the circuit section. When the predetermined low-temperature condition is satisfied, the heating means is driven to raise the temperature, so that the circuit performance is reliably prevented from changing due to dew condensation or temperature change, and the communication performance is improved.
There is an effect that a vehicle-mounted device for TC can be obtained.

According to a fifth aspect of the present invention, in the fourth aspect, the temperature detecting means is constituted by a thermistor disposed close to the circuit section, so that the temperature of the circuit section can be reliably detected. There is an effect that a vehicle-mounted device for ETC in which communication characteristics are improved by preventing a change in circuit characteristics due to dew condensation or a temperature change can be obtained.

According to the sixth aspect of the present invention, in the fourth or fifth aspect, the CPU has a sleep function and cancels the sleep function when a low-temperature condition is satisfied. There is an effect that an in-vehicle device for ETC with improved communication performance by preventing fluctuations in circuit characteristics due to dew condensation or temperature change without incurring an increase.

According to a seventh aspect of the present invention, in any one of the fourth to sixth aspects, the heating means includes a heating element driven and controlled by the CPU.
U drives the heating element when the low-temperature condition is satisfied, so that the temperature is surely raised, so that a vehicle-mounted device for ETC that has improved communication performance by preventing fluctuations in circuit characteristics due to dew condensation and temperature change is obtained. Has the effect.

According to an eighth aspect of the present invention, in the seventh aspect, the temperature detecting means and the heat generating element are disposed in close contact with the shield cover of the communication circuit, so that the temperature of the communication circuit can be raised more reliably. Thus, there is an effect that a vehicle-mounted device for ETC with improved communication performance by reliably preventing a change in circuit characteristics due to dew condensation or temperature change can be obtained.

According to a ninth aspect of the present invention, in the seventh or eighth aspect, the heating element is constituted by a resistance element having an on / off switch circuit, so that the temperature of the circuit portion is reliably raised. There is an effect that an on-vehicle device for ETC that can be obtained is obtained.

According to a tenth aspect of the present invention, in any one of the fourth to ninth aspects, the CPU
Determines that the low-temperature condition is satisfied when the detected temperature immediately after power-on of the circuit section indicates a predetermined temperature or lower, or when the rate of change of the detected temperature immediately after power-on of the circuit section indicates a predetermined value or higher. Therefore, there is an effect that an in-vehicle device for ETC that can surely raise the temperature of the circuit section immediately after the power is turned on at the time of low temperature is obtained.

According to the eleventh aspect of the present invention, in the tenth aspect, since the criterion of the low-temperature condition corresponds to the dew temperature of the circuit portion, it is possible to reliably prevent dew condensation on the circuit portion. There is an effect that a vehicle-mounted device can be obtained.

According to the twelfth aspect of the present invention, in any one of the fourth to ninth aspects, the criterion of the low temperature condition corresponds to the lower limit temperature of the characteristic compensation range of the circuit section. In particular, there is an effect that an in-vehicle device for ETC that can secure the operating characteristics of the communication circuit at a low temperature can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing Embodiment 1 of the present invention.

FIG. 2 is a block diagram showing a second embodiment of the present invention.

FIG. 3 is a perspective view showing a second embodiment of the present invention.

FIG. 4 is a block diagram showing a third embodiment of the present invention.

FIG. 5 is a perspective view showing a third embodiment of the present invention.

FIG. 6 is a block diagram showing a fourth embodiment of the present invention.

FIG. 7 is a perspective view showing a fourth embodiment of the present invention.

FIG. 8 is a block diagram showing a fifth embodiment of the present invention.

FIG. 9 is a perspective view showing a fifth embodiment of the present invention.

FIG. 10 is a block diagram showing a conventional vehicle-mounted device for ETC.

FIG. 11 is a perspective view showing a conventional vehicle-mounted device for ETC.

[Explanation of symbols]

1A-1E On-board unit, 2 IC card, 10, 10C-
10E CPU, 11 communication circuit, 12 antenna, 14
SAM, 15 power supply unit, 20 temperature detection means, 21
Heating element, Tc detection temperature, TR power transistor.

Claims (12)

[Claims] 1. An E mounted on a vehicle using a toll road
A vehicle-mounted TC device, a communication circuit for transmitting / receiving information to / from a roadside device, a CPU for reading and writing at least security information between a detachably mounted IC card, A communication circuit and a power supply unit for supplying power to the CPU, wherein the ETC on-vehicle device in which the upper surface of the communication circuit is covered with a shield cover, wherein a heat-generating unit is arranged in proximity to at least the circuit unit including the communication circuit. A vehicle-mounted device for ETC characterized by the following. 2. The on-vehicle ETC device according to claim 1, wherein said heat generating means is also configured by said power supply unit. 3. The ETC according to claim 1, wherein the heat generating means is also configured by a power transistor in the power supply unit, and the power transistor is disposed in close contact with a shield cover of the communication circuit. Onboard equipment. 4. A comprising a temperature detecting means for detecting a temperature of the circuit portion, wherein the CPU, when the detected temperature of the circuit portion is a predetermined low temperature condition is satisfied, characterized by raising the temperature driving said heat generating means The vehicle-mounted device for ETC according to any one of claims 1 to 3. 5. The vehicle-mounted ETC device according to claim 4, wherein said temperature detecting means is constituted by a thermistor arranged close to said circuit section. 6. The ET according to claim 4, wherein the CPU has a sleep function, and cancels the sleep function when the low-temperature condition is satisfied.
On-board unit for C. 7. The heating device according to claim 4, wherein the heating unit includes a heating element driven and controlled by the CPU, and the CPU drives the heating element when the low temperature condition is satisfied. 6. The vehicle-mounted device for ETC according to any one of 6 to 6. 8. The vehicle-mounted ETC device according to claim 7, wherein the temperature detecting means and the heating element are arranged in close contact with a shield cover of the communication circuit. 9. The ETC on-vehicle device according to claim 7, wherein the heating element is constituted by a resistance element having an on / off switch circuit. 10. The CPU according to claim 1, wherein the detected temperature immediately after power-on of the circuit unit is equal to or lower than a predetermined temperature, or when the rate of change of the detected temperature immediately after power-on of the circuit unit is equal to or higher than a predetermined value. The vehicle-mounted device for ETC according to any one of claims 4 to 9, wherein it is determined that the low temperature condition is satisfied. 11. The criterion for determining a low temperature condition corresponds to a dew temperature of the circuit section.
The vehicle-mounted device for ETC according to 0. 12. The E according to claim 4, wherein the criterion of the low-temperature condition corresponds to a lower limit temperature of a characteristic compensation range of the circuit section.
In-vehicle device for TC.