JP2024024885A - Display device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a display of incorrect measurements even when a reference voltage input to an AD converter circuit drops.

SOLUTION: A display device M for a vehicle of the disclosure includes: a display part 4 that displays vehicle information; a stabilized power supply 1 that outputs reference power supply RV; an AD converter circuit 2 that AD-converts the reference power supply RV as a reference voltage V2; and a control part 3 that receives a digital signal D AD-converted by the AD converter circuit 2 and causes the display part 4 to display vehicle information measured based on the digital signal D. The stabilized power supply 1 outputs a flag signal PG to the control part 3, which outputs whether a voltage V2 of the reference power supply RV is equal to or higher than a specified value. When the control part 3 detects an abnormality in the reference power supply RV based on the flag signal PG, it determines that the digital signal D AD-converted by the AD converter circuit 2 is abnormal.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present disclosure relates to a technique for preventing incorrect measurement values from being displayed in a vehicle display device when a reference voltage of an AD (Analog to Digital) converter circuit drops.

The vehicle display device disclosed in Patent Document 1 calculates the remaining fuel amount by AD converting an analog signal output from a fuel sensor using an AD converter circuit, and displays this remaining fuel amount.

Japanese Patent Application Publication No. 10-122929

However, if the reference voltage input to the AD converter circuit drops, there is a problem that the input analog signal will be converted into an incorrect digital value.

The present disclosure solves the above-mentioned problems, and aims to provide a vehicle display device that prevents display of erroneous measured values even when the reference voltage input to the AD converter circuit drops. shall be.

The vehicle display device of the present disclosure includes:
a display section that displays vehicle information;
a stabilized power supply that outputs a reference power supply;
an AD converter circuit that performs AD conversion using the reference power source as a reference voltage;
a control unit to which a digital signal AD-converted by the AD converter circuit is input, and causes the display unit to display vehicle information measured based on the digital signal;
A vehicle display device comprising:
The stabilized power supply outputs a flag signal to the control unit that outputs whether the voltage of the reference power supply is equal to or higher than a specified value,
When detecting an abnormality in the reference power supply based on the flag signal, the control unit determines that the digital signal AD-converted by the AD converter circuit is abnormal.

According to the present disclosure, it is possible to provide a vehicle display device that prevents display of erroneous measured values even when the reference voltage input to the AD converter circuit drops.

FIG. 2 is an electrical configuration diagram of a vehicle display device.

(First embodiment)
The vehicle display device M is an instrument that displays vehicle information, and is built into the instrument panel of the vehicle. The vehicle information is, for example, information related to vehicle operation, such as vehicle running speed, engine rotation speed, battery voltage, remaining fuel amount, tire air pressure, and route guidance information.

The vehicle display device M includes a stabilized power source 1, an AD converter circuit 2, a control section 3, and a display section 4.

The stabilized power supply 1 is, for example, a DC stabilized power supply such as a switching power supply circuit. The stabilized power source 1 is supplied with battery power at a battery voltage V1 from a battery BAT mounted on the vehicle, transforms the battery power into a reference voltage V2, and outputs the voltage as a reference power RV. The battery voltage V1 varies depending on the deterioration of the battery and the state of charging, and is usually between 12V and 9V. The reference voltage V2 is 5V.

When the stabilized power source 1 transforms the input battery power source V1 and outputs it as a reference power source RV, the stabilized power source 1 sends a flag signal PG to the control unit 3 when the output voltage reaches a set voltage value (here, the reference voltage V2). It has a power good output function.

The power good output function outputs a HI signal or a LO signal. The power good output function outputs an LO signal as a flag signal PG when the output voltage is less than a set voltage value. The power good output function outputs a HI signal as a flag signal PG when the output voltage is equal to or higher than a set voltage value.

The AD converter circuit 2 is a circuit that converts an input analog signal A into a discrete digital signal D.

The first AD converter circuit 21 receives the power output from the battery BAT as an analog signal A1 via a voltage dividing circuit. The first AD converter circuit 21 converts the analog signal A1 into a digital signal D1 and outputs it to the control section 3.

The second AD converter circuit 22 receives an analog signal A2 related to the remaining fuel output from the remaining fuel sensor SEN. The second AD converter circuit 22 converts the analog signal A2 into a digital signal D2 and outputs it to the control section 3.

The control unit 3 is a control integrated circuit such as a microcontroller. The control unit 3 is supplied with power from a stabilized power source different from the stabilized power source 1 (not shown).

The display unit 4 is a liquid crystal display or an organic EL display that displays images. The control unit 4 is supplied with power from a stabilized power source different from the stabilized power source 1 (not shown).

Next, the control by which the control section 3 displays vehicle information on the display section 4 will be explained. Here, as an example, battery voltage and remaining fuel amount will be illustrated.

(Battery voltage display)
The control unit 3 determines that the digital signal D1 regarding the battery voltage inputted from the first AD converter circuit 21 while the flag signal PG is a HI signal is normal, and holds it as time series data Tv. This time series data Tv is a data group of five inputs most recently.

Regarding the digital signal D1 related to the battery voltage input from the first AD converter circuit 21 while the flag signal PG is the LO signal, the control unit 3 determines that the digital signal D1 AD-converted by the first AD converter circuit 21 is abnormal. It is determined that the data is not retained as time series data Tv and is discarded. That is, the control unit 3 excludes the digital signal D1 related to the battery voltage inputted from the first AD converter circuit 21 while the flag signal PG is the LO signal from the time series data Tv.

