JP2016115988A - Transmitter - Google Patents

Abstract

There is provided a transmission device capable of outputting a transmission signal having a pulse width in compliance with a communication standard even in an environment with a large temperature change. A transmission apparatus 10 that transmits a pulsed transmission signal in a communication standard in which a pulse width allowable range is defined, and a UART unit 214 that generates a pulsed data signal based on information to be transmitted. And a logical sum of a PWM unit 215 that generates a periodic pulse signal having a duty ratio with a pulse width determined based on a communication standard, a data signal generated by the UART unit 214, and a periodic pulse signal generated by the PWM unit 215. , An AND circuit 22 that generates an output signal having a pulse width that falls within the allowable pulse width range, and a transmission unit 30 that outputs a transmission signal based on the output signal generated by the AND circuit 22. [Selection] Figure 2

Description

  The present invention relates to a transmission apparatus, and more particularly to a technique for outputting a signal with a pulse width conforming to a standard.

  A technique for converting a pulse width of a pulse signal into a narrow pulse width to obtain a transmission signal is known. For example, in Patent Document 1, an input pulse signal having a duty ratio of 50% is converted into a narrow pulse signal having a duty ratio of 3/16, and used as a drive signal for driving an infrared communication LED. Since the LED is driven by this drive signal, the transmission signal output by the LED has a narrow pulse width, like the drive signal.

  In the technique disclosed in Patent Document 1, an operation amplifier is configured by connecting bipolar transistors in multiple stages, and the pulse width is converted by operating the bipolar transistor with a charging voltage of a capacitor.

JP 2005-303091 A

  For pulsed transmission signals, the allowable range of the pulse width may be defined by the communication standard. In the configuration in which the pulse width is converted by a differential amplifier configured by connecting bipolar transistors in multiple stages, the pulse width varies depending on the temperature due to the temperature dependence of the bipolar transistor. Therefore, if the technique of Patent Document 1 is applied to a transmission device that outputs a pulsed transmission signal in accordance with a communication standard in which a pulse width allowable range is defined, there is a possibility that the communication standard cannot be observed. In particular, when the transmission device is mounted on a vehicle, since the temperature change of the transmission device is severe, there is a high possibility that the communication standard cannot be observed.

  The present invention has been made based on this situation, and an object of the present invention is to provide a transmission device capable of outputting a transmission signal having a pulse width in compliance with a communication standard even in an environment where a temperature change is large. is there.

  The above object is achieved by a combination of the features described in the independent claims, and the subclaims define further advantageous embodiments of the invention. Reference numerals in parentheses described in the claims indicate a correspondence relationship with specific means described in the embodiments described later as one aspect, and do not limit the technical scope of the present invention. .

  In order to achieve the above object, the present invention provides a transmission device for transmitting a pulsed transmission signal in a communication standard in which a pulse width allowable range is defined, and a pulsed data signal based on information to be transmitted A data signal generation unit (214) that generates a periodic pulse signal (215) that generates a periodic pulse signal having a duty ratio with a pulse width determined based on a communication standard, and a data signal generated by the data signal generation unit An output signal generator (22) that performs a logical operation on the periodic pulse signal generated by the periodic pulse generator and generates an output signal having a pulse width that falls within the allowable pulse width range, and an output signal generated by the output signal generator And a transmission unit (30) for outputting a transmission signal.

  According to the present invention, an output signal is generated by performing a logical operation on the data signal and the periodic pulse signal. Since the logical operation time is less affected by temperature, the output signal is less affected by temperature. Since a pulsed transmission signal is output based on this output signal, a transmission signal complying with the communication standard can be output even in an environment where the temperature change is large.

