JP2014067156A - Drive recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive recorder capable of improving accuracy of determining the generation of recording trigger when a vehicle starts to move.SOLUTION: When the vehicle starts to move, a drive recorder 1 measures the number of pulses output from a speed sensor 15 for an arbitrary time, and when the speed obtained by this measurement is below the setting value previously set, the drive recorder 1 determines whether the acceleration speed detected by a G sensor 13 is below a first threshold value (S3). When the acceleration speed is above the first threshold value, the drive recorder 1 generates a recording trigger, and registers the data reading as "an announcement of an alert for a sudden start" in a memory card 17 (S5). Further, when the speed is above the setting value, the drive recorder 1 determines whether a speed difference between the speed of this time and the speed measured a few second before is below a second threshold value (S4), and when the speed difference is above the second threshold value, the drive recorder 1 registers the same data.

Description

  The present invention relates to a drive recorder that records image data when a recording trigger occurs.

  Conventionally, some drive recorders use speed information calculated based on a pulse signal from a speed sensor as a reference for determining the occurrence of a recording trigger. The speed sensor is attached to an axle or the like that transmits power to the tire, and outputs a pulse signal having a cycle corresponding to the rotation cycle of the tire.

  When calculating speed information using the speed sensor, the drive recorder calculates a speed based on the pulse after a predetermined number of pulses are input.

  As a prior art document of this type, Patent Document 1 may use acceleration information detected by an acceleration sensor when determining whether or not a recording trigger is generated in a drive recorder, or may use speed information acquired from a speed sensor. It has been shown that it may be used.

JP 2012-128694 A

  However, in the conventional drive recorder, when the vehicle suddenly starts from a stopped state, the speed is calculated without a predetermined number of pulses being input, and thus the calculated speed may not be an appropriate value.

  That is, when calculating the acceleration at the time of departure such as sudden start using a speed sensor, the number of pulses detected in a short time is small, and it is measured depending on the position of the axle that drives the stopped tire. The value of the number of pulses to be changed will change. Therefore, it is difficult to say that the speed value obtained from the number of pulses within a predetermined time immediately after departure is accurate.

  As described above, using the pulse signal from the speed sensor for the determination of the occurrence of the recording trigger at the time of departure has lowered the accuracy of the determination of the occurrence of the recording trigger.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a drive recorder capable of improving the accuracy of determination of occurrence of a recording trigger at the time of departure.

In order to achieve the above-described object, the drive recorder according to the present invention is characterized by the following (1) and (2).
(1) a speed signal receiving unit that receives the pulse signal from a speed sensor that outputs the pulse signal at intervals according to the rotation cycle of the tire of the vehicle;
An acceleration signal receiving unit for receiving a signal including acceleration information output from the acceleration sensor;
With
A drive recorder that records image data when a recording trigger occurs,
After the vehicle starts, the recording trigger is generated based on the signal received by the acceleration signal receiving unit from the acceleration sensor until the speed signal receiving unit receives a predetermined number of pulse signals from the speed sensor. Whether or not
After the speed signal receiving unit has received the predetermined number of pulse signals from the speed sensor, based on the pulse signal received from the speed sensor, determine whether the recording trigger has occurred,
about.
(2) A drive recorder configured as described in (1) above,
The predetermined number is a value that determines that the speed obtained from the number of pulse signals detected by the speed sensor at the time of departure is accurate.
about.

  According to the drive recorder having the above configuration (1) or (2), after the vehicle starts, until the drive recorder receives a predetermined number of pulse signals from the speed sensor, based on the signal received from the acceleration sensor, It is determined whether a recording trigger has occurred. On the other hand, after receiving a predetermined number of pulse signals from the speed sensor, the drive recorder determines whether a recording trigger has occurred based on the pulse signal received from the speed sensor.

  According to the present invention, after the vehicle has started, the drive recorder determines whether or not a recording trigger has occurred based on the signal received from the acceleration sensor until a predetermined number of pulse signals are received from the speed sensor. . On the other hand, after receiving a predetermined number of pulse signals from the speed sensor, the drive recorder determines whether a recording trigger has occurred based on the pulse signal received from the speed sensor. Thereby, the accuracy of the determination of the occurrence of the recording trigger at the time of departure can be improved.

  The present invention has been briefly described above. Further, the details of the present invention will be further clarified by reading through a mode for carrying out the invention described below (hereinafter referred to as “embodiment”) with reference to the accompanying drawings. .

FIG. 1 is a block diagram showing a configuration of a drive recorder 1 in the embodiment. FIG. 2A to FIG. 2C are diagrams for explaining the vehicle speed detection operation by the speed sensor 15. FIG. 3 is a flowchart showing an operation procedure of the drive recorder 1.