The control unit 3 causes the display unit 4 to display the battery voltage calculated based on the moving average value of the time series data Tv. This moving average may be a simple moving average or an exponential moving average.

In addition, if the time during which the flag signal PG is the LO signal is longer than a predetermined time (for example, 5 seconds), the control unit 3 stops displaying the battery voltage, and displays a failure in the battery voltage detection circuit on the display unit 4. Displays an error message indicating that this has occurred. If the time during which the flag signal PG is an LO signal is less than a predetermined time (for example, 5 seconds), the control unit 3 maintains the display of the battery voltage calculated based on the moving average value of the time series data Tv. be done.

Furthermore, when a predetermined period of time (for example, 5 seconds) has elapsed since the start of the error display and the time during which the flag signal PG is a HI signal has elapsed, the control unit 3 again displays the data based on the moving average value of the time series data Tv. The calculated battery voltage is displayed on the display unit 4.

(Display of remaining fuel amount)
The control unit 3 determines that the digital signal D2 regarding the remaining fuel inputted from the second AD converter circuit 22 while the flag signal PG is a HI signal is normal, and holds it as time series data Tf. This time series data Tf is a data group of the 10 most recently input data.

Regarding the digital signal D2 regarding the remaining fuel input from the second AD converter circuit 22 while the flag signal PG is the LO signal, the control unit 3 determines that the digital signal D2 AD-converted by the second AD converter circuit 22 is abnormal. It is determined that the data is not retained as time series data Tf and is discarded. That is, the control unit 3 excludes the digital signal D2 related to the remaining fuel inputted from the second AD converter circuit 22 while the flag signal PG is the LO signal from the time series data Tf.

The control unit 3 causes the display unit 4 to display the amount of remaining fuel calculated based on the moving average value of the time series data Tf. This moving average may be a simple moving average or an exponential moving average.

In addition, when the number of times that the digital signal D2 AD-converted by the second AD converter circuit 22 is determined to be abnormal is 10 or more times in a row, the control unit 3 causes the display unit 4 to display a malfunction in the remaining fuel amount detection circuit. Displays an error message indicating that this has occurred. In other words, the control unit 3 determines that there is a failure when the abnormal digital signal D2 is continuously input more than the maximum number of times held as the time series data Tf.

Furthermore, if the number of times that the digital signal D2 AD-converted by the second AD converter circuit 22 is determined to be normal after starting the error display is 10 or more times in a row, the control unit 3 displays the error display again in a time-series manner. The remaining fuel amount calculated based on the moving average value of the data Tf is displayed on the display section 4.

The above is the description regarding the first embodiment of the vehicle display device M of the present disclosure.

The vehicle display device M of the present disclosure includes:
a display section 4 that displays vehicle information;
a stabilized power supply 1 that outputs a reference power supply RV;
an AD converter circuit 2 that performs AD conversion on the reference power supply RV as a reference voltage V2;
This is a display device for a vehicle, comprising: a control unit 3 into which a digital signal D that has been AD converted by the AD converter circuit 2 is input, and causes the display unit 4 to display vehicle information measured based on the digital signal D. .
The stabilized power supply 1 outputs to the control unit 3 a flag signal PG that outputs whether the voltage V2 of the reference power supply RV is equal to or higher than a specified value,
When the control unit 3 detects an abnormality in the reference power supply RV based on the flag signal PG, it determines that the digital signal D AD-converted by the AD converter circuit 2 is abnormal.

With this configuration, even if the reference voltage RV input to the AD converter circuit 2 drops, it is possible to prevent incorrect measurement values from being displayed.

(Other embodiments)
The vehicle display device M of the present disclosure may be modified as follows.

Other sensors may be used instead of the remaining fuel sensor SEN. For example, it may be a sensor that detects vehicle speed or a sensor that detects tire air pressure. Alternatively, it may be a sensor that detects the operation state of an operation switch that controls a function of the vehicle.

It is preferable that the reference voltage V2 of the reference power supply RV supplied by the stabilized power supply 1 is higher than the operating voltage of the control unit 3. However, if the reference voltage V2 is equivalent to the operating voltage of the control section 3, the stabilized power supply 1 may supply power to the control section 3.

The display unit 4 is not limited to a display that displays images, but may be another display device. For example, it may be a pointer-type meter that includes a dial and a pointer that indicates the dial.

M...Vehicle display device 1...Stabilized power supply circuit 2...AD converter circuit 21...First AD converter circuit 22...Second AD converter circuit 3...Control section 4...Display section BAT...In-vehicle battery SEN...Sensor

Claims (3)

a display section that displays vehicle information;
a stabilized power supply that outputs a reference power supply;
an AD converter circuit that performs AD conversion using the reference power source as a reference voltage;
a control unit to which a digital signal AD-converted by the AD converter circuit is input, and causes the display unit to display vehicle information measured based on the digital signal;
A vehicle display device comprising:
The stabilized power supply outputs a flag signal to the control unit that outputs whether the voltage of the reference power supply is equal to or higher than a specified value,
When the control unit detects an abnormality in the reference power source based on the flag signal, the control unit determines that the digital signal AD-converted by the AD converter circuit is abnormal.
A vehicle display device characterized by: The control unit measures the vehicle information based on time series data composed of the plurality of digital signals input at different times,
The control unit excludes the digital signal while detecting an abnormality in the reference power source from the time series data.
The vehicle display device according to claim 1, characterized in that: The stabilized power source converts the power supplied from the vehicle battery into the reference power source and outputs the converted power.
The vehicle display device according to claim 2, characterized in that:

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