It is a figure explaining the state in which the transmitter 10 of embodiment is mounted in the fuel cell vehicle 1. FIG. It is a block diagram which shows the structure of the transmitter 10 of FIG. It is an example of the data signal which the UART part 214 outputs. It is an example of the periodic pulse signal which the PWM part 215 produced | generated. 3 is an example of an output signal output from an AND circuit 22; 2 is a detailed configuration example of an AND circuit 22;

<Outline of configuration>
Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the transmission device 10 of the embodiment is mounted on a fuel cell vehicle 1 and includes an ECU 20 and a transmission unit 30. When the hydrogen tank 1t mounted on the fuel cell vehicle 1 is filled with hydrogen, the transmission device 10 transmits the gas state in the hydrogen tank 1t to the receiving unit 2r provided in the hydrogen filling nozzle 2. . Specifically, the gas state is temperature and pressure.

  The ECU 20 acquires the state from the state detection unit 1s that detects the state of the gas in the hydrogen tank 1t, and generates an output signal that is determined based on the acquired state. Then, the output signal is output to the transmission unit 30. Based on the output signal, the transmission unit 30 outputs a transmission signal that is light including infrared light and is pulsed.

  The transmission signal needs to be transmitted according to the standard defined in the communication standard SAEJ2799. In this communication standard, a baud rate, a pulse width, a pulse time allowable range, that is, a pulse width allowable range, a rise time upper limit value, a fall time upper limit value, and the like are defined. Specifically, the baud rate is 38400 bps, the pulse width is 3/16 bit width, the allowable pulse time range is 1.41 μs to 5.48 μs, the upper limit value of the rise time, and the upper limit value of the fall time are both 600 ns. . The pulse time is a time that exceeds 50% of the peak value, the rise time is the time until the signal intensity becomes 10% to 90% of the peak value, and the fall time is the signal intensity. This is the time from 90% to 10% of the peak value.

<Detailed Configuration of ECU 20>
As shown in FIG. 2, the ECU 20 includes an MCU 21, an AND circuit 22, and a resistor 23. The MCU 21 is a microcomputer including a CPU 211, a memory 212, a clock signal generation unit 213, a UART (Universal Asynchronous Receiver Transmitter) 214, a PWM (Pulse Width Modulation) unit 215, and the like.

  The memory 212 stores a program executed by the CPU 211. The CPU 211 executes a program stored in the memory 212, thereby generating bit data to be output to the UART unit 214, controlling the UART unit 214, and controlling the PWM unit 215. Bit data is data representing the state of the gas in the hydrogen tank 1t acquired from the state detection unit 1s.

  The clock signal generation unit 213 has a known configuration that generates a clock signal based on the signal generated by the crystal oscillator. The clock signal corresponds to the reference signal in the claims, and the clock signal generation unit 213 corresponds to the reference signal generation unit in the claims.

  The UART unit 214 is the same as a well-known UART widely provided in microcomputers, and is a circuit that serially transfers input data as a data signal that is a pulsed electric signal. Since the bit data is input to the UART unit 214, the data signal is a signal representing the state of gas in the hydrogen tank 1t. The state of the gas in the hydrogen tank 1t is information to be transmitted, and this UART unit 214 corresponds to a data signal generation unit in claims.

  FIG. 3 shows an example of a data signal output from the UART unit 214. The UART unit 214 determines the rising point and falling point of the data signal pulse based on the clock signal supplied from the clock signal generation unit 213. When these rise time and fall time are determined, the pulse width time is determined. One pulse of the data signal generated by the UART unit 214 is one bit.

  The PWM unit 215 is the same as a well-known PWM unit widely provided in microcomputers, and is a circuit that generates a periodic pulse signal having a duty ratio instructed to the CPU 211 by being controlled by the CPU 211. This periodic pulse signal is generated based on the clock signal as in the UART unit 214. Therefore, the rising point of the periodic pulse signal is also determined by the clock signal.

  The PWM unit 215 of the present embodiment corresponds to the periodic pulse generation unit of the claims, and generates a periodic pulse signal having a duty ratio with a pulse width determined based on the communication standard described above. For example, when the pulse width is 3/16 bits and the baud rate is 38400 bps, a periodic pulse signal having a time of 3/16 bits of unit bits determined by the baud rate is generated. FIG. 4 illustrates a periodic pulse signal generated by the PWM unit 215.

