JPH04349588A - Automotive drive recorder - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving state storage device, and more particularly to a drive recorder for an automobile.

0002

BACKGROUND OF THE INVENTION Modern automobiles have largely adopted microcomputerized electronic control for engine systems, transmission systems, brake systems, suspension systems, etc., and this trend is expected to increase in the future. In such an environment, the safety of electronic control using microcomputers has been thoroughly studied, but when an accident occurs, it is currently difficult to clearly determine whether the cause is human or product-related. . This makes the user question the safety of the vehicle.

0003

[Problems to be Solved by the Invention] The purpose of the present invention is to store various data immediately before the occurrence of an accident and clarify the cause of the accident by analyzing the data, in order to eliminate the above-mentioned sense of distrust among car users. .

0004

[Means for Solving the Problems] The present invention stores data for a certain period of time in a RAM using a microcomputer, detects the occurrence of an accident, and stores the data in the RAM in a non-volatile memory (
The data is transferred to an EEPROM (EEPROM) and held there.

Even if the power from the battery disappears due to an accident, the drive recorder system can maintain its own power while data is transferred from the RAM to the EEPROM.

[0006]

[Operation] The microcomputer takes in necessary external data at a fixed sampling time interval Ts and sends the data to RA.
Write to M. The data stored in the RAM is data for a certain period of time To immediately before the accident, which is necessary to estimate the cause of the accident, and the RAM capacity is as follows, where the number of data is Di.

0
007]

[Math 1]

[0008] That is, the data is stored in the RAM while being updated at intervals of Ts, and the data in the entire RAM is always To.

[0009] When the microcomputer detects the occurrence of an accident, it stops writing data to the RAM, and the data has already been written to the RAM.
The data stored in is transferred to the EEPROM, and the data for the time To immediately before the accident is held in non-volatile memory.

That is, the number of rewrites that can be guaranteed to retain the internal data of the EEPROM is limited to about tens of thousands of times, and therefore, if rewriting is performed at the sample time Ts, the guaranteed number of rewrites is significantly exceeded. Therefore, the sample time Ts
Rewriting is performed in RAM, and in the event of an accident, the RAM data is rewritten to EEPROM.

Even if the power from the battery disappears due to an accident, the drive recorder system battery serves as the operating power during the transfer time from the RAM to the EEPROM, ensuring the operation of the microcomputer.

0012

Embodiment FIG. 1 shows an embodiment of the present invention. The microcomputer 1 has a RAM 2 and an EEPROM 3, and an input signal processing circuit 4 and an accident detection processing device 5 are input thereto. Microcomputer 1, RAM 2 and EEPR
OM3 is supplied with a power supply voltage from the vehicle battery voltage VB by a constant voltage circuit 6. By the way, the battery voltage V
When B disappears, the voltage charged in capacitor C by the voltage division between resistors R1 and R2 is discharged by resistor R2, but during the period when the voltage is higher than the voltage of battery 7, comparator 8
is output, transistor 9 is turned on, and power is supplied to the system. It has a charging circuit 10 as a countermeasure against voltage consumption of the battery 7,
Charging is performed by the vehicle battery. Vehicle key SW
At the same time that the microcomputer 1 turns on, the microcomputer 1 performs a processing operation according to the flowchart shown in FIG. One word of input data DATA1 obtained from the input signal processing circuit 4 from the RAM address ADRS at the first sampling time
~Write 5 digits of DATA5. And address AD
Increase R by 5, and if no accident is detected, input 5 input data D from the address increased by 5 at the next sample time.
Write ATA1 to DATA5. By repeating this, 5
When the final address ADRE becomes an integer multiple of
Input data DA with DR as start address ADRS
Input data is written to RAM2 while rewriting TA1 to DATA5. FIG. 3 shows the state of input data written to RAM2.

When the accident signal is input from the detection processing circuit 5 to the microcomputer 1, data writing to the RAM 2 shown in FIG. 2 is stopped and the contents of the RAM 2 are transferred to the EEPROM. Recorded time before the accident occurred

[0014]

[Math 2]

[0015] The behavior of the input data during that time can be known.

By the way, when the G waveform of the impact at the time of a collision is input as an accident signal, even if the data in the RAM is once transferred to the EEPROM due to a malfunction, if the capacity of the EEPROM is divided as shown in FIG. It is possible to record the number of times from N=1 to N=NEND depending on the accident signal, including malfunctions. With this method, if a vehicle speed of 0 is determined as an accident signal, a record of the accident can be maintained even if the vehicle speed becomes 0 due to an accident and the vehicle subsequently moves on its own.

[0017] A plurality of input signals to be recorded are selected from which the driving state of the automobile, the engine state, the fuel supply state, and the brake state can be determined. This selection depends on the cost of the drive recorder system, and it is decided whether to adopt it or not based on differentiation.

According to one embodiment of the present invention, data for a certain period of time is continuously recorded in the RAM which has no limit on the number of times it can be rewritten, and is written to the EEPROM only when an accident occurs.
This has the effect of not being affected by ROM rewriting restrictions.

Furthermore, even if the on-vehicle battery voltage disappears when an accident occurs, data in the RAM can be reliably transferred to the EEPROM.

Furthermore, even if the accident occurrence signal malfunctions, data can be recorded in the EEPROM multiple times, which has the effect of ensuring reliable recording in the event of an accident.

[0021]

According to the present invention, data can be reliably recorded in an EEPROM without being limited by the number of rewrites.

[0022] Even if the on-vehicle battery voltage disappears due to an accident, the transfer from the RAM to the EEPROM can be ensured.

[0023] Running condition, engine condition, brake condition,
Accident conditions can be identified by recording data on fuel supply conditions.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart.

FIG. 3 is a diagram showing a recording state of a memory.

FIG. 4 is a diagram showing a recording state of a memory.

[Explanation of symbols]

1...Microcomputer, 2...RAM, 3...EEPR
OM, 7...Battery.

Claims (5)

[Claims] Claim 1: A drive recorder for recording driving conditions at the time of an automobile accident, comprising: a microcomputer, a volatile memory, a non-volatile memory, an input signal for recorded data, a processing means for the input signal, and an input signal for detecting the occurrence of an accident. and a processing means for the input signal, and a power supply means that enables the microcomputer to operate even if the onboard battery is lost, the volatile memory continuously records the input signal at a fixed sampling interval, and the volatile memory continuously records the input signal at a fixed sampling interval. A drive recorder for an automobile, characterized in that the data recorded in the volatile memory is transferred to the non-volatile memory by detecting a signal from an accident detection means. 2. In claim 1, the volatile memory is R
AM, an automobile drive recorder characterized in that the nonvolatile memory is an EEPROM. 3. In claim 1, the power supply means converts the RAM to the EEPROM after the in-vehicle battery is exhausted.
1. A drive recorder for an automobile comprising a voltage output circuit that enables a microcomputer to operate only during the transfer time to the vehicle, and then self-disappearing. 4. A drive recorder for an automobile according to claim 1, wherein said voltage output circuit comprises a storage battery, charging means for the storage battery, delay means for output voltage, and switch means for turning on and off the output voltage. 5. A drive recorder for a motor vehicle according to claim 1, wherein said input signal for recording data comprises signals of a running state, an engine state, a transmission state, a brake state, and a fuel supply state of the motor vehicle.