  A drive recorder according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a drive recorder 1 in the embodiment. The drive recorder 1 has a drive recorder main body 10 in which a known CPU, ROM, RAM, input / output interface (I / F) and the like are built in a casing.

  The drive recorder main body 10 is installed on a door sensor 11 that detects opening and closing of a door, a speaker 12 that emits a sound such as an alarm, and a windshield of a vehicle (not shown), and takes an image of the front of the vehicle. A camera 14 is connected.

  The drive recorder main body 10 is installed in a G sensor (acceleration sensor) 13 that detects the acceleration of the vehicle and senses an impact applied to the vehicle, an axle, etc., and outputs a pulse signal at intervals according to the rotation cycle of the tire. A speed sensor 15 that outputs and detects the speed of the vehicle is connected. Here, the G sensor 13 is built in the housing of the drive recorder main body 10.

  The drive recorder body 10 receives a GPS signal from a GPS satellite, detects a current position (latitude, longitude) and time of the vehicle, and an image taken by the camera 14 when a recording trigger occurs. A memory card 17 for recording such data is connected. The memory card 17 is detachably attached to the drive recorder main body 10.

  The input / output I / F built in the drive recorder body 10 includes a speed signal receiving unit that receives a pulse signal from the speed sensor 15 and an acceleration signal receiving unit that receives a signal including acceleration information output from the acceleration sensor 13. Is included.

  FIG. 2A to FIG. 2C are diagrams for explaining the vehicle speed detection operation by the speed sensor 15. As shown in FIG. 2A, a magnet 28 is attached to the outer periphery of the axle 25 that transmits power to the tire 30 of the vehicle. The speed sensor (vehicle speed sensor) 15 is attached to a position facing the axle 25 and includes a magnetoresistive element whose resistance value changes according to the strength of magnetism.

  Each time the tire 30 rotates and the magnet 28 attached to the axle 25 passes once in front of the speed sensor 15, the speed sensor 15 has a number of pulse signals corresponding to the number of magnets (for example, one or several). Is output.

  The location where the speed sensor 15 is provided is not limited to the axle 25. A magnet may be attached to a shaft that transmits torque to the tire 30, and a speed sensor may be provided so as to face the shaft. The speed sensor is not limited to one using a magnetoresistive element, and is not particularly limited as long as it can detect rotation, such as a transmission type or reflection type optical sensor.

  In the present embodiment, as shown in FIG. 2B, after the number of pulse signals output from the speed sensor 15 reaches a predetermined number (for example, value 20), a predetermined time (0.1 second, The speed signal is obtained from the number of pulse signals output from the speed sensor 15 per second). This predetermined number is set to a value that determines that the speed obtained from the number of pulse signals detected by the speed sensor at the time of departure is accurate.

  The recording trigger generation is determined from the speed difference between the speed obtained at the current time and the speed obtained a predetermined time ago, that is, the acceleration.

  Here, the speed is measured after a predetermined number of pulse signals are output for the following reason. That is, when starting from a stopped state of the tire, particularly in the case of sudden start, as shown in FIG. 2 (C), the number of pulses is small at the beginning and increases suddenly from the middle. Therefore, even if the number of pulses averaged over a predetermined time is measured, an accurate speed cannot be obtained. Also, the timing of outputting the first pulse signal varies depending on the positional relationship between the speed sensor and the magnet when the tire is stopped. Furthermore, since the determination of the occurrence of the recording trigger is made from the speed difference between the speed at the current time and the speed before a predetermined second, that is, the acceleration, it is difficult in terms of time to make the determination using the speed sensor at the start.

  Therefore, in this embodiment, it is not after the speed sensor has output a predetermined number (for example, a value of 20) of pulses, that is, after a slight start, it is determined whether or not a recording trigger is generated using the speed sensor. I didn't do it.

  The operation of the drive recorder 1 having the above configuration will be described. FIG. 3 is a flowchart showing an operation procedure of the drive recorder 1. This operation program is stored in the ROM in the drive recorder main body 10 and is executed by the CPU in the drive recorder main body 10.

  First, the drive recorder 1 determines whether or not the pulse signal is output from the speed sensor 15 and the vehicle is stopped (step S1). When the vehicle is stopped, the drive recorder 1 repeats the process of step S1.

  On the other hand, when the vehicle has started and the vehicle has not stopped, the drive recorder 1 measures the number of pulses output from the speed sensor 15 for an arbitrary time, and the speed obtained by this measurement is less than a preset set value. It is determined whether or not there is (step S2). If it is less than the set value, the number of pulses after the start has not reached the predetermined number, and the speed detected by the G sensor 13 is used instead of the speed measured by the speed sensor 15 when determining the occurrence of the recording trigger. Like that.