  The AND circuit 22 is a well-known logic circuit, and is one logic element configured with a CMOS circuit. FIG. 6 illustrates a detailed configuration of the AND circuit 22. Since this detailed configuration is well known, description of the operation is omitted.

  The AND circuit 22 receives the data signal generated by the UART unit 214 and the periodic pulse signal generated by the PWM unit 215. Therefore, the output signal is a pulse-like signal that is at a high level during a period in which both the data signal and the periodic pulse signal are at a high level. Since the pulse width of the periodic pulse signal is 3/16 bits, the pulse width of the output signal is also 3/16 bits. FIG. 5 shows an example of the output signal. The output signal is a signal that becomes high level during a period of 3/16 bits out of the period when the data signal is high level. This output signal is output to the transmission unit 30 via the resistor 23. The AND circuit 22 corresponds to an output signal generation unit in claims.

<Detailed Configuration of Transmitter 30>
The transmission unit 30 includes a resistor 31, a light emitting diode 32, a MOSFET 33, and a resistor 34. The resistor 31 has one end connected to the power source 40 and the other end connected to the anode terminal of the light emitting diode 32.

  The light emitting diode 32 is an element that emits light including infrared light, and the cathode terminal is connected to the drain terminal of the MOSFET 33. The MOSFET 33 is of an n-channel type and an enhancement type, the gate terminal is connected to one end of the resistor 34, and the source terminal is connected to the ground. The other end of the resistor 34 is connected to one end of a resistor 23 provided in the ECU 20.

  When the output signal input to the gate terminal of the MOSFET 33 is at a high level, the MOSFET 33 is turned on. Therefore, when the output signal is at a high level, the light emitting diode 32 emits light. Therefore, the light emitted from the light emitting diode 32 is also pulsed. The light emitted from the light emitting diode 32 corresponds to the transmission signal in the claims, and this light is received by the receiving unit 2 r provided in the hydrogen filling nozzle 2.

<Effect of embodiment>
According to this embodiment, a data signal generated based on the state of the gas in the hydrogen tank 1t, which is information to be transmitted, and a periodic pulse signal with a duty ratio having a pulse width determined based on the communication standard are ANDed. The circuit 22 performs an AND operation to generate an output signal. Since the calculation time in the AND circuit 22 is not easily affected by temperature change, the output signal is not easily affected by temperature. The MOSFET 33 is driven by this output signal, and the light emitting diode 32 emits light in conjunction with the turning on of the MOSFET 33. Therefore, the pulse width of the light emitted from the light emitting diode 32 is set to a pulse width complying with the communication standard even in an environment with a large temperature change. It can be.

  Further, the output signal is less likely to fluctuate due to the temperature even in an environment where the temperature change is large, and this output signal is a drive signal for driving the MOSFET 33. Therefore, the light output from the light emitting diode 32 controlled by the MOSFET 33, that is, the rise time and fall time of the transmission signal can comply with the communication standard even in an environment where the temperature change is large.

  In this embodiment, since the UART unit 214 and the PWM unit 215 generate the data signal and the periodic pulse signal based on the clock signal generated by the same clock signal generation unit 213, the data signal and the periodic pulse signal are generated. Are synchronized with each other. Therefore, it is possible to suppress the output signal from deviating from the pulse width of the periodic pulse signal due to the difference between the rising edge of the pulse of the data signal and the rising edge of the periodic pulse signal. For this reason, it is possible to further suppress the light emitted from the light emitting diode 32 having a pulse shape corresponding to the output signal from deviating from the communication standard.

  The AND circuit 22 is formed of a CMOS circuit, and the MOSFET is less susceptible to temperature than the bipolar transistor. Therefore, by making the AND circuit 22 a CMOS circuit, the pulse width is less likely to fluctuate even in an environment where the temperature change is large.

  Further, the MOSFET 33 is also used as an element for controlling on / off of the light emitting diode 32. Since the MOSFET has a small characteristic change due to temperature change, the light emitted from the light emitting diode 32 also deviates from the communication standard. Can be suppressed more.

  In this embodiment, the output signal is generated by the clock signal generation unit 213, the UART unit 214, the PWM unit 215, and the AND circuit 22, and among them, the clock signal generation unit 213, the UART unit 214, and the PWM unit. The MCU 21 includes the MCU 21. The clock signal generation unit 213, the UART unit 214, and the PWM unit 215 are functions that the MCU 21 generally includes. Therefore, a general-purpose and inexpensive MCU can be used.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the above-mentioned embodiment, The following modification is also contained in the technical scope of this invention, Furthermore, the summary other than the following is also included. Various modifications can be made without departing from the scope.

<Modification 1>
For example, in the above-described embodiment, the AND circuit 22 is provided as the logic circuit, and the AND circuit 22 calculates the logical sum of the data signal and the periodic pulse signal to generate the output signal. However, the NAND circuit is used as the logic circuit. It may be used. When a NAND circuit is used instead of the AND circuit 22, the PWM unit 215 generates a periodic pulse signal in which the high level and the low level in FIG. 4 are switched and inputs the periodic pulse signal to the NAND circuit.

<Modification 2>
Instead of providing a logic circuit such as the AND circuit 22, the CPU 211 executes a logic operation program stored in the memory 212, performs a logic operation of the data signal and the periodic pulse signal in software, and outputs an output signal. May be generated. In this case, the data signal generation unit and the periodic pulse generation unit may be configured by software.

<Modifications 3 to 5>
Further, the clock signal generation unit 213 may be arranged outside the MCU 21 (Modification 3). Further, a logic circuit such as the AND circuit 22 may be configured by an element other than a CMOS (Modification 4). Further, the element for controlling on / off of the light emitting diode 32 may be an element other than the MOSFET, for example, a bipolar transistor (Modification 5).

DESCRIPTION OF SYMBOLS 1: Fuel cell vehicle, 1s: State detection part, 1t: Hydrogen tank, 2: Hydrogen filling nozzle, 2r: Reception part, 10: Transmission apparatus, 20: ECU, 22: AND circuit, 23: Resistance, 30: Transmission part , 31: resistor, 32: light emitting diode, 33: MOSFET, 34: resistor, 40: power supply, 211: CPU, 212: memory, 213: clock signal generation unit, 214: UART unit, 215: PWM unit

Claims (6)

A transmission device that transmits a pulsed transmission signal in a communication standard in which a pulse width allowable range is defined,
A data signal generator (214) that generates a pulsed data signal based on information to be transmitted;
A periodic pulse generator (215) for generating a periodic pulse signal having a duty ratio with a pulse width determined based on the communication standard;
Output signal generation for logically operating the data signal generated by the data signal generation unit and the periodic pulse signal generated by the periodic pulse generation unit to generate an output signal having a pulse width that falls within the allowable pulse width range Part (22);
A transmission apparatus comprising: a transmission unit (30) that outputs the transmission signal based on the output signal generated by the output signal generation unit. In claim 1,
A reference signal generation unit (213) for generating a reference signal;
The data signal generation unit determines a rising point of the data signal based on the reference signal generated by the reference signal generation unit,
The transmission apparatus according to claim 1, wherein the periodic pulse generator determines a rising point of the periodic pulse signal based on the reference signal generated by the reference signal generator. In claim 2,
A microcomputer (21),
The transmission apparatus, wherein the microcomputer includes the reference signal generation unit, the data signal generation unit, and the output signal generation unit. In any one of Claims 1-3,
The transmission apparatus according to claim 1, wherein the output signal generation unit includes a CMOS.   The transmission apparatus according to claim 1, wherein the transmission apparatus is mounted on a vehicle. In any one of Claims 1-5,
The transmitter includes a light emitting diode (32) and a MOSFET (33) for controlling on / off of the light emitting diode,
The MOSFET is controlled to be turned on / off based on the output signal.

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