  That is, when the speed obtained by the measurement in step S2 is less than the set value, the drive recorder 1 determines whether or not the acceleration (G value) detected by the G sensor 13 is less than the first threshold ( Step S3). The first threshold is a value for determining whether or not to generate a recording trigger. If it is less than the first threshold, the drive recorder 1 returns to the process of step S1.

  On the other hand, if the acceleration is greater than or equal to the first threshold value in step S3, the drive recorder 1 generates a recording trigger and records “sudden start warning announcement” data in the memory card 17 (step S5). This “sudden start warning announcement” data indicates that a recording trigger due to a sudden start has occurred.

  Further, in the process of step S5, together with the recording of the sudden start warning announcement data, the image data photographed by the camera 14 is also recorded on the memory card 17 when the recording trigger is generated. At this time, the speaker 12 may pronounce a sudden start. Thereafter, the drive recorder 1 returns to the process of step S1.

  On the other hand, if the speed obtained by the measurement in step S2 is greater than or equal to the set value, the drive recorder 1 has a speed difference between the current speed and the previous speed measured a predetermined second before the second threshold value. It is discriminate | determined (step S4). This predetermined second can be arbitrarily set to 1 second, 5 seconds, or the like. This second threshold is a value for determining whether or not to generate a recording trigger.

  If the speed difference is less than the second threshold, the drive recorder 1 returns to the process of step S1. On the other hand, if the speed difference is greater than or equal to the second threshold value in step S4, the drive recorder 1 proceeds to the process of step S5. That is, as described above, the drive recorder 1 records the “sudden start warning announcement” data on the memory card 17.

  As described above, when the drive recorder departs from the vehicle, the number of pulse signals detected by the speed sensor is less than a predetermined number, that is, when the speed representing the number of pulses measured within an arbitrary time is less than a set value, Whether or not a recording trigger is generated is determined using the detected acceleration. This arbitrary time is set to a relatively long time such that a predetermined number or more of pulse signals can be obtained at the time of departure. When the number of pulse signals detected by the speed sensor reaches a predetermined number or more, the drive recorder determines whether or not a recording trigger has occurred at the speed detected by the speed sensor.

  Therefore, at the time of sudden start, even if the speed sensor does not obtain a speed difference until a predetermined number (for example, a value of 20) of pulse signals is detected and it is difficult to determine the occurrence of a recording trigger, Recording trigger generation can be accurately determined by measuring acceleration with an acceleration sensor. Thereby, it is possible to improve the accuracy of the determination of the occurrence of the recording trigger at the start. In addition, the user can be alerted more accurately. In addition, this alerting makes it possible for the user to be careful when driving, which can be useful for preventing accidents.

  The present invention is not limited to the configuration of the above-described embodiment, and any configuration that can achieve the function of the configuration of the present embodiment is applicable.

  For example, in the above embodiment, when the speed obtained from the number of pulses measured within an arbitrary time is less than the set value in step S2, the number of pulses after starting has not reached the predetermined number. It may be as follows. That is, the process of step S2 may be a process of simply determining whether or not the measured number of pulses has reached a predetermined number without considering the time. If the measured number is less than the predetermined number, the process of step S3 If the number is equal to or greater than the predetermined number, the process may proceed to step S4.

  Further, the acceleration sensor is not particularly limited, and may be a semiconductor type such as a piezoresistive element type or a capacitance type, or an optical type or a mechanical type.

  INDUSTRIAL APPLICATION When a recording trigger generate | occur | produces, when recording image data, this invention can improve the precision of the recording trigger generation | occurrence | production determination at the time of departure, and is useful.

DESCRIPTION OF SYMBOLS 1 Drive recorder 10 Drive recorder main body 11 Door sensor 12 Speaker 13 G sensor (acceleration sensor)
14 Camera 15 Speed sensor (vehicle speed sensor)
16 GPS receiver 17 Memory card

Claims (2)

A speed signal receiving unit that receives the pulse signal from a speed sensor that outputs a pulse signal at intervals according to a rotation cycle of a tire of the vehicle;
An acceleration signal receiving unit for receiving a signal including acceleration information output from the acceleration sensor;
With
A drive recorder that records image data when a recording trigger occurs,
After the vehicle starts, the recording trigger is generated based on the signal received by the acceleration signal receiving unit from the acceleration sensor until the speed signal receiving unit receives a predetermined number of pulse signals from the speed sensor. Whether or not
After the speed signal receiving unit has received the predetermined number of pulse signals from the speed sensor, based on the pulse signal received from the speed sensor, determine whether the recording trigger has occurred,
A drive recorder characterized by that. The predetermined number is a value that determines that the speed obtained from the number of pulse signals detected by the speed sensor at the time of departure is accurate.
The drive recorder according to claim 1.

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